shared_dynamic_string_map.h

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/*
 * Copyright 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http:///www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#ifndef PAGESPEED_KERNEL_SHAREDMEM_SHARED_DYNAMIC_STRING_MAP_H_
#define PAGESPEED_KERNEL_SHAREDMEM_SHARED_DYNAMIC_STRING_MAP_H_

#include <cstddef>

#include "pagespeed/kernel/base/abstract_mutex.h"
#include "pagespeed/kernel/base/abstract_shared_mem.h"
#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/base/scoped_ptr.h"
#include "pagespeed/kernel/base/string.h"
#include "pagespeed/kernel/base/string_util.h"

namespace net_instaweb {

class MessageHandler;
class Writer;

struct Entry {
  int value;
  size_t string_offset;
};

class SharedDynamicStringMap {
 public:
  SharedDynamicStringMap(size_t number_of_strings,
                         size_t average_string_length,
                         AbstractSharedMem* shm_runtime,
                         const GoogleString& filename_prefix,
                         const GoogleString& filename_suffix);

  bool InitSegment(bool parent, MessageHandler* message_handler);

  int IncrementElement(const StringPiece& string);

  int LookupElement(const StringPiece& string) const;

  void GetKeys(StringSet* strings);

  int GetNumberInserted() const;

  void GlobalCleanup(MessageHandler* message_handler);

  void Dump(Writer* writer, MessageHandler* message_handler);

 private:
  void ClearSegment(MessageHandler* message_handler);

  int FindEntry(const StringPiece& string,
                bool lock,
                Entry** entry_pointer) const;
  Entry* GetEntry(size_t n) const;
  Entry* GetFirstEntry() const;

  AbstractMutex* GetMutex(size_t n) const;
  int InsertString(const StringPiece& string, Entry* entry_pointer);
  char* GetStringAtOffset(size_t offset) const;

  static size_t NextPowerOfTwo(size_t n);


  size_t number_of_strings_;
  size_t average_string_length_;
  size_t mutex_size_;
  size_t table_size_;
  size_t mutex_offset_;
  size_t strings_offset_;
  size_t string_offset_offset_;
  size_t number_inserted_offset_;
  size_t table_offset_;
  size_t total_size_;

  scoped_ptr<AbstractMutex> insert_string_mutex_;

  const GoogleString segment_name_;
  AbstractSharedMem* shm_runtime_;
  scoped_ptr<AbstractSharedMemSegment> segment_;

  
};

}  

#endif