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authoranastasy888 <anastasy888@yandex-team.ru>2022-02-10 16:45:54 +0300
committerDaniil Cherednik <dcherednik@yandex-team.ru>2022-02-10 16:45:54 +0300
commit49f765d71da452ea93138a25559dfa68dd76c7f3 (patch)
tree1016041feb637349e401dcc0fa85217dd2c2c639 /contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h
parent7353a3fdea9c67c256980c00a2b3b67f09b23a27 (diff)
downloadydb-49f765d71da452ea93138a25559dfa68dd76c7f3.tar.gz
Restoring authorship annotation for <anastasy888@yandex-team.ru>. Commit 1 of 2.
Diffstat (limited to 'contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h')
-rw-r--r--contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h1910
1 files changed, 955 insertions, 955 deletions
diff --git a/contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h b/contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h
index 0762a852df..23ba954b1f 100644
--- a/contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h
+++ b/contrib/restricted/abseil-cpp-tstring/y_absl/synchronization/mutex.h
@@ -1,67 +1,67 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// -----------------------------------------------------------------------------
-// mutex.h
-// -----------------------------------------------------------------------------
-//
-// This header file defines a `Mutex` -- a mutually exclusive lock -- and the
-// most common type of synchronization primitive for facilitating locks on
-// shared resources. A mutex is used to prevent multiple threads from accessing
-// and/or writing to a shared resource concurrently.
-//
-// Unlike a `std::mutex`, the Abseil `Mutex` provides the following additional
-// features:
-// * Conditional predicates intrinsic to the `Mutex` object
-// * Shared/reader locks, in addition to standard exclusive/writer locks
-// * Deadlock detection and debug support.
-//
-// The following helper classes are also defined within this file:
-//
-// MutexLock - An RAII wrapper to acquire and release a `Mutex` for exclusive/
-// write access within the current scope.
-//
-// ReaderMutexLock
-// - An RAII wrapper to acquire and release a `Mutex` for shared/read
-// access within the current scope.
-//
-// WriterMutexLock
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// mutex.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines a `Mutex` -- a mutually exclusive lock -- and the
+// most common type of synchronization primitive for facilitating locks on
+// shared resources. A mutex is used to prevent multiple threads from accessing
+// and/or writing to a shared resource concurrently.
+//
+// Unlike a `std::mutex`, the Abseil `Mutex` provides the following additional
+// features:
+// * Conditional predicates intrinsic to the `Mutex` object
+// * Shared/reader locks, in addition to standard exclusive/writer locks
+// * Deadlock detection and debug support.
+//
+// The following helper classes are also defined within this file:
+//
+// MutexLock - An RAII wrapper to acquire and release a `Mutex` for exclusive/
+// write access within the current scope.
+//
+// ReaderMutexLock
+// - An RAII wrapper to acquire and release a `Mutex` for shared/read
+// access within the current scope.
+//
+// WriterMutexLock
// - Effectively an alias for `MutexLock` above, designed for use in
// distinguishing reader and writer locks within code.
-//
-// In addition to simple mutex locks, this file also defines ways to perform
-// locking under certain conditions.
-//
+//
+// In addition to simple mutex locks, this file also defines ways to perform
+// locking under certain conditions.
+//
// Condition - (Preferred) Used to wait for a particular predicate that
// depends on state protected by the `Mutex` to become true.
// CondVar - A lower-level variant of `Condition` that relies on
// application code to explicitly signal the `CondVar` when
// a condition has been met.
-//
-// See below for more information on using `Condition` or `CondVar`.
-//
-// Mutexes and mutex behavior can be quite complicated. The information within
-// this header file is limited, as a result. Please consult the Mutex guide for
-// more complete information and examples.
-
-#ifndef ABSL_SYNCHRONIZATION_MUTEX_H_
-#define ABSL_SYNCHRONIZATION_MUTEX_H_
-
-#include <atomic>
-#include <cstdint>
+//
+// See below for more information on using `Condition` or `CondVar`.
+//
+// Mutexes and mutex behavior can be quite complicated. The information within
+// this header file is limited, as a result. Please consult the Mutex guide for
+// more complete information and examples.
+
+#ifndef ABSL_SYNCHRONIZATION_MUTEX_H_
+#define ABSL_SYNCHRONIZATION_MUTEX_H_
+
+#include <atomic>
+#include <cstdint>
#include <util/generic/string.h>
-
+
#include "y_absl/base/const_init.h"
#include "y_absl/base/internal/identity.h"
#include "y_absl/base/internal/low_level_alloc.h"
@@ -72,460 +72,460 @@
#include "y_absl/synchronization/internal/kernel_timeout.h"
#include "y_absl/synchronization/internal/per_thread_sem.h"
#include "y_absl/time/time.h"
-
+
namespace y_absl {
ABSL_NAMESPACE_BEGIN
-
-class Condition;
-struct SynchWaitParams;
-
-// -----------------------------------------------------------------------------
-// Mutex
-// -----------------------------------------------------------------------------
-//
-// A `Mutex` is a non-reentrant (aka non-recursive) Mutually Exclusive lock
-// on some resource, typically a variable or data structure with associated
-// invariants. Proper usage of mutexes prevents concurrent access by different
-// threads to the same resource.
-//
-// A `Mutex` has two basic operations: `Mutex::Lock()` and `Mutex::Unlock()`.
-// The `Lock()` operation *acquires* a `Mutex` (in a state known as an
-// *exclusive* -- or write -- lock), while the `Unlock()` operation *releases* a
-// Mutex. During the span of time between the Lock() and Unlock() operations,
-// a mutex is said to be *held*. By design all mutexes support exclusive/write
-// locks, as this is the most common way to use a mutex.
-//
-// The `Mutex` state machine for basic lock/unlock operations is quite simple:
-//
-// | | Lock() | Unlock() |
-// |----------------+------------+----------|
-// | Free | Exclusive | invalid |
-// | Exclusive | blocks | Free |
-//
-// Attempts to `Unlock()` must originate from the thread that performed the
-// corresponding `Lock()` operation.
-//
-// An "invalid" operation is disallowed by the API. The `Mutex` implementation
-// is allowed to do anything on an invalid call, including but not limited to
-// crashing with a useful error message, silently succeeding, or corrupting
-// data structures. In debug mode, the implementation attempts to crash with a
-// useful error message.
-//
-// `Mutex` is not guaranteed to be "fair" in prioritizing waiting threads; it
-// is, however, approximately fair over long periods, and starvation-free for
-// threads at the same priority.
-//
-// The lock/unlock primitives are now annotated with lock annotations
-// defined in (base/thread_annotations.h). When writing multi-threaded code,
-// you should use lock annotations whenever possible to document your lock
-// synchronization policy. Besides acting as documentation, these annotations
-// also help compilers or static analysis tools to identify and warn about
-// issues that could potentially result in race conditions and deadlocks.
-//
-// For more information about the lock annotations, please see
-// [Thread Safety Analysis](http://clang.llvm.org/docs/ThreadSafetyAnalysis.html)
-// in the Clang documentation.
-//
-// See also `MutexLock`, below, for scoped `Mutex` acquisition.
-
-class ABSL_LOCKABLE Mutex {
- public:
- // Creates a `Mutex` that is not held by anyone. This constructor is
- // typically used for Mutexes allocated on the heap or the stack.
- //
- // To create `Mutex` instances with static storage duration
- // (e.g. a namespace-scoped or global variable), see
+
+class Condition;
+struct SynchWaitParams;
+
+// -----------------------------------------------------------------------------
+// Mutex
+// -----------------------------------------------------------------------------
+//
+// A `Mutex` is a non-reentrant (aka non-recursive) Mutually Exclusive lock
+// on some resource, typically a variable or data structure with associated
+// invariants. Proper usage of mutexes prevents concurrent access by different
+// threads to the same resource.
+//
+// A `Mutex` has two basic operations: `Mutex::Lock()` and `Mutex::Unlock()`.
+// The `Lock()` operation *acquires* a `Mutex` (in a state known as an
+// *exclusive* -- or write -- lock), while the `Unlock()` operation *releases* a
+// Mutex. During the span of time between the Lock() and Unlock() operations,
+// a mutex is said to be *held*. By design all mutexes support exclusive/write
+// locks, as this is the most common way to use a mutex.
+//
+// The `Mutex` state machine for basic lock/unlock operations is quite simple:
+//
+// | | Lock() | Unlock() |
+// |----------------+------------+----------|
+// | Free | Exclusive | invalid |
+// | Exclusive | blocks | Free |
+//
+// Attempts to `Unlock()` must originate from the thread that performed the
+// corresponding `Lock()` operation.
+//
+// An "invalid" operation is disallowed by the API. The `Mutex` implementation
+// is allowed to do anything on an invalid call, including but not limited to
+// crashing with a useful error message, silently succeeding, or corrupting
+// data structures. In debug mode, the implementation attempts to crash with a
+// useful error message.
+//
+// `Mutex` is not guaranteed to be "fair" in prioritizing waiting threads; it
+// is, however, approximately fair over long periods, and starvation-free for
+// threads at the same priority.
+//
+// The lock/unlock primitives are now annotated with lock annotations
+// defined in (base/thread_annotations.h). When writing multi-threaded code,
+// you should use lock annotations whenever possible to document your lock
+// synchronization policy. Besides acting as documentation, these annotations
+// also help compilers or static analysis tools to identify and warn about
+// issues that could potentially result in race conditions and deadlocks.
+//
+// For more information about the lock annotations, please see
+// [Thread Safety Analysis](http://clang.llvm.org/docs/ThreadSafetyAnalysis.html)
+// in the Clang documentation.
+//
+// See also `MutexLock`, below, for scoped `Mutex` acquisition.
+
+class ABSL_LOCKABLE Mutex {
+ public:
+ // Creates a `Mutex` that is not held by anyone. This constructor is
+ // typically used for Mutexes allocated on the heap or the stack.
+ //
+ // To create `Mutex` instances with static storage duration
+ // (e.g. a namespace-scoped or global variable), see
// `Mutex::Mutex(y_absl::kConstInit)` below instead.
- Mutex();
-
- // Creates a mutex with static storage duration. A global variable
- // constructed this way avoids the lifetime issues that can occur on program
+ Mutex();
+
+ // Creates a mutex with static storage duration. A global variable
+ // constructed this way avoids the lifetime issues that can occur on program
// startup and shutdown. (See y_absl/base/const_init.h.)
- //
- // For Mutexes allocated on the heap and stack, instead use the default
- // constructor, which can interact more fully with the thread sanitizer.
- //
- // Example usage:
- // namespace foo {
+ //
+ // For Mutexes allocated on the heap and stack, instead use the default
+ // constructor, which can interact more fully with the thread sanitizer.
+ //
+ // Example usage:
+ // namespace foo {
// ABSL_CONST_INIT y_absl::Mutex mu(y_absl::kConstInit);
- // }
+ // }
explicit constexpr Mutex(y_absl::ConstInitType);
-
- ~Mutex();
-
- // Mutex::Lock()
- //
- // Blocks the calling thread, if necessary, until this `Mutex` is free, and
- // then acquires it exclusively. (This lock is also known as a "write lock.")
- void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION();
-
- // Mutex::Unlock()
- //
- // Releases this `Mutex` and returns it from the exclusive/write state to the
+
+ ~Mutex();
+
+ // Mutex::Lock()
+ //
+ // Blocks the calling thread, if necessary, until this `Mutex` is free, and
+ // then acquires it exclusively. (This lock is also known as a "write lock.")
+ void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION();
+
+ // Mutex::Unlock()
+ //
+ // Releases this `Mutex` and returns it from the exclusive/write state to the
// free state. Calling thread must hold the `Mutex` exclusively.
- void Unlock() ABSL_UNLOCK_FUNCTION();
-
- // Mutex::TryLock()
- //
- // If the mutex can be acquired without blocking, does so exclusively and
- // returns `true`. Otherwise, returns `false`. Returns `true` with high
- // probability if the `Mutex` was free.
- bool TryLock() ABSL_EXCLUSIVE_TRYLOCK_FUNCTION(true);
-
- // Mutex::AssertHeld()
- //
- // Return immediately if this thread holds the `Mutex` exclusively (in write
- // mode). Otherwise, may report an error (typically by crashing with a
- // diagnostic), or may return immediately.
- void AssertHeld() const ABSL_ASSERT_EXCLUSIVE_LOCK();
-
- // ---------------------------------------------------------------------------
- // Reader-Writer Locking
- // ---------------------------------------------------------------------------
-
- // A Mutex can also be used as a starvation-free reader-writer lock.
- // Neither read-locks nor write-locks are reentrant/recursive to avoid
- // potential client programming errors.
- //
- // The Mutex API provides `Writer*()` aliases for the existing `Lock()`,
- // `Unlock()` and `TryLock()` methods for use within applications mixing
- // reader/writer locks. Using `Reader*()` and `Writer*()` operations in this
- // manner can make locking behavior clearer when mixing read and write modes.
- //
- // Introducing reader locks necessarily complicates the `Mutex` state
- // machine somewhat. The table below illustrates the allowed state transitions
- // of a mutex in such cases. Note that ReaderLock() may block even if the lock
- // is held in shared mode; this occurs when another thread is blocked on a
- // call to WriterLock().
- //
- // ---------------------------------------------------------------------------
- // Operation: WriterLock() Unlock() ReaderLock() ReaderUnlock()
- // ---------------------------------------------------------------------------
- // State
- // ---------------------------------------------------------------------------
- // Free Exclusive invalid Shared(1) invalid
- // Shared(1) blocks invalid Shared(2) or blocks Free
- // Shared(n) n>1 blocks invalid Shared(n+1) or blocks Shared(n-1)
- // Exclusive blocks Free blocks invalid
- // ---------------------------------------------------------------------------
- //
- // In comments below, "shared" refers to a state of Shared(n) for any n > 0.
-
- // Mutex::ReaderLock()
- //
- // Blocks the calling thread, if necessary, until this `Mutex` is either free,
- // or in shared mode, and then acquires a share of it. Note that
- // `ReaderLock()` will block if some other thread has an exclusive/writer lock
- // on the mutex.
-
- void ReaderLock() ABSL_SHARED_LOCK_FUNCTION();
-
- // Mutex::ReaderUnlock()
- //
- // Releases a read share of this `Mutex`. `ReaderUnlock` may return a mutex to
- // the free state if this thread holds the last reader lock on the mutex. Note
- // that you cannot call `ReaderUnlock()` on a mutex held in write mode.
- void ReaderUnlock() ABSL_UNLOCK_FUNCTION();
-
- // Mutex::ReaderTryLock()
- //
- // If the mutex can be acquired without blocking, acquires this mutex for
- // shared access and returns `true`. Otherwise, returns `false`. Returns
- // `true` with high probability if the `Mutex` was free or shared.
- bool ReaderTryLock() ABSL_SHARED_TRYLOCK_FUNCTION(true);
-
- // Mutex::AssertReaderHeld()
- //
- // Returns immediately if this thread holds the `Mutex` in at least shared
- // mode (read mode). Otherwise, may report an error (typically by
- // crashing with a diagnostic), or may return immediately.
- void AssertReaderHeld() const ABSL_ASSERT_SHARED_LOCK();
-
- // Mutex::WriterLock()
- // Mutex::WriterUnlock()
- // Mutex::WriterTryLock()
- //
- // Aliases for `Mutex::Lock()`, `Mutex::Unlock()`, and `Mutex::TryLock()`.
- //
- // These methods may be used (along with the complementary `Reader*()`
- // methods) to distingish simple exclusive `Mutex` usage (`Lock()`,
- // etc.) from reader/writer lock usage.
- void WriterLock() ABSL_EXCLUSIVE_LOCK_FUNCTION() { this->Lock(); }
-
- void WriterUnlock() ABSL_UNLOCK_FUNCTION() { this->Unlock(); }
-
- bool WriterTryLock() ABSL_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
- return this->TryLock();
- }
-
- // ---------------------------------------------------------------------------
- // Conditional Critical Regions
- // ---------------------------------------------------------------------------
-
- // Conditional usage of a `Mutex` can occur using two distinct paradigms:
- //
- // * Use of `Mutex` member functions with `Condition` objects.
- // * Use of the separate `CondVar` abstraction.
- //
- // In general, prefer use of `Condition` and the `Mutex` member functions
- // listed below over `CondVar`. When there are multiple threads waiting on
- // distinctly different conditions, however, a battery of `CondVar`s may be
- // more efficient. This section discusses use of `Condition` objects.
- //
- // `Mutex` contains member functions for performing lock operations only under
- // certain conditions, of class `Condition`. For correctness, the `Condition`
- // must return a boolean that is a pure function, only of state protected by
- // the `Mutex`. The condition must be invariant w.r.t. environmental state
- // such as thread, cpu id, or time, and must be `noexcept`. The condition will
- // always be invoked with the mutex held in at least read mode, so you should
- // not block it for long periods or sleep it on a timer.
- //
- // Since a condition must not depend directly on the current time, use
- // `*WithTimeout()` member function variants to make your condition
- // effectively true after a given duration, or `*WithDeadline()` variants to
- // make your condition effectively true after a given time.
- //
- // The condition function should have no side-effects aside from debug
- // logging; as a special exception, the function may acquire other mutexes
- // provided it releases all those that it acquires. (This exception was
- // required to allow logging.)
-
- // Mutex::Await()
- //
- // Unlocks this `Mutex` and blocks until simultaneously both `cond` is `true`
- // and this `Mutex` can be reacquired, then reacquires this `Mutex` in the
- // same mode in which it was previously held. If the condition is initially
- // `true`, `Await()` *may* skip the release/re-acquire step.
- //
- // `Await()` requires that this thread holds this `Mutex` in some mode.
- void Await(const Condition &cond);
-
- // Mutex::LockWhen()
- // Mutex::ReaderLockWhen()
- // Mutex::WriterLockWhen()
- //
- // Blocks until simultaneously both `cond` is `true` and this `Mutex` can
- // be acquired, then atomically acquires this `Mutex`. `LockWhen()` is
- // logically equivalent to `*Lock(); Await();` though they may have different
- // performance characteristics.
- void LockWhen(const Condition &cond) ABSL_EXCLUSIVE_LOCK_FUNCTION();
-
- void ReaderLockWhen(const Condition &cond) ABSL_SHARED_LOCK_FUNCTION();
-
- void WriterLockWhen(const Condition &cond) ABSL_EXCLUSIVE_LOCK_FUNCTION() {
- this->LockWhen(cond);
- }
-
- // ---------------------------------------------------------------------------
- // Mutex Variants with Timeouts/Deadlines
- // ---------------------------------------------------------------------------
-
- // Mutex::AwaitWithTimeout()
- // Mutex::AwaitWithDeadline()
- //
+ void Unlock() ABSL_UNLOCK_FUNCTION();
+
+ // Mutex::TryLock()
+ //
+ // If the mutex can be acquired without blocking, does so exclusively and
+ // returns `true`. Otherwise, returns `false`. Returns `true` with high
+ // probability if the `Mutex` was free.
+ bool TryLock() ABSL_EXCLUSIVE_TRYLOCK_FUNCTION(true);
+
+ // Mutex::AssertHeld()
+ //
+ // Return immediately if this thread holds the `Mutex` exclusively (in write
+ // mode). Otherwise, may report an error (typically by crashing with a
+ // diagnostic), or may return immediately.
+ void AssertHeld() const ABSL_ASSERT_EXCLUSIVE_LOCK();
+
+ // ---------------------------------------------------------------------------
+ // Reader-Writer Locking
+ // ---------------------------------------------------------------------------
+
+ // A Mutex can also be used as a starvation-free reader-writer lock.
+ // Neither read-locks nor write-locks are reentrant/recursive to avoid
+ // potential client programming errors.
+ //
+ // The Mutex API provides `Writer*()` aliases for the existing `Lock()`,
+ // `Unlock()` and `TryLock()` methods for use within applications mixing
+ // reader/writer locks. Using `Reader*()` and `Writer*()` operations in this
+ // manner can make locking behavior clearer when mixing read and write modes.
+ //
+ // Introducing reader locks necessarily complicates the `Mutex` state
+ // machine somewhat. The table below illustrates the allowed state transitions
+ // of a mutex in such cases. Note that ReaderLock() may block even if the lock
+ // is held in shared mode; this occurs when another thread is blocked on a
+ // call to WriterLock().
+ //
+ // ---------------------------------------------------------------------------
+ // Operation: WriterLock() Unlock() ReaderLock() ReaderUnlock()
+ // ---------------------------------------------------------------------------
+ // State
+ // ---------------------------------------------------------------------------
+ // Free Exclusive invalid Shared(1) invalid
+ // Shared(1) blocks invalid Shared(2) or blocks Free
+ // Shared(n) n>1 blocks invalid Shared(n+1) or blocks Shared(n-1)
+ // Exclusive blocks Free blocks invalid
+ // ---------------------------------------------------------------------------
+ //
+ // In comments below, "shared" refers to a state of Shared(n) for any n > 0.
+
+ // Mutex::ReaderLock()
+ //
+ // Blocks the calling thread, if necessary, until this `Mutex` is either free,
+ // or in shared mode, and then acquires a share of it. Note that
+ // `ReaderLock()` will block if some other thread has an exclusive/writer lock
+ // on the mutex.
+
+ void ReaderLock() ABSL_SHARED_LOCK_FUNCTION();
+
+ // Mutex::ReaderUnlock()
+ //
+ // Releases a read share of this `Mutex`. `ReaderUnlock` may return a mutex to
+ // the free state if this thread holds the last reader lock on the mutex. Note
+ // that you cannot call `ReaderUnlock()` on a mutex held in write mode.
+ void ReaderUnlock() ABSL_UNLOCK_FUNCTION();
+
+ // Mutex::ReaderTryLock()
+ //
+ // If the mutex can be acquired without blocking, acquires this mutex for
+ // shared access and returns `true`. Otherwise, returns `false`. Returns
+ // `true` with high probability if the `Mutex` was free or shared.
+ bool ReaderTryLock() ABSL_SHARED_TRYLOCK_FUNCTION(true);
+
+ // Mutex::AssertReaderHeld()
+ //
+ // Returns immediately if this thread holds the `Mutex` in at least shared
+ // mode (read mode). Otherwise, may report an error (typically by
+ // crashing with a diagnostic), or may return immediately.
+ void AssertReaderHeld() const ABSL_ASSERT_SHARED_LOCK();
+
+ // Mutex::WriterLock()
+ // Mutex::WriterUnlock()
+ // Mutex::WriterTryLock()
+ //
+ // Aliases for `Mutex::Lock()`, `Mutex::Unlock()`, and `Mutex::TryLock()`.
+ //
+ // These methods may be used (along with the complementary `Reader*()`
+ // methods) to distingish simple exclusive `Mutex` usage (`Lock()`,
+ // etc.) from reader/writer lock usage.
+ void WriterLock() ABSL_EXCLUSIVE_LOCK_FUNCTION() { this->Lock(); }
+
+ void WriterUnlock() ABSL_UNLOCK_FUNCTION() { this->Unlock(); }
+
+ bool WriterTryLock() ABSL_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
+ return this->TryLock();
+ }
+
+ // ---------------------------------------------------------------------------
+ // Conditional Critical Regions
+ // ---------------------------------------------------------------------------
+
+ // Conditional usage of a `Mutex` can occur using two distinct paradigms:
+ //
+ // * Use of `Mutex` member functions with `Condition` objects.
+ // * Use of the separate `CondVar` abstraction.
+ //
+ // In general, prefer use of `Condition` and the `Mutex` member functions
+ // listed below over `CondVar`. When there are multiple threads waiting on
+ // distinctly different conditions, however, a battery of `CondVar`s may be
+ // more efficient. This section discusses use of `Condition` objects.
+ //
+ // `Mutex` contains member functions for performing lock operations only under
+ // certain conditions, of class `Condition`. For correctness, the `Condition`
+ // must return a boolean that is a pure function, only of state protected by
+ // the `Mutex`. The condition must be invariant w.r.t. environmental state
+ // such as thread, cpu id, or time, and must be `noexcept`. The condition will
+ // always be invoked with the mutex held in at least read mode, so you should
+ // not block it for long periods or sleep it on a timer.
+ //
+ // Since a condition must not depend directly on the current time, use
+ // `*WithTimeout()` member function variants to make your condition
+ // effectively true after a given duration, or `*WithDeadline()` variants to
+ // make your condition effectively true after a given time.
+ //
+ // The condition function should have no side-effects aside from debug
+ // logging; as a special exception, the function may acquire other mutexes
+ // provided it releases all those that it acquires. (This exception was
+ // required to allow logging.)
+
+ // Mutex::Await()
+ //
+ // Unlocks this `Mutex` and blocks until simultaneously both `cond` is `true`
+ // and this `Mutex` can be reacquired, then reacquires this `Mutex` in the
+ // same mode in which it was previously held. If the condition is initially
+ // `true`, `Await()` *may* skip the release/re-acquire step.
+ //
+ // `Await()` requires that this thread holds this `Mutex` in some mode.
+ void Await(const Condition &cond);
+
+ // Mutex::LockWhen()
+ // Mutex::ReaderLockWhen()
+ // Mutex::WriterLockWhen()
+ //
+ // Blocks until simultaneously both `cond` is `true` and this `Mutex` can
+ // be acquired, then atomically acquires this `Mutex`. `LockWhen()` is
+ // logically equivalent to `*Lock(); Await();` though they may have different
+ // performance characteristics.
+ void LockWhen(const Condition &cond) ABSL_EXCLUSIVE_LOCK_FUNCTION();
+
+ void ReaderLockWhen(const Condition &cond) ABSL_SHARED_LOCK_FUNCTION();
+
+ void WriterLockWhen(const Condition &cond) ABSL_EXCLUSIVE_LOCK_FUNCTION() {
+ this->LockWhen(cond);
+ }
+
+ // ---------------------------------------------------------------------------
+ // Mutex Variants with Timeouts/Deadlines
+ // ---------------------------------------------------------------------------
+
+ // Mutex::AwaitWithTimeout()
+ // Mutex::AwaitWithDeadline()
+ //
// Unlocks this `Mutex` and blocks until simultaneously:
- // - either `cond` is true or the {timeout has expired, deadline has passed}
- // and
- // - this `Mutex` can be reacquired,
- // then reacquire this `Mutex` in the same mode in which it was previously
- // held, returning `true` iff `cond` is `true` on return.
- //
+ // - either `cond` is true or the {timeout has expired, deadline has passed}
+ // and
+ // - this `Mutex` can be reacquired,
+ // then reacquire this `Mutex` in the same mode in which it was previously
+ // held, returning `true` iff `cond` is `true` on return.
+ //
// If the condition is initially `true`, the implementation *may* skip the
// release/re-acquire step and return immediately.
//
- // Deadlines in the past are equivalent to an immediate deadline.
- // Negative timeouts are equivalent to a zero timeout.
- //
- // This method requires that this thread holds this `Mutex` in some mode.
+ // Deadlines in the past are equivalent to an immediate deadline.
+ // Negative timeouts are equivalent to a zero timeout.
+ //
+ // This method requires that this thread holds this `Mutex` in some mode.
bool AwaitWithTimeout(const Condition &cond, y_absl::Duration timeout);
-
+
bool AwaitWithDeadline(const Condition &cond, y_absl::Time deadline);
-
- // Mutex::LockWhenWithTimeout()
- // Mutex::ReaderLockWhenWithTimeout()
- // Mutex::WriterLockWhenWithTimeout()
- //
- // Blocks until simultaneously both:
- // - either `cond` is `true` or the timeout has expired, and
- // - this `Mutex` can be acquired,
- // then atomically acquires this `Mutex`, returning `true` iff `cond` is
- // `true` on return.
- //
- // Negative timeouts are equivalent to a zero timeout.
+
+ // Mutex::LockWhenWithTimeout()
+ // Mutex::ReaderLockWhenWithTimeout()
+ // Mutex::WriterLockWhenWithTimeout()
+ //
+ // Blocks until simultaneously both:
+ // - either `cond` is `true` or the timeout has expired, and
+ // - this `Mutex` can be acquired,
+ // then atomically acquires this `Mutex`, returning `true` iff `cond` is
+ // `true` on return.
+ //
+ // Negative timeouts are equivalent to a zero timeout.
bool LockWhenWithTimeout(const Condition &cond, y_absl::Duration timeout)
- ABSL_EXCLUSIVE_LOCK_FUNCTION();
+ ABSL_EXCLUSIVE_LOCK_FUNCTION();
bool ReaderLockWhenWithTimeout(const Condition &cond, y_absl::Duration timeout)
- ABSL_SHARED_LOCK_FUNCTION();
+ ABSL_SHARED_LOCK_FUNCTION();
bool WriterLockWhenWithTimeout(const Condition &cond, y_absl::Duration timeout)
- ABSL_EXCLUSIVE_LOCK_FUNCTION() {
- return this->LockWhenWithTimeout(cond, timeout);
- }
-
- // Mutex::LockWhenWithDeadline()
- // Mutex::ReaderLockWhenWithDeadline()
- // Mutex::WriterLockWhenWithDeadline()
- //
- // Blocks until simultaneously both:
- // - either `cond` is `true` or the deadline has been passed, and
- // - this `Mutex` can be acquired,
- // then atomically acquires this Mutex, returning `true` iff `cond` is `true`
- // on return.
- //
- // Deadlines in the past are equivalent to an immediate deadline.
+ ABSL_EXCLUSIVE_LOCK_FUNCTION() {
+ return this->LockWhenWithTimeout(cond, timeout);
+ }
+
+ // Mutex::LockWhenWithDeadline()
+ // Mutex::ReaderLockWhenWithDeadline()
+ // Mutex::WriterLockWhenWithDeadline()
+ //
+ // Blocks until simultaneously both:
+ // - either `cond` is `true` or the deadline has been passed, and
+ // - this `Mutex` can be acquired,
+ // then atomically acquires this Mutex, returning `true` iff `cond` is `true`
+ // on return.
