// Writes a stream of chunks such that no chunk is split across a block boundary
@Override
public synchronized void addRecord(Slice record, boolean force) throws IOException {
Preconditions.checkState(!closed.get(), "Log has been closed");
SliceInput sliceInput = record.input();
// used to track first, middle and last blocks
boolean begin = true;
// Fragment the record int chunks as necessary and write it. Note that if record
// is empty, we still want to iterate once to write a single
// zero-length chunk.
do {
int bytesRemainingInBlock = BLOCK_SIZE - blockOffset;
Preconditions.checkState(bytesRemainingInBlock >= 0);
// Switch to a new block if necessary
if (bytesRemainingInBlock < HEADER_SIZE) {
if (bytesRemainingInBlock > 0) {
// Fill the rest of the block with zeros
// todo lame... need a better way to write zeros
fileChannel.write(ByteBuffer.allocate(bytesRemainingInBlock));
}
blockOffset = 0;
bytesRemainingInBlock = BLOCK_SIZE - blockOffset;
}
// Invariant: we never leave less than HEADER_SIZE bytes available in a block
int bytesAvailableInBlock = bytesRemainingInBlock - HEADER_SIZE;
Preconditions.checkState(bytesAvailableInBlock >= 0);
// if there are more bytes in the record then there are available in the block,
// fragment the record; otherwise write to the end of the record
boolean end;
int fragmentLength;
if (sliceInput.available() > bytesAvailableInBlock) {
end = false;
fragmentLength = bytesAvailableInBlock;
} else {
end = true;
fragmentLength = sliceInput.available();
}
// determine block type
LogChunkType type;
if (begin && end) {
type = LogChunkType.FULL;
} else if (begin) {
type = LogChunkType.FIRST;
} else if (end) {
type = LogChunkType.LAST;
} else {
type = LogChunkType.MIDDLE;
}
// write the chunk
writeChunk(type, sliceInput.readSlice(fragmentLength));
// we are no longer on the first chunk
begin = false;
} while (sliceInput.isReadable());
if (force) {
fileChannel.force(false);
}
}
private void readLog(
String standby,
int bucket,
Position pos,
int batchSize,
Entrys entrys,
boolean availableRollback,
int deep) {
if (deep > 50) {
return;
}
long fileNumber = pos.fileNumber();
if (!logQ.contains(fileNumber)) {
throw new IfileNotFoundException(
bucket + "-bucket log file[" + fileNumber + "] does not exist!");
}
String key = generateKey(standby, bucket, fileNumber);
LogReader0 logReader = logCache.get(key);
if (logReader == null) {
return;
}
if (availableRollback) {
if (pos.pointer() > 0) {
logger.warn("{}-bucket log happen rollback, position={}.", bucket, pos);
logReader.setPosition(pos.pointer());
} else {
// 设置回滚点
pos.pointer(logReader.pointer());
}
}
boolean full = false;
for (Slice record = logReader.readRecord(); record != null; record = logReader.readRecord()) {
SliceInput sliceInput = record.input();
// read header
if (sliceInput.available() < 12) {
logReader.reportCorruption(sliceInput.available(), "log record too small");
continue;
}
long sequenceBegin = sliceInput.readLong();
int updateSize = sliceInput.readInt();
// read entries
try {
int c = readWriteBatch(bucket, sliceInput, updateSize, entrys);
if (c < 1) {
continue;
}
} catch (IOException e) {
Throwables.propagate(e);
}
// update the maxSequence
pos.curMaxSeq(sequenceBegin + updateSize - 1);
pos.maxSeq(pos.curMaxSeq());
if (entrys.size() >= batchSize) {
full = true;
break;
}
}
if (!full && logReader.eof(logsOffset.get(fileNumber))) {
boolean next = false;
for (long n : logQ) {
if (next) {
pos.fileNumber(n);
break;
}
if (n == fileNumber) {
next = true;
}
}
if (fileNumber != pos.fileNumber()) {
if (entrys.size() < batchSize) {
readLog(standby, bucket, pos, batchSize, entrys, false, ++deep);
}
}
}
}