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

Since nothing writes to this map in the browser atm, this does not have any visible effect.

BUG=13156,25454
TEST=unittest

Review URL: http://codereview.chromium.org/501138

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@35092 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 73 insertions, 0 deletions

diff --git a/chrome/browser/mach_broker_mac.h b/chrome/browser/mach_broker_mac.h
new file mode 100644
index 0000000..67f4fec
--- /dev/null
+++ b/chrome/browser/mach_broker_mac.h
@@ -0,0 +1,73 @@
+// 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>
+
+#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
+// 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 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.
+  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_
+