+/**************************************************************************
+ *
+ * Copyright 2011 Zack Rusin
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ **************************************************************************/
+
+
#include "trace_snappyfile.hpp"
#include <snappy.h>
using namespace Trace;
+/*
+ * Snappy file format.
+ * -------------------
+ *
+ * Snappy at its core is just a compressoin algorithm so we're
+ * creating a new file format which uses snappy compression
+ * to hold the trace data.
+ *
+ * The file is composed of a number of chunks, they are:
+ * chunk {
+ * uint32 - specifying the length of the compressed data
+ * compressed data
+ * }
+ * File can contain any number of such chunks.
+ * The default size of an uncompressed chunk is specified in
+ * SNAPPY_CHUNK_SIZE.
+ *
+ * Note:
+ * Currently the default size for a a to-be-compressed data is
+ * 1mb, meaning that the compressed data will be <= 1mb.
+ * The reason it's 1mb is because it seems
+ * to offer a pretty good compression/disk io speed ratio
+ * but that might change.
+ *
+ */
+
SnappyFile::SnappyFile(const std::string &filename,
File::Mode mode)
: File(),
m_cachePtr = NULL;
}
-void SnappyFile::rawFlush(FlushType type)
+void SnappyFile::rawFlush()
{
- if (type == FlushDeep) {
- flushCache();
- }
+ flushCache();
m_stream.flush();
}
m_cacheSize = size;
}
-void SnappyFile::writeCompressedLength(size_t value)
+void SnappyFile::writeCompressedLength(uint32_t value)
{
- m_stream.write((char*)&value, sizeof value);
+ m_stream.write((const char*)&value, sizeof value);
}
-size_t SnappyFile::readCompressedLength()
+uint32_t SnappyFile::readCompressedLength()
{
- size_t len;
+ uint32_t len;
m_stream.read((char*)&len, sizeof len);
return len;
}