src/stack_trace_table.h

// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
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// ---
// Author: Andrew Fikes
//
// Utility class for coalescing sampled stack traces.  Not thread-safe.

#ifndef TCMALLOC_STACK_TRACE_TABLE_H_
#define TCMALLOC_STACK_TRACE_TABLE_H_

#include <config.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>                     // for uintptr_t
#endif
#include "common.h"

namespace tcmalloc {

class PERFTOOLS_DLL_DECL StackTraceTable {
 public:
  // REQUIRES: L < pageheap_lock
  StackTraceTable();
  ~StackTraceTable();

  // Adds stack trace "t" to table.
  //
  // REQUIRES: L >= pageheap_lock
  void AddTrace(const StackTrace& t);

  // Returns stack traces formatted per MallocExtension guidelines.
  // May return NULL on error.  Clears state before returning.
  //
  // REQUIRES: L < pageheap_lock
  void** ReadStackTracesAndClear();

  // Exposed for PageHeapAllocator
  struct Bucket {
    // Key
    uintptr_t hash;
    StackTrace trace;

    // Payload
    int count;
    Bucket* next;

    bool KeyEqual(uintptr_t h, const StackTrace& t) const;
  };

  // For testing
  int depth_total() const { return depth_total_; }
  int bucket_total() const { return bucket_total_; }

 private:
  static const int kHashTableSize = 1 << 14; // => table_ is 128k

  bool error_;
  int depth_total_;
  int bucket_total_;
  Bucket** table_;
};

}  // namespace tcmalloc

#endif  // TCMALLOC_STACK_TRACE_TABLE_H_