Lots of work on debugging diff xmit

luprex/core/cpp/animqueue.cpp

@@ -463,23 +463,29 @@ void AnimQueue::deserialize(StreamBuffer *sb) {
     version_number_ = 0;
 }
 
-bool AnimQueue::need_patch(const AnimQueue &auth) const {
-    // Sanity check.
+bool AnimQueue::version_identical(const AnimQueue &auth) const {
+    return version_number_ == auth.version_number_;
+}
+
+bool AnimQueue::diff(const AnimQueue &auth, StreamBuffer *sb) const {
     assert(valid());
     assert(auth.valid());
 
-    // Fast path to detect equivalence.
-    if (version_number_ == auth.version_number_) {
+    // Fast path to equivalence detection
+    if (version_identical(auth)) {
+        assert(size_and_steps_equal(auth));
+        sb->write_uint8(255);
         return false;
     }
 
-    // Otherwise, do a direct comparison.
-    return !size_and_steps_equal(auth);
-}
+    // Another path to equivalence detection
+    if (size_and_steps_equal(auth)) {
+        sb->write_uint8(255);
+        return false;
+    }
 
-
-void AnimQueue::diff(const AnimQueue &auth, StreamBuffer *sb) const {
     // Write the first element.
+    assert(auth.steps_.size() < 255);
     sb->write_uint8(auth.steps_.size());
     sb->write_uint8(auth.size_limit_);
     const AnimStep &first = auth.steps_[0];
@@ -517,10 +523,16 @@ void AnimQueue::diff(const AnimQueue &auth, StreamBuffer *sb) const {
             }
         }
     }
+    return true;
 }
 
-void AnimQueue::patch(StreamBuffer *sb) {
+void AnimQueue::patch(StreamBuffer *sb, DebugCollector *dbc) {
     int len = sb->read_uint8();
+    if (len == 255) {
+        return;
+    }
+    DebugLine(dbc) << "AnimQueue modified";
+
     size_limit_ = sb->read_uint8();
     // Decode the diff, stop at eof.
     std::deque<AnimStep> old = std::move(steps_);
@@ -557,7 +569,7 @@ const AnimStep &AnimQueue::back() const {
 static bool diff_works(const AnimQueue &master, AnimQueue &sync) {
     StreamBuffer sb;
     sync.diff(master, &sb);
-    sync.patch(&sb);
+    sync.patch(&sb, nullptr);
     return sync.size_and_steps_equal(master);
 }
 
@@ -658,7 +670,8 @@ LuaDefine(unittests_animqueue, "c") {
     LuaAssert(L, diff_works(aq, aqds));
 
     // compare again, should be no differences.
-    LuaAssert(L, !aqds.need_patch(aq));
+    LuaAssert(L, aqds.version_identical(aq));
+    LuaAssert(L, aqds.size_and_steps_equal(aq));
     LuaAssert(L, diff_works(aq, aqds));
 
     // Discard all but the last action.