1 files changed, 11 insertions, 60 deletions

diff --git a/src/mongo/db/session.h b/src/mongo/db/session.h
index ba01d6458f5..ad5a9dfb82b 100644
--- a/src/mongo/db/session.h
+++ b/src/mongo/db/session.h
@@ -32,13 +32,12 @@
 
 #include "mongo/base/disallow_copying.h"
 #include "mongo/db/logical_session_id.h"
+#include "mongo/db/operation_context.h"
 #include "mongo/util/concurrency/with_lock.h"
 #include "mongo/util/decorable.h"
 
 namespace mongo {
 
-class OperationContext;
-
 /**
  * A decorable container for state associated with an active session running on a MongoD or MongoS
  * server. Refer to SessionCatalog for more information on the semantics of sessions.
@@ -46,10 +45,11 @@ class OperationContext;
 class Session : public Decorable<Session> {
     MONGO_DISALLOW_COPYING(Session);
 
+    friend class ObservableSession;
     friend class SessionCatalog;
 
 public:
-    explicit Session(LogicalSessionId sessionId);
+    explicit Session(LogicalSessionId sessionId) : _sessionId(std::move(sessionId)) {}
 
     /**
      * The logical session id that this object represents.
@@ -58,72 +58,23 @@ public:
         return _sessionId;
     }
 
-    /**
-     * Returns a pointer to the current operation running on this Session, or nullptr if there is no
-     * operation currently running on this Session.
-     */
-    OperationContext* currentOperation() const;
-
-    /**
-     * Increments the number of "killers" for this session and returns a 'kill token' to to be
-     * passed later on to 'checkOutSessionForKill' method of the SessionCatalog in order to permit
-     * the caller to execute any kill cleanup tasks. This token is later on passed to
-     * '_markNotKilled' in order to decrement the number of "killers".
-     *
-     * Marking session as killed is an internal property only that will cause any further calls to
-     * 'checkOutSession' to block until 'checkOutSessionForKill' is called the same number of times
-     * as 'kill' was called and the returned scoped object destroyed.
-     *
-     * If the first killer finds the session checked-out, this method will also interrupt the
-     * operation context which has it checked-out.
-     *
-     * Must be called under the owning SessionCatalog's lock.
-     */
-    struct KillToken {
-        KillToken(LogicalSessionId lsid) : lsidToKill(std::move(lsid)) {}
-        KillToken(KillToken&&) = default;
-        KillToken& operator=(KillToken&&) = default;
-
-        LogicalSessionId lsidToKill;
-    };
-    KillToken kill(WithLock sessionCatalogLock, ErrorCodes::Error reason = ErrorCodes::Interrupted);
-
-    /**
-     * Returns whether 'kill' has been called on this session.
-     */
-    bool killed() const;
+    OperationContext* currentOperation_forTest() const {
+        return _checkoutOpCtx;
+    }
 
 private:
-    /**
-     * Set/clear the current check-out state of the session by storing the operation which has this
-     * session currently checked-out.
-     *
-     * Must be called under the SessionCatalog mutex and internally will acquire the Session mutex.
-     */
-    void _markCheckedOut(WithLock sessionCatalogLock, OperationContext* checkoutOpCtx);
-    void _markCheckedIn(WithLock sessionCatalogLock);
-
-    /**
-     * Used by the session catalog when checking a session back in after a call to 'kill'. See the
-     * comments for 'kill for more details.
-     */
-    void _markNotKilled(WithLock sessionCatalogLock, KillToken killToken);
-
     // The id of the session with which this object is associated
     const LogicalSessionId _sessionId;
 
-    // Protects the member variables below. The order of lock acquisition should always be:
-    //
-    // 1) SessionCatalog mutex (if applicable)
-    // 2) Session mutex
-    // 3) Any decoration mutexes and/or the currently running Client's lock
-    mutable stdx::mutex _mutex;
-
     // A pointer back to the currently running operation on this Session, or nullptr if there
     // is no operation currently running for the Session.
+    //
+    // May be read by holders of the SessionCatalog mutex. May only be set when clear or cleared
+    // when set, and the opCtx being set or cleared must have its client locked at the time.
     OperationContext* _checkoutOpCtx{nullptr};
 
-    // Incremented every time 'kill' is invoked and decremented by '_markNotKilled'.
+    // Counter indicating the number of times ObservableSession::kill has been called on this
+    // session, which have not yet had a corresponding call to checkOutSessionForKill.
     int _killsRequested{0};
 };