StatusWith<executor::TaskExecutor::EventHandle> AsyncClusterClientCursor::nextEvent() {
stdx::lock_guard<stdx::mutex> lk(_mutex);
if (_lifecycleState != kAlive) {
// Can't schedule further network operations if the ACCC is being killed.
return Status(ErrorCodes::IllegalOperation,
"nextEvent() called on a killed async cluster client cursor");
}
if (_currentEvent.isValid()) {
// We can't make a new event if there's still an unsignaled one, as every event must
// eventually be signaled.
return Status(ErrorCodes::IllegalOperation,
"nextEvent() called before an outstanding event was signaled");
}
// Schedule remote work on hosts for which we need more results.
for (size_t i = 0; i < _remotes.size(); ++i) {
auto& remote = _remotes[i];
// It is illegal to call this method if there is an error received from any shard.
invariant(remote.status.isOK());
if (!remote.hasNext() && !remote.exhausted() && !remote.cbHandle.isValid()) {
// If we already have established a cursor with this remote, and there is no outstanding
// request for which we have a valid callback handle, send a getMore with the
// appropriate cursorId. Otherwise, send the cursor-establishing command.
BSONObj cmdObj = remote.cursorId
? GetMoreRequest(_params.nsString, *remote.cursorId, _params.batchSize).toBSON()
: _params.cmdObj;
RemoteCommandRequest request(
remote.hostAndPort, _params.nsString.db().toString(), cmdObj);
auto callbackStatus = _executor->scheduleRemoteCommand(
request,
stdx::bind(&AsyncClusterClientCursor::handleBatchResponse,
this,
stdx::placeholders::_1,
i));
if (!callbackStatus.isOK()) {
return callbackStatus.getStatus();
}
remote.cbHandle = callbackStatus.getValue();
}
}
auto eventStatus = _executor->makeEvent();
if (!eventStatus.isOK()) {
return eventStatus;
}
_currentEvent = eventStatus.getValue();
return _currentEvent;
}
Status AsyncResultsMerger::askForNextBatch_inlock(size_t remoteIndex) {
auto& remote = _remotes[remoteIndex];
invariant(!remote.cbHandle.isValid());
// If mongod returned less docs than the requested batchSize then modify the next getMore
// request to fetch the remaining docs only. If the remote node has a plan with OR for top k and
// a full sort as is the case for the OP_QUERY find then this optimization will prevent
// switching to the full sort plan branch.
BSONObj cmdObj;
if (remote.cursorId) {
auto adjustedBatchSize = _params.batchSize;
if (_params.batchSize && *_params.batchSize > remote.fetchedCount) {
adjustedBatchSize = *_params.batchSize - remote.fetchedCount;
}
cmdObj = GetMoreRequest(_params.nsString,
*remote.cursorId,
adjustedBatchSize,
_awaitDataTimeout,
boost::none,
boost::none)
.toBSON();
} else {
// Do the first time shard host resolution.
invariant(_params.readPreference);
Status resolveStatus = remote.resolveShardIdToHostAndPort(*_params.readPreference);
if (!resolveStatus.isOK()) {
return resolveStatus;
}
remote.fetchedCount = 0;
cmdObj = *remote.initialCmdObj;
}
executor::RemoteCommandRequest request(remote.getTargetHost(),
_params.nsString.db().toString(),
cmdObj,
_metadataObj,
_params.txn);
auto callbackStatus = _executor->scheduleRemoteCommand(
request,
stdx::bind(
&AsyncResultsMerger::handleBatchResponse, this, stdx::placeholders::_1, remoteIndex));
if (!callbackStatus.isOK()) {
return callbackStatus.getStatus();
}
remote.cbHandle = callbackStatus.getValue();
return Status::OK();
}
Status AsyncResultsMerger::askForNextBatch_inlock(OperationContext* opCtx, size_t remoteIndex) {
auto& remote = _remotes[remoteIndex];
invariant(!remote.cbHandle.isValid());
// If mongod returned less docs than the requested batchSize then modify the next getMore
// request to fetch the remaining docs only. If the remote node has a plan with OR for top k and
// a full sort as is the case for the OP_QUERY find then this optimization will prevent
// switching to the full sort plan branch.
auto adjustedBatchSize = _params->batchSize;
if (_params->batchSize && *_params->batchSize > remote.fetchedCount) {
adjustedBatchSize = *_params->batchSize - remote.fetchedCount;
}
BSONObj cmdObj = GetMoreRequest(_params->nsString,
remote.cursorId,
adjustedBatchSize,
_awaitDataTimeout,
boost::none,
boost::none)
.toBSON();
executor::RemoteCommandRequest request(
remote.getTargetHost(), _params->nsString.db().toString(), cmdObj, _metadataObj, opCtx);
auto callbackStatus =
_executor->scheduleRemoteCommand(request,
stdx::bind(&AsyncResultsMerger::handleBatchResponse,
this,
stdx::placeholders::_1,
opCtx,
remoteIndex));
if (!callbackStatus.isOK()) {
return callbackStatus.getStatus();
}
remote.cbHandle = callbackStatus.getValue();
return Status::OK();
}
