add ydb deps

1 files changed, 344 insertions, 0 deletions

diff --git a/contrib/tools/python3/src/Python/ceval_gil.h b/contrib/tools/python3/src/Python/ceval_gil.h
new file mode 100644
index 00000000000..476ed7f1a2d
--- /dev/null
+++ b/contrib/tools/python3/src/Python/ceval_gil.h
@@ -0,0 +1,344 @@
+/*
+ * Implementation of the Global Interpreter Lock (GIL).
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+
+#include "pycore_atomic.h"
+
+
+/*
+   Notes about the implementation:
+
+   - The GIL is just a boolean variable (locked) whose access is protected
+     by a mutex (gil_mutex), and whose changes are signalled by a condition
+     variable (gil_cond). gil_mutex is taken for short periods of time,
+     and therefore mostly uncontended.
+
+   - In the GIL-holding thread, the main loop (PyEval_EvalFrameEx) must be
+     able to release the GIL on demand by another thread. A volatile boolean
+     variable (gil_drop_request) is used for that purpose, which is checked
+     at every turn of the eval loop. That variable is set after a wait of
+     `interval` microseconds on `gil_cond` has timed out.
+
+      [Actually, another volatile boolean variable (eval_breaker) is used
+       which ORs several conditions into one. Volatile booleans are
+       sufficient as inter-thread signalling means since Python is run
+       on cache-coherent architectures only.]
+
+   - A thread wanting to take the GIL will first let pass a given amount of
+     time (`interval` microseconds) before setting gil_drop_request. This
+     encourages a defined switching period, but doesn't enforce it since
+     opcodes can take an arbitrary time to execute.
+
+     The `interval` value is available for the user to read and modify
+     using the Python API `sys.{get,set}switchinterval()`.
+
+   - When a thread releases the GIL and gil_drop_request is set, that thread
+     ensures that another GIL-awaiting thread gets scheduled.
+     It does so by waiting on a condition variable (switch_cond) until
+     the value of last_holder is changed to something else than its
+     own thread state pointer, indicating that another thread was able to
+     take the GIL.
+
+     This is meant to prohibit the latency-adverse behaviour on multi-core
+     machines where one thread would speculatively release the GIL, but still
+     run and end up being the first to re-acquire it, making the "timeslices"
+     much longer than expected.
+     (Note: this mechanism is enabled with FORCE_SWITCHING above)
+*/
+
+#include "condvar.h"
+
+#define MUTEX_INIT(mut) \
+    if (PyMUTEX_INIT(&(mut))) { \
+        Py_FatalError("PyMUTEX_INIT(" #mut ") failed"); };
+#define MUTEX_FINI(mut) \
+    if (PyMUTEX_FINI(&(mut))) { \
+        Py_FatalError("PyMUTEX_FINI(" #mut ") failed"); };
+#define MUTEX_LOCK(mut) \
+    if (PyMUTEX_LOCK(&(mut))) { \
+        Py_FatalError("PyMUTEX_LOCK(" #mut ") failed"); };
+#define MUTEX_UNLOCK(mut) \
+    if (PyMUTEX_UNLOCK(&(mut))) { \
+        Py_FatalError("PyMUTEX_UNLOCK(" #mut ") failed"); };
+
+#define COND_INIT(cond) \
+    if (PyCOND_INIT(&(cond))) { \
+        Py_FatalError("PyCOND_INIT(" #cond ") failed"); };
+#define COND_FINI(cond) \
+    if (PyCOND_FINI(&(cond))) { \
+        Py_FatalError("PyCOND_FINI(" #cond ") failed"); };
+#define COND_SIGNAL(cond) \
+    if (PyCOND_SIGNAL(&(cond))) { \
+        Py_FatalError("PyCOND_SIGNAL(" #cond ") failed"); };
+#define COND_WAIT(cond, mut) \
+    if (PyCOND_WAIT(&(cond), &(mut))) { \
+        Py_FatalError("PyCOND_WAIT(" #cond ") failed"); };
+#define COND_TIMED_WAIT(cond, mut, microseconds, timeout_result) \
+    { \
+        int r = PyCOND_TIMEDWAIT(&(cond), &(mut), (microseconds)); \
+        if (r < 0) \
+            Py_FatalError("PyCOND_WAIT(" #cond ") failed"); \
+        if (r) /* 1 == timeout, 2 == impl. can't say, so assume timeout */ \
+            timeout_result = 1; \
+        else \
+            timeout_result = 0; \
+    } \
+
+
+#define DEFAULT_INTERVAL 5000
+
+static void _gil_initialize(struct _gil_runtime_state *gil)
+{
+    _Py_atomic_int uninitialized = {-1};
+    gil->locked = uninitialized;
+    gil->interval = DEFAULT_INTERVAL;
+}
+
+static int gil_created(struct _gil_runtime_state *gil)
+{
+    return (_Py_atomic_load_explicit(&gil->locked, _Py_memory_order_acquire) >= 0);
+}
+
+static void create_gil(struct _gil_runtime_state *gil)
+{
+    MUTEX_INIT(gil->mutex);
+#ifdef FORCE_SWITCHING
+    MUTEX_INIT(gil->switch_mutex);
+#endif
+    COND_INIT(gil->cond);
+#ifdef FORCE_SWITCHING
+    COND_INIT(gil->switch_cond);
+#endif
+    _Py_atomic_store_relaxed(&gil->last_holder, 0);
+    _Py_ANNOTATE_RWLOCK_CREATE(&gil->locked);
+    _Py_atomic_store_explicit(&gil->locked, 0, _Py_memory_order_release);
+}
+
+static void destroy_gil(struct _gil_runtime_state *gil)
+{
+    /* some pthread-like implementations tie the mutex to the cond
+     * and must have the cond destroyed first.
