grpcio-sys 0.5.0-alpha

FFI bindings to gRPC c core library
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125

/*
 *
 * 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 "src/cpp/server/dynamic_thread_pool.h"

#include <mutex>

#include <grpc/support/log.h>

#include "src/core/lib/gprpp/thd.h"

namespace grpc {

DynamicThreadPool::DynamicThread::DynamicThread(DynamicThreadPool* pool)
    : pool_(pool),
      thd_("grpcpp_dynamic_pool",
           [](void* th) {
             static_cast<DynamicThreadPool::DynamicThread*>(th)->ThreadFunc();
           },
           this) {
  thd_.Start();
}
DynamicThreadPool::DynamicThread::~DynamicThread() { thd_.Join(); }

void DynamicThreadPool::DynamicThread::ThreadFunc() {
  pool_->ThreadFunc();
  // Now that we have killed ourselves, we should reduce the thread count
  std::unique_lock<std::mutex> lock(pool_->mu_);
  pool_->nthreads_--;
  // Move ourselves to dead list
  pool_->dead_threads_.push_back(this);

  if ((pool_->shutdown_) && (pool_->nthreads_ == 0)) {
    pool_->shutdown_cv_.notify_one();
  }
}

void DynamicThreadPool::ThreadFunc() {
  for (;;) {
    // Wait until work is available or we are shutting down.
    std::unique_lock<std::mutex> lock(mu_);
    if (!shutdown_ && callbacks_.empty()) {
      // If there are too many threads waiting, then quit this thread
      if (threads_waiting_ >= reserve_threads_) {
        break;
      }
      threads_waiting_++;
      cv_.wait(lock);
      threads_waiting_--;
    }
    // Drain callbacks before considering shutdown to ensure all work
    // gets completed.
    if (!callbacks_.empty()) {
      auto cb = callbacks_.front();
      callbacks_.pop();
      lock.unlock();
      cb();
    } else if (shutdown_) {
      break;
    }
  }
}

DynamicThreadPool::DynamicThreadPool(int reserve_threads)
    : shutdown_(false),
      reserve_threads_(reserve_threads),
      nthreads_(0),
      threads_waiting_(0) {
  for (int i = 0; i < reserve_threads_; i++) {
    std::lock_guard<std::mutex> lock(mu_);
    nthreads_++;
    new DynamicThread(this);
  }
}

void DynamicThreadPool::ReapThreads(std::list<DynamicThread*>* tlist) {
  for (auto t = tlist->begin(); t != tlist->end(); t = tlist->erase(t)) {
    delete *t;
  }
}

DynamicThreadPool::~DynamicThreadPool() {
  std::unique_lock<std::mutex> lock(mu_);
  shutdown_ = true;
  cv_.notify_all();
  while (nthreads_ != 0) {
    shutdown_cv_.wait(lock);
  }
  ReapThreads(&dead_threads_);
}

void DynamicThreadPool::Add(const std::function<void()>& callback) {
  std::lock_guard<std::mutex> lock(mu_);
  // Add works to the callbacks list
  callbacks_.push(callback);
  // Increase pool size or notify as needed
  if (threads_waiting_ == 0) {
    // Kick off a new thread
    nthreads_++;
    new DynamicThread(this);
  } else {
    cv_.notify_one();
  }
  // Also use this chance to harvest dead threads
  if (!dead_threads_.empty()) {
    ReapThreads(&dead_threads_);
  }
}

}  // namespace grpc