updateDependencyTree() — netty Function Reference

Source Code

codec-http2/src/main/java/io/netty/handler/codec/http2/WeightedFairQueueByteDistributor.java lines 195–254

    @Override
    public void updateDependencyTree(int childStreamId, int parentStreamId, short weight, boolean exclusive) {
        State state = state(childStreamId);
        if (state == null) {
            // If there is no State object that means there is no Http2Stream object and we would have to keep the
            // State object in the stateOnlyMap and stateOnlyRemovalQueue. However if maxStateOnlySize is 0 this means
            // stateOnlyMap and stateOnlyRemovalQueue are empty collections and cannot be modified so we drop the State.
            if (maxStateOnlySize == 0) {
                return;
            }
            state = new State(childStreamId);
            stateOnlyRemovalQueue.add(state);
            stateOnlyMap.put(childStreamId, state);
        }

        State newParent = state(parentStreamId);
        if (newParent == null) {
            // If there is no State object that means there is no Http2Stream object and we would have to keep the
            // State object in the stateOnlyMap and stateOnlyRemovalQueue. However if maxStateOnlySize is 0 this means
            // stateOnlyMap and stateOnlyRemovalQueue are empty collections and cannot be modified so we drop the State.
            if (maxStateOnlySize == 0) {
                return;
            }
            newParent = new State(parentStreamId);
            stateOnlyRemovalQueue.add(newParent);
            stateOnlyMap.put(parentStreamId, newParent);
            // Only the stream which was just added will change parents. So we only need an array of size 1.
            List<ParentChangedEvent> events = new ArrayList<ParentChangedEvent>(1);
            connectionState.takeChild(newParent, false, events);
            notifyParentChanged(events);
        }

        // if activeCountForTree == 0 then it will not be in its parent's pseudoTimeQueue and thus should not be counted
        // toward parent.totalQueuedWeights.
        if (state.activeCountForTree != 0 && state.parent != null) {
            state.parent.totalQueuedWeights += weight - state.weight;
        }
        state.weight = weight;

        if (newParent != state.parent || exclusive && newParent.children.size() != 1) {
            final List<ParentChangedEvent> events;
            if (newParent.isDescendantOf(state)) {
                events = new ArrayList<ParentChangedEvent>(2 + (exclusive ? newParent.children.size() : 0));
                state.parent.takeChild(newParent, false, events);
            } else {
                events = new ArrayList<ParentChangedEvent>(1 + (exclusive ? newParent.children.size() : 0));
            }
            newParent.takeChild(state, exclusive, events);
            notifyParentChanged(events);
        }

        // The location in the dependency tree impacts the priority in the stateOnlyRemovalQueue map. If we created new
        // State objects we must check if we exceeded the limit after we insert into the dependency tree to ensure the
        // stateOnlyRemovalQueue has been updated.
        while (stateOnlyRemovalQueue.size() > maxStateOnlySize) {
            State stateToRemove = stateOnlyRemovalQueue.poll();
            stateToRemove.parent.removeChild(stateToRemove);
            stateOnlyMap.remove(stateToRemove.streamId);
        }
    }