SERVER-15249 move QuorumCheck class declaration to header file for testing

1 files changed, 78 insertions, 4 deletions

diff --git a/src/mongo/db/repl/check_quorum_for_config_change.h b/src/mongo/db/repl/check_quorum_for_config_change.h
index be824d3bf98..04f3f87b340 100644
--- a/src/mongo/db/repl/check_quorum_for_config_change.h
+++ b/src/mongo/db/repl/check_quorum_for_config_change.h
@@ -28,14 +28,88 @@
 
 #pragma once
 
-namespace mongo {
-
-    class Status;
+#include "mongo/base/status.h"
+#include "mongo/db/repl/replication_executor.h"
+#include "mongo/db/repl/scatter_gather_algorithm.h"
 
+namespace mongo {
 namespace repl {
 
     class ReplicaSetConfig;
-    class ReplicationExecutor;
+
+    /**
+     * Quorum checking state machine.
+     *
+     * Usage: Construct a QuorumChecker, pass in a pointer to the configuration for which you're
+     * checking quorum, and the integer index of the member config representing the "executing"
+     * node.  Use ScatterGatherRunner or otherwise execute a scatter-gather procedure as described
+     * in the class comment for the ScatterGatherAlgorithm class.  After
+     * hasReceivedSufficientResponses() returns true, you may call getFinalStatus() to get the
+     * result of the quorum check.
+     */
+    class QuorumChecker : public ScatterGatherAlgorithm {
+        MONGO_DISALLOW_COPYING(QuorumChecker);
+    public:
+        /**
+         * Constructs a QuorumChecker that is used to confirm that sufficient nodes are up to accept
+         * "rsConfig".  "myIndex" is the index of the local node, which is assumed to be up.
+         *
+         * "rsConfig" must stay in scope until QuorumChecker's destructor completes.
+         */
+        QuorumChecker(const ReplicaSetConfig* rsConfig, int myIndex);
+        virtual ~QuorumChecker();
+
+        virtual std::vector<ReplicationExecutor::RemoteCommandRequest> getRequests() const;
+        virtual void processResponse(
+                const ReplicationExecutor::RemoteCommandRequest& request,
+                const ResponseStatus& response);
+
+        virtual bool hasReceivedSufficientResponses() const;
+
+        Status getFinalStatus() const { return _finalStatus; }
+
+    private:
+        /**
+         * Callback that executes after _haveReceivedSufficientReplies() becomes true.
+         *
+         * Computes the quorum result based on responses received so far, stores it into
+         * _finalStatus, and enables QuorumChecker::run() to return.
+         */
+        void _onQuorumCheckComplete();
+
+        /**
+         * Updates the QuorumChecker state based on the data from a single heartbeat response.
+         */
+        void _tabulateHeartbeatResponse(
+                const ReplicationExecutor::RemoteCommandRequest& request,
+                const ResponseStatus& response);
+
+        // Pointer to the replica set configuration for which we're checking quorum.
+        const ReplicaSetConfig* const _rsConfig;
+
+        // Index of the local node's member configuration in _rsConfig.
+        const int _myIndex;
+
+        // List of nodes believed to be down.
+        std::vector<HostAndPort> _down;
+
+        // List of voting nodes that have responded affirmatively.
+        std::vector<HostAndPort> _voters;
+
+        // Total number of responses and timeouts processed.
+        int _numResponses;
+
+        // Number of electable nodes that have responded affirmatively.
+        int _numElectable;
+
+        // Set to a non-OK status if a response from a remote node indicates
+        // that the quorum check should definitely fail, such as because of
+        // a replica set name mismatch.
+        Status _vetoStatus;
+
+        // Final status of the quorum check, returned by run().
+        Status _finalStatus;
+    };
 
     /**
      * Performs a quorum call to determine if a sufficient number of nodes are up