{-# LANGUAGE RecordWildCards #-}
module Network.HTTP2.Priority.PSQ (
Key
, Weight
, Deficit
, Precedence(..)
, newPrecedence
, PriorityQueue(..)
, Heap
, empty
, isEmpty
, enqueue
, dequeue
, delete
) where
import Data.Array (Array, listArray, (!))
import Data.IntPSQ (IntPSQ)
import qualified Data.IntPSQ as P
type Key = Int
type Weight = Int
type Deficit = Word
data Precedence = Precedence {
Precedence -> Deficit
deficit :: Deficit
, Precedence -> Weight
weight :: Weight
, Precedence -> Weight
dependency :: Key
} deriving Weight -> Precedence -> ShowS
[Precedence] -> ShowS
Precedence -> String
(Weight -> Precedence -> ShowS)
-> (Precedence -> String)
-> ([Precedence] -> ShowS)
-> Show Precedence
forall a.
(Weight -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [Precedence] -> ShowS
$cshowList :: [Precedence] -> ShowS
show :: Precedence -> String
$cshow :: Precedence -> String
showsPrec :: Weight -> Precedence -> ShowS
$cshowsPrec :: Weight -> Precedence -> ShowS
Show
newPrecedence :: Weight -> Precedence
newPrecedence :: Weight -> Precedence
newPrecedence Weight
w = Deficit -> Weight -> Weight -> Precedence
Precedence Deficit
0 Weight
w Weight
0
instance Eq Precedence where
Precedence Deficit
d1 Weight
_ Weight
_ == :: Precedence -> Precedence -> Bool
== Precedence Deficit
d2 Weight
_ Weight
_ = Deficit
d1 Deficit -> Deficit -> Bool
forall a. Eq a => a -> a -> Bool
== Deficit
d2
instance Ord Precedence where
Precedence Deficit
d1 Weight
_ Weight
_ < :: Precedence -> Precedence -> Bool
< Precedence Deficit
d2 Weight
_ Weight
_ = Deficit
d1 Deficit -> Deficit -> Bool
forall a. Eq a => a -> a -> Bool
/= Deficit
d2 Bool -> Bool -> Bool
&& Deficit
d2 Deficit -> Deficit -> Deficit
forall a. Num a => a -> a -> a
- Deficit
d1 Deficit -> Deficit -> Bool
forall a. Ord a => a -> a -> Bool
<= Deficit
deficitStepsW
Precedence Deficit
d1 Weight
_ Weight
_ <= :: Precedence -> Precedence -> Bool
<= Precedence Deficit
d2 Weight
_ Weight
_ = Deficit
d2 Deficit -> Deficit -> Deficit
forall a. Num a => a -> a -> a
- Deficit
d1 Deficit -> Deficit -> Bool
forall a. Ord a => a -> a -> Bool
<= Deficit
deficitStepsW
type Heap a = IntPSQ Precedence a
data PriorityQueue a = PriorityQueue {
PriorityQueue a -> Deficit
baseDeficit :: Deficit
, PriorityQueue a -> Heap a
queue :: Heap a
}
deficitSteps :: Int
deficitSteps :: Weight
deficitSteps = Weight
65536
deficitStepsW :: Word
deficitStepsW :: Deficit
deficitStepsW = Weight -> Deficit
forall a b. (Integral a, Num b) => a -> b
fromIntegral Weight
deficitSteps
deficitList :: [Deficit]
deficitList :: [Deficit]
deficitList = (Double -> Deficit) -> [Double] -> [Deficit]
forall a b. (a -> b) -> [a] -> [b]
map Double -> Deficit
forall a b. (RealFrac a, Integral b) => a -> b
calc [Double]
idxs
where
idxs :: [Double]
idxs = [Double
1..Double
256] :: [Double]
calc :: a -> b
calc a
w = a -> b
forall a b. (RealFrac a, Integral b) => a -> b
round (Weight -> a
forall a b. (Integral a, Num b) => a -> b
fromIntegral Weight
deficitSteps a -> a -> a
forall a. Fractional a => a -> a -> a
/ a
w)
deficitTable :: Array Int Deficit
deficitTable :: Array Weight Deficit
deficitTable = (Weight, Weight) -> [Deficit] -> Array Weight Deficit
forall i e. Ix i => (i, i) -> [e] -> Array i e
listArray (Weight
1,Weight
256) [Deficit]
deficitList
weightToDeficit :: Weight -> Deficit
weightToDeficit :: Weight -> Deficit
weightToDeficit Weight
w = Array Weight Deficit
deficitTable Array Weight Deficit -> Weight -> Deficit
forall i e. Ix i => Array i e -> i -> e
! Weight
w
empty :: PriorityQueue a
empty :: PriorityQueue a
empty = Deficit -> Heap a -> PriorityQueue a
forall a. Deficit -> Heap a -> PriorityQueue a
PriorityQueue Deficit
0 Heap a
forall p v. IntPSQ p v
P.empty
isEmpty :: PriorityQueue a -> Bool
isEmpty :: PriorityQueue a -> Bool
isEmpty PriorityQueue{Deficit
Heap a
queue :: Heap a
baseDeficit :: Deficit
queue :: forall a. PriorityQueue a -> Heap a
baseDeficit :: forall a. PriorityQueue a -> Deficit
..} = Heap a -> Bool
forall p v. IntPSQ p v -> Bool
P.null Heap a
queue
enqueue :: Key -> Precedence -> a -> PriorityQueue a -> PriorityQueue a
