public static final ByteBuffer makeMessageBuffer(
final List<Long> msgIds, final List<PutCommand> reqs) {
if (msgIds == null || reqs == null) {
throw new IllegalArgumentException("Null id list or request list");
}
if (msgIds.size() != reqs.size()) {
throw new IllegalArgumentException("id list is not adapte to request list");
}
int capacity = 0;
for (final PutCommand req : reqs) {
capacity += 4 + 4 + 8 + 4 + req.getData().length;
}
final ByteBuffer buffer = ByteBuffer.allocate(capacity);
for (int i = 0; i < reqs.size(); i++) {
final PutCommand req = reqs.get(i);
final long msgId = msgIds.get(i);
buffer.putInt(req.getData().length);
buffer.putInt(CheckSum.crc32(req.getData()));
buffer.putLong(msgId);
buffer.putInt(req.getFlag());
buffer.put(req.getData());
}
buffer.flip();
return buffer;
}
/**
* 校验checksum
*
* @param msg
* @param checksum
*/
public static final void vailidateMessage(
final int offset, final int msgLen, final int checksum, final byte[] data)
throws InvalidMessageException {
if (checksum != CheckSum.crc32(data, offset, msgLen)) {
throw new InvalidMessageException("Invalid message");
}
}
@Test
public void testCheckSum() throws Exception {
byte[] data2 = new byte[1024];
byte[] data1 = new byte[1024];
for (int i = 0; i < data1.length; i++) {
data1[i] = (byte) (i % 127);
data2[i] = (byte) (i % 127);
}
assertEquals(CheckSum.crc32(data1), CheckSum.crc32(data1));
assertEquals(CheckSum.crc32(data2), CheckSum.crc32(data2));
assertEquals(CheckSum.crc32(data1), CheckSum.crc32(data2));
}
/**
* 创建消息buffer，实际存储在服务器的结构如下：
*
* <ul>
* <li>message length(4 bytes),including attribute and payload
* <li>checksum(4 bytes)
* <li>message id(8 bytes)
* <li>message flag(4 bytes)
* <li>attribute length(4 bytes) + attribute,optional
* <li>payload
* </ul>
*
* @param req
* @return
*/
public static final ByteBuffer makeMessageBuffer(final long msgId, final PutCommand req) {
// message length + checksum + id +flag + data
final ByteBuffer buffer = ByteBuffer.allocate(4 + 4 + 8 + 4 + req.getData().length);
buffer.putInt(req.getData().length);
int checkSum = CheckSum.crc32(req.getData());
// If client passes checksum,compare them
if (req.getCheckSum() != -1) {
if (checkSum != req.getCheckSum()) {
throw new InvalidCheckSumException(
"Checksum failure,message may be corrupted when transfering on networking.");
}
}
buffer.putInt(checkSum);
buffer.putLong(msgId);
buffer.putInt(req.getFlag());
buffer.put(req.getData());
buffer.flip();
return buffer;
}
