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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_THREAD_H_
#define BASE_THREAD_H_
#include <stdint.h>
#include <string>
#include "base/message_loop.h"
#include "base/platform_thread.h"
namespace base {
// A simple thread abstraction that establishes a MessageLoop on a new thread.
// The consumer uses the MessageLoop of the thread to cause code to execute on
// the thread. When this object is destroyed the thread is terminated. All
// pending tasks queued on the thread's message loop will run to completion
// before the thread is terminated.
class Thread : PlatformThread::Delegate {
public:
struct Options {
// Specifies the type of message loop that will be allocated on the thread.
MessageLoop::Type message_loop_type;
// Specifies the maximum stack size that the thread is allowed to use.
// This does not necessarily correspond to the thread's initial stack size.
// A value of 0 indicates that the default maximum should be used.
size_t stack_size;
// Specifies the transient and permanent hang timeouts for background hang
// monitoring. A value of 0 indicates there is no timeout.
uint32_t transient_hang_timeout;
uint32_t permanent_hang_timeout;
Options()
: message_loop_type(MessageLoop::TYPE_DEFAULT),
stack_size(0),
transient_hang_timeout(0),
permanent_hang_timeout(0) {}
Options(MessageLoop::Type type, size_t size)
: message_loop_type(type),
stack_size(size),
transient_hang_timeout(0),
permanent_hang_timeout(0) {}
};
// Constructor.
// name is a display string to identify the thread.
explicit Thread(const char* name);
// Destroys the thread, stopping it if necessary.
//
// NOTE: If you are subclassing from Thread, and you wish for your CleanUp
// method to be called, then you need to call Stop() from your destructor.
//
virtual ~Thread();
// Starts the thread. Returns true if the thread was successfully started;
// otherwise, returns false. Upon successful return, the message_loop()
// getter will return non-null.
//
// Note: This function can't be called on Windows with the loader lock held;
// i.e. during a DllMain, global object construction or destruction, atexit()
// callback.
bool Start();
// Starts the thread. Behaves exactly like Start in addition to allow to
// override the default options.
//
// Note: This function can't be called on Windows with the loader lock held;
// i.e. during a DllMain, global object construction or destruction, atexit()
// callback.
bool StartWithOptions(const Options& options);
// Signals the thread to exit and returns once the thread has exited. After
// this method returns, the Thread object is completely reset and may be used
// as if it were newly constructed (i.e., Start may be called again).
//
// Stop may be called multiple times and is simply ignored if the thread is
// already stopped.
//
// NOTE: This method is optional. It is not strictly necessary to call this
// method as the Thread's destructor will take care of stopping the thread if
// necessary.
//
void Stop();
// Signals the thread to exit in the near future.
//
// WARNING: This function is not meant to be commonly used. Use at your own
// risk. Calling this function will cause message_loop() to become invalid in
// the near future. This function was created to workaround a specific
// deadlock on Windows with printer worker thread. In any other case, Stop()
// should be used.
//
// StopSoon should not be called multiple times as it is risky to do so. It
// could cause a timing issue in message_loop() access. Call Stop() to reset
// the thread object once it is known that the thread has quit.
void StopSoon();
// Returns the message loop for this thread. Use the MessageLoop's
// PostTask methods to execute code on the thread. This only returns
// non-null after a successful call to Start. After Stop has been called,
// this will return NULL.
//
// NOTE: You must not call this MessageLoop's Quit method directly. Use
// the Thread's Stop method instead.
//
MessageLoop* message_loop() const { return message_loop_; }
// Set the name of this thread (for display in debugger too).
const std::string& thread_name() { return name_; }
// The native thread handle.
PlatformThreadHandle thread_handle() { return thread_; }
// The thread ID.
PlatformThreadId thread_id() const { return thread_id_; }
// Reset thread ID as current thread.
PlatformThreadId reset_thread_id() {
thread_id_ = PlatformThread::CurrentId();
return thread_id_;
}
// Returns true if the thread has been started, and not yet stopped.
// When a thread is running, the thread_id_ is non-zero.
bool IsRunning() const { return thread_id_ != 0; }
protected:
// Called just prior to starting the message loop
virtual void Init() {}
// Called just after the message loop ends
virtual void CleanUp() {}
static void SetThreadWasQuitProperly(bool flag);
static bool GetThreadWasQuitProperly();
private:
// PlatformThread::Delegate methods:
virtual void ThreadMain() override;
// We piggy-back on the startup_data_ member to know if we successfully
// started the thread. This way we know that we need to call Join.
bool thread_was_started() const { return startup_data_ != NULL; }
// Used to pass data to ThreadMain.
struct StartupData;
StartupData* startup_data_;
// The thread's handle.
PlatformThreadHandle thread_;
// The thread's message loop. Valid only while the thread is alive. Set
// by the created thread.
MessageLoop* message_loop_;
// Our thread's ID.
PlatformThreadId thread_id_;
// The name of the thread. Used for debugging purposes.
std::string name_;
friend class ThreadQuitTask;
DISALLOW_COPY_AND_ASSIGN(Thread);
};
} // namespace base
#endif // BASE_THREAD_H_
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