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Store full hash in the slot #22

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Merged
merged 3 commits into from
Sep 16, 2021
Merged

Store full hash in the slot #22

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22760ef
Fix dict
tkf Sep 13, 2021
edafde1
Store full hash in the slot
tkf Sep 15, 2021
872c617
Merge branch 'master' into fullhash
tkf Sep 16, 2021
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49 changes: 31 additions & 18 deletions src/dict.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -142,7 +142,8 @@ end
@inline function cleanup_pairnode!(slots, pairnodes, index)
GC.@preserve slots begin
s2ptr = pointer(slots, 2 * index)
slotid = UnsafeAtomics.load(s2ptr)
slot2 = UnsafeAtomics.load(s2ptr)
slotid = slotid_from_slot2(slot2)
end
iszero(slotid) && unreachable()
ref = pairnodes[index]
Expand Down Expand Up @@ -253,6 +254,13 @@ function ConcurrentCollections.trypop!(d::LinearProbingDict, key)
end
end

@inline slotid_from_slot2(slot2::UInt64) = slot2 & (typemax(UInt64) >> LPD_NBITS)

@inline function reconstruct_full_hash(keyinfo::KeyInfo, slot2::UInt64)
hash2 = slot2 & ~(typemax(UInt64) >> LPD_NBITS)
return (keyinfo.keydata << LPD_NBITS) | (hash2 >> (64 - LPD_NBITS))
end

function ConcurrentCollections.modify!(
f,
dict::LinearProbingDict{Key,Value},
Expand All @@ -264,8 +272,9 @@ function ConcurrentCollections.modify!(

h = hash(key)

# The upper bits of hash that would be stored in `keyinfo.keydata`:
inlinedhash = h >> LPD_NBITS
# The upper and lower bits of hash:
hash1 = h >> LPD_NBITS # stored in slot 1 (`keyinfo.keydata`)
hash2 = h << (64 - LPD_NBITS) # stored in slot 2

if 4 * length_upper_bound(dict) > length(slots)
slots, pairnodes = expand!(dict, slots, pairnodes)
Expand Down Expand Up @@ -295,8 +304,9 @@ function ConcurrentCollections.modify!(
# TODO: Handle wrap-around of slotid? Reset it during migration?
end
prepare_pairnode!(pairnodes, index, newslotid, key, something(reply))
slot2 = hash2 | newslotid
oldslot = Pair(keybits, zero(keybits))
newslot = Pair(KeyInfo{UInt64}(LPD_HASKEY, inlinedhash).bits, newslotid)
newslot = Pair(KeyInfo{UInt64}(LPD_HASKEY, hash1).bits, slot2)
s12ptr = Ptr{typeof(oldslot)}(s1ptr)
found = UnsafeAtomics.cas!(s12ptr, oldslot, newslot)
if found === oldslot
Expand All @@ -321,10 +331,12 @@ function ConcurrentCollections.modify!(
# no need to retry.
end
elseif keyinfo.haskey
if keyinfo.keydata ==′ inlinedhash
slotid = UnsafeAtomics.load(s2ptr)
if keyinfo.keydata ==′ hash1
slot2 = UnsafeAtomics.load(s2ptr)
slotid = slotid_from_slot2(slot2)
stored_hash = reconstruct_full_hash(keyinfo, slot2)
node = load_pairnode(pairnodes, index, slotid)
if isequal(node.key, key)
if stored_hash == h && isequal(node.key, key)
vref = ValueRef{Value}(node)
while true
reply = f(vref)::Union{Keep,Nothing,Delete,Some}
Expand All @@ -339,8 +351,8 @@ function ConcurrentCollections.modify!(
end

# Deletion:
oldslot = Pair(keybits, slotid)
newslot = Pair(setstate(keyinfo, LPD_DELETED).bits, slotid)
oldslot = Pair(keybits, slot2)
newslot = Pair(setstate(keyinfo, LPD_DELETED).bits, slot2)
s12ptr = Ptr{typeof(oldslot)}(s1ptr)
if UnsafeAtomics.cas!(s12ptr, oldslot, newslot) === oldslot
ndeleted = Threads.atomic_add!(dict.ndeleted, 1) + 1
Expand Down Expand Up @@ -621,9 +633,9 @@ function unsafe_migrate!(
local tryset
let s2ptr = s2ptr
@inline function tryset(keyinfo, newstate)
local slotid = UnsafeAtomics.load(s2ptr)
local oldslot = Pair(keyinfo.bits, slotid)
local newslot = Pair(setstate(keyinfo, newstate).bits, slotid)
local slot2 = UnsafeAtomics.load(s2ptr)
local oldslot = Pair(keyinfo.bits, slot2)
local newslot = Pair(setstate(keyinfo, newstate).bits, slot2)
local s12ptr = Ptr{typeof(oldslot)}(s1ptr)
return UnsafeAtomics.cas!(s12ptr, oldslot, newslot) === oldslot
end
Expand Down Expand Up @@ -659,23 +671,23 @@ function unsafe_migrate!(
newslots === nothing && continue

newkeybits = setstate(keyinfo, LPD_HASKEY).bits
slotid = UnsafeAtomics.load(s2ptr)
slot2 = UnsafeAtomics.load(s2ptr)
slotid = slotid_from_slot2(slot2)
node = load_pairnode(pairnodes, i, slotid)
key = node.key
h = reconstruct_full_hash(keyinfo, slot2)

# Insertion to `newslots` does not have to use atomics since
# it's protected by the `.migration` lock.
c = length(newslots) ÷ 2
h = reinterpret(Int, hash(key))
offset = h & (c - 1) # h % c
offset = reinterpret(Int, h) & (c - 1) # h % c
nprobes = 0
while true
# TODO: non-atomic ordering
local keybits = @inbounds newslots[2*offset+1]
local keyinfo = KeyInfo(keybits)
if keyinfo.isempty
@inbounds newslots[2*offset+1] = newkeybits
@inbounds newslots[2*offset+2] = slotid
@inbounds newslots[2*offset+2] = slot2
ref = newpairnodes[offset+1]
@atomic ref.value = node
nadded += 1
Expand Down Expand Up @@ -711,7 +723,8 @@ function Base.iterate(::LinearProbingDict, (slots, pairnodes, index))
keybits = UnsafeAtomics.load(s1ptr)
keyinfo = KeyInfo(keybits)
if keyinfo.haskey | keyinfo.ismoved
slotid = UnsafeAtomics.load(s2ptr)
slot2 = UnsafeAtomics.load(s2ptr)
slotid = slotid_from_slot2(slot2)
node = load_pairnode(pairnodes, index, slotid)
key = node.key
value = @atomic node.value
Expand Down