+     */
+    COND_FINI(gil->cond);
+    MUTEX_FINI(gil->mutex);
+#ifdef FORCE_SWITCHING
+    COND_FINI(gil->switch_cond);
+    MUTEX_FINI(gil->switch_mutex);
+#endif
+    _Py_atomic_store_explicit(&gil->locked, -1,
+                              _Py_memory_order_release);
+    _Py_ANNOTATE_RWLOCK_DESTROY(&gil->locked);
+}
+
+#ifdef HAVE_FORK
+static void recreate_gil(struct _gil_runtime_state *gil)
+{
+    _Py_ANNOTATE_RWLOCK_DESTROY(&gil->locked);
+    /* XXX should we destroy the old OS resources here? */
+    create_gil(gil);
+}
+#endif
+
+static void
+drop_gil(struct _ceval_runtime_state *ceval, struct _ceval_state *ceval2,
+         PyThreadState *tstate)
+{
+    struct _gil_runtime_state *gil = &ceval->gil;
+    if (!_Py_atomic_load_relaxed(&gil->locked)) {
+        Py_FatalError("drop_gil: GIL is not locked");
+    }
+
+    /* tstate is allowed to be NULL (early interpreter init) */
+    if (tstate != NULL) {
+        /* Sub-interpreter support: threads might have been switched
+           under our feet using PyThreadState_Swap(). Fix the GIL last
+           holder variable so that our heuristics work. */
+        _Py_atomic_store_relaxed(&gil->last_holder, (uintptr_t)tstate);
+    }
+
+    MUTEX_LOCK(gil->mutex);
+    _Py_ANNOTATE_RWLOCK_RELEASED(&gil->locked, /*is_write=*/1);
+    _Py_atomic_store_relaxed(&gil->locked, 0);
+    COND_SIGNAL(gil->cond);
+    MUTEX_UNLOCK(gil->mutex);
+
+#ifdef FORCE_SWITCHING
+    if (_Py_atomic_load_relaxed(&ceval2->gil_drop_request) && tstate != NULL) {
+        MUTEX_LOCK(gil->switch_mutex);
+        /* Not switched yet => wait */
+        if (((PyThreadState*)_Py_atomic_load_relaxed(&gil->last_holder)) == tstate)
+        {
+            assert(is_tstate_valid(tstate));
+            RESET_GIL_DROP_REQUEST(tstate->interp);
+            /* NOTE: if COND_WAIT does not atomically start waiting when
+               releasing the mutex, another thread can run through, take
+               the GIL and drop it again, and reset the condition
+               before we even had a chance to wait for it. */
+            COND_WAIT(gil->switch_cond, gil->switch_mutex);
+        }
+        MUTEX_UNLOCK(gil->switch_mutex);
+    }
+#endif
+}
+
+
+/* Check if a Python thread must exit immediately, rather than taking the GIL
+   if Py_Finalize() has been called.
+
+   When this function is called by a daemon thread after Py_Finalize() has been
+   called, the GIL does no longer exist.
+
+   tstate must be non-NULL. */
+static inline int
+tstate_must_exit(PyThreadState *tstate)
+{
+    /* bpo-39877: Access _PyRuntime directly rather than using
+       tstate->interp->runtime to support calls from Python daemon threads.
+       After Py_Finalize() has been called, tstate can be a dangling pointer:
+       point to PyThreadState freed memory. */
+    PyThreadState *finalizing = _PyRuntimeState_GetFinalizing(&_PyRuntime);
+    return (finalizing != NULL && finalizing != tstate);
+}
+
+
+/* Take the GIL.
+
+   The function saves errno at entry and restores its value at exit.
+
+   tstate must be non-NULL. */
+static void
+take_gil(PyThreadState *tstate)
+{
+    int err = errno;
+
+    assert(tstate != NULL);
+
+    if (tstate_must_exit(tstate)) {
+        /* bpo-39877: If Py_Finalize() has been called and tstate is not the
+           thread which called Py_Finalize(), exit immediately the thread.