+ //
+ // Deadlines in the past are equivalent to an immediate deadline.
bool LockWhenWithDeadline(const Condition &cond, y_absl::Time deadline)
- ABSL_EXCLUSIVE_LOCK_FUNCTION();
+ ABSL_EXCLUSIVE_LOCK_FUNCTION();
bool ReaderLockWhenWithDeadline(const Condition &cond, y_absl::Time deadline)
- ABSL_SHARED_LOCK_FUNCTION();
+ ABSL_SHARED_LOCK_FUNCTION();
bool WriterLockWhenWithDeadline(const Condition &cond, y_absl::Time deadline)
- ABSL_EXCLUSIVE_LOCK_FUNCTION() {
- return this->LockWhenWithDeadline(cond, deadline);
- }
-
- // ---------------------------------------------------------------------------
- // Debug Support: Invariant Checking, Deadlock Detection, Logging.
- // ---------------------------------------------------------------------------
-
- // Mutex::EnableInvariantDebugging()
- //
- // If `invariant`!=null and if invariant debugging has been enabled globally,
- // cause `(*invariant)(arg)` to be called at moments when the invariant for
- // this `Mutex` should hold (for example: just after acquire, just before
- // release).
- //
- // The routine `invariant` should have no side-effects since it is not
- // guaranteed how many times it will be called; it should check the invariant
- // and crash if it does not hold. Enabling global invariant debugging may
- // substantially reduce `Mutex` performance; it should be set only for
- // non-production runs. Optimization options may also disable invariant
- // checks.
- void EnableInvariantDebugging(void (*invariant)(void *), void *arg);
-
- // Mutex::EnableDebugLog()
- //
- // Cause all subsequent uses of this `Mutex` to be logged via
- // `ABSL_RAW_LOG(INFO)`. Log entries are tagged with `name` if no previous
- // call to `EnableInvariantDebugging()` or `EnableDebugLog()` has been made.
- //
- // Note: This method substantially reduces `Mutex` performance.
- void EnableDebugLog(const char *name);
-
- // Deadlock detection
-
- // Mutex::ForgetDeadlockInfo()
- //
- // Forget any deadlock-detection information previously gathered
- // about this `Mutex`. Call this method in debug mode when the lock ordering
- // of a `Mutex` changes.
- void ForgetDeadlockInfo();
-
- // Mutex::AssertNotHeld()
- //
- // Return immediately if this thread does not hold this `Mutex` in any
- // mode; otherwise, may report an error (typically by crashing with a
- // diagnostic), or may return immediately.
- //
- // Currently this check is performed only if all of:
- // - in debug mode
- // - SetMutexDeadlockDetectionMode() has been set to kReport or kAbort
- // - number of locks concurrently held by this thread is not large.
- // are true.
- void AssertNotHeld() const;
-
- // Special cases.
-
- // A `MuHow` is a constant that indicates how a lock should be acquired.
- // Internal implementation detail. Clients should ignore.
- typedef const struct MuHowS *MuHow;
-
- // Mutex::InternalAttemptToUseMutexInFatalSignalHandler()
- //
- // Causes the `Mutex` implementation to prepare itself for re-entry caused by
- // future use of `Mutex` within a fatal signal handler. This method is
- // intended for use only for last-ditch attempts to log crash information.
- // It does not guarantee that attempts to use Mutexes within the handler will
- // not deadlock; it merely makes other faults less likely.
- //
- // WARNING: This routine must be invoked from a signal handler, and the
- // signal handler must either loop forever or terminate the process.
- // Attempts to return from (or `longjmp` out of) the signal handler once this
- // call has been made may cause arbitrary program behaviour including
- // crashes and deadlocks.
- static void InternalAttemptToUseMutexInFatalSignalHandler();
-
- private:
- std::atomic<intptr_t> mu_; // The Mutex state.
-
- // Post()/Wait() versus associated PerThreadSem; in class for required
- // friendship with PerThreadSem.
+ ABSL_EXCLUSIVE_LOCK_FUNCTION() {
+ return this->LockWhenWithDeadline(cond, deadline);
+ }
+
+ // ---------------------------------------------------------------------------
+ // Debug Support: Invariant Checking, Deadlock Detection, Logging.
+ // ---------------------------------------------------------------------------
+
+ // Mutex::EnableInvariantDebugging()
+ //
+ // If `invariant`!=null and if invariant debugging has been enabled globally,
+ // cause `(*invariant)(arg)` to be called at moments when the invariant for
+ // this `Mutex` should hold (for example: just after acquire, just before
+ // release).
+ //
+ // The routine `invariant` should have no side-effects since it is not
+ // guaranteed how many times it will be called; it should check the invariant
+ // and crash if it does not hold. Enabling global invariant debugging may
+ // substantially reduce `Mutex` performance; it should be set only for
+ // non-production runs. Optimization options may also disable invariant
+ // checks.
+ void EnableInvariantDebugging(void (*invariant)(void *), void *arg);
+
+ // Mutex::EnableDebugLog()
+ //
+ // Cause all subsequent uses of this `Mutex` to be logged via
+ // `ABSL_RAW_LOG(INFO)`. Log entries are tagged with `name` if no previous
+ // call to `EnableInvariantDebugging()` or `EnableDebugLog()` has been made.
+ //
+ // Note: This method substantially reduces `Mutex` performance.
+ void EnableDebugLog(const char *name);
+
+ // Deadlock detection
+
+ // Mutex::ForgetDeadlockInfo()
+ //
+ // Forget any deadlock-detection information previously gathered
+ // about this `Mutex`. Call this method in debug mode when the lock ordering
+ // of a `Mutex` changes.
+ void ForgetDeadlockInfo();
+
+ // Mutex::AssertNotHeld()
+ //
+ // Return immediately if this thread does not hold this `Mutex` in any
+ // mode; otherwise, may report an error (typically by crashing with a
+ // diagnostic), or may return immediately.
+ //
+ // Currently this check is performed only if all of:
+ // - in debug mode
+ // - SetMutexDeadlockDetectionMode() has been set to kReport or kAbort
+ // - number of locks concurrently held by this thread is not large.
+ // are true.
+ void AssertNotHeld() const;
+
+ // Special cases.
+
+ // A `MuHow` is a constant that indicates how a lock should be acquired.
+ // Internal implementation detail. Clients should ignore.
+ typedef const struct MuHowS *MuHow;
+
+ // Mutex::InternalAttemptToUseMutexInFatalSignalHandler()
+ //
+ // Causes the `Mutex` implementation to prepare itself for re-entry caused by
+ // future use of `Mutex` within a fatal signal handler. This method is
+ // intended for use only for last-ditch attempts to log crash information.
+ // It does not guarantee that attempts to use Mutexes within the handler will
+ // not deadlock; it merely makes other faults less likely.
+ //
+ // WARNING: This routine must be invoked from a signal handler, and the
+ // signal handler must either loop forever or terminate the process.
+ // Attempts to return from (or `longjmp` out of) the signal handler once this
+ // call has been made may cause arbitrary program behaviour including
+ // crashes and deadlocks.
+ static void InternalAttemptToUseMutexInFatalSignalHandler();
+
+ private:
+ std::atomic<intptr_t> mu_; // The Mutex state.
+
+ // Post()/Wait() versus associated PerThreadSem; in class for required
+ // friendship with PerThreadSem.
static void IncrementSynchSem(Mutex *mu, base_internal::PerThreadSynch *w);
static bool DecrementSynchSem(Mutex *mu, base_internal::PerThreadSynch *w,
synchronization_internal::KernelTimeout t);
-
- // slow path acquire
- void LockSlowLoop(SynchWaitParams *waitp, int flags);
- // wrappers around LockSlowLoop()
- bool LockSlowWithDeadline(MuHow how, const Condition *cond,
- synchronization_internal::KernelTimeout t,
- int flags);
- void LockSlow(MuHow how, const Condition *cond,
- int flags) ABSL_ATTRIBUTE_COLD;
- // slow path release
- void UnlockSlow(SynchWaitParams *waitp) ABSL_ATTRIBUTE_COLD;
- // Common code between Await() and AwaitWithTimeout/Deadline()
- bool AwaitCommon(const Condition &cond,
- synchronization_internal::KernelTimeout t);
- // Attempt to remove thread s from queue.
- void TryRemove(base_internal::PerThreadSynch *s);
- // Block a thread on mutex.
- void Block(base_internal::PerThreadSynch *s);
- // Wake a thread; return successor.
- base_internal::PerThreadSynch *Wakeup(base_internal::PerThreadSynch *w);
-
- friend class CondVar; // for access to Trans()/Fer().
- void Trans(MuHow how); // used for CondVar->Mutex transfer
- void Fer(
- base_internal::PerThreadSynch *w); // used for CondVar->Mutex transfer
-
- // Catch the error of writing Mutex when intending MutexLock.
- Mutex(const volatile Mutex * /*ignored*/) {} // NOLINT(runtime/explicit)
-
- Mutex(const Mutex&) = delete;
- Mutex& operator=(const Mutex&) = delete;
-};
-
-// -----------------------------------------------------------------------------
-// Mutex RAII Wrappers
-// -----------------------------------------------------------------------------
-
-// MutexLock
-//
-// `MutexLock` is a helper class, which acquires and releases a `Mutex` via
-// RAII.
-//
-// Example:
-//
-// Class Foo {
+
+ // slow path acquire
+ void LockSlowLoop(SynchWaitParams *waitp, int flags);
+ // wrappers around LockSlowLoop()
+ bool LockSlowWithDeadline(MuHow how, const Condition *cond,
+ synchronization_internal::KernelTimeout t,
+ int flags);
+ void LockSlow(MuHow how, const Condition *cond,
+ int flags) ABSL_ATTRIBUTE_COLD;
+ // slow path release
+ void UnlockSlow(SynchWaitParams *waitp) ABSL_ATTRIBUTE_COLD;
+ // Common code between Await() and AwaitWithTimeout/Deadline()
+ bool AwaitCommon(const Condition &cond,
+ synchronization_internal::KernelTimeout t);
+ // Attempt to remove thread s from queue.
+ void TryRemove(base_internal::PerThreadSynch *s);
+ // Block a thread on mutex.
+ void Block(base_internal::PerThreadSynch *s);
+ // Wake a thread; return successor.
+ base_internal::PerThreadSynch *Wakeup(base_internal::PerThreadSynch *w);
+
+ friend class CondVar; // for access to Trans()/Fer().
+ void Trans(MuHow how); // used for CondVar->Mutex transfer
+ void Fer(
+ base_internal::PerThreadSynch *w); // used for CondVar->Mutex transfer
+
+ // Catch the error of writing Mutex when intending MutexLock.
+ Mutex(const volatile Mutex * /*ignored*/) {} // NOLINT(runtime/explicit)
+
+ Mutex(const Mutex&) = delete;
+ Mutex& operator=(const Mutex&) = delete;
+};
+
+// -----------------------------------------------------------------------------
+// Mutex RAII Wrappers
+// -----------------------------------------------------------------------------
+
+// MutexLock
+//
+// `MutexLock` is a helper class, which acquires and releases a `Mutex` via
+// RAII.
+//
+// Example:
+//
+// Class Foo {
// public:
-// Foo::Bar* Baz() {
+// Foo::Bar* Baz() {
// MutexLock lock(&mu_);
-// ...
-// return bar;
-// }
-//
-// private:
+// ...
+// return bar;
+// }
+//
+// private:
// Mutex mu_;
-// };
-class ABSL_SCOPED_LOCKABLE MutexLock {
- public:
+// };
+class ABSL_SCOPED_LOCKABLE MutexLock {
+ public:
// Constructors
// Calls `mu->Lock()` and returns when that call returns. That is, `*mu` is
// guaranteed to be locked when this object is constructed. Requires that
// `mu` be dereferenceable.
- explicit MutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu) : mu_(mu) {
- this->mu_->Lock();
- }
-
+ explicit MutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu) : mu_(mu) {
+ this->mu_->Lock();
+ }
+
// Like above, but calls `mu->LockWhen(cond)` instead. That is, in addition to
// the above, the condition given by `cond` is also guaranteed to hold when
// this object is constructed.
@@ -535,113 +535,113 @@ class ABSL_SCOPED_LOCKABLE MutexLock {
this->mu_->LockWhen(cond);
}
- MutexLock(const MutexLock &) = delete; // NOLINT(runtime/mutex)
- MutexLock(MutexLock&&) = delete; // NOLINT(runtime/mutex)
- MutexLock& operator=(const MutexLock&) = delete;
- MutexLock& operator=(MutexLock&&) = delete;
-
- ~MutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->Unlock(); }
-
- private:
- Mutex *const mu_;
-};
-
-// ReaderMutexLock
-//
-// The `ReaderMutexLock` is a helper class, like `MutexLock`, which acquires and
-// releases a shared lock on a `Mutex` via RAII.
-class ABSL_SCOPED_LOCKABLE ReaderMutexLock {
- public:
- explicit ReaderMutexLock(Mutex *mu) ABSL_SHARED_LOCK_FUNCTION(mu) : mu_(mu) {
- mu->ReaderLock();
- }
-
+ MutexLock(const MutexLock &) = delete; // NOLINT(runtime/mutex)
+ MutexLock(MutexLock&&) = delete; // NOLINT(runtime/mutex)
+ MutexLock& operator=(const MutexLock&) = delete;
+ MutexLock& operator=(MutexLock&&) = delete;
+
+ ~MutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->Unlock(); }
+
+ private:
+ Mutex *const mu_;
+};
+
+// ReaderMutexLock
+//
+// The `ReaderMutexLock` is a helper class, like `MutexLock`, which acquires and
+// releases a shared lock on a `Mutex` via RAII.
+class ABSL_SCOPED_LOCKABLE ReaderMutexLock {
+ public:
+ explicit ReaderMutexLock(Mutex *mu) ABSL_SHARED_LOCK_FUNCTION(mu) : mu_(mu) {
+ mu->ReaderLock();
+ }
+
explicit ReaderMutexLock(Mutex *mu, const Condition &cond)
ABSL_SHARED_LOCK_FUNCTION(mu)
: mu_(mu) {
mu->ReaderLockWhen(cond);
}
- ReaderMutexLock(const ReaderMutexLock&) = delete;
- ReaderMutexLock(ReaderMutexLock&&) = delete;
- ReaderMutexLock& operator=(const ReaderMutexLock&) = delete;
- ReaderMutexLock& operator=(ReaderMutexLock&&) = delete;
-
- ~ReaderMutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->ReaderUnlock(); }
-
- private:
- Mutex *const mu_;
-};
-
-// WriterMutexLock
-//
-// The `WriterMutexLock` is a helper class, like `MutexLock`, which acquires and
-// releases a write (exclusive) lock on a `Mutex` via RAII.
-class ABSL_SCOPED_LOCKABLE WriterMutexLock {
- public:
- explicit WriterMutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
- : mu_(mu) {
- mu->WriterLock();
- }
-
+ ReaderMutexLock(const ReaderMutexLock&) = delete;
+ ReaderMutexLock(ReaderMutexLock&&) = delete;
+ ReaderMutexLock& operator=(const ReaderMutexLock&) = delete;
+ ReaderMutexLock& operator=(ReaderMutexLock&&) = delete;
+
+ ~ReaderMutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->ReaderUnlock(); }
+
+ private:
+ Mutex *const mu_;
+};
+
+// WriterMutexLock
+//
+// The `WriterMutexLock` is a helper class, like `MutexLock`, which acquires and
+// releases a write (exclusive) lock on a `Mutex` via RAII.
+class ABSL_SCOPED_LOCKABLE WriterMutexLock {
+ public:
+ explicit WriterMutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
+ : mu_(mu) {
+ mu->WriterLock();
+ }
+
explicit WriterMutexLock(Mutex *mu, const Condition &cond)
ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
: mu_(mu) {
mu->WriterLockWhen(cond);
}
- WriterMutexLock(const WriterMutexLock&) = delete;
- WriterMutexLock(WriterMutexLock&&) = delete;
- WriterMutexLock& operator=(const WriterMutexLock&) = delete;
- WriterMutexLock& operator=(WriterMutexLock&&) = delete;
-
- ~WriterMutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->WriterUnlock(); }
-
- private:
- Mutex *const mu_;
-};
-
-// -----------------------------------------------------------------------------
-// Condition
-// -----------------------------------------------------------------------------
-//
-// As noted above, `Mutex` contains a number of member functions which take a
-// `Condition` as an argument; clients can wait for conditions to become `true`
-// before attempting to acquire the mutex. These sections are known as
-// "condition critical" sections. To use a `Condition`, you simply need to
-// construct it, and use within an appropriate `Mutex` member function;
-// everything else in the `Condition` class is an implementation detail.
-//
-// A `Condition` is specified as a function pointer which returns a boolean.
-// `Condition` functions should be pure functions -- their results should depend
-// only on passed arguments, should not consult any external state (such as
-// clocks), and should have no side-effects, aside from debug logging. Any
-// objects that the function may access should be limited to those which are
-// constant while the mutex is blocked on the condition (e.g. a stack variable),
-// or objects of state protected explicitly by the mutex.
-//
-// No matter which construction is used for `Condition`, the underlying
-// function pointer / functor / callable must not throw any
-// exceptions. Correctness of `Mutex` / `Condition` is not guaranteed in
-// the face of a throwing `Condition`. (When Abseil is allowed to depend
-// on C++17, these function pointers will be explicitly marked
-// `noexcept`; until then this requirement cannot be enforced in the
-// type system.)
-//
+ WriterMutexLock(const WriterMutexLock&) = delete;
+ WriterMutexLock(WriterMutexLock&&) = delete;
+ WriterMutexLock& operator=(const WriterMutexLock&) = delete;
+ WriterMutexLock& operator=(WriterMutexLock&&) = delete;
+
+ ~WriterMutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->WriterUnlock(); }
+
+ private:
+ Mutex *const mu_;
+};
+
+// -----------------------------------------------------------------------------
+// Condition
+// -----------------------------------------------------------------------------
+//
+// As noted above, `Mutex` contains a number of member functions which take a
+// `Condition` as an argument; clients can wait for conditions to become `true`
+// before attempting to acquire the mutex. These sections are known as
+// "condition critical" sections. To use a `Condition`, you simply need to
+// construct it, and use within an appropriate `Mutex` member function;
+// everything else in the `Condition` class is an implementation detail.
+//
+// A `Condition` is specified as a function pointer which returns a boolean.
+// `Condition` functions should be pure functions -- their results should depend
+// only on passed arguments, should not consult any external state (such as
+// clocks), and should have no side-effects, aside from debug logging. Any
+// objects that the function may access should be limited to those which are
+// constant while the mutex is blocked on the condition (e.g. a stack variable),
+// or objects of state protected explicitly by the mutex.
+//
+// No matter which construction is used for `Condition`, the underlying
+// function pointer / functor / callable must not throw any
+// exceptions. Correctness of `Mutex` / `Condition` is not guaranteed in
+// the face of a throwing `Condition`. (When Abseil is allowed to depend
+// on C++17, these function pointers will be explicitly marked
+// `noexcept`; until then this requirement cannot be enforced in the
+// type system.)
+//
// Note: to use a `Condition`, you need only construct it and pass it to a
// suitable `Mutex' member function, such as `Mutex::Await()`, or to the
// constructor of one of the scope guard classes.
-//
+//
// Example using LockWhen/Unlock:
-//
-// // assume count_ is not internal reference count
-// int count_ ABSL_GUARDED_BY(mu_);
+//
+// // assume count_ is not internal reference count
+// int count_ ABSL_GUARDED_BY(mu_);
// Condition count_is_zero(+[](int *count) { return *count == 0; }, &count_);
-//
+//
// mu_.LockWhen(count_is_zero);
// // ...
// mu_.Unlock();
-//
+//
// Example using a scope guard:
//
// {
@@ -649,236 +649,236 @@ class ABSL_SCOPED_LOCKABLE WriterMutexLock {
// // ...
// }
//
-// When multiple threads are waiting on exactly the same condition, make sure
-// that they are constructed with the same parameters (same pointer to function
-// + arg, or same pointer to object + method), so that the mutex implementation
-// can avoid redundantly evaluating the same condition for each thread.
-class Condition {
- public:
- // A Condition that returns the result of "(*func)(arg)"
- Condition(bool (*func)(void *), void *arg);
-
- // Templated version for people who are averse to casts.
