Pass StatsTable shared memory via global descriptors on Posix rather than using named shared memory.

base/metrics/stats_table.h

 // Copyright (c) 2011 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.
 //
 // A StatsTable is a table of statistics.  It can be used across multiple
 // processes and threads, maintaining cheap statistics counters without
 // locking.
 //
 // The goal is to make it very cheap and easy for developers to add
 // counters to code, without having to build one-off utilities or mechanisms
 // to track the counters, and also to allow a single "view" to display
 // the contents of all counters.
 //
 // To achieve this, StatsTable creates a shared memory segment to store
 // the data for the counters.  Upon creation, it has a specific size
 // which governs the maximum number of counters and concurrent
 // threads/processes which can use it.
 //
 
 #ifndef BASE_METRICS_STATS_TABLE_H_
 #define BASE_METRICS_STATS_TABLE_H_
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/containers/hash_tables.h"
+#include "base/memory/shared_memory.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_local_storage.h"
 
 namespace base {
 
 class BASE_EXPORT StatsTable {
  public:
   // Create a new StatsTable.
   // If a StatsTable already exists with the specified name, this StatsTable
   // will use the same shared memory segment as the original.  Otherwise,
@@ skipping 71 matching lines @@
   // Gets the sum of the values for a particular counter for a given pid.
   // If the counter does not exist, creates the counter.
   int GetCounterValue(const std::string& name, int pid);
 
   // The maxinum number of counters/rows in the table.
   int GetMaxCounters() const;
 
   // The maxinum number of threads/columns in the table.
   int GetMaxThreads() const;
 
+#if defined(OS_POSIX)
+  // Get the underlying shared memory handle for the table.
+  base::SharedMemoryHandle GetSharedMemoryHandle() const;
+#endif
+
   // The maximum length (in characters) of a Thread's name including
   // null terminator, as stored in the shared memory.
   static const int kMaxThreadNameLength = 32;
 
   // The maximum length (in characters) of a Counter's name including
   // null terminator, as stored in the shared memory.
   static const int kMaxCounterNameLength = 64;
 
   // Convenience function to lookup a counter location for a
   // counter by name for the calling thread.  Will register
   // the thread if it is not already registered.
   static int* FindLocation(const char *name);
 
  private:
-  class Private;
+  class Internal;
   struct TLSData;
   typedef hash_map<std::string, int> CountersMap;
 
   // Returns the space occupied by a thread in the table.  Generally used
   // if a thread terminates but the process continues.  This function
   // does not zero out the thread's counters.
   // Cannot be used inside a posix tls destructor.
   void UnregisterThread();
 
   // This variant expects the tls data to be passed in, so it is safe to
@@ skipping 21 matching lines @@
   // to kMaxCounterNameLength-1 characters.
   //
   // On success, returns the counter_id for the newly added counter.
   // On failure, returns 0.
   int AddCounter(const std::string& name);
 
   // Get the TLS data for the calling thread.  Returns NULL if none is
   // initialized.
   TLSData* GetTLSData() const;
 
-  Private* impl_;
+  Internal* internal_;
 
   // The counters_lock_ protects the counters_ hash table.
   base::Lock counters_lock_;
 
   // The counters_ hash map is an in-memory hash of the counters.
   // It is used for quick lookup of counters, but is cannot be used
   // as a substitute for what is in the shared memory.  Even though
   // we don't have a counter in our hash table, another process may
   // have created it.
   CountersMap counters_;
   ThreadLocalStorage::Slot tls_index_;
 
   DISALLOW_COPY_AND_ASSIGN(StatsTable);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_STATS_TABLE_H_