enqueue :: Weight -> Precedence -> a -> PriorityQueue a -> PriorityQueue a
enqueue Weight
k p :: Precedence
p@Precedence{Weight
Deficit
dependency :: Weight
weight :: Weight
deficit :: Deficit
dependency :: Precedence -> Weight
weight :: Precedence -> Weight
deficit :: Precedence -> Deficit
..} a
v PriorityQueue{Deficit
Heap a
queue :: Heap a
baseDeficit :: Deficit
queue :: forall a. PriorityQueue a -> Heap a
baseDeficit :: forall a. PriorityQueue a -> Deficit
..} =
Deficit -> Heap a -> PriorityQueue a
forall a. Deficit -> Heap a -> PriorityQueue a
PriorityQueue Deficit
baseDeficit Heap a
queue'
where
d :: Deficit
d = Weight -> Deficit
weightToDeficit Weight
weight
b :: Deficit
b = if Deficit
deficit Deficit -> Deficit -> Bool
forall a. Eq a => a -> a -> Bool
== Deficit
0 then Deficit
baseDeficit else Deficit
deficit
deficit' :: Deficit
deficit' = Deficit -> Deficit -> Deficit
forall a. Ord a => a -> a -> a
max (Deficit
b Deficit -> Deficit -> Deficit
forall a. Num a => a -> a -> a
+ Deficit
d) Deficit
baseDeficit
p' :: Precedence
p' = Precedence
p { deficit :: Deficit
deficit = Deficit
deficit' }
queue' :: Heap a
queue' = Weight -> Precedence -> a -> Heap a -> Heap a
forall p v. Ord p => Weight -> p -> v -> IntPSQ p v -> IntPSQ p v
P.insert Weight
k Precedence
p' a
v Heap a
queue
dequeue :: PriorityQueue a -> Maybe (Key, Precedence, a, PriorityQueue a)
dequeue :: PriorityQueue a -> Maybe (Weight, Precedence, a, PriorityQueue a)
dequeue PriorityQueue{Deficit
Heap a
queue :: Heap a
baseDeficit :: Deficit
queue :: forall a. PriorityQueue a -> Heap a
baseDeficit :: forall a. PriorityQueue a -> Deficit
..} = case Heap a -> Maybe (Weight, Precedence, a, Heap a)
forall p v. Ord p => IntPSQ p v -> Maybe (Weight, p, v, IntPSQ p v)
P.minView Heap a
queue of
Maybe (Weight, Precedence, a, Heap a)
Nothing -> Maybe (Weight, Precedence, a, PriorityQueue a)
forall a. Maybe a
Nothing
Just (Weight
k, Precedence
p, a
v, Heap a
queue') -> let base :: Deficit
base = Precedence -> Deficit
deficit Precedence
p
in (Weight, Precedence, a, PriorityQueue a)
-> Maybe (Weight, Precedence, a, PriorityQueue a)
forall a. a -> Maybe a
Just (Weight
k, Precedence
p, a
v, Deficit -> Heap a -> PriorityQueue a
forall a. Deficit -> Heap a -> PriorityQueue a
PriorityQueue Deficit
base Heap a
queue')
delete :: Key -> PriorityQueue a -> (Maybe a, PriorityQueue a)
delete :: Weight -> PriorityQueue a -> (Maybe a, PriorityQueue a)
delete Weight
k q :: PriorityQueue a
q@PriorityQueue{Deficit
Heap a
queue :: Heap a
baseDeficit :: Deficit
queue :: forall a. PriorityQueue a -> Heap a
baseDeficit :: forall a. PriorityQueue a -> Deficit
..} = case (Maybe (Precedence, a) -> (Maybe a, Maybe (Precedence, a)))
-> Weight -> Heap a -> (Maybe a, Heap a)
forall p v b.
Ord p =>
(Maybe (p, v) -> (b, Maybe (p, v)))
-> Weight -> IntPSQ p v -> (b, IntPSQ p v)
P.alter Maybe (Precedence, a) -> (Maybe a, Maybe (Precedence, a))
forall a a a. Maybe (a, a) -> (Maybe a, Maybe a)
f Weight
k Heap a
queue of
(mv :: Maybe a
mv@(Just a
_), Heap a
queue') -> case Heap a -> Maybe (Weight, Precedence, a, Heap a)
forall p v. Ord p => IntPSQ p v -> Maybe (Weight, p, v, IntPSQ p v)
P.minView Heap a
queue of
Maybe (Weight, Precedence, a, Heap a)
Nothing -> String -> (Maybe a, PriorityQueue a)
forall a. HasCallStack => String -> a
error String
"delete"
Just (Weight
k',Precedence
p',a
_,Heap a
_)
| Weight
k' Weight -> Weight -> Bool
forall a. Eq a => a -> a -> Bool
== Weight
k -> (Maybe a
mv, Deficit -> Heap a -> PriorityQueue a
forall a. Deficit -> Heap a -> PriorityQueue a
PriorityQueue (Precedence -> Deficit
deficit Precedence
p') Heap a
queue')
| Bool
otherwise -> (Maybe a
mv, Deficit -> Heap a -> PriorityQueue a
forall a. Deficit -> Heap a -> PriorityQueue a
PriorityQueue Deficit
baseDeficit Heap a
queue')
(Maybe a
Nothing, Heap a
_) -> (Maybe a
forall a. Maybe a
Nothing, PriorityQueue a
q)
where
f :: Maybe (a, a) -> (Maybe a, Maybe a)
f Maybe (a, a)
Nothing = (Maybe a
forall a. Maybe a
Nothing, Maybe a
forall a. Maybe a
Nothing)
f (Just (a
_,a
v)) = (a -> Maybe a
forall a. a -> Maybe a
Just a
v, Maybe a
forall a. Maybe a
Nothing)