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//
// Copyright 2015 gRPC 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
//
// http://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.
//
//
#include <vector>
#include "y_absl/base/thread_annotations.h"
#include <grpc/grpc.h>
#include <grpc/support/cpu.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <grpc/support/time.h>
#include <grpcpp/completion_queue.h>
#include <grpcpp/impl/completion_queue_tag.h>
#include <grpcpp/impl/grpc_library.h>
#include "src/core/lib/gpr/useful.h"
#include "src/core/lib/gprpp/sync.h"
#include "src/core/lib/gprpp/thd.h"
#include "src/core/lib/gprpp/env.h"
#include "src/core/lib/gpr/string.h"
namespace grpc {
namespace {
size_t GetNextingThreadNumFromEnv() {
auto value = grpc_core::GetEnv("GRPC_NEXTING_THREAD_NUM_ENV");
if (!value.has_value()) return 0;
int parse_succeeded = gpr_parse_nonnegative_int(value->c_str());
if (parse_succeeded <= 0) {
return 0;
}
return static_cast<size_t>(parse_succeeded);
}
gpr_once g_once_init_callback_alternative = GPR_ONCE_INIT;
grpc_core::Mutex* g_callback_alternative_mu;
// Implement a ref-counted callback CQ for global use in the alternative
// implementation so that its threads are only created once. Do this using
// explicit ref-counts and raw pointers rather than a shared-ptr since that
// has a non-trivial destructor and thus can't be used for global variables.
struct CallbackAlternativeCQ {
int refs Y_ABSL_GUARDED_BY(g_callback_alternative_mu) = 0;
CompletionQueue* cq Y_ABSL_GUARDED_BY(g_callback_alternative_mu);
std::vector<grpc_core::Thread>* nexting_threads
Y_ABSL_GUARDED_BY(g_callback_alternative_mu);
CompletionQueue* Ref() {
grpc_core::MutexLock lock(&*g_callback_alternative_mu);
refs++;
if (refs == 1) {
cq = new CompletionQueue;
int num_nexting_threads =
grpc_core::Clamp(gpr_cpu_num_cores() / 2, 2u, 16u);
auto threads_limit_env = GetNextingThreadNumFromEnv();
if (threads_limit_env) {
gpr_log(GPR_INFO, "Nexting thread number changed via env from %d to %zd", num_nexting_threads, threads_limit_env);
num_nexting_threads = static_cast<int>(threads_limit_env);
}
nexting_threads = new std::vector<grpc_core::Thread>;
for (int i = 0; i < num_nexting_threads; i++) {
nexting_threads->emplace_back(
"nexting_thread",
[](void* arg) {
grpc_completion_queue* cq =
static_cast<CompletionQueue*>(arg)->cq();
while (true) {
// Use the raw Core next function rather than the C++ Next since
// Next incorporates FinalizeResult and we actually want that
// called from the callback functor itself.
// TODO(vjpai): Migrate below to next without a timeout or idle
// phase. That's currently starving out some other polling,
// though.
auto ev = grpc_completion_queue_next(
cq,
gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
gpr_time_from_millis(1000, GPR_TIMESPAN)),
nullptr);
if (ev.type == GRPC_QUEUE_SHUTDOWN) {
return;
}
if (ev.type == GRPC_QUEUE_TIMEOUT) {
gpr_sleep_until(
gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
gpr_time_from_millis(100, GPR_TIMESPAN)));
continue;
}
GPR_DEBUG_ASSERT(ev.type == GRPC_OP_COMPLETE);
// We can always execute the callback inline rather than
// pushing it to another Executor thread because this
// thread is definitely running on a background thread, does not
// hold any application locks before executing the callback,
// and cannot be entered recursively.
auto* functor =
static_cast<grpc_completion_queue_functor*>(ev.tag);
functor->functor_run(functor, ev.success);
}
},
cq);
}
for (auto& th : *nexting_threads) {
th.Start();
}
}
return cq;
}
void Unref() {
grpc_core::MutexLock lock(g_callback_alternative_mu);
refs--;
if (refs == 0) {
cq->Shutdown();
for (auto& th : *nexting_threads) {
th.Join();
}
delete nexting_threads;
delete cq;
}
}
};
CallbackAlternativeCQ g_callback_alternative_cq;
} // namespace
// 'CompletionQueue' constructor can safely call GrpcLibraryCodegen(false) here
// i.e not have GrpcLibraryCodegen call grpc_init(). This is because, to create
// a 'grpc_completion_queue' instance (which is being passed as the input to
// this constructor), one must have already called grpc_init().
CompletionQueue::CompletionQueue(grpc_completion_queue* take)
: GrpcLibrary(false), cq_(take) {
InitialAvalanching();
}
void CompletionQueue::Shutdown() {
#ifndef NDEBUG
if (!ServerListEmpty()) {
gpr_log(GPR_ERROR,
"CompletionQueue shutdown being shutdown before its server.");
}
#endif
CompleteAvalanching();
}
CompletionQueue::NextStatus CompletionQueue::AsyncNextInternal(
void** tag, bool* ok, gpr_timespec deadline) {
for (;;) {
auto ev = grpc_completion_queue_next(cq_, deadline, nullptr);
switch (ev.type) {
case GRPC_QUEUE_TIMEOUT:
return TIMEOUT;
case GRPC_QUEUE_SHUTDOWN:
return SHUTDOWN;
case GRPC_OP_COMPLETE:
auto core_cq_tag =
static_cast<grpc::internal::CompletionQueueTag*>(ev.tag);
*ok = ev.success != 0;
*tag = core_cq_tag;
if (core_cq_tag->FinalizeResult(tag, ok)) {
return GOT_EVENT;
}
break;
}
}
}
CompletionQueue::CompletionQueueTLSCache::CompletionQueueTLSCache(
CompletionQueue* cq)
: cq_(cq), flushed_(false) {
grpc_completion_queue_thread_local_cache_init(cq_->cq_);
}
CompletionQueue::CompletionQueueTLSCache::~CompletionQueueTLSCache() {
GPR_ASSERT(flushed_);
}
bool CompletionQueue::CompletionQueueTLSCache::Flush(void** tag, bool* ok) {
int res = 0;
void* res_tag;
flushed_ = true;
if (grpc_completion_queue_thread_local_cache_flush(cq_->cq_, &res_tag,
&res)) {
auto core_cq_tag =
static_cast<grpc::internal::CompletionQueueTag*>(res_tag);
*ok = res == 1;
if (core_cq_tag->FinalizeResult(tag, ok)) {
return true;
}
}
return false;
}
CompletionQueue* CompletionQueue::CallbackAlternativeCQ() {
gpr_once_init(&g_once_init_callback_alternative,
[] { g_callback_alternative_mu = new grpc_core::Mutex(); });
return g_callback_alternative_cq.Ref();
}
void CompletionQueue::ReleaseCallbackAlternativeCQ(CompletionQueue* cq)
Y_ABSL_NO_THREAD_SAFETY_ANALYSIS {
(void)cq;
// This accesses g_callback_alternative_cq without acquiring the mutex
// but it's considered safe because it just reads the pointer address.
GPR_DEBUG_ASSERT(cq == g_callback_alternative_cq.cq);
g_callback_alternative_cq.Unref();
}
} // namespace grpc
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