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c89fdd716c
PlatformThread's API is using old style function pointers, causes casting, is unintuitive and forces artificial call sequences, and is additionally possible to misuse in release mode. Fix this by an API face lift: 1. The class is turned into a handle, which can be empty. 2. The only way of getting a non-empty PlatformThread is by calling SpawnJoinable or SpawnDetached, clearly conveying the semantics to the code reader. 3. Handles can be Finalized, which works differently for joinable and detached threads: a) Handles for detached threads are simply closed where applicable. b) Joinable threads are joined before handles are closed. 4. The destructor finalizes handles. No explicit call is needed. Fixed: webrtc:12727 Change-Id: Id00a0464edf4fc9e552b6a1fbb5d2e1280e88811 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215075 Commit-Queue: Markus Handell <handellm@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Tommi <tommi@webrtc.org> Cr-Commit-Position: refs/heads/master@{#33923}
113 lines
3.7 KiB
C++
113 lines
3.7 KiB
C++
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef RTC_BASE_PLATFORM_THREAD_H_
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#define RTC_BASE_PLATFORM_THREAD_H_
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#include <functional>
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#include <string>
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#include "absl/strings/string_view.h"
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#include "absl/types/optional.h"
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#include "rtc_base/platform_thread_types.h"
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namespace rtc {
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enum class ThreadPriority {
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kLow = 1,
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kNormal,
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kHigh,
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kRealtime,
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};
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struct ThreadAttributes {
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ThreadPriority priority = ThreadPriority::kNormal;
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ThreadAttributes& SetPriority(ThreadPriority priority_param) {
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priority = priority_param;
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return *this;
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}
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};
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// Represents a simple worker thread.
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class PlatformThread final {
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public:
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// Handle is the base platform thread handle.
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#if defined(WEBRTC_WIN)
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using Handle = HANDLE;
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#else
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using Handle = pthread_t;
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#endif // defined(WEBRTC_WIN)
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// This ctor creates the PlatformThread with an unset handle (returning true
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// in empty()) and is provided for convenience.
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// TODO(bugs.webrtc.org/12727) Look into if default and move support can be
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// removed.
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PlatformThread() = default;
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// Moves |rhs| into this, storing an empty state in |rhs|.
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// TODO(bugs.webrtc.org/12727) Look into if default and move support can be
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// removed.
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PlatformThread(PlatformThread&& rhs);
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// Moves |rhs| into this, storing an empty state in |rhs|.
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// TODO(bugs.webrtc.org/12727) Look into if default and move support can be
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// removed.
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PlatformThread& operator=(PlatformThread&& rhs);
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// For a PlatformThread that's been spawned joinable, the destructor suspends
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// the calling thread until the created thread exits unless the thread has
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// already exited.
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virtual ~PlatformThread();
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// Finalizes any allocated resources.
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// For a PlatformThread that's been spawned joinable, Finalize() suspends
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// the calling thread until the created thread exits unless the thread has
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// already exited.
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// empty() returns true after completion.
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void Finalize();
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// Returns true if default constructed, moved from, or Finalize()ed.
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bool empty() const { return !handle_.has_value(); }
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// Creates a started joinable thread which will be joined when the returned
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// PlatformThread destructs or Finalize() is called.
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static PlatformThread SpawnJoinable(
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std::function<void()> thread_function,
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absl::string_view name,
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ThreadAttributes attributes = ThreadAttributes());
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// Creates a started detached thread. The caller has to use external
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// synchronization as nothing is provided by the PlatformThread construct.
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static PlatformThread SpawnDetached(
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std::function<void()> thread_function,
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absl::string_view name,
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ThreadAttributes attributes = ThreadAttributes());
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// Returns the base platform thread handle of this thread.
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absl::optional<Handle> GetHandle() const;
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#if defined(WEBRTC_WIN)
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// Queue a Windows APC function that runs when the thread is alertable.
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bool QueueAPC(PAPCFUNC apc_function, ULONG_PTR data);
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#endif
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private:
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PlatformThread(Handle handle, bool joinable);
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static PlatformThread SpawnThread(std::function<void()> thread_function,
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absl::string_view name,
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ThreadAttributes attributes,
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bool joinable);
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absl::optional<Handle> handle_;
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bool joinable_ = false;
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};
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} // namespace rtc
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#endif // RTC_BASE_PLATFORM_THREAD_H_
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