bool MigrationSourceManager::transferMods(OperationContext* txn,
const MigrationSessionId& sessionId,
string& errmsg,
BSONObjBuilder& b) {
long long size = 0;
{
AutoGetCollectionForRead ctx(txn, _getNS());
stdx::lock_guard<stdx::mutex> sl(_mutex);
if (!_sessionId) {
errmsg = "no active migration!";
return false;
}
// TODO after 3.4 release, !sessionId.isEmpty() can be removed: versions >= 3.2 will
// all have sessionId implemented. (two more instances below).
// A mongod version < v3.2 will not have sessionId, in which case it is empty and ignored.
if (!sessionId.isEmpty() && !_sessionId->matches(sessionId)) {
errmsg = str::stream() << "requested migration session id " << sessionId.toString()
<< " does not match active session id "
<< _sessionId->toString();
return false;
}
// TODO: fix SERVER-16540 race
_xfer(txn, _nss.ns(), ctx.getDb(), &_deleted, b, "deleted", size, false);
_xfer(txn, _nss.ns(), ctx.getDb(), &_reload, b, "reload", size, true);
}
b.append("size", size);
return true;
}
void StartChunkCloneRequest::appendAsCommand(
BSONObjBuilder* builder,
const NamespaceString& nss,
const MigrationSessionId& sessionId,
const ConnectionString& configServerConnectionString,
const ConnectionString& fromShardConnectionString,
const ShardId& fromShardId,
const ShardId& toShardId,
const BSONObj& chunkMinKey,
const BSONObj& chunkMaxKey,
const BSONObj& shardKeyPattern,
const MigrationSecondaryThrottleOptions& secondaryThrottle) {
invariant(builder->asTempObj().isEmpty());
invariant(nss.isValid());
invariant(fromShardConnectionString.isValid());
builder->append(kRecvChunkStart, nss.ns());
sessionId.append(builder);
builder->append(kConfigServerConnectionString, configServerConnectionString.toString());
builder->append(kFromShardConnectionString, fromShardConnectionString.toString());
builder->append(kFromShardId, fromShardId.toString());
builder->append(kToShardId, toShardId.toString());
builder->append(kChunkMinKey, chunkMinKey);
builder->append(kChunkMaxKey, chunkMaxKey);
builder->append(kShardKeyPattern, shardKeyPattern);
secondaryThrottle.append(builder);
}
/**
* Create the migration transfer mods request BSON object to send to the source shard.
*
* 'sessionId' unique identifier for this migration.
*/
BSONObj createTransferModsRequest(const NamespaceString& nss, const MigrationSessionId& sessionId) {
BSONObjBuilder builder;
builder.append("_transferMods", nss.ns());
sessionId.append(&builder);
return builder.obj();
}
/**
* Create the migration clone request BSON object to send to the source shard.
*
* 'sessionId' unique identifier for this migration.
*/
BSONObj createMigrateCloneRequest(const NamespaceString& nss, const MigrationSessionId& sessionId) {
BSONObjBuilder builder;
builder.append("_migrateClone", nss.ns());
sessionId.append(&builder);
return builder.obj();
}
bool MigrationSourceManager::clone(OperationContext* txn,
const MigrationSessionId& sessionId,
string& errmsg,
BSONObjBuilder& result) {
ElapsedTracker tracker(internalQueryExecYieldIterations, internalQueryExecYieldPeriodMS);
int allocSize = 0;
{
AutoGetCollection autoColl(txn, _getNS(), MODE_IS);
stdx::lock_guard<stdx::mutex> sl(_mutex);
if (!_sessionId) {
errmsg = "not active";
return false;
}
// A mongod version < v3.2 will not have sessionId, in which case it is empty and ignored.
if (!sessionId.isEmpty() && !_sessionId->matches(sessionId)) {
errmsg = str::stream() << "requested migration session id " << sessionId.toString()
<< " does not match active session id "
<< _sessionId->toString();
return false;
}
Collection* collection = autoColl.getCollection();
if (!collection) {
errmsg = str::stream() << "collection " << _nss.toString() << " does not exist";
return false;
}
allocSize = std::min(
BSONObjMaxUserSize,
static_cast<int>((12 + collection->averageObjectSize(txn)) * cloneLocsRemaining()));
}
bool isBufferFilled = false;
BSONArrayBuilder clonedDocsArrayBuilder(allocSize);
while (!isBufferFilled) {
AutoGetCollection autoColl(txn, _getNS(), MODE_IS);
stdx::lock_guard<stdx::mutex> sl(_mutex);
if (!_sessionId) {
errmsg = "not active";
return false;
}
// A mongod version < v3.2 will not have sessionId, in which case it is empty and ignored.
if (!sessionId.isEmpty() && !_sessionId->matches(sessionId)) {
errmsg = str::stream() << "migration session id changed from " << sessionId.toString()
<< " to " << _sessionId->toString()
<< " while initial clone was active";
return false;
}
// TODO: fix SERVER-16540 race
Collection* collection = autoColl.getCollection();
if (!collection) {
errmsg = str::stream() << "collection " << _nss.toString() << " does not exist";
return false;
}
stdx::lock_guard<stdx::mutex> lk(_cloneLocsMutex);
std::set<RecordId>::iterator cloneLocsIter = _cloneLocs.begin();
for (; cloneLocsIter != _cloneLocs.end(); ++cloneLocsIter) {
if (tracker.intervalHasElapsed()) // should I yield?
break;
RecordId recordId = *cloneLocsIter;
Snapshotted<BSONObj> doc;
if (!collection->findDoc(txn, recordId, &doc)) {
// doc was deleted
continue;
}
// Use the builder size instead of accumulating 'doc's size so that we take
// into consideration the overhead of BSONArray indices, and *always*
// append one doc.
if (clonedDocsArrayBuilder.arrSize() != 0 &&
(clonedDocsArrayBuilder.len() + doc.value().objsize() + 1024) >
BSONObjMaxUserSize) {
isBufferFilled = true; // break out of outer while loop
break;
}
clonedDocsArrayBuilder.append(doc.value());
}
_cloneLocs.erase(_cloneLocs.begin(), cloneLocsIter);
// Note: must be holding _cloneLocsMutex, don't move this inside while condition!
if (_cloneLocs.empty()) {
break;
}
}
result.appendArray("objects", clonedDocsArrayBuilder.arr());
return true;
}
