rocksdb/thrift/lib/cpp/transport/TMemPagedFactory.h

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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 _THRIFT_TRANSPORT_TMEMPAGEDFACTORY_H_
#define _THRIFT_TRANSPORT_TMEMPAGEDFACTORY_H_ 1
#include "external/google_base/spinlock.h"
namespace apache { namespace thrift { namespace transport {
/*
* struct keeps information about memory usage for specific page
*/
struct FixedSizeMemoryPage {
FixedSizeMemoryPage* next_; //!< chain hook
uint8_t buffer_[]; //!< pointer to the buffer
};
/**
* Fixed size memory pages factory
* Thread safe
*
*/
class FixedSizeMemoryPageFactory {
public:
/**
* Constructor
*/
FixedSizeMemoryPageFactory(size_t pageSize, //!< page size in bytes
size_t maxMemoryUsage, //!< max memory usage
size_t cacheMemorySize); //!< max memory in cache
/**
* Destructor
*/
~FixedSizeMemoryPageFactory();
/**
* Releases all unused memory
*/
void releaseMemory();
/**
* Requests for a page allocation
*/
FixedSizeMemoryPage* getPage(bool throwOnError = true);
/**
* Returns current page size
*/
size_t getPageSize() const;
/**
* Returns page back to factory
*/
void returnPage(FixedSizeMemoryPage* page);
private:
const size_t pageSize_;
const size_t maxMemoryUsage_;
const size_t cacheMemorySize_;
size_t numAllocatedPages_;
size_t numCachedPages_;
FixedSizeMemoryPage* cachedPages_;
mutable facebook::SpinLock lock_;
};
}}} // apache::thrift::transport
#endif // #ifndef _THRIFT_TRANSPORT_TMEMPAGEDFACTORY_H_