Mac: Create a pid->task_t mapping in the browser process.

chrome/browser/mach_broker_mac.h

+// Copyright (c) 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 CHROME_BROWSER_MACH_BROKER_H_
+#define CHROME_BROWSER_MACH_BROKER_H_
+
+#include <map>

[Mark Mentovai, 2009/12/21 19:23:10]

C++ system headers come after C system headers.

+
+#include <mach/mach.h>
+
+#include "base/lock.h"
+#include "base/process.h"
+#include "base/process_util.h"
+#include "base/singleton.h"
+
+// 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

[viettrungluu, 2009/12/19 07:46:37]

I bet you didn't realize that I would object to |socketpair()| even more
(because that refers to a function, which is of course nonsense in this
context), did you?

$ man -k socketpair
socketpair(2)            - create a pair of connected sockets

|socketpair()| does in fact create a pair of connected sockets, or a socket pair
for short.

[Mark Mentovai, 2009/12/21 19:23:10]

I agree with Trung.  This should be spelled "not over the socket pair 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

[Mark Mentovai, 2009/12/21 19:23:10]

And as long as we're being anal in this paragraph, IPC is three capital letters
and Mach is one.  Mach again at lines 47 and 62.

+// 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 MachBroker : public base::ProcessMetrics::PortProvider {
+ public:
+  // Returns the global MachBroker.
+  static MachBroker* instance();
+
+  struct MachInfo {
+    MachInfo() : mach_task_(MACH_PORT_NULL) {}
+
+    MachInfo& SetTask(mach_port_t task) {
+      mach_task_ = task;
+      return *this;
+    }
+
+    mach_port_t mach_task_;
+  };
+
+  // Adds mach info for a given pid.
+  void RegisterPid(base::ProcessHandle pid, const MachInfo& mach_info);
+
+  // Removes all mappings belonging to |pid| from the broker.
+  void Invalidate(base::ProcessHandle pid);
+
+  // Implement |ProcessMetrics::PortProvider|.
+  virtual mach_port_t TaskForPid(base::ProcessHandle process) const;
+
+ private:
+  // Private constructor.

[Mark Mentovai, 2009/12/21 19:23:10]

This is a "duh" comment.

+  MachBroker() {}
+  friend struct DefaultSingletonTraits<MachBroker>;
+  friend class MachBrokerTest;
+
+  // Stores mach info for every process in the broker.
+  typedef std::map<base::ProcessHandle, MachInfo> MachMap;
+  MachMap mach_map_;
+
+  // Mutex that guards |mach_map_|.
+  mutable Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(MachBroker);
+};
+
+#endif  // CHROME_BROWSER_MACH_BROKER_H_
+