third_party/WebKit/Source/wtf/InstanceCounter.cpp

/*
 * 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:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS 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 APPLE OR ITS 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.
 */

#include "wtf/InstanceCounter.h"

#include "wtf/HashMap.h"
#include "wtf/StdLibExtras.h"
#include "wtf/ThreadingPrimitives.h"
#include "wtf/text/StringBuilder.h"
#include "wtf/text/StringHash.h"
#include "wtf/text/WTFString.h"

namespace WTF {

#if ENABLE(INSTANCE_COUNTER)

#if COMPILER(CLANG)
const size_t stringWithTypeNamePrefixLength =
    sizeof("const char *WTF::getStringWithTypeName() [T = ") - 1;
const size_t stringWithTypeNamePostfixLength = sizeof("]") - 1;
#elif COMPILER(GCC)
const size_t stringWithTypeNamePrefixLength =
    sizeof("const char* WTF::getStringWithTypeName() [with T = ") - 1;
const size_t stringWithTypeNamePostfixLength = sizeof("]") - 1;
#elif COMPILER(MSVC)
const size_t stringWithTypeNamePrefixLength =
    sizeof("const char *__cdecl WTF::getStringWithTypeName<class ") - 1;
const size_t stringWithTypeNamePostfixLength = sizeof(">(void)") - 1;
#else
#warning \
    "Extracting typename is supported only in compiler GCC, CLANG and MSVC at this moment"
#endif

// This function is used to stringify a typename T without using RTTI.
// The result of stringWithTypeName<T>() is given as |funcName|.
// |extractTypeNameFromFunctionName| then extracts a typename string from
// |funcName|.
String extractTypeNameFromFunctionName(const char* funcName) {
#if COMPILER(CLANG) || COMPILER(GCC) || COMPILER(MSVC)
  size_t funcNameLength = strlen(funcName);
  DCHECK_GT(funcNameLength,
            stringWithTypeNamePrefixLength + stringWithTypeNamePostfixLength);

  const char* funcNameWithoutPrefix = funcName + stringWithTypeNamePrefixLength;
  return String(funcNameWithoutPrefix, funcNameLength -
                                           stringWithTypeNamePrefixLength -
                                           stringWithTypeNamePostfixLength);
#else
  return String("unknown");
#endif
}

class InstanceCounter {
 public:
  void incrementInstanceCount(const String& instanceName, void* ptr);
  void decrementInstanceCount(const String& instanceName, void* ptr);
  String dump();

  static InstanceCounter* instance() {
    DEFINE_STATIC_LOCAL(InstanceCounter, self, ());
    return &self;
  }

 private:
  InstanceCounter() {}

  Mutex m_mutex;
  HashMap<String, int> m_counterMap;
};

void incrementInstanceCount(const char* stringWithTypeNameName, void* ptr) {
  String instanceName = extractTypeNameFromFunctionName(stringWithTypeNameName);
  InstanceCounter::instance()->incrementInstanceCount(instanceName, ptr);
}

void decrementInstanceCount(const char* stringWithTypeNameName, void* ptr) {
  String instanceName = extractTypeNameFromFunctionName(stringWithTypeNameName);
  InstanceCounter::instance()->decrementInstanceCount(instanceName, ptr);
}

String dumpRefCountedInstanceCounts() {
  return InstanceCounter::instance()->dump();
}

void InstanceCounter::incrementInstanceCount(const String& instanceName,
                                             void* ptr) {
  MutexLocker locker(m_mutex);
  HashMap<String, int>::AddResult result = m_counterMap.add(instanceName, 1);
  if (!result.isNewEntry)
    ++(result.storedValue->value);
}

void InstanceCounter::decrementInstanceCount(const String& instanceName,
                                             void* ptr) {
  MutexLocker locker(m_mutex);
  HashMap<String, int>::iterator it = m_counterMap.find(instanceName);
  DCHECK(it != m_counterMap.end());

  --(it->value);
  if (!it->value)
    m_counterMap.remove(it);
}

String InstanceCounter::dump() {
  MutexLocker locker(m_mutex);

  StringBuilder builder;

  builder.append('{');
  HashMap<String, int>::iterator it = m_counterMap.begin();
  HashMap<String, int>::iterator itEnd = m_counterMap.end();
  for (; it != itEnd; ++it) {
    if (it != m_counterMap.begin())
      builder.append(',');
    builder.append('"');
    builder.append(it->key);
    builder.append("\": ");
    builder.appendNumber(it->value);
  }
  builder.append('}');

  return builder.toString();
}

#else

String dumpRefCountedInstanceCounts() {
  return String("{}");
}

#endif  // ENABLE(INSTANCE_COUNTER)

}  // namespace WTF