/* tail an oplog. ok to return, will be re-called. */ void SyncTail::oplogApplication() { ReplicationCoordinator* replCoord = getGlobalReplicationCoordinator(); while(!inShutdown()) { OpQueue ops; OperationContextImpl txn; Timer batchTimer; int lastTimeChecked = 0; do { int now = batchTimer.seconds(); // apply replication batch limits if (!ops.empty()) { if (now > replBatchLimitSeconds) break; if (ops.getDeque().size() > replBatchLimitOperations) break; } // occasionally check some things // (always checked in the first iteration of this do-while loop, because // ops is empty) if (ops.empty() || now > lastTimeChecked) { BackgroundSync* bgsync = BackgroundSync::get(); if (bgsync->getInitialSyncRequestedFlag()) { // got a resync command Lock::DBLock lk(txn.lockState(), "local", MODE_X); WriteUnitOfWork wunit(&txn); Client::Context ctx(&txn, "local"); ctx.db()->dropCollection(&txn, "local.oplog.rs"); // Note: the following order is important. // The bgsync thread uses an empty optime as a sentinel to know to wait // for initial sync (done in this thread after we return); thus, we must // ensure the lastAppliedOptime is empty before pausing the bgsync thread // via stop(). // We must clear the sync source blacklist after calling stop() // because the bgsync thread, while running, may update the blacklist. replCoord->setMyLastOptime(&txn, OpTime()); bgsync->stop(); replCoord->clearSyncSourceBlacklist(); wunit.commit(); return; } lastTimeChecked = now; // can we become secondary? // we have to check this before calling mgr, as we must be a secondary to // become primary tryToGoLiveAsASecondary(&txn, replCoord); // TODO(emilkie): This can be removed once we switch over from legacy; // this code is what moves 1-node sets to PRIMARY state. // normally msgCheckNewState gets called periodically, but in a single node // replset there are no heartbeat threads, so we do it here to be sure. this is // relevant if the singleton member has done a stepDown() and needs to come back // up. if (theReplSet && theReplSet->config().members.size() == 1 && theReplSet->myConfig().potentiallyHot()) { Manager* mgr = theReplSet->mgr; // When would mgr be null? During replsettest'ing, in which case we should // fall through and actually apply ops as if we were a real secondary. if (mgr) { mgr->send(stdx::bind(&Manager::msgCheckNewState, theReplSet->mgr)); sleepsecs(1); // There should never be ops to sync in a 1-member set, anyway return; } } } const int slaveDelaySecs = replCoord->getSlaveDelaySecs().total_seconds(); if (!ops.empty() && slaveDelaySecs > 0) { const BSONObj& lastOp = ops.getDeque().back(); const unsigned int opTimestampSecs = lastOp["ts"]._opTime().getSecs(); // Stop the batch as the lastOp is too new to be applied. If we continue // on, we can get ops that are way ahead of the delay and this will // make this thread sleep longer when handleSlaveDelay is called // and apply ops much sooner than we like. if (opTimestampSecs > static_cast<unsigned int>(time(0) - slaveDelaySecs)) { break; } } // keep fetching more ops as long as we haven't filled up a full batch yet } while (!tryPopAndWaitForMore(&ops, replCoord) && // tryPopAndWaitForMore returns true // when we need to end a batch early (ops.getSize() < replBatchLimitBytes) && !inShutdown()); // For pausing replication in tests while (MONGO_FAIL_POINT(rsSyncApplyStop)) { sleepmillis(0); } if (ops.empty()) { continue; } const BSONObj& lastOp = ops.getDeque().back(); handleSlaveDelay(lastOp); if (replCoord->getCurrentMemberState().primary() && !replCoord->isWaitingForApplierToDrain()) { severe() << "attempting to replicate ops while primary"; fassertFailed(28527); } // Set minValid to the last op to be applied in this next batch. // This will cause this node to go into RECOVERING state // if we should crash and restart before updating the oplog OpTime minValid = lastOp["ts"]._opTime(); setMinValid(&txn, minValid); multiApply(ops.getDeque()); applyOpsToOplog(&ops.getDeque()); // If we're just testing (no manager), don't keep looping if we exhausted the bgqueue // TODO(spencer): Remove repltest.cpp dbtest or make this work with the new replication // coordinator if (theReplSet && !theReplSet->mgr) { BSONObj op; if (!peek(&op)) { return; } } } }