SERVER-37564 Remove unused deadlock detector

1 files changed, 0 insertions, 99 deletions

diff --git a/src/mongo/db/concurrency/lock_manager.h b/src/mongo/db/concurrency/lock_manager.h
index 7b137715412..75922ac7c18 100644
--- a/src/mongo/db/concurrency/lock_manager.h
+++ b/src/mongo/db/concurrency/lock_manager.h
@@ -134,9 +134,6 @@ public:
                          BSONObjBuilder* result);
 
 private:
-    // The deadlock detector needs to access the buckets and locks directly
-    friend class DeadlockDetector;
-
     // The lockheads need access to the partitions
     friend struct LockHead;
 
@@ -219,100 +216,4 @@ private:
     static const unsigned _numPartitions;
     Partition* _partitions;
 };
-
-
-/**
- * Iteratively builds the wait-for graph, starting from a given blocked Locker and stops either
- * when all reachable nodes have been checked or if a cycle is detected. This class is
- * thread-safe. Because locks may come and go in parallel with deadlock detection, it may
- * report false positives, but if there is a stable cycle it will be discovered.
- *
- * Implemented as a separate class in order to facilitate diagnostics and also unit-testing for
- * cases where locks come and go in parallel with deadlock detection.
- */
-class DeadlockDetector {
-public:
-    /**
-     * Initializes the wait-for graph builder with the LM to operate on and a locker object
-     * from which to start the search. Deadlock will only be reported if there is a wait cycle
-     * in which the initial locker participates.
-     */
-    DeadlockDetector(const LockManager& lockMgr, const Locker* initialLocker);
-
-    DeadlockDetector& check() {
-        while (next()) {
-        }
-
-        return *this;
-    }
-
-    /**
-     * Processes the next wait for node and queues up its set of owners to the unprocessed
-     * queue.
-     *
-     * @return true if there are more unprocessed nodes and no cycle has been discovered yet;
-     *          false if either all reachable nodes have been processed or
-     */
-    bool next();
-
-    /**
-     * Checks whether a cycle exists in the wait-for graph, which has been built so far. It's
-     * only useful to call this after next() has returned false.
-     */
-    bool hasCycle() const;
-
-    /**
-     * Produces a string containing the wait-for graph that has been built so far.
-     */
-    std::string toString() const;
-
-private:
-    // An entry in the owners list below means that some locker L is blocked on some resource
-    // resId, which is currently held by the given set of owners. The reason to store it in
-    // such form is in order to avoid storing pointers to the lockers or to have to look them
-    // up by id, both of which require some form of synchronization other than locking the
-    // bucket for the resource. Instead, given the resId, we can lock the bucket for the lock
-    // and find the respective LockRequests and continue our scan forward.
-    typedef std::vector<LockerId> ConflictingOwnersList;
-
-    struct Edges {
-        explicit Edges(ResourceId resId) : resId(resId) {}
-
-        // Resource id indicating the lock node
-        ResourceId resId;
-
-        // List of lock owners/pariticipants with which the initial locker conflicts for
-        // obtaining the lock
-        ConflictingOwnersList owners;
-    };
-
-    typedef std::map<LockerId, Edges> WaitForGraph;
-    typedef WaitForGraph::value_type WaitForGraphPair;
-
-
-    // We don't want to hold locks between iteration cycles, so just store the resourceId and
-    // the lockerId so we can directly find them from the lock manager.
-    struct UnprocessedNode {
-        UnprocessedNode(LockerId lockerId, ResourceId resId) : lockerId(lockerId), resId(resId) {}
-
-        LockerId lockerId;
-        ResourceId resId;
-    };
-
-    typedef std::deque<UnprocessedNode> UnprocessedNodesQueue;
-
-
-    void _processNextNode(const UnprocessedNode& node);
-
-
-    // Not owned. Lifetime must be longer than that of the graph builder.
-    const LockManager& _lockMgr;
-    const LockerId _initialLockerId;
-
-    UnprocessedNodesQueue _queue;
-    WaitForGraph _graph;
-
-    bool _foundCycle;
-};
-
 }  // namespace mongo