- //
- // To use a lambda, prepend it with unary plus, which converts the lambda
- // into a function pointer:
- // Condition(+[](T* t) { return ...; }, arg).
- //
- // Note: lambdas in this case must contain no bound variables.
- //
- // See class comment for performance advice.
- template<typename T>
- Condition(bool (*func)(T *), T *arg);
-
- // Templated version for invoking a method that returns a `bool`.
- //
- // `Condition(object, &Class::Method)` constructs a `Condition` that evaluates
- // `object->Method()`.
- //
+// When multiple threads are waiting on exactly the same condition, make sure
+// that they are constructed with the same parameters (same pointer to function
+// + arg, or same pointer to object + method), so that the mutex implementation
+// can avoid redundantly evaluating the same condition for each thread.
+class Condition {
+ public:
+ // A Condition that returns the result of "(*func)(arg)"
+ Condition(bool (*func)(void *), void *arg);
+
+ // Templated version for people who are averse to casts.
+ //
+ // To use a lambda, prepend it with unary plus, which converts the lambda
+ // into a function pointer:
+ // Condition(+[](T* t) { return ...; }, arg).
+ //
+ // Note: lambdas in this case must contain no bound variables.
+ //
+ // See class comment for performance advice.
+ template<typename T>
+ Condition(bool (*func)(T *), T *arg);
+
+ // Templated version for invoking a method that returns a `bool`.
+ //
+ // `Condition(object, &Class::Method)` constructs a `Condition` that evaluates
+ // `object->Method()`.
+ //
// Implementation Note: `y_absl::internal::identity` is used to allow methods to
- // come from base classes. A simpler signature like
- // `Condition(T*, bool (T::*)())` does not suffice.
- template<typename T>
+ // come from base classes. A simpler signature like
+ // `Condition(T*, bool (T::*)())` does not suffice.
+ template<typename T>
Condition(T *object, bool (y_absl::internal::identity<T>::type::* method)());
-
- // Same as above, for const members
- template<typename T>
- Condition(const T *object,
+
+ // Same as above, for const members
+ template<typename T>
+ Condition(const T *object,
bool (y_absl::internal::identity<T>::type::* method)() const);
-
- // A Condition that returns the value of `*cond`
- explicit Condition(const bool *cond);
-
- // Templated version for invoking a functor that returns a `bool`.
- // This approach accepts pointers to non-mutable lambdas, `std::function`,
- // the result of` std::bind` and user-defined functors that define
- // `bool F::operator()() const`.
- //
- // Example:
- //
- // auto reached = [this, current]() {
- // mu_.AssertReaderHeld(); // For annotalysis.
- // return processed_ >= current;
- // };
- // mu_.Await(Condition(&reached));
+
+ // A Condition that returns the value of `*cond`
+ explicit Condition(const bool *cond);
+
+ // Templated version for invoking a functor that returns a `bool`.
+ // This approach accepts pointers to non-mutable lambdas, `std::function`,
+ // the result of` std::bind` and user-defined functors that define
+ // `bool F::operator()() const`.
+ //
+ // Example:
+ //
+ // auto reached = [this, current]() {
+ // mu_.AssertReaderHeld(); // For annotalysis.
+ // return processed_ >= current;
+ // };
+ // mu_.Await(Condition(&reached));
//
// NOTE: never use "mu_.AssertHeld()" instead of "mu_.AssertReaderHeld()" in
// the lambda as it may be called when the mutex is being unlocked from a
// scope holding only a reader lock, which will make the assertion not
// fulfilled and crash the binary.
-
- // See class comment for performance advice. In particular, if there
- // might be more than one waiter for the same condition, make sure
- // that all waiters construct the condition with the same pointers.
-
- // Implementation note: The second template parameter ensures that this
- // constructor doesn't participate in overload resolution if T doesn't have
- // `bool operator() const`.
- template <typename T, typename E = decltype(
- static_cast<bool (T::*)() const>(&T::operator()))>
- explicit Condition(const T *obj)
- : Condition(obj, static_cast<bool (T::*)() const>(&T::operator())) {}
-
- // A Condition that always returns `true`.
- static const Condition kTrue;
-
- // Evaluates the condition.
- bool Eval() const;
-
- // Returns `true` if the two conditions are guaranteed to return the same
- // value if evaluated at the same time, `false` if the evaluation *may* return
- // different results.
- //
- // Two `Condition` values are guaranteed equal if both their `func` and `arg`
- // components are the same. A null pointer is equivalent to a `true`
- // condition.
- static bool GuaranteedEqual(const Condition *a, const Condition *b);
-
- private:
- typedef bool (*InternalFunctionType)(void * arg);
- typedef bool (Condition::*InternalMethodType)();
- typedef bool (*InternalMethodCallerType)(void * arg,
- InternalMethodType internal_method);
-
- bool (*eval_)(const Condition*); // Actual evaluator
- InternalFunctionType function_; // function taking pointer returning bool
- InternalMethodType method_; // method returning bool
- void *arg_; // arg of function_ or object of method_
-
- Condition(); // null constructor used only to create kTrue
-
- // Various functions eval_ can point to:
- static bool CallVoidPtrFunction(const Condition*);
- template <typename T> static bool CastAndCallFunction(const Condition* c);
- template <typename T> static bool CastAndCallMethod(const Condition* c);
-};
-
-// -----------------------------------------------------------------------------
-// CondVar
-// -----------------------------------------------------------------------------
-//
-// A condition variable, reflecting state evaluated separately outside of the
-// `Mutex` object, which can be signaled to wake callers.
-// This class is not normally needed; use `Mutex` member functions such as
-// `Mutex::Await()` and intrinsic `Condition` abstractions. In rare cases
-// with many threads and many conditions, `CondVar` may be faster.
-//
-// The implementation may deliver signals to any condition variable at
-// any time, even when no call to `Signal()` or `SignalAll()` is made; as a
-// result, upon being awoken, you must check the logical condition you have
-// been waiting upon.
-//
-// Examples:
-//
-// Usage for a thread waiting for some condition C protected by mutex mu:
-// mu.Lock();
-// while (!C) { cv->Wait(&mu); } // releases and reacquires mu
-// // C holds; process data
-// mu.Unlock();
-//
-// Usage to wake T is:
-// mu.Lock();
+
+ // See class comment for performance advice. In particular, if there
+ // might be more than one waiter for the same condition, make sure
+ // that all waiters construct the condition with the same pointers.
+
+ // Implementation note: The second template parameter ensures that this
+ // constructor doesn't participate in overload resolution if T doesn't have
+ // `bool operator() const`.
+ template <typename T, typename E = decltype(
+ static_cast<bool (T::*)() const>(&T::operator()))>
+ explicit Condition(const T *obj)
+ : Condition(obj, static_cast<bool (T::*)() const>(&T::operator())) {}
+
+ // A Condition that always returns `true`.
+ static const Condition kTrue;
+
+ // Evaluates the condition.
+ bool Eval() const;
+
+ // Returns `true` if the two conditions are guaranteed to return the same
+ // value if evaluated at the same time, `false` if the evaluation *may* return
+ // different results.
+ //
+ // Two `Condition` values are guaranteed equal if both their `func` and `arg`
+ // components are the same. A null pointer is equivalent to a `true`
+ // condition.
+ static bool GuaranteedEqual(const Condition *a, const Condition *b);
+
+ private:
+ typedef bool (*InternalFunctionType)(void * arg);
+ typedef bool (Condition::*InternalMethodType)();
+ typedef bool (*InternalMethodCallerType)(void * arg,
+ InternalMethodType internal_method);
+
+ bool (*eval_)(const Condition*); // Actual evaluator
+ InternalFunctionType function_; // function taking pointer returning bool
+ InternalMethodType method_; // method returning bool
+ void *arg_; // arg of function_ or object of method_
+
+ Condition(); // null constructor used only to create kTrue
+
+ // Various functions eval_ can point to:
+ static bool CallVoidPtrFunction(const Condition*);
+ template <typename T> static bool CastAndCallFunction(const Condition* c);
+ template <typename T> static bool CastAndCallMethod(const Condition* c);
+};
+
+// -----------------------------------------------------------------------------
+// CondVar
+// -----------------------------------------------------------------------------
+//
+// A condition variable, reflecting state evaluated separately outside of the
+// `Mutex` object, which can be signaled to wake callers.
+// This class is not normally needed; use `Mutex` member functions such as
+// `Mutex::Await()` and intrinsic `Condition` abstractions. In rare cases
+// with many threads and many conditions, `CondVar` may be faster.
+//
+// The implementation may deliver signals to any condition variable at
+// any time, even when no call to `Signal()` or `SignalAll()` is made; as a
+// result, upon being awoken, you must check the logical condition you have
+// been waiting upon.
+//
+// Examples:
+//
+// Usage for a thread waiting for some condition C protected by mutex mu:
+// mu.Lock();
+// while (!C) { cv->Wait(&mu); } // releases and reacquires mu
+// // C holds; process data
+// mu.Unlock();
+//
+// Usage to wake T is:
+// mu.Lock();
// // process data, possibly establishing C
// if (C) { cv->Signal(); }
// mu.Unlock();
-//
-// If C may be useful to more than one waiter, use `SignalAll()` instead of
-// `Signal()`.
-//
-// With this implementation it is efficient to use `Signal()/SignalAll()` inside
-// the locked region; this usage can make reasoning about your program easier.
-//
-class CondVar {
- public:
+//
+// If C may be useful to more than one waiter, use `SignalAll()` instead of
+// `Signal()`.
+//
+// With this implementation it is efficient to use `Signal()/SignalAll()` inside
+// the locked region; this usage can make reasoning about your program easier.
+//
+class CondVar {
+ public:
// A `CondVar` allocated on the heap or on the stack can use the this
// constructor.
- CondVar();
- ~CondVar();
-
- // CondVar::Wait()
- //
- // Atomically releases a `Mutex` and blocks on this condition variable.
- // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
- // spurious wakeup), then reacquires the `Mutex` and returns.
- //
- // Requires and ensures that the current thread holds the `Mutex`.
- void Wait(Mutex *mu);
-
- // CondVar::WaitWithTimeout()
- //
- // Atomically releases a `Mutex` and blocks on this condition variable.
- // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
- // spurious wakeup), or until the timeout has expired, then reacquires
- // the `Mutex` and returns.
