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rocksdb/thrift/lib/cpp/util/ThriftSerializer-inl.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.
*/
// @author Karl Voskuil (karl@facebook.com)
// @author Mark Rabkin (mrabkin@facebook.com)
//
#ifndef COMMON_STRINGS_THRIFT_SERIALIZER_INL_H
#define COMMON_STRINGS_THRIFT_SERIALIZER_INL_H
#include <stdexcept>
#include <string>
#include "common/logging/logging.h"
#include "thrift/lib/cpp/util/ThriftSerializer.h"
namespace apache { namespace thrift { namespace util {
template <typename T, typename P>
template <class String>
void
ThriftSerializer<T, P>::serialize(const T& fields, String* serialized)
{
// prepare or reset buffer
//
// note: Three cases:
//
// 1) The buffer has never been prepared. Call prepare().
//
// 2) The buffer was last used for a deserialize() call. In this
// case, the buffer is pointing to a now-invalid constant
// string, and the buffer should be reallocated.
//
// 3) The buffer was last used for a serialize() call. In this
// case, the buffer is still pointing to a valid buffer, but it
// contains the serialization from the last serialize(), and
// the buffer just needs to be reset.
//
// This would be a little simpler if we allocated separate buffers
// and protocols for serialization and deserialization, but it
// seemed to me that this fit the common use cases better. The case
// that performs poorly (20% slower) is doing many alternating
// serializations and deserializations.
if (!prepared_ || lastDeserialized_) {
prepare();
} else {
buffer_->resetBuffer();
}
lastDeserialized_ = false;
// serialize fields into buffer
fields.write(protocol_.get());
// assign buffer to string
uint8_t *byteBuffer;
uint32_t byteBufferSize;
buffer_->getBuffer(&byteBuffer, &byteBufferSize);
serialized->assign((const char*)byteBuffer, byteBufferSize);
}
template <typename T, typename P>
void
ThriftSerializer<T, P>::serialize(const T& fields,
const uint8_t** serializedBuffer,
size_t* serializedLen) {
CHECK(serializedBuffer);
CHECK(serializedLen);
// prepare or reset buffer
if (!prepared_ || lastDeserialized_) {
prepare();
} else {
buffer_->resetBuffer();
}
lastDeserialized_ = false;
// serialize fields into buffer
fields.write(protocol_.get());
// assign buffer to string
uint8_t *byteBuffer;
uint32_t byteBufferSize;
buffer_->getBuffer(&byteBuffer, &byteBufferSize);
*serializedBuffer = byteBuffer;
*serializedLen = byteBufferSize;
}
// Deserializes a thrift object, but assumes that the object passed in the
// fields argument is "clean". If your thrift class contains optional fields,
// you should use deserialize() instead (see below), otherwise optional fields
// that were previously set by other calls to this function won't get reset,
// and will appear to have been desearialized along with the other fields.
template <typename T, typename P>
template <class String>
uint32_t
ThriftSerializer<T, P>::deserializeClean(const String& serialized, T* fields)
{
// prepare buffer if necessary
if (!prepared_) {
prepare();
}
lastDeserialized_ = true;
// reset buffer transport to passed string
buffer_->resetBuffer((uint8_t*)serialized.data(), serialized.size());
// deserialize buffer into fields
return fields->read(protocol_.get());
}
template <typename T, typename P>
uint32_t
ThriftSerializer<T, P>::deserialize(const uint8_t* serializedBuffer,
size_t length,
T* fields)
{
// prepare buffer if necessary
if (!prepared_) {
prepare();
}
lastDeserialized_ = true;
// reset buffer transport to passed string
buffer_->resetBuffer((uint8_t*)serializedBuffer, length);
// need to clean the existing structure, as fields->read() will not overwrite
// the optional fields that were not set in the serialized object.
T emptyFields;
swap(emptyFields, *fields);
// deserialize buffer into fields
return fields->read(protocol_.get());
}
template <typename T, typename P>
void
ThriftSerializer<T, P>::setVersion(int8_t version)
{
version_ = version;
setVersion_ = true;
}
template <typename T, typename P>
void
ThriftSerializer<T, P>::prepare()
{
// create memory buffer to use as transport
//
// note: TMemoryBuffer won't write to the buffer unless it is the
// owner of it, which means that we can't pass in our own local
// buffer. Either must malloc a buffer which TMemoryBuffer will
// free, or else just let it malloc its own. This has the added
// benefit that TMemoryBuffer will grow the buffer size as
// necessary.
//
// The initial allocation of the memory buffer might seem
// unnecessary in case of parsing (since the memory buffer will be
// reset to point to the string passed to parseSerializer()), but
// it's apparently necessary for some protocols.
buffer_.reset(new TMemoryBuffer());
// create a protocol for the memory buffer transport
protocol_.reset(new Protocol(buffer_));
if (setVersion_) {
protocol_->setVersion(version_);
}
prepared_ = true;
}
}}} // namespace apache::thrift::util
#endif