thread.cc

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#define FML_USED_ON_EMBEDDER
 
#include "flutter/fml/thread.h"
 
#include <memory>
#include <string>
#include <utility>
 
#include "flutter/fml/build_config.h"
#include "flutter/fml/message_loop.h"
#include "flutter/fml/synchronization/waitable_event.h"
 
#if defined(FML_OS_WIN)
#include <windows.h>
#elif defined(OS_FUCHSIA)
#include <lib/zx/thread.h>
#else
#include <pthread.h>
#endif
 
namespace fml {
 
typedef std::function<void()> ThreadFunction;
 
class ThreadHandle {
 public:
  explicit ThreadHandle(ThreadFunction&& function);
  ~ThreadHandle();
 
  void Join();
 
 private:
#if defined(FML_OS_WIN)
  HANDLE thread_;
#else
  pthread_t thread_;
#endif
};
 
#if defined(FML_OS_WIN)
ThreadHandle::ThreadHandle(ThreadFunction&& function) {
  thread_ = (HANDLE*)_beginthreadex(
      nullptr, Thread::GetDefaultStackSize(),
      [](void* arg) -> unsigned {
        std::unique_ptr<ThreadFunction> function(
            reinterpret_cast<ThreadFunction*>(arg));
        (*function)();
        return 0;
      },
      new ThreadFunction(std::move(function)), 0, nullptr);
  FML_CHECK(thread_ != nullptr);
}
 
void ThreadHandle::Join() {
  WaitForSingleObjectEx(thread_, INFINITE, FALSE);
}
 
ThreadHandle::~ThreadHandle() {
  CloseHandle(thread_);
}
#else
ThreadHandle::ThreadHandle(ThreadFunction&& function) {
  pthread_attr_t attr;
  pthread_attr_init(&attr);
  int result = pthread_attr_setstacksize(&attr, Thread::GetDefaultStackSize());
  FML_CHECK(result == 0);
  result = pthread_create(
      &thread_, &attr,
      [](void* arg) -> void* {
        std::unique_ptr<ThreadFunction> function(
            reinterpret_cast<ThreadFunction*>(arg));
        (*function)();
        return nullptr;
      },
      new ThreadFunction(std::move(function)));
  FML_CHECK(result == 0);
  result = pthread_attr_destroy(&attr);
  FML_CHECK(result == 0);
}
 
void ThreadHandle::Join() {
  pthread_join(thread_, nullptr);
}
 
ThreadHandle::~ThreadHandle() {}
#endif
 
#if defined(FML_OS_WIN)
// The information on how to set the thread name comes from
// a MSDN article: http://msdn2.microsoft.com/en-us/library/xcb2z8hs.aspx
const DWORD kVCThreadNameException = 0x406D1388;
typedef struct tagTHREADNAME_INFO {
  DWORD dwType;      // Must be 0x1000.
  LPCSTR szName;     // Pointer to name (in user addr space).
  DWORD dwThreadID;  // Thread ID (-1=caller thread).
  DWORD dwFlags;     // Reserved for future use, must be zero.
} THREADNAME_INFO;
#endif
 
void SetThreadName(const std::string& name) {
  if (name == "") {
    return;
  }
#if defined(FML_OS_MACOSX)
  pthread_setname_np(name.c_str());
#elif defined(FML_OS_LINUX) || defined(FML_OS_ANDROID)
  // Linux thread names are limited to 16 characters including the terminating
  // null.
  constexpr std::string::size_type kLinuxMaxThreadNameLen = 15;
  pthread_setname_np(pthread_self(),
                     name.substr(0, kLinuxMaxThreadNameLen).c_str());
#elif defined(FML_OS_WIN)
  THREADNAME_INFO info;
  info.dwType = 0x1000;
  info.szName = name.c_str();
  info.dwThreadID = GetCurrentThreadId();
  info.dwFlags = 0;
  __try {
    RaiseException(kVCThreadNameException, 0, sizeof(info) / sizeof(DWORD),
                   reinterpret_cast<DWORD_PTR*>(&info));
  } __except (EXCEPTION_CONTINUE_EXECUTION) {
  }
#elif defined(OS_FUCHSIA)
  zx::thread::self()->set_property(ZX_PROP_NAME, name.c_str(), name.size());
#else
  FML_DLOG(INFO) << "Could not set the thread name to '" << name
                 << "' on this platform.";
#endif
}
 
void Thread::SetCurrentThreadName(const Thread::ThreadConfig& config) {
  SetThreadName(config.name);
}
 
Thread::Thread(const std::string& name)
    : Thread(Thread::SetCurrentThreadName, ThreadConfig(name)) {}
 
Thread::Thread(const ThreadConfigSetter& setter, const ThreadConfig& config)
    : joined_(false) {
  fml::AutoResetWaitableEvent latch;
  fml::RefPtr<fml::TaskRunner> runner;
 
  thread_ = std::make_unique<ThreadHandle>(
      [&latch, &runner, setter, config]() -> void {
        setter(config);
        fml::MessageLoop::EnsureInitializedForCurrentThread();
        auto& loop = MessageLoop::GetCurrent();
        runner = loop.GetTaskRunner();
        latch.Signal();
        loop.Run();
      });
  latch.Wait();
  task_runner_ = runner;
}
 
Thread::~Thread() {
  Join();
}
 
fml::RefPtr<fml::TaskRunner> Thread::GetTaskRunner() const {
  return task_runner_;
}
 
void Thread::Join() {
  if (joined_) {
    return;
  }
  joined_ = true;
  task_runner_->PostTask([]() { MessageLoop::GetCurrent().Terminate(); });
  thread_->Join();
}
 
size_t Thread::GetDefaultStackSize() {
  return 1024 * 1024 * 2;
}
 
}  // namespace fml