Spooky hash, smarter animqueue diffs

luprex/core/cpp/animqueue.hpp

@@ -19,6 +19,27 @@
 // set_plane, or an other setter. These setters are meant to only be used
 // immediately after calling 'add' to populate the new step. 
 //
+// VERSION NUMBERS
+//
+// The version number field: if the version number in the synchronous model is
+// equal to the version number in the master model, then the two animqueues are
+// guaranteed to be equal. Here's how we achieve that invariant:
+//
+// * In the master model, the version number starts at 1 and is incremented
+//   every time the animation queue is mutated.
+//
+// * In the synchronous model, the version number is set to zero every time the
+//   animation queue is mutated.  Note that master version numbers are never
+//   zero. Applying a patch also sets the version number to zero.
+//
+// * Serializing and deserializing causes the version number to be saved and
+//   restored in both master and synchronous models.
+//
+// * The routine 'update_version' should be called after difference
+//   transmission.  This copies the version number from the master to the
+//   synchronous model.  This is guaranteed to be safe because we just finished
+//   difference transmission, therefore, the animatio queues should match.
+//
 ///////////////////////////////////////////////////////////////////
 
 #ifndef ANIMQUEUE_HPP
@@ -138,25 +159,28 @@ public:
 
 class AnimQueue {
 private:
+    util::WorldType world_type_;
     int32_t size_limit_;
     std::deque<AnimStep> steps_;
+    int64_t version_number_;
 
+    // Called whenever the animation queue is mutated.
+    // serialization and deserialization
+    void mutated();
 public:    
-    AnimQueue();
+    AnimQueue(util::WorldType wt);
     
-    bool exactly_equal(const AnimQueue &aq) const;
-
+    // Simple getters.
     const AnimStep &nth(int n) const { return steps_[n]; }
     size_t size() const { return steps_.size(); }
     int32_t size_limit() const { return size_limit_; }
 
-    // Discard all but the most recent N steps.
-    void keep_only(int n);
+    // Return true if the size limit and steps are identical.
+    bool size_and_steps_equal(const AnimQueue &aq) const;
 
-    // Clear the steps.
+    // Clear the steps.  Doesn't affect size_limit.
     // The resulting steps aren't empty.  There will be one
     // step in the queue, which will be on the plane "", at (0,0,0).
-    // Doesn't affect size_limit.
     void clear_steps();
     
     // Mutator to create a new step.
@@ -167,13 +191,10 @@ public:
     void deserialize(StreamBuffer *sb);
 
     // Difference transmission
-    //
-    // When there are no differences, make_patch returns false but
-    // still writes out a valid patch.
-    //
     bool make_patch(const AnimQueue &auth, StreamBuffer *sb) const;
     void apply_patch(StreamBuffer *sb);
-
+    void update_version(const AnimQueue &auth);
+    
     // Get the final resting place after all animations are complete.
     const AnimStep &back() const;