bool OplogBufferCollection::peek(OperationContext* txn, Value* value) {
stdx::lock_guard<stdx::mutex> lk(_mutex);
if (_count == 0) {
return false;
}
return _peekOneSide_inlock(txn, value, true);
}
bool OplogBufferCollection::blockingPeek(OperationContext* txn,
Value* value,
Seconds waitDuration) {
stdx::unique_lock<stdx::mutex> lk(_mutex);
if (!_cvNoLongerEmpty.wait_for(
lk, waitDuration.toSystemDuration(), [&]() {
return _count != 0;
})) {
return false;
}
return _peekOneSide_inlock(txn, value, true);
}
boost::optional<OplogBuffer::Value> OplogBufferCollection::lastObjectPushed(
OperationContext* txn) const {
stdx::lock_guard<stdx::mutex> lk(_mutex);
if (_count == 0) {
return boost::none;
}
Value value;
bool res = _peekOneSide_inlock(txn, &value, false);
if (!res) {
return boost::none;
}
return value;
}
bool OplogBufferCollection::_pop_inlock(OperationContext* txn, Value* value) {
// If there is a sentinel, and it was pushed right after the last BSONObj to be popped was
// pushed, then we pop off a sentinel instead and decrease the count by 1.
if (!_sentinels.empty() && (_lastPoppedTimestamp == _sentinels.front())) {
_sentinels.pop();
_count--;
*value = BSONObj();
return true;
}
if (!_peekOneSide_inlock(txn, value, true)) {
return false;
}
_lastPoppedTimestamp = (*value)["ts"].timestamp();
invariant(_count > 0);
invariant(_size >= std::size_t(value->objsize()));
_count--;
_size -= value->objsize();
return true;
}