private WriteBatchImpl readWriteBatch(SliceInput record, int updateSize) throws IOException {
WriteBatchImpl writeBatch = new WriteBatchImpl();
int entries = 0;
while (record.isReadable()) {
entries++;
ValueType valueType = ValueType.getValueTypeByPersistentId(record.readByte());
if (valueType == VALUE) {
Slice key = readLengthPrefixedBytes(record);
Slice value = readLengthPrefixedBytes(record);
writeBatch.put(key, value);
} else if (valueType == DELETION) {
Slice key = readLengthPrefixedBytes(record);
writeBatch.delete(key);
} else {
throw new IllegalStateException("Unexpected value type " + valueType);
}
}
if (entries != updateSize) {
throw new IOException(
String.format(
"Expected %d entries in log record but found %s entries", updateSize, entries));
}
return writeBatch;
}
private long recoverLogFile(long fileNumber, VersionEdit edit) throws IOException {
Preconditions.checkState(mutex.isHeldByCurrentThread());
File file = new File(databaseDir, Filename.logFileName(fileNumber));
FileChannel channel = new FileInputStream(file).getChannel();
try {
LogMonitor logMonitor = LogMonitors.logMonitor();
LogReader logReader = new LogReader(channel, logMonitor, true, 0);
// Log(options_.info_log, "Recovering log #%llu", (unsigned long long) log_number);
// Read all the records and add to a memtable
long maxSequence = 0;
MemTable memTable = null;
for (Slice record = logReader.readRecord(); record != null; record = logReader.readRecord()) {
SliceInput sliceInput = record.input();
// read header
if (sliceInput.available() < 12) {
logMonitor.corruption(sliceInput.available(), "log record too small");
continue;
}
long sequenceBegin = sliceInput.readLong();
int updateSize = sliceInput.readInt();
// read entries
WriteBatchImpl writeBatch = readWriteBatch(sliceInput, updateSize);
// apply entries to memTable
if (memTable == null) {
memTable = new MemTable(internalKeyComparator);
}
writeBatch.forEach(new InsertIntoHandler(memTable, sequenceBegin));
// update the maxSequence
long lastSequence = sequenceBegin + updateSize - 1;
if (lastSequence > maxSequence) {
maxSequence = lastSequence;
}
// flush mem table if necessary
if (memTable.approximateMemoryUsage() > options.writeBufferSize()) {
writeLevel0Table(memTable, edit, null);
memTable = null;
}
}
// flush mem table
if (memTable != null && !memTable.isEmpty()) {
writeLevel0Table(memTable, edit, null);
}
return maxSequence;
} finally {
channel.close();
}
}