void ClusterCursorManager::reapZombieCursors() {
// List all zombie cursors under the manager lock, and kill them one-by-one while not holding
// the lock (ClusterClientCursor::kill() is blocking, so we don't want to hold a lock while
// issuing the kill).
stdx::unique_lock<stdx::mutex> lk(_mutex);
std::vector<std::pair<NamespaceString, CursorId>> zombieCursorDescriptors;
for (auto& nsContainerPair : _namespaceToContainerMap) {
const NamespaceString& nss = nsContainerPair.first;
for (auto& cursorIdEntryPair : nsContainerPair.second.entryMap) {
CursorId cursorId = cursorIdEntryPair.first;
const CursorEntry& entry = cursorIdEntryPair.second;
if (!entry.getKillPending()) {
continue;
}
zombieCursorDescriptors.emplace_back(nss, cursorId);
}
}
for (auto& namespaceCursorIdPair : zombieCursorDescriptors) {
StatusWith<std::unique_ptr<ClusterClientCursor>> zombieCursor =
detachCursor_inlock(namespaceCursorIdPair.first, namespaceCursorIdPair.second);
if (!zombieCursor.isOK()) {
// Cursor in use, or has already been deleted.
continue;
}
lk.unlock();
zombieCursor.getValue()->kill();
lk.lock();
// Cursor deleted as it goes out of scope.
}
}
void ClusterCursorManager::checkInCursor(std::unique_ptr<ClusterClientCursor> cursor,
const NamespaceString& nss,
CursorId cursorId,
CursorState cursorState) {
stdx::unique_lock<stdx::mutex> lk(_mutex);
invariant(cursor);
const bool remotesExhausted = cursor->remotesExhausted();
CursorEntry* entry = getEntry_inlock(nss, cursorId);
invariant(entry);
entry->returnCursor(std::move(cursor));
if (cursorState == CursorState::NotExhausted || entry->getKillPending()) {
return;
}
if (!remotesExhausted) {
// The cursor still has open remote cursors that need to be cleaned up. Schedule for
// deletion by the reaper thread by setting the kill pending flag.
entry->setKillPending();
return;
}
// The cursor is exhausted, is not already scheduled for deletion, and does not have any
// remote cursor state left to clean up. We can delete the cursor right away.
auto detachedCursor = detachCursor_inlock(nss, cursorId);
invariantOK(detachedCursor.getStatus());
// Deletion of the cursor can happen out of the lock.
lk.unlock();
detachedCursor.getValue().reset();
}
