private void flushBufferedData() throws IOException {
if (o == 0) {
return;
}
checksum.reset();
checksum.update(buffer, 0, o);
final int check = (int) checksum.getValue();
int compressedLength = compressor.compress(buffer, 0, o, compressedBuffer, HEADER_LENGTH);
final int compressMethod;
if (compressedLength >= o) {
compressMethod = COMPRESSION_METHOD_RAW;
compressedLength = o;
System.arraycopy(buffer, 0, compressedBuffer, HEADER_LENGTH, o);
} else {
compressMethod = COMPRESSION_METHOD_LZ4;
}
compressedBuffer[MAGIC_LENGTH] = (byte) (compressMethod | compressionLevel);
writeIntLE(compressedLength, compressedBuffer, MAGIC_LENGTH + 1);
writeIntLE(o, compressedBuffer, MAGIC_LENGTH + 5);
writeIntLE(check, compressedBuffer, MAGIC_LENGTH + 9);
assert MAGIC_LENGTH + 13 == HEADER_LENGTH;
out.write(compressedBuffer, 0, HEADER_LENGTH + compressedLength);
o = 0;
}
/**
* Create a new {@link OutputStream} with configurable block size. Large blocks require more
* memory at compression and decompression time but should improve the compression ratio.
*
* @param out the {@link OutputStream} to feed
* @param blockSize the maximum number of bytes to try to compress at once, must be >= 64 and <=
* 32 M
* @param compressor the {@link LZ4Compressor} instance to use to compress data
* @param checksum the {@link Checksum} instance to use to check data for integrity.
* @param syncFlush true if pending data should also be flushed on {@link #flush()}
*/
public LZ4BlockOutputStream(
OutputStream out,
int blockSize,
LZ4Compressor compressor,
Checksum checksum,
boolean syncFlush) {
super(out);
this.blockSize = blockSize;
this.compressor = compressor;
this.checksum = checksum;
this.compressionLevel = compressionLevel(blockSize);
this.buffer = new byte[blockSize];
this.compressedBuffer = new byte[HEADER_LENGTH + compressor.maxCompressedLength(blockSize)];
this.syncFlush = syncFlush;
o = 0;
finished = false;
System.arraycopy(MAGIC, 0, compressedBuffer, 0, MAGIC_LENGTH);
}
