static void handleCursorCommand(CursorId id, BSONObj& cmdObj, BSONObjBuilder& result) {
BSONElement batchSizeElem = cmdObj.getFieldDotted("cursor.batchSize");
const long long batchSize = batchSizeElem.isNumber()
? batchSizeElem.numberLong()
: 101; // same as query
// Using limited cursor API that ignores many edge cases. Should be sufficient for commands.
ClientCursor::Pin pin(id);
ClientCursor* cursor = pin.c();
massert(16958, "Cursor shouldn't have been deleted",
cursor);
// Make sure this cursor won't disappear on us
fassert(16959, !cursor->c()->shouldDestroyOnNSDeletion());
fassert(16960, !cursor->c()->requiresLock());
try {
// can't use result BSONObjBuilder directly since it won't handle exceptions correctly.
BSONArrayBuilder resultsArray;
const int byteLimit = MaxBytesToReturnToClientAtOnce;
for (int objs = 0;
objs < batchSize && cursor->ok() && resultsArray.len() <= byteLimit;
objs++) {
// TODO may need special logic if cursor->current() would cause results to be > 16MB
resultsArray.append(cursor->current());
cursor->advance();
}
// The initial ok() on a cursor may be very expensive so we don't do it when batchSize
// is 0 since that indicates a desire for a fast return.
if (batchSize != 0 && !cursor->ok()) {
// There is no more data. Kill the cursor.
pin.release();
ClientCursor::erase(id);
id = 0;
}
BSONObjBuilder cursorObj(result.subobjStart("cursor"));
cursorObj.append("id", id);
cursorObj.append("ns", cursor->ns());
cursorObj.append("firstBatch", resultsArray.arr());
cursorObj.done();
}
catch (...) {
// Clean up cursor on way out of scope.
pin.release();
ClientCursor::erase(id);
throw;
}
}
static void handleCursorCommand(CursorId id, BSONObj& cmdObj, BSONObjBuilder& result) {
BSONElement batchSizeElem = cmdObj.getFieldDotted("cursor.batchSize");
const long long batchSize = batchSizeElem.isNumber()
? batchSizeElem.numberLong()
: 101; // same as query
// Using limited cursor API that ignores many edge cases. Should be sufficient for commands.
ClientCursorPin pin(id);
ClientCursor* cursor = pin.c();
massert(16958, "Cursor shouldn't have been deleted",
cursor);
// Make sure this cursor won't disappear on us
fassert(16959, !cursor->c()->shouldDestroyOnNSDeletion());
fassert(16960, !cursor->c()->requiresLock());
try {
const string cursorNs = cursor->ns(); // we need this after cursor may have been deleted
// can't use result BSONObjBuilder directly since it won't handle exceptions correctly.
BSONArrayBuilder resultsArray;
const int byteLimit = MaxBytesToReturnToClientAtOnce;
for (int objCount = 0; objCount < batchSize && cursor->ok(); objCount++) {
BSONObj current = cursor->current();
if (resultsArray.len() + current.objsize() > byteLimit)
break; // too big. current will be the first doc in the second batch
resultsArray.append(current);
cursor->advance();
}
// The initial ok() on a cursor may be very expensive so we don't do it when batchSize
// is 0 since that indicates a desire for a fast return.
if (batchSize != 0 && !cursor->ok()) {
// There is no more data. Kill the cursor.
pin.release();
ClientCursor::erase(id);
id = 0;
cursor = NULL; // make it an obvious error to use cursor after this point
}
if (cursor) {
// If a time limit was set on the pipeline, remaining time is "rolled over" to the
// cursor (for use by future getmore ops).
cursor->setLeftoverMaxTimeMicros( cc().curop()->getRemainingMaxTimeMicros() );
}
BSONObjBuilder cursorObj(result.subobjStart("cursor"));
cursorObj.append("id", id);
cursorObj.append("ns", cursorNs);
cursorObj.append("firstBatch", resultsArray.arr());
cursorObj.done();
}
catch (...) {
// Clean up cursor on way out of scope.
pin.release();
ClientCursor::erase(id);
throw;
}
}
void DocumentSourceCursor::loadBatch() {
if (!_cursorId) {
dispose();
return;
}
// We have already validated the sharding version when we constructed the cursor
// so we shouldn't check it again.
Lock::DBRead lk(ns);
Client::Context ctx(ns, storageGlobalParams.dbpath, /*doVersion=*/false);
ClientCursorPin pin(_cursorId);
ClientCursor* cursor = pin.c();
uassert(16950, "Cursor deleted. Was the collection or database dropped?",
cursor);
cursor->c()->recoverFromYield();
int memUsageBytes = 0;
for( ; cursor->ok(); cursor->advance() ) {
yieldSometimes(cursor);
if ( !cursor->ok() ) {
// The cursor was exhausted during the yield.
break;
}
if ( !cursor->currentMatches() || cursor->currentIsDup() )
continue;
// grab the matching document
if (canUseCoveredIndex(cursor)) {
// Can't have collection metadata if we are here
BSONObj indexKey = cursor->currKey();
_currentBatch.push_back(Document(cursor->c()->keyFieldsOnly()->hydrate(indexKey)));
}
else {
BSONObj next = cursor->current();
// check to see if this is a new object we don't own yet
// because of a chunk migration
if (_collMetadata) {
KeyPattern kp( _collMetadata->getKeyPattern() );
if ( !_collMetadata->keyBelongsToMe( kp.extractSingleKey( next ) ) ) continue;
}
_currentBatch.push_back(_projection
? documentFromBsonWithDeps(next, _dependencies)
: Document(next));
}
if (_limit) {
if (++_docsAddedToBatches == _limit->getLimit()) {
break;
}
verify(_docsAddedToBatches < _limit->getLimit());
}
memUsageBytes += _currentBatch.back().getApproximateSize();
if (memUsageBytes > MaxBytesToReturnToClientAtOnce) {
// End this batch and prepare cursor for yielding.
cursor->advance();
if (cursor->c()->supportYields()) {
ClientCursor::YieldData data;
cursor->prepareToYield(data);
} else {
cursor->c()->noteLocation();
}
return;
}
}
// If we got here, there aren't any more documents.
// The Cursor must be released, see SERVER-6123.
pin.release();
ClientCursor::erase(_cursorId);
_cursorId = 0;
_collMetadata.reset();
}
