Network.HTTP2.Priority

This is partial implementation of the priority of HTTP/2.

This implementation does support structured priority queue but not support re-structuring. This means that it is assumed that an entry created by a Priority frame is never closed. The entry behaves an intermediate node, not a leaf.

This queue is fair for weight. Consider two weights: 201 and 101. Repeating enqueue/dequeue probably produces 201, 201, 101, 201, 201, 101, ...

Only one entry per stream should be enqueued.

Precedence

data Precedence

Internal representation of priority in priority queues. The precedence of a dequeued entry should be specified to enqueue when the entry is enqueued again.

Instances

Eq Precedence

Methods

(==) :: Precedence -> Precedence -> Bool

(/=) :: Precedence -> Precedence -> Bool

Ord Precedence

Methods

compare :: Precedence -> Precedence -> Ordering

(<) :: Precedence -> Precedence -> Bool

(<=) :: Precedence -> Precedence -> Bool

(>) :: Precedence -> Precedence -> Bool

(>=) :: Precedence -> Precedence -> Bool

max :: Precedence -> Precedence -> Precedence

min :: Precedence -> Precedence -> Precedence

Show Precedence

Methods

showsPrec :: Int -> Precedence -> ShowS

show :: Precedence -> String

showList :: [Precedence] -> ShowS

defaultPrecedence :: Precedence

Default precedence.

toPrecedence :: Priority -> Precedence

Converting Priority to Precedence. When an entry is enqueued at the first time, this function should be used.

PriorityTree

data PriorityTree a

Abstract data type for priority trees.

newPriorityTree :: IO (PriorityTree a)

Creating a new priority tree.

PriorityTree functions

prepare :: PriorityTree a -> StreamId -> Priority -> IO ()

Bringing up the structure of the priority tree. This must be used for Priority frame.

enqueue :: PriorityTree a -> StreamId -> Precedence -> a -> IO ()

Enqueuing an entry to the priority tree. This must be used for Header frame.

dequeue :: PriorityTree a -> IO (StreamId, Precedence, a)

Dequeuing an entry from the priority tree.

dequeueSTM :: PriorityTree a -> STM (StreamId, Precedence, a)

Dequeuing an entry from the priority tree.

isEmpty :: PriorityTree a -> IO Bool

Checking if the priority tree is empty.

isEmptySTM :: PriorityTree a -> STM Bool

Checking if the priority tree is empty.

delete :: PriorityTree a -> StreamId -> Precedence -> IO (Maybe a)

Deleting the entry corresponding to StreamId. delete and enqueue are used to change the priority of a live stream.