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/**
* Copyright (C) 2008 10gen 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::kReplication
#include "mongo/platform/basic.h"
#include "mongo/db/repl/rs_initialsync.h"
#include "mongo/bson/optime.h"
#include "mongo/db/auth/authorization_manager.h"
#include "mongo/db/auth/authorization_manager_global.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/client.h"
#include "mongo/db/cloner.h"
#include "mongo/db/dbhelpers.h"
#include "mongo/db/operation_context_impl.h"
#include "mongo/db/operation_context_impl.h"
#include "mongo/db/repl/bgsync.h"
#include "mongo/db/repl/initial_sync.h"
#include "mongo/db/repl/minvalid.h"
#include "mongo/db/repl/oplog.h"
#include "mongo/db/repl/oplogreader.h"
#include "mongo/db/repl/replication_coordinator_global.h"
#include "mongo/util/exit.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
namespace repl {
namespace {
using std::list;
using std::string;
/**
* Truncates the oplog (removes any documents) and resets internal variables that were
* originally initialized or affected by using values from the oplog at startup time. These
* include the last applied optime, the last fetched optime, and the sync source blacklist.
* Also resets the bgsync thread so that it reconnects its sync source after the oplog has been
* truncated.
*/
void truncateAndResetOplog(OperationContext* txn,
ReplicationCoordinator* replCoord,
BackgroundSync* bgsync) {
AutoGetDb autoDb(txn, "local", MODE_X);
massert(28585, "no local database found", autoDb.getDb());
invariant(txn->lockState()->isCollectionLockedForMode(rsoplog, MODE_X));
// Note: the following order is important.
// The bgsync thread uses an empty optime as a sentinel to know to wait
// for initial sync; thus, we must
// ensure the lastAppliedOptime is empty before restarting 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(OpTime());
bgsync->stop();
replCoord->clearSyncSourceBlacklist();
// Truncate the oplog in case there was a prior initial sync that failed.
Collection* collection = autoDb.getDb()->getCollection(rsoplog);
fassert(28565, collection);
WriteUnitOfWork wunit(txn);
Status status = collection->truncate(txn);
fassert(28564, status);
wunit.commit();
}
bool _initialSyncClone(OperationContext* txn,
Cloner& cloner,
const std::string& host,
const list<string>& dbs,
bool dataPass) {
for( list<string>::const_iterator i = dbs.begin(); i != dbs.end(); i++ ) {
const string db = *i;
if ( db == "local" )
continue;
if ( dataPass )
log() << "initial sync cloning db: " << db;
else
log() << "initial sync cloning indexes for : " << db;
string err;
int errCode;
CloneOptions options;
options.fromDB = db;
options.logForRepl = false;
options.slaveOk = true;
options.useReplAuth = true;
options.snapshot = false;
options.mayYield = true;
options.mayBeInterrupted = false;
options.syncData = dataPass;
options.syncIndexes = ! dataPass;
// Make database stable
ScopedTransaction transaction(txn, MODE_IX);
Lock::DBLock dbWrite(txn->lockState(), db, MODE_X);
if (!cloner.go(txn, db, host, options, NULL, err, &errCode)) {
log() << "initial sync: error while "
<< (dataPass ? "cloning " : "indexing ") << db
<< ". " << (err.empty() ? "" : err + ". ");
return false;
}
}
return true;
}
/**
* Replays the sync target's oplog from lastOp to the latest op on the sync target.
*
* @param syncer either initial sync (can reclone missing docs) or "normal" sync (no recloning)
* @param r the oplog reader
* @return if applying the oplog succeeded
*/
bool _initialSyncApplyOplog( OperationContext* ctx,
repl::SyncTail& syncer,
OplogReader* r) {
const OpTime startOpTime = getGlobalReplicationCoordinator()->getMyLastOptime();
BSONObj lastOp;
try {
// It may have been a long time since we last used this connection to
// query the oplog, depending on the size of the databases we needed to clone.
// A common problem is that TCP keepalives are set too infrequent, and thus
// our connection here is terminated by a firewall due to inactivity.
