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// Copyright (c) 2012 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.
#include <map>
#include <string>
#include <mach/mach.h>
#include "base/memory/singleton.h"
#include "base/process/process_handle.h"
#include "base/process/process_metrics.h"
#include "base/synchronization/lock.h"
#include "content/public/browser/browser_child_process_observer.h"
#include "content/public/browser/notification_observer.h"
#include "content/public/browser/notification_registrar.h"
namespace content {
// On OS X, the mach_port_t of a process is required to collect metrics about
// the process. Running |task_for_pid()| is only allowed for privileged code.
// However, a process has port rights to all its subprocesses, so let the
// browser's child processes send their Mach port to the browser over IPC.
// This way, the brower can at least collect metrics of its child processes,
// which is what it's most interested in anyway.
// Mach ports can only be sent over Mach IPC, not over the |socketpair()| that
// the regular IPC system uses. Hence, the child processes open a Mach
// connection shortly after launching and ipc their mach data to the browser
// process. This data is kept in a global |MachBroker| object.
// Since this data arrives over a separate channel, it is not available
// immediately after a child process has been started.
class CONTENT_EXPORT MachBroker : public base::ProcessMetrics::PortProvider,
public BrowserChildProcessObserver,
public NotificationObserver {
// For use in child processes. This will send the task port of the current
// process over Mach IPC to the port registered by name (via this class) in
// the parent process. Returns true if the message was sent successfully
// and false if otherwise.
static bool ChildSendTaskPortToParent();
// Returns the global MachBroker.
static MachBroker* GetInstance();
// The lock that protects this MachBroker object. Clients MUST acquire and
// release this lock around calls to EnsureRunning(), PlaceholderForPid(),
// and FinalizePid().
base::Lock& GetLock();
// Performs any necessary setup that cannot happen in the constructor.
// Callers MUST acquire the lock given by GetLock() before calling this
// method (and release the lock afterwards).
void EnsureRunning();
// Adds a placeholder to the map for the given pid with MACH_PORT_NULL.
// Callers are expected to later update the port with FinalizePid(). Callers
// MUST acquire the lock given by GetLock() before calling this method (and
// release the lock afterwards).
void AddPlaceholderForPid(base::ProcessHandle pid);
// Implement |ProcessMetrics::PortProvider|.
virtual mach_port_t TaskForPid(base::ProcessHandle process) const OVERRIDE;
// Implement |BrowserChildProcessObserver|.
virtual void BrowserChildProcessHostDisconnected(
const ChildProcessData& data) OVERRIDE;
virtual void BrowserChildProcessCrashed(
const ChildProcessData& data) OVERRIDE;
// Implement |NotificationObserver|.
virtual void Observe(int type,
const NotificationSource& source,
const NotificationDetails& details) OVERRIDE;
friend class MachBrokerTest;
friend class MachListenerThreadDelegate;
friend struct DefaultSingletonTraits<MachBroker>;
virtual ~MachBroker();
// Updates the mapping for |pid| to include the given |mach_info|. Does
// nothing if PlaceholderForPid() has not already been called for the given
// |pid|. Callers MUST acquire the lock given by GetLock() before calling
// this method (and release the lock afterwards).
void FinalizePid(base::ProcessHandle pid, mach_port_t task_port);
// Removes all mappings belonging to |pid| from the broker.
void InvalidatePid(base::ProcessHandle pid);
// Returns the Mach port name to use when sending or receiving messages.
// Does the Right Thing in the browser and in child processes.
static std::string GetMachPortName();
// Callback used to register notifications on the UI thread.
void RegisterNotifications();
// True if the listener thread has been started.
bool listener_thread_started_;
// Used to register for notifications received by NotificationObserver.
// Accessed only on the UI thread.
NotificationRegistrar registrar_;
// Stores mach info for every process in the broker.
typedef std::map<base::ProcessHandle, mach_port_t> MachMap;
MachMap mach_map_;
// Mutex that guards |mach_map_|.
mutable base::Lock lock_;
} // namespace content