#include <snappy.h>
+#include <iostream>
+
#include <assert.h>
#include <string.h>
m_cachePtr(0),
m_cacheSize(0)
{
- m_compressedCache = new char[SNAPPY_CHUNK_SIZE];
+ size_t maxCompressedLength =
+ snappy::MaxCompressedLength(SNAPPY_CHUNK_SIZE);
+ m_compressedCache = new char[maxCompressedLength];
}
SnappyFile::~SnappyFile()
bool SnappyFile::rawRead(void *buffer, int length)
{
- if (m_stream.eof()) {
+ if (endOfData()) {
return false;
}
- if (freeCacheSize() > length) {
- memcpy(buffer, m_cachePtr, length);
- m_cachePtr += length;
- } else if (freeCacheSize() == length) {
+
+ if (freeCacheSize() >= length) {
memcpy(buffer, m_cachePtr, length);
m_cachePtr += length;
- flushCache();
} else {
int sizeToRead = length;
int offset = 0;
if (m_stream.eof())
return;
//assert(m_cachePtr == m_cache + m_cacheSize);
+ m_currentOffset.chunk = m_stream.tellg();
size_t compressedLength;
compressedLength = readCompressedLength();
m_stream.read((char*)m_compressedCache, compressedLength);
+ /*
+ * The reason we peek here is because the last read will
+ * read all the way until the last character, but that will not
+ * trigger m_stream.eof() to be set, so by calling peek
+ * we assure that if we in fact have read the entire stream
+ * then the m_stream.eof() is always set.
+ */
+ m_stream.peek();
::snappy::GetUncompressedLength(m_compressedCache, compressedLength,
&m_cacheSize);
if (m_cache)
m_stream.read((char*)&len, sizeof len);
return len;
}
+
+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
+ flushCache();
+ assert(m_cacheSize >= offset.offsetInChunk);
+ // seek within our cache to the correct location within the chunk
+ m_cachePtr = m_cache + offset.offsetInChunk;
+
+}