// Solution is to increase the TCP keepalive frequency.
lastOp = r->getLastOp(rsoplog);
} catch ( SocketException & ) {
HostAndPort host = r->getHost();
log() << "connection lost to " << host.toString() <<
"; is your tcp keepalive interval set appropriately?";
if ( !r->connect(host) ) {
error() << "initial sync couldn't connect to " << host.toString();
throw;
}
// retry
lastOp = r->getLastOp(rsoplog);
}
if (lastOp.isEmpty()) {
error() << "initial sync lastOp is empty";
sleepsecs(1);
return false;
}
OpTime stopOpTime = lastOp["ts"]._opTime();
// If we already have what we need then return.
if (stopOpTime == startOpTime)
return true;
verify( !stopOpTime.isNull() );
verify( stopOpTime > startOpTime );
// apply till stopOpTime
try {
LOG(2) << "Applying oplog entries from " << startOpTime.toStringPretty()
<< " until " << stopOpTime.toStringPretty();
syncer.oplogApplication(ctx, stopOpTime);
}
catch (const DBException&) {
log() << "replSet initial sync failed during oplog application phase, and will retry";
getGlobalReplicationCoordinator()->setMyLastOptime(OpTime());
BackgroundSync::get()->setLastAppliedHash(0);
sleepsecs(5);
return false;
}
return true;
}
void _tryToApplyOpWithRetry(OperationContext* txn, InitialSync* init, const BSONObj& op) {
try {
if (!init->syncApply(txn, op)) {
bool retry;
{
ScopedTransaction transaction(txn, MODE_X);
Lock::GlobalWrite lk(txn->lockState());
retry = init->shouldRetry(txn, op);
}
if (retry) {
// retry
if (!init->syncApply(txn, op)) {
uasserted(28542,
str::stream() << "During initial sync, failed to apply op: "
<< op);
}
}
// If shouldRetry() returns false, fall through.
// This can happen if the document that was moved and missed by Cloner
// subsequently got deleted and no longer exists on the Sync Target at all
}
}
catch (const DBException& e) {
error() << "exception: " << causedBy(e) << " on: " << op.toString();
uasserted(28541,
str::stream() << "During initial sync, failed to apply op: "
<< op);
}
}
/**
* Do the initial sync for this member. There are several steps to this process:
*
* 0. Add _initialSyncFlag to minValid collection to tell us to restart initial sync if we
* crash in the middle of this procedure
* 1. Record start time.
* 2. Clone.
* 3. Set minValid1 to sync target's latest op time.
* 4. Apply ops from start to minValid1, fetching missing docs as needed.
* 5. Set minValid2 to sync target's latest op time.
* 6. Apply ops from minValid1 to minValid2.
* 7. Build indexes.
* 8. Set minValid3 to sync target's latest op time.
* 9. Apply ops from minValid2 to minValid3.
10. Cleanup minValid collection: remove _initialSyncFlag field, set ts to minValid3 OpTime
*
* At that point, initial sync is finished. Note that the oplog from the sync target is applied
* three times: step 4, 6, and 8. 4 may involve refetching, 6 should not. By the end of 6,
* this member should have consistent data. 8 is "cosmetic," it is only to get this member
* closer to the latest op time before it can transition out of startup state
*
* Returns a Status with ErrorCode::ShutdownInProgress if the node enters shutdown,
* ErrorCode::InitialSyncOplogSourceMissing if the node fails to find an sync source, Status::OK
* if everything worked, and ErrorCode::InitialSyncFailure for all other error cases.
*/
Status _initialSync() {
log() << "initial sync pending";
BackgroundSync* bgsync(BackgroundSync::get());
OperationContextImpl txn;
ReplicationCoordinator* replCoord(getGlobalReplicationCoordinator());
truncateAndResetOplog(&txn, replCoord, bgsync);
OplogReader r;
OpTime now(Milliseconds(curTimeMillis64()).total_seconds(), 0);
while (r.getHost().empty()) {
// We must prime the sync source selector so that it considers all candidates regardless
// of oplog position, by passing in "now" as the last op fetched time.
