2 * Copyright 2014 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
19 #include <folly/wangle/channel/ChannelHandler.h>
20 #include <folly/io/async/EventBase.h>
21 #include <folly/io/async/EventBaseManager.h>
22 #include <folly/io/IOBuf.h>
23 #include <folly/io/IOBufQueue.h>
25 namespace folly { namespace wangle {
28 * OutputBufferingHandler buffers writes in order to minimize syscalls. The
29 * transport will be written to once per event loop instead of on every write.
31 class OutputBufferingHandler : public BytesToBytesHandler,
32 protected EventBase::LoopCallback {
34 Future<void> write(Context* ctx, std::unique_ptr<IOBuf> buf) override {
37 return ctx->fireWrite(std::move(buf));
40 // Delay sends to optimize for fewer syscalls
42 DCHECK(!isLoopCallbackScheduled());
43 // Buffer all the sends, and call writev once per event loop.
44 sends_ = std::move(buf);
45 ctx->getTransport()->getEventBase()->runInLoop(this);
47 DCHECK(isLoopCallbackScheduled());
48 sends_->prependChain(std::move(buf));
51 auto f = p.getFuture();
52 promises_.push_back(std::move(p));
57 void runLoopCallback() noexcept override {
58 MoveWrapper<std::vector<Promise<void>>> promises(std::move(promises_));
59 ctx_->fireWrite(std::move(sends_)).then([promises](Try<void> t) mutable {
60 for (auto& p : *promises) {
66 std::vector<Promise<void>> promises_;
67 std::unique_ptr<IOBuf> sends_{nullptr};
68 bool queueSends_{true};