Squashed 'third_party/gperftools/' content from commit 54505f1

Change-Id: Id02e833828732b0efe7dac722b8485279e67c5fa
git-subtree-dir: third_party/gperftools
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diff --git a/src/heap-profile-stats.h b/src/heap-profile-stats.h
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+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// Copyright (c) 2013, 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.
+
+// This file defines structs to accumulate memory allocation and deallocation
+// counts.  These structs are commonly used for malloc (in HeapProfileTable)
+// and mmap (in MemoryRegionMap).
+
+// A bucket is data structure for heap profiling to store a pair of a stack
+// trace and counts of (de)allocation.  Buckets are stored in a hash table
+// which is declared as "HeapProfileBucket**".
+//
+// A hash value is computed from a stack trace.  Collision in the hash table
+// is resolved by separate chaining with linked lists.  The links in the list
+// are implemented with the member "HeapProfileBucket* next".
+//
+// A structure of a hash table HeapProfileBucket** bucket_table would be like:
+// bucket_table[0] => NULL
+// bucket_table[1] => HeapProfileBucket() => HeapProfileBucket() => NULL
+// ...
+// bucket_table[i] => HeapProfileBucket() => NULL
+// ...
+// bucket_table[n] => HeapProfileBucket() => NULL
+
+#ifndef HEAP_PROFILE_STATS_H_
+#define HEAP_PROFILE_STATS_H_
+
+struct HeapProfileStats {
+  // Returns true if the two HeapProfileStats are semantically equal.
+  bool Equivalent(const HeapProfileStats& other) const {
+    return allocs - frees == other.allocs - other.frees &&
+        alloc_size - free_size == other.alloc_size - other.free_size;
+  }
+
+  int32 allocs;      // Number of allocation calls.
+  int32 frees;       // Number of free calls.
+  int64 alloc_size;  // Total size of all allocated objects so far.
+  int64 free_size;   // Total size of all freed objects so far.
+};
+
+// Allocation and deallocation statistics per each stack trace.
+struct HeapProfileBucket : public HeapProfileStats {
+  // Longest stack trace we record.
+  static const int kMaxStackDepth = 32;
+
+  uintptr_t hash;           // Hash value of the stack trace.
+  int depth;                // Depth of stack trace.
+  const void** stack;       // Stack trace.
+  HeapProfileBucket* next;  // Next entry in hash-table.
+};
+
+#endif  // HEAP_PROFILE_STATS_H_