r.connectToSyncSource(&txn, now, replCoord);
if (r.getHost().empty()) {
std::string msg =
"no valid sync sources found in current replset to do an initial sync";
log() << msg;
return Status(ErrorCodes::InitialSyncOplogSourceMissing, msg);
}
if (inShutdown()) {
return Status(ErrorCodes::ShutdownInProgress, "shutting down");
}
}
InitialSync init(bgsync);
init.setHostname(r.getHost().toString());
BSONObj lastOp = r.getLastOp(rsoplog);
if ( lastOp.isEmpty() ) {
std::string msg = "initial sync couldn't read remote oplog";
log() << msg;
sleepsecs(15);
return Status(ErrorCodes::InitialSyncFailure, msg);
}
if (getGlobalReplicationCoordinator()->getSettings().fastsync) {
log() << "fastsync: skipping database clone";
// prime oplog
try {
_tryToApplyOpWithRetry(&txn, &init, lastOp);
_logOpObjRS(&txn, lastOp);
return Status::OK();
} catch (DBException& e) {
// Return if in shutdown
if (inShutdown()) {
return Status(ErrorCodes::ShutdownInProgress, "shutdown in progress");
}
throw;
}
}
// Add field to minvalid document to tell us to restart initial sync if we crash
setInitialSyncFlag(&txn);
log() << "initial sync drop all databases";
dropAllDatabasesExceptLocal(&txn);
log() << "initial sync clone all databases";
list<string> dbs = r.conn()->getDatabaseNames();
Cloner cloner;
if (!_initialSyncClone(&txn, cloner, r.conn()->getServerAddress(), dbs, true)) {
return Status(ErrorCodes::InitialSyncFailure, "initial sync failed data cloning");
}
log() << "initial sync data copy, starting syncup";
// prime oplog
_tryToApplyOpWithRetry(&txn, &init, lastOp);
_logOpObjRS(&txn, lastOp);
std::string msg = "oplog sync 1 of 3";
log() << msg;
if (!_initialSyncApplyOplog(&txn, init, &r)) {
return Status(ErrorCodes::InitialSyncFailure,
str::stream() << "initial sync failed: " << msg);
}
// Now we sync to the latest op on the sync target _again_, as we may have recloned ops
// that were "from the future" compared with minValid. During this second application,
// nothing should need to be recloned.
msg = "oplog sync 2 of 3";
log() << msg;
if (!_initialSyncApplyOplog(&txn, init, &r)) {
return Status(ErrorCodes::InitialSyncFailure,
str::stream() << "initial sync failed: " << msg);
}
// data should now be consistent
msg = "initial sync building indexes";
log() << msg;
if (!_initialSyncClone(&txn, cloner, r.conn()->getServerAddress(), dbs, false)) {
return Status(ErrorCodes::InitialSyncFailure,
str::stream() << "initial sync failed: " << msg);
}
msg = "oplog sync 3 of 3";
log() << msg;
SyncTail tail(bgsync, multiSyncApply);
if (!_initialSyncApplyOplog(&txn, tail, &r)) {
return Status(ErrorCodes::InitialSyncFailure,
str::stream() << "initial sync failed: " << msg);
}
// ---------
Status status = getGlobalAuthorizationManager()->initialize(&txn);
if (!status.isOK()) {
warning() << "Failed to reinitialize auth data after initial sync. " << status;
return status;
}
log() << "initial sync finishing up";
{
ScopedTransaction scopedXact(&txn, MODE_IX);
AutoGetDb autodb(&txn, "local", MODE_X);
OpTime lastOpTimeWritten(getGlobalReplicationCoordinator()->getMyLastOptime());
log() << "replSet set minValid=" << lastOpTimeWritten;
// Initial sync is now complete. Flag this by setting minValid to the last thing
// we synced.
WriteUnitOfWork wunit(&txn);
setMinValid(&txn, lastOpTimeWritten);
// Clear the initial sync flag.
clearInitialSyncFlag(&txn);
BackgroundSync::get()->setInitialSyncRequestedFlag(false);
wunit.commit();
}
// If we just cloned & there were no ops applied, we still want the primary to know where
// we're up to
bgsync->notify(&txn);
log() << "initial sync done";
return Status::OK();
}
} // namespace
void syncDoInitialSync() {
static const int maxFailedAttempts = 10;
{
OperationContextImpl txn;
createOplog(&txn);
}
int failedAttempts = 0;
while ( failedAttempts < maxFailedAttempts ) {
try {
// leave loop when successful
Status status = _initialSync();
if (status.isOK()) {
break;
}
if (status == ErrorCodes::InitialSyncOplogSourceMissing) {
sleepsecs(1);
return;
}
}
catch(const DBException& e) {
error() << e ;
// Return if in shutdown
if (inShutdown()) {
return;
}
}
if (inShutdown()) {
return;
}
error() << "initial sync attempt failed, "
<< (maxFailedAttempts - ++failedAttempts) << " attempts remaining";
sleepsecs(5);
}
// No need to print a stack
if (failedAttempts >= maxFailedAttempts) {
severe() << "The maximum number of retries have been exhausted for initial sync.";
fassertFailedNoTrace(16233);
}
}
} // namespace repl
} // namespace mongo
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