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/**
* Copyright (C) 2015 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery
#include "mongo/platform/basic.h"
#include "mongo/s/query/router_stage_merge.h"
#include "mongo/db/query/find_common.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
RouterStageMerge::RouterStageMerge(OperationContext* opCtx,
executor::TaskExecutor* executor,
ClusterClientCursorParams* params)
: RouterExecStage(opCtx),
_executor(executor),
_params(params),
_arm(opCtx, executor, params->extractARMParams()) {}
StatusWith<ClusterQueryResult> RouterStageMerge::next(ExecContext execCtx) {
// Non-tailable and tailable non-awaitData cursors always block until ready(). AwaitData
// cursors wait for ready() only until a specified time limit is exceeded.
return (_params->tailableMode == TailableModeEnum::kTailableAndAwaitData
? awaitNextWithTimeout(execCtx)
: _arm.blockingNext());
}
StatusWith<ClusterQueryResult> RouterStageMerge::awaitNextWithTimeout(ExecContext execCtx) {
invariant(_params->tailableMode == TailableModeEnum::kTailableAndAwaitData);
// If we are in kInitialFind or kGetMoreWithAtLeastOneResultInBatch context and the ARM is not
// ready, we don't block. Fall straight through to the return statement.
while (!_arm.ready() && execCtx == ExecContext::kGetMoreNoResultsYet) {
auto nextEventStatus = getNextEvent();
if (!nextEventStatus.isOK()) {
return nextEventStatus.getStatus();
}
auto event = nextEventStatus.getValue();
// Block until there are further results to return, or our time limit is exceeded.
auto waitStatus = _executor->waitForEvent(
getOpCtx(), event, awaitDataState(getOpCtx()).waitForInsertsDeadline);
if (!waitStatus.isOK()) {
return waitStatus.getStatus();
}
// Swallow timeout errors for tailable awaitData cursors, stash the event that we were
// waiting on, and return EOF.
if (waitStatus == stdx::cv_status::timeout) {
_leftoverEventFromLastTimeout = std::move(event);
return ClusterQueryResult{};
}
}
// We reach this point either if the ARM is ready, or if the ARM is !ready and we are in
// kInitialFind or kGetMoreWithAtLeastOneResultInBatch ExecContext. In the latter case, we
// return EOF immediately rather than blocking for further results.
return _arm.ready() ? _arm.nextReady() : ClusterQueryResult{};
}
StatusWith<EventHandle> RouterStageMerge::getNextEvent() {
// If we abandoned a previous event due to a mongoS-side timeout, wait for it first.
if (_leftoverEventFromLastTimeout) {
invariant(_params->tailableMode == TailableModeEnum::kTailableAndAwaitData);
auto event = _leftoverEventFromLastTimeout;
_leftoverEventFromLastTimeout = EventHandle();
return event;
}
return _arm.nextEvent();
}
void RouterStageMerge::kill(OperationContext* opCtx) {
_arm.blockingKill(opCtx);
}
bool RouterStageMerge::remotesExhausted() {
return _arm.remotesExhausted();
}
std::size_t RouterStageMerge::getNumRemotes() const {
return _arm.getNumRemotes();
}
Status RouterStageMerge::doSetAwaitDataTimeout(Milliseconds awaitDataTimeout) {
return _arm.setAwaitDataTimeout(awaitDataTimeout);
}
void RouterStageMerge::addNewShardCursors(std::vector<RemoteCursor>&& newShards) {
_arm.addNewShardCursors(std::move(newShards));
}
} // namespace mongo
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