browser_thread.h | Explore in Territory

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
#define CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_

#include <memory>
#include <string>
#include <utility>

#include "base/check.h"
#include "base/functional/callback.h"
#include "base/location.h"
#include "base/macros/uniquify.h"
#include "base/memory/scoped_refptr.h"
#include "base/task/single_thread_task_runner.h"
#include "base/thread_annotations.h"
#include "content/common/content_export.h"
#include "content/public/browser/browser_task_traits.h"

#if defined(UNIT_TEST)
#include "base/logging.h"
#endif

namespace content {

// Use DCHECK_CURRENTLY_ON(BrowserThread::ID) to DCHECK that a function can only
// be called on the named BrowserThread.
#define DCHECK_CURRENTLY_ON(thread_identifier) …

// Use CHECK_CURRENTLY_ON(BrowserThread::ID) to CHECK that a function can only
// be called on the named BrowserThread.
#define CHECK_CURRENTLY_ON(thread_identifier, ...) …

// GUARDED_BY_BROWSER_THREAD() enforces that a member variable is only accessed
// from a scope that invokes DCHECK_CURRENTLY_ON() or CHECK_CURRENTLY_ON() or
// from a function annotated with VALID_BROWSER_THREAD_REQUIRED(). The code will
// not compile if the member variable is accessed and these conditions are not
// met.
#define GUARDED_BY_BROWSER_THREAD(thread_identifier) …

// VALID_CONTEXT_REQUIRED() enforces that a member function is only accessed
// from a scope that invokes DCHECK_CURRENTLY_ON() or CHECK_CURRENTLY_ON() or
// from another function annotated with VALID_BROWSER_THREAD_REQUIRED(). The
// code will not compile if the member function is accessed and these conditions
// are not met.
#define VALID_BROWSER_THREAD_REQUIRED(thread_identifier) …

// The main entry point to post tasks to the UI thread. Tasks posted with the
// same |traits| will run in posting order (i.e. according to the
// SequencedTaskRunner contract). Tasks posted with different |traits| can be
// re-ordered. You may keep a reference to this task runner, it's always
// thread-safe to post to it though it may start returning false at some point
// during shutdown when it definitely is no longer accepting tasks.
//
// In unit tests, there must be a content::BrowserTaskEnvironment in scope for
// this API to be available.
CONTENT_EXPORT scoped_refptr<base::SingleThreadTaskRunner>
GetUIThreadTaskRunner(const BrowserTaskTraits& traits = { … };

// The BrowserThread::IO counterpart to GetUIThreadTaskRunner().
CONTENT_EXPORT scoped_refptr<base::SingleThreadTaskRunner>
GetIOThreadTaskRunner(const BrowserTaskTraits& traits = { … };

///////////////////////////////////////////////////////////////////////////////
// BrowserThread
//
// Utility functions for threads that are known by a browser-wide name.
class CONTENT_EXPORT BrowserThread { … };

namespace internal {

class THREAD_ANNOTATION_ATTRIBUTE__(capability("BrowserThread checker"))
    CONTENT_EXPORT BrowserThreadChecker { … };

// Returns the global BrowserThreadChecker associated with `thread_identifier`.
CONTENT_EXPORT const BrowserThreadChecker& GetBrowserThreadChecker(
    BrowserThread::ID thread_identifier);

// CHECK version.
class CONTENT_EXPORT SCOPED_LOCKABLE ScopedValidateBrowserThreadChecker { … };

// DCHECK version.
// Note: When DCHECKs are disabled, this class needs to be completely optimized
// out in order to not regress binary size. This is achieved by inlining the
// constructor and the destructor. When DCHECKs are enabled, the constructor
// is not unnecessarily inlined.
class CONTENT_EXPORT SCOPED_LOCKABLE ScopedValidateBrowserThreadDebugChecker { … };

}  // namespace internal

}  // namespace content

#endif  // CONTENT_PUBLIC_BROWSER_BROWSER_THREAD_H_
chromium/content/public/browser/browser_thread.h
