private void sendAck() {
// Send results back
DTask dt, origDt = _dt; // _dt can go null the instant it is send over wire
assert origDt != null; // Freed after completion
while ((dt = _dt) != null) { // Retry loop for broken TCP sends
AutoBuffer ab = null;
try {
// Start the ACK with results back to client. If the client is
// asking for a class/id mapping (or any job running at FETCH_ACK
// priority) then return a udp.fetchack byte instead of a udp.ack.
// The receiver thread then knows to handle the mapping at the higher
// priority.
UDP.udp udp = dt.priority() == H2O.FETCH_ACK_PRIORITY ? UDP.udp.fetchack : UDP.udp.ack;
ab = new AutoBuffer(_client, udp._prior).putTask(udp, _tsknum).put1(SERVER_UDP_SEND);
assert ab.position() == 1 + 2 + 4 + 1;
dt.write(ab); // Write the DTask - could be very large write
dt._repliedTcp = ab.hasTCP(); // Resends do not need to repeat TCP result
ab.close(); // Then close; send final byte
_computedAndReplied = true; // After the final handshake, set computed+replied bit
break; // Break out of retry loop
} catch (AutoBuffer.AutoBufferException e) {
if (!_client._heartbeat._client) // Report on servers only; clients allowed to be flaky
Log.info(
"IOException during ACK, "
+ e._ioe.getMessage()
+ ", t#"
+ _tsknum
+ " AB="
+ ab
+ ", waiting and retrying...");
ab.drainClose();
if (_client._heartbeat._client) // Dead client will not accept a TCP ACK response?
this.CAS_DT(dt, null); // cancel the ACK
try {
Thread.sleep(100);
} catch (InterruptedException ignore) {
}
} catch (Exception e) { // Custom serializer just barfed?
Log.err(e); // Log custom serializer exception
ab.drainClose();
}
} // end of while(true)
if (dt == null)
Log.info(
"Cancelled remote task#"
+ _tsknum
+ " "
+ origDt.getClass()
+ " to "
+ _client
+ " has been cancelled by remote");
else {
if (dt instanceof MRTask && dt.logVerbose())
Log.debug("Done remote task#" + _tsknum + " " + dt.getClass() + " to " + _client);
_client.record_task_answer(this); // Setup for retrying Ack & AckAck, if not canceled
}
}
// Re-send strictly the ack, because we're missing an AckAck
final void resend_ack() {
assert _computedAndReplied : "Found RPCCall not computed " + _tsknum;
DTask dt = _dt;
if (dt == null) return; // Received ACKACK already
UDP.udp udp = dt.priority() == H2O.FETCH_ACK_PRIORITY ? UDP.udp.fetchack : UDP.udp.ack;
AutoBuffer rab = new AutoBuffer(_client, dt.priority()).putTask(udp, _tsknum);
boolean wasTCP = dt._repliedTcp;
if (wasTCP) rab.put1(RPC.SERVER_TCP_SEND); // Original reply sent via TCP
else {
rab.put1(RPC.SERVER_UDP_SEND); // Original reply sent via UDP
assert rab.position() == 1 + 2 + 4 + 1;
dt.write(rab);
}
assert sz_check(rab)
: "Resend of " + _dt.getClass() + " changes size from " + _size + " to " + rab.size();
assert dt._repliedTcp == wasTCP;
rab.close();
dt._repliedTcp = wasTCP;
// Double retry until we exceed existing age. This is the time to delay
// until we try again. Note that we come here immediately on creation,
// so the first doubling happens before anybody does any waiting. Also
// note the generous 5sec cap: ping at least every 5 sec.
_retry += (_retry < MAX_TIMEOUT) ? _retry : MAX_TIMEOUT;
}
public synchronized RPC<V> call() {
// Any Completer will not be carried over to remote; add it to the RPC call
// so completion is signaled after the remote comes back.
CountedCompleter cc = _dt.getCompleter();
if (cc != null) handleCompleter(cc);
// If running on self, just submit to queues & do locally
if (_target == H2O.SELF) return handleLocal();
// Keep a global record, for awhile
if (_target != null) _target.taskPut(_tasknum, this);
try {
if (_nack) return this; // Racing Nack rechecked under lock; no need to send retry
// We could be racing timeouts-vs-replies. Blow off timeout if we have an answer.
if (isDone()) {
if (_target != null) _target.taskRemove(_tasknum);
return this;
}
// Default strategy: (re)fire the packet and (re)start the timeout. We
// "count" exactly 1 failure: just whether or not we shipped via TCP ever
// once. After that we fearlessly (re)send UDP-sized packets until the
// server replies.
// Pack classloader/class & the instance data into the outgoing
// AutoBuffer. If it fits in a single UDP packet, ship it. If not,
// finish off the current AutoBuffer (which is now going TCP style), and
// make a new UDP-sized packet. On a re-send of a TCP-sized hunk, just
// send the basic UDP control packet.
if (!_sentTcp) {
while (true) { // Retry loop for broken TCP sends
AutoBuffer ab = new AutoBuffer(_target, _dt.priority());
try {
final boolean t;
int offset = ab.position();
ab.putTask(UDP.udp.exec, _tasknum).put1(CLIENT_UDP_SEND);
ab.put(_dt);
t = ab.hasTCP();
assert sz_check(ab)
: "Resend of "
+ _dt.getClass()
+ " changes size from "
+ _size
+ " to "
+ ab.size()
+ " for task#"
+ _tasknum;
ab.close(); // Then close; send final byte
_sentTcp = t; // Set after close (and any other possible fail)
break; // Break out of retry loop
} catch (AutoBuffer.AutoBufferException e) {
Log.info(
"IOException during RPC call: "
+ e._ioe.getMessage()
+ ", AB="
+ ab
+ ", for task#"
+ _tasknum
+ ", waiting and retrying...");
ab.drainClose();
try {
Thread.sleep(500);
} catch (InterruptedException ignore) {
}
}
} // end of while(true)
} else {
// Else it was sent via TCP in a prior attempt, and we've timed out.
// This means the caller's ACK/answer probably got dropped and we need
// him to resend it (or else the caller is still processing our
// request). Send a UDP reminder - but with the CLIENT_TCP_SEND flag
// instead of the UDP send, and no DTask (since it previously went via
// TCP, no need to resend it).
AutoBuffer ab = new AutoBuffer(_target, _dt.priority()).putTask(UDP.udp.exec, _tasknum);
ab.put1(CLIENT_TCP_SEND).close();
}
// Double retry until we exceed existing age. This is the time to delay
// until we try again. Note that we come here immediately on creation,
// so the first doubling happens before anybody does any waiting. Also
// note the generous 5sec cap: ping at least every 5 sec.
_retry += (_retry < MAX_TIMEOUT) ? _retry : MAX_TIMEOUT;
// Put self on the "TBD" list of tasks awaiting Timeout.
// So: dont really 'forget' but remember me in a little bit.
// UDPTimeOutThread.PENDING.put(_tasknum, this);
return this;
} catch (Throwable t) {
t.printStackTrace();
throw Log.throwErr(t);
}
}
