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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_MACH_BROKER_MAC_H_
      6 #define CONTENT_BROWSER_MACH_BROKER_MAC_H_
      7 
      8 #include <map>
      9 #include <string>
     10 
     11 #include <mach/mach.h>
     12 
     13 #include "base/memory/singleton.h"
     14 #include "base/process/process_handle.h"
     15 #include "base/process/process_metrics.h"
     16 #include "base/synchronization/lock.h"
     17 #include "content/public/browser/browser_child_process_observer.h"
     18 #include "content/public/browser/notification_observer.h"
     19 #include "content/public/browser/notification_registrar.h"
     20 
     21 namespace content {
     22 
     23 // On OS X, the mach_port_t of a process is required to collect metrics about
     24 // the process. Running |task_for_pid()| is only allowed for privileged code.
     25 // However, a process has port rights to all its subprocesses, so let the
     26 // browser's child processes send their Mach port to the browser over IPC.
     27 // This way, the brower can at least collect metrics of its child processes,
     28 // which is what it's most interested in anyway.
     29 //
     30 // Mach ports can only be sent over Mach IPC, not over the |socketpair()| that
     31 // the regular IPC system uses. Hence, the child processes open a Mach
     32 // connection shortly after launching and ipc their mach data to the browser
     33 // process. This data is kept in a global |MachBroker| object.
     34 //
     35 // Since this data arrives over a separate channel, it is not available
     36 // immediately after a child process has been started.
     37 class CONTENT_EXPORT MachBroker : public base::ProcessMetrics::PortProvider,
     38                                   public BrowserChildProcessObserver,
     39                                   public NotificationObserver {
     40  public:
     41   // For use in child processes. This will send the task port of the current
     42   // process over Mach IPC to the port registered by name (via this class) in
     43   // the parent process. Returns true if the message was sent successfully
     44   // and false if otherwise.
     45   static bool ChildSendTaskPortToParent();
     46 
     47   // Returns the global MachBroker.
     48   static MachBroker* GetInstance();
     49 
     50   // The lock that protects this MachBroker object.  Clients MUST acquire and
     51   // release this lock around calls to EnsureRunning(), PlaceholderForPid(),
     52   // and FinalizePid().
     53   base::Lock& GetLock();
     54 
     55   // Performs any necessary setup that cannot happen in the constructor.
     56   // Callers MUST acquire the lock given by GetLock() before calling this
     57   // method (and release the lock afterwards).
     58   void EnsureRunning();
     59 
     60   // Adds a placeholder to the map for the given pid with MACH_PORT_NULL.
     61   // Callers are expected to later update the port with FinalizePid().  Callers
     62   // MUST acquire the lock given by GetLock() before calling this method (and
     63   // release the lock afterwards).
     64   void AddPlaceholderForPid(base::ProcessHandle pid);
     65 
     66   // Implement |ProcessMetrics::PortProvider|.
     67   virtual mach_port_t TaskForPid(base::ProcessHandle process) const OVERRIDE;
     68 
     69   // Implement |BrowserChildProcessObserver|.
     70   virtual void BrowserChildProcessHostDisconnected(
     71       const ChildProcessData& data) OVERRIDE;
     72   virtual void BrowserChildProcessCrashed(
     73       const ChildProcessData& data) OVERRIDE;
     74 
     75   // Implement |NotificationObserver|.
     76   virtual void Observe(int type,
     77                        const NotificationSource& source,
     78                        const NotificationDetails& details) OVERRIDE;
     79  private:
     80   friend class MachBrokerTest;
     81   friend class MachListenerThreadDelegate;
     82   friend struct DefaultSingletonTraits<MachBroker>;
     83 
     84   MachBroker();
     85   virtual ~MachBroker();
     86 
     87   // Updates the mapping for |pid| to include the given |mach_info|.  Does
     88   // nothing if PlaceholderForPid() has not already been called for the given
     89   // |pid|.  Callers MUST acquire the lock given by GetLock() before calling
     90   // this method (and release the lock afterwards).
     91   void FinalizePid(base::ProcessHandle pid, mach_port_t task_port);
     92 
     93   // Removes all mappings belonging to |pid| from the broker.
     94   void InvalidatePid(base::ProcessHandle pid);
     95 
     96   // Returns the Mach port name to use when sending or receiving messages.
     97   // Does the Right Thing in the browser and in child processes.
     98   static std::string GetMachPortName();
     99   // Callback used to register notifications on the UI thread.
    100   void RegisterNotifications();
    101 
    102   // True if the listener thread has been started.
    103   bool listener_thread_started_;
    104 
    105   // Used to register for notifications received by NotificationObserver.
    106   // Accessed only on the UI thread.
    107   NotificationRegistrar registrar_;
    108 
    109   // Stores mach info for every process in the broker.
    110   typedef std::map<base::ProcessHandle, mach_port_t> MachMap;
    111   MachMap mach_map_;
    112 
    113   // Mutex that guards |mach_map_|.
    114   mutable base::Lock lock_;
    115 
    116   DISALLOW_COPY_AND_ASSIGN(MachBroker);
    117 };
    118 
    119 }  // namespace content
    120 
    121 #endif  // CONTENT_BROWSER_MACH_BROKER_MAC_H_
    122