- //
- // Returns true if the timeout has expired without this `CondVar`
- // being signalled in any manner. If both the timeout has expired
- // and this `CondVar` has been signalled, the implementation is free
- // to return `true` or `false`.
- //
- // Requires and ensures that the current thread holds the `Mutex`.
+ CondVar();
+ ~CondVar();
+
+ // CondVar::Wait()
+ //
+ // Atomically releases a `Mutex` and blocks on this condition variable.
+ // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
+ // spurious wakeup), then reacquires the `Mutex` and returns.
+ //
+ // Requires and ensures that the current thread holds the `Mutex`.
+ void Wait(Mutex *mu);
+
+ // CondVar::WaitWithTimeout()
+ //
+ // Atomically releases a `Mutex` and blocks on this condition variable.
+ // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
+ // spurious wakeup), or until the timeout has expired, then reacquires
+ // the `Mutex` and returns.
+ //
+ // Returns true if the timeout has expired without this `CondVar`
+ // being signalled in any manner. If both the timeout has expired
+ // and this `CondVar` has been signalled, the implementation is free
+ // to return `true` or `false`.
+ //
+ // Requires and ensures that the current thread holds the `Mutex`.
bool WaitWithTimeout(Mutex *mu, y_absl::Duration timeout);
-
- // CondVar::WaitWithDeadline()
- //
- // Atomically releases a `Mutex` and blocks on this condition variable.
- // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
- // spurious wakeup), or until the deadline has passed, then reacquires
- // the `Mutex` and returns.
- //
- // Deadlines in the past are equivalent to an immediate deadline.
- //
- // Returns true if the deadline has passed without this `CondVar`
- // being signalled in any manner. If both the deadline has passed
- // and this `CondVar` has been signalled, the implementation is free
- // to return `true` or `false`.
- //
- // Requires and ensures that the current thread holds the `Mutex`.
+
+ // CondVar::WaitWithDeadline()
+ //
+ // Atomically releases a `Mutex` and blocks on this condition variable.
+ // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
+ // spurious wakeup), or until the deadline has passed, then reacquires
+ // the `Mutex` and returns.
+ //
+ // Deadlines in the past are equivalent to an immediate deadline.
+ //
+ // Returns true if the deadline has passed without this `CondVar`
+ // being signalled in any manner. If both the deadline has passed
+ // and this `CondVar` has been signalled, the implementation is free
+ // to return `true` or `false`.
+ //
+ // Requires and ensures that the current thread holds the `Mutex`.
bool WaitWithDeadline(Mutex *mu, y_absl::Time deadline);
-
- // CondVar::Signal()
- //
- // Signal this `CondVar`; wake at least one waiter if one exists.
- void Signal();
-
- // CondVar::SignalAll()
- //
- // Signal this `CondVar`; wake all waiters.
- void SignalAll();
-
- // CondVar::EnableDebugLog()
- //
- // Causes all subsequent uses of this `CondVar` to be logged via
- // `ABSL_RAW_LOG(INFO)`. Log entries are tagged with `name` if `name != 0`.
- // Note: this method substantially reduces `CondVar` performance.
- void EnableDebugLog(const char *name);
-
- private:
- bool WaitCommon(Mutex *mutex, synchronization_internal::KernelTimeout t);
- void Remove(base_internal::PerThreadSynch *s);
- void Wakeup(base_internal::PerThreadSynch *w);
- std::atomic<intptr_t> cv_; // Condition variable state.
- CondVar(const CondVar&) = delete;
- CondVar& operator=(const CondVar&) = delete;
-};
-
-
-// Variants of MutexLock.
-//
-// If you find yourself using one of these, consider instead using
-// Mutex::Unlock() and/or if-statements for clarity.
-
-// MutexLockMaybe
-//
-// MutexLockMaybe is like MutexLock, but is a no-op when mu is null.
-class ABSL_SCOPED_LOCKABLE MutexLockMaybe {
- public:
- explicit MutexLockMaybe(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
- : mu_(mu) {
- if (this->mu_ != nullptr) {
- this->mu_->Lock();
- }
- }
+
+ // CondVar::Signal()
+ //
+ // Signal this `CondVar`; wake at least one waiter if one exists.
+ void Signal();
+
+ // CondVar::SignalAll()
+ //
+ // Signal this `CondVar`; wake all waiters.
+ void SignalAll();
+
+ // CondVar::EnableDebugLog()
+ //
+ // Causes all subsequent uses of this `CondVar` to be logged via
+ // `ABSL_RAW_LOG(INFO)`. Log entries are tagged with `name` if `name != 0`.
+ // Note: this method substantially reduces `CondVar` performance.
+ void EnableDebugLog(const char *name);
+
+ private:
+ bool WaitCommon(Mutex *mutex, synchronization_internal::KernelTimeout t);
+ void Remove(base_internal::PerThreadSynch *s);
+ void Wakeup(base_internal::PerThreadSynch *w);
+ std::atomic<intptr_t> cv_; // Condition variable state.
+ CondVar(const CondVar&) = delete;
+ CondVar& operator=(const CondVar&) = delete;
+};
+
+
+// Variants of MutexLock.
+//
+// If you find yourself using one of these, consider instead using
+// Mutex::Unlock() and/or if-statements for clarity.
+
+// MutexLockMaybe
+//
+// MutexLockMaybe is like MutexLock, but is a no-op when mu is null.
+class ABSL_SCOPED_LOCKABLE MutexLockMaybe {
+ public:
+ explicit MutexLockMaybe(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
+ : mu_(mu) {
+ if (this->mu_ != nullptr) {
+ this->mu_->Lock();
+ }
+ }
explicit MutexLockMaybe(Mutex *mu, const Condition &cond)
ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
@@ -888,28 +888,28 @@ class ABSL_SCOPED_LOCKABLE MutexLockMaybe {
}
}
- ~MutexLockMaybe() ABSL_UNLOCK_FUNCTION() {
- if (this->mu_ != nullptr) { this->mu_->Unlock(); }
- }
-
- private:
- Mutex *const mu_;
- MutexLockMaybe(const MutexLockMaybe&) = delete;
- MutexLockMaybe(MutexLockMaybe&&) = delete;
- MutexLockMaybe& operator=(const MutexLockMaybe&) = delete;
- MutexLockMaybe& operator=(MutexLockMaybe&&) = delete;
-};
-
-// ReleasableMutexLock
-//
-// ReleasableMutexLock is like MutexLock, but permits `Release()` of its
-// mutex before destruction. `Release()` may be called at most once.
-class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
- public:
- explicit ReleasableMutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
- : mu_(mu) {
- this->mu_->Lock();
- }
+ ~MutexLockMaybe() ABSL_UNLOCK_FUNCTION() {
+ if (this->mu_ != nullptr) { this->mu_->Unlock(); }
+ }
+
+ private:
+ Mutex *const mu_;
+ MutexLockMaybe(const MutexLockMaybe&) = delete;
+ MutexLockMaybe(MutexLockMaybe&&) = delete;
+ MutexLockMaybe& operator=(const MutexLockMaybe&) = delete;
+ MutexLockMaybe& operator=(MutexLockMaybe&&) = delete;
+};
+
+// ReleasableMutexLock
+//
+// ReleasableMutexLock is like MutexLock, but permits `Release()` of its
+// mutex before destruction. `Release()` may be called at most once.
+class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
+ public:
+ explicit ReleasableMutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
+ : mu_(mu) {
+ this->mu_->Lock();
+ }
explicit ReleasableMutexLock(Mutex *mu, const Condition &cond)
ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
@@ -917,166 +917,166 @@ class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
this->mu_->LockWhen(cond);
}
- ~ReleasableMutexLock() ABSL_UNLOCK_FUNCTION() {
- if (this->mu_ != nullptr) { this->mu_->Unlock(); }
- }
-
- void Release() ABSL_UNLOCK_FUNCTION();
-
- private:
- Mutex *mu_;
- ReleasableMutexLock(const ReleasableMutexLock&) = delete;
- ReleasableMutexLock(ReleasableMutexLock&&) = delete;
- ReleasableMutexLock& operator=(const ReleasableMutexLock&) = delete;
- ReleasableMutexLock& operator=(ReleasableMutexLock&&) = delete;
-};
-
-inline Mutex::Mutex() : mu_(0) {
- ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
-}
-
+ ~ReleasableMutexLock() ABSL_UNLOCK_FUNCTION() {
+ if (this->mu_ != nullptr) { this->mu_->Unlock(); }
+ }
+
+ void Release() ABSL_UNLOCK_FUNCTION();
+
+ private:
+ Mutex *mu_;
+ ReleasableMutexLock(const ReleasableMutexLock&) = delete;
+ ReleasableMutexLock(ReleasableMutexLock&&) = delete;
+ ReleasableMutexLock& operator=(const ReleasableMutexLock&) = delete;
+ ReleasableMutexLock& operator=(ReleasableMutexLock&&) = delete;
+};
+
+inline Mutex::Mutex() : mu_(0) {
+ ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
+}
+
inline constexpr Mutex::Mutex(y_absl::ConstInitType) : mu_(0) {}
-
-inline CondVar::CondVar() : cv_(0) {}
-
-// static
-template <typename T>
-bool Condition::CastAndCallMethod(const Condition *c) {
- typedef bool (T::*MemberType)();
- MemberType rm = reinterpret_cast<MemberType>(c->method_);
- T *x = static_cast<T *>(c->arg_);
- return (x->*rm)();
-}
-
-// static
-template <typename T>
-bool Condition::CastAndCallFunction(const Condition *c) {
- typedef bool (*FuncType)(T *);
- FuncType fn = reinterpret_cast<FuncType>(c->function_);
- T *x = static_cast<T *>(c->arg_);
- return (*fn)(x);
-}
-
-template <typename T>
-inline Condition::Condition(bool (*func)(T *), T *arg)
- : eval_(&CastAndCallFunction<T>),
- function_(reinterpret_cast<InternalFunctionType>(func)),
- method_(nullptr),
- arg_(const_cast<void *>(static_cast<const void *>(arg))) {}
-
-template <typename T>
-inline Condition::Condition(T *object,
+
+inline CondVar::CondVar() : cv_(0) {}
+
+// static
+template <typename T>
+bool Condition::CastAndCallMethod(const Condition *c) {
+ typedef bool (T::*MemberType)();
+ MemberType rm = reinterpret_cast<MemberType>(c->method_);
+ T *x = static_cast<T *>(c->arg_);
+ return (x->*rm)();
+}
+
+// static
+template <typename T>
+bool Condition::CastAndCallFunction(const Condition *c) {
+ typedef bool (*FuncType)(T *);
+ FuncType fn = reinterpret_cast<FuncType>(c->function_);
+ T *x = static_cast<T *>(c->arg_);
+ return (*fn)(x);
+}
+
+template <typename T>
+inline Condition::Condition(bool (*func)(T *), T *arg)
+ : eval_(&CastAndCallFunction<T>),
+ function_(reinterpret_cast<InternalFunctionType>(func)),
+ method_(nullptr),
+ arg_(const_cast<void *>(static_cast<const void *>(arg))) {}
+
+template <typename T>
+inline Condition::Condition(T *object,
bool (y_absl::internal::identity<T>::type::*method)())
- : eval_(&CastAndCallMethod<T>),
- function_(nullptr),
- method_(reinterpret_cast<InternalMethodType>(method)),
- arg_(object) {}
-
-template <typename T>
-inline Condition::Condition(const T *object,
+ : eval_(&CastAndCallMethod<T>),
+ function_(nullptr),
+ method_(reinterpret_cast<InternalMethodType>(method)),
+ arg_(object) {}
+
+template <typename T>
+inline Condition::Condition(const T *object,
bool (y_absl::internal::identity<T>::type::*method)()
- const)
- : eval_(&CastAndCallMethod<T>),
- function_(nullptr),
- method_(reinterpret_cast<InternalMethodType>(method)),
- arg_(reinterpret_cast<void *>(const_cast<T *>(object))) {}
-
-// Register a hook for profiling support.
