Fix: race-conditions in GUI updates when downloading HTTP files
(cherry picked from commit 56c6df4702015fda7cc7a05b67bfe90b3ede1ad0) See: https://github.com/OpenTTD/OpenTTD/issues/11636 See: https://github.com/OpenTTD/OpenTTD/pull/11639wip-string
Patric Stout
6 months ago
committed by
Jonathan G Rennison
parent
673a0dc5de
commit
6e7c92e3af
@ -0,0 +1,124 @@
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/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file http.h Shared functions for implementations of HTTP requests.
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*/
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#ifndef NETWORK_CORE_HTTP_SHARED_H
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#define NETWORK_CORE_HTTP_SHARED_H
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#include "http.h"
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#include <condition_variable>
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#include <mutex>
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#include <vector>
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/** Converts a HTTPCallback to a Thread-Safe variant. */
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class HTTPThreadSafeCallback {
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private:
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/** Entries on the queue for later handling. */
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class Callback {
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public:
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Callback(const char *data, size_t length) : data(data), length(length), failure(false) {}
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Callback() : data(nullptr), length(0), failure(true) {}
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const char *data;
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size_t length;
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bool failure;
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};
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public:
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/**
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* Similar to HTTPCallback::OnFailure, but thread-safe.
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*/
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void OnFailure()
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{
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std::lock_guard<std::mutex> lock(this->mutex);
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this->queue.emplace_back();
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}
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/**
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* Similar to HTTPCallback::OnReceiveData, but thread-safe.
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*/
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void OnReceiveData(const char *data, size_t length)
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{
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std::lock_guard<std::mutex> lock(this->mutex);
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this->queue.emplace_back(data, length);
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}
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/**
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* Process everything on the queue.
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*
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* Should be called from the Game Thread.
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*/
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void HandleQueue()
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{
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this->cancelled = callback->IsCancelled();
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std::lock_guard<std::mutex> lock(this->mutex);
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for (auto &item : this->queue) {
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if (item.failure) {
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this->callback->OnFailure();
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} else {
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this->callback->OnReceiveData(item.data, item.length);
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}
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}
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this->queue.clear();
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this->queue_cv.notify_all();
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}
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/**
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* Wait till the queue is dequeued.
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*/
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void WaitTillEmpty()
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{
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std::unique_lock<std::mutex> lock(this->mutex);
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while (!queue.empty()) {
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this->queue_cv.wait(lock);
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}
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}
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/**
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* Check if the queue is empty.
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*/
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bool IsQueueEmpty()
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{
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std::lock_guard<std::mutex> lock(this->mutex);
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return this->queue.empty();
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}
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HTTPThreadSafeCallback(HTTPCallback *callback) : callback(callback) {}
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~HTTPThreadSafeCallback()
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{
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std::lock_guard<std::mutex> lock(this->mutex);
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/* Free all data that was not handled. */
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for (auto &item : this->queue) {
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if (!item.failure) {
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free(item.data);
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}
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}
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queue.clear();
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queue_cv.notify_all();
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}
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std::atomic<bool> cancelled = false;
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private:
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HTTPCallback *callback; ///< The callback to send data back on.
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std::mutex mutex; ///< Mutex to protect the queue.
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std::vector<Callback> queue; ///< Queue of data to send back.
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std::condition_variable queue_cv; ///< Condition variable to wait for the queue to be empty.
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};
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#endif /* NETWORK_CORE_HTTP_SHARED_H */
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