#include <snappy.h>
+#include <iostream>
+
#include <assert.h>
#include <string.h>
//read in the initial buffer if we're reading
if (m_stream.is_open() && mode == File::Read) {
+ m_stream.seekg(0, std::ios::end);
+ m_endPos = m_stream.tellg();
+ m_stream.seekg(0, std::ios::beg);
+
// read the snappy file identifier
unsigned char byte1, byte2;
m_stream >> byte1;
m_stream >> byte2;
assert(byte1 == SNAPPY_BYTE1 && byte2 == SNAPPY_BYTE2);
- flushCache();
+ flushReadCache();
} else if (m_stream.is_open() && mode == File::Write) {
// write the snappy file identifier
m_stream << SNAPPY_BYTE1;
} else if (freeCacheSize() == length) {
memcpy(m_cachePtr, buffer, length);
m_cachePtr += length;
- flushCache();
+ flushWriteCache();
} else {
int sizeToWrite = length;
memcpy(m_cachePtr, (const char*)buffer + offset, endSize);
sizeToWrite -= endSize;
m_cachePtr += endSize;
- flushCache();
+ flushWriteCache();
}
if (sizeToWrite) {
int offset = length - sizeToWrite;
memcpy((char*)buffer + offset, m_cachePtr, chunkSize);
m_cachePtr += chunkSize;
sizeToRead -= chunkSize;
- if (sizeToRead > 0)
- flushCache();
- if (!m_cacheSize)
+ if (sizeToRead > 0) {
+ flushReadCache();
+ }
+ if (!m_cacheSize) {
break;
+ }
}
}
void SnappyFile::rawClose()
{
- flushCache();
+ if (m_mode == File::Write) {
+ flushWriteCache();
+ }
m_stream.close();
delete [] m_cache;
m_cache = NULL;
void SnappyFile::rawFlush()
{
- flushCache();
+ assert(m_mode == File::Write);
+ flushWriteCache();
m_stream.flush();
}
-void SnappyFile::flushCache()
+void SnappyFile::flushWriteCache()
{
- if (m_mode == File::Write) {
+ size_t inputLength = usedCacheSize();
+
+ if (inputLength) {
size_t compressedLength;
- ::snappy::RawCompress(m_cache, SNAPPY_CHUNK_SIZE - freeCacheSize(),
+ ::snappy::RawCompress(m_cache, inputLength,
m_compressedCache, &compressedLength);
writeCompressedLength(compressedLength);
m_stream.write(m_compressedCache, compressedLength);
m_cachePtr = m_cache;
- } else if (m_mode == File::Read) {
- //assert(m_cachePtr == m_cache + m_cacheSize);
- size_t compressedLength;
- compressedLength = readCompressedLength();
+ }
+ assert(m_cachePtr == m_cache);
+}
- if (compressedLength) {
- m_stream.read((char*)m_compressedCache, compressedLength);
- ::snappy::GetUncompressedLength(m_compressedCache, compressedLength,
- &m_cacheSize);
- createCache(m_cacheSize);
+void SnappyFile::flushReadCache(size_t skipLength)
+{
+ //assert(m_cachePtr == m_cache + m_cacheSize);
+ m_currentOffset.chunk = m_stream.tellg();
+ size_t compressedLength;
+ compressedLength = readCompressedLength();
+
+ if (compressedLength) {
+ m_stream.read((char*)m_compressedCache, compressedLength);
+ ::snappy::GetUncompressedLength(m_compressedCache, compressedLength,
+ &m_cacheSize);
+ createCache(m_cacheSize);
+ if (skipLength < m_cacheSize) {
::snappy::RawUncompress(m_compressedCache, compressedLength,
m_cache);
- } else {
- createCache(0);
}
+ } else {
+ createCache(0);
}
}
}
return length;
}
+
+bool SnappyFile::supportsOffsets() const
+{
+ return true;
+}
+
+File::Offset SnappyFile::currentOffset()
+{
+ m_currentOffset.offsetInChunk = m_cachePtr - m_cache;
+ return m_currentOffset;
+}
+
+void SnappyFile::setCurrentOffset(const File::Offset &offset)
+{
+ // to remove eof bit
+ m_stream.clear();
+ // seek to the start of a chunk
+ m_stream.seekg(offset.chunk, std::ios::beg);
+ // load the chunk
+ flushReadCache();
+ assert(m_cacheSize >= offset.offsetInChunk);
+ // seek within our cache to the correct location within the chunk
+ m_cachePtr = m_cache + offset.offsetInChunk;
+
+}
+
+bool SnappyFile::rawSkip(size_t length)
+{
+ if (endOfData()) {
+ return false;
+ }
+
+ if (freeCacheSize() >= length) {
+ m_cachePtr += length;
+ } else {
+ size_t sizeToRead = length;
+ while (sizeToRead) {
+ size_t chunkSize = std::min(freeCacheSize(), sizeToRead);
+ m_cachePtr += chunkSize;
+ sizeToRead -= chunkSize;
+ if (sizeToRead > 0) {
+ flushReadCache(sizeToRead);
+ }
+ if (!m_cacheSize) {
+ break;
+ }
+ }
+ }
+
+ return true;
+}
+
+int SnappyFile::rawPercentRead()
+{
+ return 100 * (double(m_stream.tellg()) / double(m_endPos));
+}