-//
-// The function pointer registered here will be called whenever a mutex is
+ const)
+ : eval_(&CastAndCallMethod<T>),
+ function_(nullptr),
+ method_(reinterpret_cast<InternalMethodType>(method)),
+ arg_(reinterpret_cast<void *>(const_cast<T *>(object))) {}
+
+// Register a hook for profiling support.
+//
+// The function pointer registered here will be called whenever a mutex is
// contended. The callback is given the y_absl/base/cycleclock.h timestamp when
-// waiting began.
-//
-// Calls to this function do not race or block, but there is no ordering
-// guaranteed between calls to this function and call to the provided hook.
-// In particular, the previously registered hook may still be called for some
-// time after this function returns.
-void RegisterMutexProfiler(void (*fn)(int64_t wait_timestamp));
-
-// Register a hook for Mutex tracing.
-//
-// The function pointer registered here will be called whenever a mutex is
-// contended. The callback is given an opaque handle to the contended mutex,
-// an event name, and the number of wait cycles (as measured by
+// waiting began.
+//
+// Calls to this function do not race or block, but there is no ordering
+// guaranteed between calls to this function and call to the provided hook.
+// In particular, the previously registered hook may still be called for some
+// time after this function returns.
+void RegisterMutexProfiler(void (*fn)(int64_t wait_timestamp));
+
+// Register a hook for Mutex tracing.
+//
+// The function pointer registered here will be called whenever a mutex is
+// contended. The callback is given an opaque handle to the contended mutex,
+// an event name, and the number of wait cycles (as measured by
// //y_absl/base/internal/cycleclock.h, and which may not be real
-// "cycle" counts.)
-//
-// The only event name currently sent is "slow release".
-//
-// This has the same memory ordering concerns as RegisterMutexProfiler() above.
-void RegisterMutexTracer(void (*fn)(const char *msg, const void *obj,
+// "cycle" counts.)
+//
+// The only event name currently sent is "slow release".
+//
+// This has the same memory ordering concerns as RegisterMutexProfiler() above.
+void RegisterMutexTracer(void (*fn)(const char *msg, const void *obj,
int64_t wait_cycles));
-
-// TODO(gfalcon): Combine RegisterMutexProfiler() and RegisterMutexTracer()
-// into a single interface, since they are only ever called in pairs.
-
-// Register a hook for CondVar tracing.
-//
-// The function pointer registered here will be called here on various CondVar
-// events. The callback is given an opaque handle to the CondVar object and
-// a string identifying the event. This is thread-safe, but only a single
-// tracer can be registered.
-//
-// Events that can be sent are "Wait", "Unwait", "Signal wakeup", and
-// "SignalAll wakeup".
-//
-// This has the same memory ordering concerns as RegisterMutexProfiler() above.
-void RegisterCondVarTracer(void (*fn)(const char *msg, const void *cv));
-
-// Register a hook for symbolizing stack traces in deadlock detector reports.
-//
-// 'pc' is the program counter being symbolized, 'out' is the buffer to write
-// into, and 'out_size' is the size of the buffer. This function can return
+
+// TODO(gfalcon): Combine RegisterMutexProfiler() and RegisterMutexTracer()
+// into a single interface, since they are only ever called in pairs.
+
+// Register a hook for CondVar tracing.
+//
+// The function pointer registered here will be called here on various CondVar
+// events. The callback is given an opaque handle to the CondVar object and
+// a string identifying the event. This is thread-safe, but only a single
+// tracer can be registered.
+//
+// Events that can be sent are "Wait", "Unwait", "Signal wakeup", and
+// "SignalAll wakeup".
+//
+// This has the same memory ordering concerns as RegisterMutexProfiler() above.
+void RegisterCondVarTracer(void (*fn)(const char *msg, const void *cv));
+
+// Register a hook for symbolizing stack traces in deadlock detector reports.
+//
+// 'pc' is the program counter being symbolized, 'out' is the buffer to write
+// into, and 'out_size' is the size of the buffer. This function can return
// false if symbolizing failed, or true if a NUL-terminated symbol was written
-// to 'out.'
-//
-// This has the same memory ordering concerns as RegisterMutexProfiler() above.
-//
+// to 'out.'
+//
+// This has the same memory ordering concerns as RegisterMutexProfiler() above.
+//
// DEPRECATED: The default symbolizer function is y_absl::Symbolize() and the
-// ability to register a different hook for symbolizing stack traces will be
-// removed on or after 2023-05-01.
+// ability to register a different hook for symbolizing stack traces will be
+// removed on or after 2023-05-01.
ABSL_DEPRECATED("y_absl::RegisterSymbolizer() is deprecated and will be removed "
- "on or after 2023-05-01")
-void RegisterSymbolizer(bool (*fn)(const void *pc, char *out, int out_size));
-
-// EnableMutexInvariantDebugging()
-//
-// Enable or disable global support for Mutex invariant debugging. If enabled,
-// then invariant predicates can be registered per-Mutex for debug checking.
-// See Mutex::EnableInvariantDebugging().
-void EnableMutexInvariantDebugging(bool enabled);
-
-// When in debug mode, and when the feature has been enabled globally, the
-// implementation will keep track of lock ordering and complain (or optionally
-// crash) if a cycle is detected in the acquired-before graph.
-
-// Possible modes of operation for the deadlock detector in debug mode.
-enum class OnDeadlockCycle {
- kIgnore, // Neither report on nor attempt to track cycles in lock ordering
- kReport, // Report lock cycles to stderr when detected
- kAbort, // Report lock cycles to stderr when detected, then abort
-};
-
-// SetMutexDeadlockDetectionMode()
-//
-// Enable or disable global support for detection of potential deadlocks
-// due to Mutex lock ordering inversions. When set to 'kIgnore', tracking of
-// lock ordering is disabled. Otherwise, in debug builds, a lock ordering graph
-// will be maintained internally, and detected cycles will be reported in
-// the manner chosen here.
-void SetMutexDeadlockDetectionMode(OnDeadlockCycle mode);
-
+ "on or after 2023-05-01")
+void RegisterSymbolizer(bool (*fn)(const void *pc, char *out, int out_size));
+
+// EnableMutexInvariantDebugging()
+//
+// Enable or disable global support for Mutex invariant debugging. If enabled,
+// then invariant predicates can be registered per-Mutex for debug checking.
+// See Mutex::EnableInvariantDebugging().
+void EnableMutexInvariantDebugging(bool enabled);
+
+// When in debug mode, and when the feature has been enabled globally, the
+// implementation will keep track of lock ordering and complain (or optionally
+// crash) if a cycle is detected in the acquired-before graph.
+
+// Possible modes of operation for the deadlock detector in debug mode.
+enum class OnDeadlockCycle {
+ kIgnore, // Neither report on nor attempt to track cycles in lock ordering
+ kReport, // Report lock cycles to stderr when detected
+ kAbort, // Report lock cycles to stderr when detected, then abort
+};
+
+// SetMutexDeadlockDetectionMode()
+//
+// Enable or disable global support for detection of potential deadlocks
+// due to Mutex lock ordering inversions. When set to 'kIgnore', tracking of
+// lock ordering is disabled. Otherwise, in debug builds, a lock ordering graph
+// will be maintained internally, and detected cycles will be reported in
+// the manner chosen here.
+void SetMutexDeadlockDetectionMode(OnDeadlockCycle mode);
+
ABSL_NAMESPACE_END
} // namespace y_absl
-
-// In some build configurations we pass --detect-odr-violations to the
-// gold linker. This causes it to flag weak symbol overrides as ODR
-// violations. Because ODR only applies to C++ and not C,
-// --detect-odr-violations ignores symbols not mangled with C++ names.
-// By changing our extension points to be extern "C", we dodge this
-// check.
-extern "C" {
+
+// In some build configurations we pass --detect-odr-violations to the
+// gold linker. This causes it to flag weak symbol overrides as ODR
+// violations. Because ODR only applies to C++ and not C,
+// --detect-odr-violations ignores symbols not mangled with C++ names.
+// By changing our extension points to be extern "C", we dodge this
+// check.
+extern "C" {
void ABSL_INTERNAL_C_SYMBOL(AbslInternalMutexYield)();
-} // extern "C"
-
-#endif // ABSL_SYNCHRONIZATION_MUTEX_H_
+} // extern "C"
+
+#endif // ABSL_SYNCHRONIZATION_MUTEX_H_