1 /*
2 * Copyright (c) Facebook, Inc. and its affiliates.
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17 #pragma once
18
19 namespace wangle {
20
21 template <typename T, typename R, typename P>
22 folly::Future<BroadcastHandler<T, R>*>
getHandler()23 BroadcastPool<T, R, P>::BroadcastManager::getHandler() {
24 // getFuture() returns a completed future if we are already connected
25 // Set the executor to the InlineExecutor because subsequent code depends
26 // on the future callback being called inline to ensure that the handler
27 // is not garbage collected before use.
28 auto future =
29 sharedPromise_.getFuture().via(&folly::InlineExecutor::instance());
30
31 if (connectStarted_) {
32 // Either already connected, in which case the future has the handler,
33 // or there's an outstanding connect request and the promise will be
34 // fulfilled when the connect request completes.
35 return future;
36 }
37
38 // Kickoff connect request and fulfill all pending promises on completion
39 connectStarted_ = true;
40
41 broadcastPool_->serverPool_->connect(client_.get(), routingData_)
42 .thenValue([this](DefaultPipeline* pipeline) {
43 DestructorGuard dg(this);
44 pipeline->setPipelineManager(this);
45
46 auto pipelineFactory = broadcastPool_->broadcastPipelineFactory_;
47 try {
48 pipelineFactory->setRoutingData(pipeline, routingData_);
49 } catch (const std::exception& ex) {
50 handleConnectError(ex);
51 return;
52 }
53
54 if (deletingBroadcast_) {
55 // setRoutingData() could result in an error that would cause the
56 // BroadcastPipeline to get deleted.
57 handleConnectError(std::runtime_error(
58 "Broadcast deleted due to upstream connection error"));
59 return;
60 }
61
62 auto handler = pipelineFactory->getBroadcastHandler(pipeline);
63 CHECK(handler);
64 sharedPromise_.setValue(handler);
65
66 // If all the observers go away before connect returns, then the
67 // BroadcastHandler will be idle without any subscribers. Close
68 // the pipeline and remove the broadcast from the pool so that
69 // connections are not leaked.
70 handler->closeIfIdle();
71 })
72 .thenError(
73 folly::tag_t<std::exception>{},
74 [this](const std::exception& ex) { handleConnectError(ex); });
75
76 return future;
77 }
78
79 template <typename T, typename R, typename P>
deletePipeline(PipelineBase * pipeline)80 void BroadcastPool<T, R, P>::BroadcastManager::deletePipeline(
81 PipelineBase* pipeline) {
82 CHECK(client_->getPipeline() == pipeline);
83 deletingBroadcast_ = true;
84 broadcastPool_->deleteBroadcast(routingData_);
85 }
86
87 template <typename T, typename R, typename P>
handleConnectError(const std::exception & ex)88 void BroadcastPool<T, R, P>::BroadcastManager::handleConnectError(
89 const std::exception& ex) noexcept {
90 LOG(ERROR) << "Error connecting to upstream: " << ex.what();
91
92 auto sharedPromise = std::move(sharedPromise_);
93 broadcastPool_->deleteBroadcast(routingData_);
94 sharedPromise.setException(folly::make_exception_wrapper<std::exception>(ex));
95 }
96
97 template <typename T, typename R, typename P>
getHandler(const R & routingData)98 folly::Future<BroadcastHandler<T, R>*> BroadcastPool<T, R, P>::getHandler(
99 const R& routingData) {
100 const auto& iter = broadcasts_.find(routingData);
101 if (iter != broadcasts_.end()) {
102 return iter->second->getHandler();
103 }
104
105 typename BroadcastManager::UniquePtr broadcast(
106 new BroadcastManager(this, routingData));
107
108 auto broadcastPtr = broadcast.get();
109 broadcasts_.insert(std::make_pair(routingData, std::move(broadcast)));
110
111 // The executor on this future is set to be an InlineExecutor to ensure that
112 // the continuation can be run inline and satisfy the lifetime requirement
113 // on the return value of this function.
114 return broadcastPtr->getHandler();
115 }
116
117 } // namespace wangle
118