Netty5/Codec/HTTP2 5.0.0.Alpha5 · io.netty5.handler.codec.http2.WeightedFairQueueByteDistributor

A StreamByteDistributor that is sensitive to stream priority and uses Weighted Fair Queueing approach for distributing bytes.

Inspiration for this distributor was taken from Linux's Completely Fair Scheduler to model the distribution of bytes to simulate an "ideal multi-tasking CPU", but in this case we are simulating an "ideal multi-tasking NIC".

Each write operation will use the allocationQuantum(int) to know how many more bytes should be allocated relative to the next stream which wants to write. This is to balance fairness while also considering goodput.

Nested and Inner Type Summary

Modifier and Type	Class and Description
private static class	WeightedFairQueueByteDistributor.ParentChangedEvent Allows a correlation to be made between a stream and its old parent before a parent change occurs.
private class	WeightedFairQueueByteDistributor.State The remote flow control state for a single stream.
private static class	WeightedFairQueueByteDistributor.StateOnlyComparator A comparator for `State` which has no associated `Http2Stream` object.
private static class	WeightedFairQueueByteDistributor.StatePseudoTimeComparator

Field Summary

Modifier and Type	Field and Description
private int	allocationQuantum The minimum number of bytes that we will attempt to allocate to a stream.
private final Http2Connection	connection
private final WeightedFairQueueByteDistributor.State	connectionState
private static final int	DEFAULT_MAX_STATE_ONLY_SIZE FireFox currently uses 5 streams to establish QoS classes.
pack-priv static final int	INITIAL_CHILDREN_MAP_SIZE The initial size of the children map is chosen to be conservative on initial memory allocations under the assumption that most streams will have a small number of children.
private final int	maxStateOnlySize
private final Http2Connection.PropertyKey	stateKey
private final IntObjectMap<WeightedFairQueueByteDistributor.State>	stateOnlyMap If there is no Http2Stream object, but we still persist priority information then this is where the state will reside.
private final PriorityQueue<WeightedFairQueueByteDistributor.State>	stateOnlyRemovalQueue This queue will hold streams that are not active and provides the capability to retain priority for streams which have no `Http2Stream` object.

Constructor Summary

Access	Constructor and Description
public	WeightedFairQueueByteDistributor(Http2Connection connection)
public	WeightedFairQueueByteDistributor(Http2Connection connection, int maxStateOnlySize)

Method Summary

Modifier and Type	Method and Description
public void	allocationQuantum(int the amount of bytes that will be allocated to each stream. Must be > 0. allocationQuantum) Sets the amount of bytes that will be allocated to each stream.
public boolean	distribute(int the maximum number of bytes to write. maxBytes, StreamByteDistributor.Writer writer) Implements io.netty5.handler.codec.http2.StreamByteDistributor.distribute. Distributes up to `maxBytes` to those streams containing streamable bytes and iterates across those streams to write the appropriate bytes.
private int	distribute(int maxBytes, StreamByteDistributor.Writer writer, WeightedFairQueueByteDistributor.State state)
private int	distributeToChildren(int maxBytes, StreamByteDistributor.Writer writer, WeightedFairQueueByteDistributor.State state) It is a pre-condition that `state.poll()` returns a non-`null` value.
pack-priv boolean	isChild(int childId, int parentId, short weight) For testing only!
pack-priv void	notifyParentChanged(List<WeightedFairQueueByteDistributor.ParentChangedEvent> The events (top down order) which have changed events) Notify all listeners of the priority tree change events (in ascending order)
pack-priv int	numChildren(int streamId) For testing only!
private WeightedFairQueueByteDistributor.State	state(Http2Stream stream)
private WeightedFairQueueByteDistributor.State	state(int streamId)
public void	updateDependencyTree(int The stream identifier associated with the child stream. childStreamId, int The stream identifier associated with the parent stream. May be `0`, to make `childStreamId` and immediate child of the connection. parentStreamId, short The weight which is used relative to other child streams for `parentStreamId`. This value must be between 1 and 256 (inclusive). weight, boolean If `childStreamId` should be the exclusive dependency of `parentStreamId`. exclusive) Implements io.netty5.handler.codec.http2.StreamByteDistributor.updateDependencyTree. Explicitly update the dependency tree.
public void	updateStreamableBytes(StreamByteDistributor.StreamState state) Implements io.netty5.handler.codec.http2.StreamByteDistributor.updateStreamableBytes. Called when the streamable bytes for a stream has changed.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

public final Class WeightedFairQueueByteDistributor

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary