Squash: Fix bugs

trunk/3rdparty/gperftools-2-fit/src/profiledata.h

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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// Copyright (c) 2007, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// ---
+// Author: Sanjay Ghemawat
+//         Chris Demetriou (refactoring)
+//
+// Collect profiling data.
+//
+// The profile data file format is documented in
+// docs/cpuprofile-fileformat.html
+
+
+#ifndef BASE_PROFILEDATA_H_
+#define BASE_PROFILEDATA_H_
+
+#include <config.h>
+#include <time.h>   // for time_t
+#include <stdint.h>
+#include "base/basictypes.h"
+
+// A class that accumulates profile samples and writes them to a file.
+//
+// Each sample contains a stack trace and a count.  Memory usage is
+// reduced by combining profile samples that have the same stack trace
+// by adding up the associated counts.
+//
+// Profile data is accumulated in a bounded amount of memory, and will
+// flushed to a file as necessary to stay within the memory limit.
+//
+// Use of this class assumes external synchronization.  The exact
+// requirements of that synchronization are that:
+//
+//  - 'Add' may be called from asynchronous signals, but is not
+//    re-entrant.
+//
+//  - None of 'Start', 'Stop', 'Reset', 'Flush', and 'Add' may be
+//    called at the same time.
+//
+//  - 'Start', 'Stop', or 'Reset' should not be called while 'Enabled'
+//     or 'GetCurrent' are running, and vice versa.
+//
+// A profiler which uses asyncronous signals to add samples will
+// typically use two locks to protect this data structure:
+//
+//  - A SpinLock which is held over all calls except for the 'Add'
+//    call made from the signal handler.
+//
+//  - A SpinLock which is held over calls to 'Start', 'Stop', 'Reset',
+//    'Flush', and 'Add'.  (This SpinLock should be acquired after
+//    the first SpinLock in all cases where both are needed.)
+class ProfileData {
+ public:
+  struct State {
+    bool     enabled;             // Is profiling currently enabled?
+    time_t   start_time;          // If enabled, when was profiling started?
+    char     profile_name[1024];  // Name of file being written, or '\0'
+    int      samples_gathered;    // Number of samples gathered to far (or 0)
+  };
+
+  class Options {
+   public:
+    Options();
+
+    // Get and set the sample frequency.
+    int frequency() const {
+      return frequency_;
+    }
+    void set_frequency(int frequency) {
+      frequency_ = frequency;
+    }
+
+   private:
+    int      frequency_;                  // Sample frequency.
+  };
+
+  static const int kMaxStackDepth = 254;  // Max stack depth stored in profile
+
+  ProfileData();
+  ~ProfileData();
+
+  // If data collection is not already enabled start to collect data
+  // into fname.  Parameters related to this profiling run are specified
+  // by 'options'.
+  //
+  // Returns true if data collection could be started, otherwise (if an
+  // error occurred or if data collection was already enabled) returns
+  // false.
+  bool Start(const char *fname, const Options& options);
+
+  // If data collection is enabled, stop data collection and write the
+  // data to disk.
+  void Stop();
+
+  // Stop data collection without writing anything else to disk, and
+  // discard any collected data.
+  void Reset();
+
+  // If data collection is enabled, record a sample with 'depth'
+  // entries from 'stack'.  (depth must be > 0.)  At most
+  // kMaxStackDepth stack entries will be recorded, starting with
+  // stack[0].
+  //
+  // This function is safe to call from asynchronous signals (but is
+  // not re-entrant).
+  void Add(int depth, const void* const* stack);
+
+  // If data collection is enabled, write the data to disk (and leave
+  // the collector enabled).
+  void FlushTable();
+
+  // Is data collection currently enabled?
+  bool enabled() const { return out_ >= 0; }
+
+  // Get the current state of the data collector.
+  void GetCurrentState(State* state) const;
+
+ private:
+  static const int kAssociativity = 4;          // For hashtable
+  static const int kBuckets = 1 << 10;          // For hashtable
+  static const int kBufferLength = 1 << 18;     // For eviction buffer
+
+  // Type of slots: each slot can be either a count, or a PC value
+  typedef uintptr_t Slot;
+
+  // Hash-table/eviction-buffer entry (a.k.a. a sample)
+  struct Entry {
+    Slot count;                  // Number of hits
+    Slot depth;                  // Stack depth
+    Slot stack[kMaxStackDepth];  // Stack contents
+  };
+
+  // Hash table bucket
+  struct Bucket {
+    Entry entry[kAssociativity];
+  };
+
+  Bucket*       hash_;          // hash table
+  Slot*         evict_;         // evicted entries
+  int           num_evicted_;   // how many evicted entries?
+  int           out_;           // fd for output file.
+  int           count_;         // How many samples recorded
+  int           evictions_;     // How many evictions
+  size_t        total_bytes_;   // How much output
+  char*         fname_;         // Profile file name
+  time_t        start_time_;    // Start time, or 0
+
+  // Move 'entry' to the eviction buffer.
+  void Evict(const Entry& entry);
+
+  // Write contents of eviction buffer to disk.
+  void FlushEvicted();
+
+  DISALLOW_COPY_AND_ASSIGN(ProfileData);
+};
+
+#endif  // BASE_PROFILEDATA_H_