+
+           This code path can be reached by a daemon thread after Py_Finalize()
+           completes. In this case, tstate is a dangling pointer: points to
+           PyThreadState freed memory. */
+        PyThread_exit_thread();
+    }
+
+    assert(is_tstate_valid(tstate));
+    PyInterpreterState *interp = tstate->interp;
+    struct _ceval_runtime_state *ceval = &interp->runtime->ceval;
+    struct _ceval_state *ceval2 = &interp->ceval;
+    struct _gil_runtime_state *gil = &ceval->gil;
+
+    /* Check that _PyEval_InitThreads() was called to create the lock */
+    assert(gil_created(gil));
+
+    MUTEX_LOCK(gil->mutex);
+
+    if (!_Py_atomic_load_relaxed(&gil->locked)) {
+        goto _ready;
+    }
+
+    int drop_requested = 0;
+    while (_Py_atomic_load_relaxed(&gil->locked)) {
+        unsigned long saved_switchnum = gil->switch_number;
+
+        unsigned long interval = (gil->interval >= 1 ? gil->interval : 1);
+        int timed_out = 0;
+        COND_TIMED_WAIT(gil->cond, gil->mutex, interval, timed_out);
+
+        /* If we timed out and no switch occurred in the meantime, it is time
+           to ask the GIL-holding thread to drop it. */
+        if (timed_out &&
+            _Py_atomic_load_relaxed(&gil->locked) &&
+            gil->switch_number == saved_switchnum)
+        {
+            if (tstate_must_exit(tstate)) {
+                MUTEX_UNLOCK(gil->mutex);
+                // gh-96387: If the loop requested a drop request in a previous
+                // iteration, reset the request. Otherwise, drop_gil() can
+                // block forever waiting for the thread which exited. Drop
+                // requests made by other threads are also reset: these threads
+                // may have to request again a drop request (iterate one more
+                // time).
+                if (drop_requested) {
+                    RESET_GIL_DROP_REQUEST(interp);
+                }
+                PyThread_exit_thread();
+            }
+            assert(is_tstate_valid(tstate));
+
+            SET_GIL_DROP_REQUEST(interp);
+            drop_requested = 1;
+        }
+    }
+
+_ready:
+#ifdef FORCE_SWITCHING
+    /* This mutex must be taken before modifying gil->last_holder:
+       see drop_gil(). */
+    MUTEX_LOCK(gil->switch_mutex);
+#endif
+    /* We now hold the GIL */
+    _Py_atomic_store_relaxed(&gil->locked, 1);
+    _Py_ANNOTATE_RWLOCK_ACQUIRED(&gil->locked, /*is_write=*/1);
+
+    if (tstate != (PyThreadState*)_Py_atomic_load_relaxed(&gil->last_holder)) {
+        _Py_atomic_store_relaxed(&gil->last_holder, (uintptr_t)tstate);
+        ++gil->switch_number;
+    }
+
+#ifdef FORCE_SWITCHING
+    COND_SIGNAL(gil->switch_cond);
+    MUTEX_UNLOCK(gil->switch_mutex);
+#endif
+
+    if (tstate_must_exit(tstate)) {
+        /* bpo-36475: If Py_Finalize() has been called and tstate is not
+           the thread which called Py_Finalize(), exit immediately the
+           thread.
+
+           This code path can be reached by a daemon thread which was waiting
+           in take_gil() while the main thread called
+           wait_for_thread_shutdown() from Py_Finalize(). */
+        MUTEX_UNLOCK(gil->mutex);
+        drop_gil(ceval, ceval2, tstate);
+        PyThread_exit_thread();
+    }
+    assert(is_tstate_valid(tstate));
+
+    if (_Py_atomic_load_relaxed(&ceval2->gil_drop_request)) {
+        RESET_GIL_DROP_REQUEST(interp);
+    }
+    else {
+        /* bpo-40010: eval_breaker should be recomputed to be set to 1 if there
+           is a pending signal: signal received by another thread which cannot
+           handle signals.
+
+           Note: RESET_GIL_DROP_REQUEST() calls COMPUTE_EVAL_BREAKER(). */
+        COMPUTE_EVAL_BREAKER(interp, ceval, ceval2);
+    }
+
+    /* Don't access tstate if the thread must exit */
+    if (tstate->async_exc != NULL) {
+        _PyEval_SignalAsyncExc(tstate->interp);
+    }
+
+    MUTEX_UNLOCK(gil->mutex);
+
+    errno = err;
+}
+
+void _PyEval_SetSwitchInterval(unsigned long microseconds)
+{
+    struct _gil_runtime_state *gil = &_PyRuntime.ceval.gil;
+    gil->interval = microseconds;
+}
+
+unsigned long _PyEval_GetSwitchInterval()
+{
+    struct _gil_runtime_state *gil = &_PyRuntime.ceval.gil;
+    return gil->interval;
+}