| /* |
| * |
| * Copyright 2015, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #include <grpc++/impl/sync.h> |
| #include <grpc++/impl/thd.h> |
| |
| #include "src/cpp/server/dynamic_thread_pool.h" |
| |
| namespace grpc { |
| DynamicThreadPool::DynamicThread::DynamicThread(DynamicThreadPool* pool) |
| : pool_(pool), |
| thd_(new grpc::thread(&DynamicThreadPool::DynamicThread::ThreadFunc, |
| this)) {} |
| DynamicThreadPool::DynamicThread::~DynamicThread() { |
| thd_->join(); |
| thd_.reset(); |
| } |
| |
| void DynamicThreadPool::DynamicThread::ThreadFunc() { |
| pool_->ThreadFunc(); |
| // Now that we have killed ourselves, we should reduce the thread count |
| grpc::unique_lock<grpc::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. |
| grpc::unique_lock<grpc::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++) { |
| grpc::lock_guard<grpc::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() { |
| grpc::unique_lock<grpc::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) { |
| grpc::lock_guard<grpc::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 |