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Persistent collections updates (part 3) #176

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merged 13 commits into from
Sep 14, 2022
Merged

Persistent collections updates (part 3) #176

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afdb471
[PersistentCollections] “trie”, “subNode” → “child”, “data” → “item”
lorentey Sep 9, 2022
ca19ecb
[PersistentDictionary] Don’t copy collision node contents into arrays
lorentey Sep 9, 2022
3bc9b42
[PersistentCollections] Standard invariant checks
lorentey Sep 9, 2022
3441a48
[PersistentDictionary] rootNode → root
lorentey Sep 9, 2022
f36649d
[PersistentDictionary] Review Iterator
lorentey Sep 9, 2022
92f3d66
[PersistentDictionary] Move members to corresponding protocol conform…
lorentey Sep 9, 2022
65bf478
[PersistentDictionary] Remove capacity property
lorentey Sep 9, 2022
493aa91
[PersistentDictionary] Conform to Codable
lorentey Sep 10, 2022
dd76591
[_CollectionsUtilities] New module. Use it to unify description/debug…
lorentey Sep 10, 2022
1e41efa
[PersistentCollections] Slap @inlinable on everything
lorentey Sep 12, 2022
4aff69e
[_CollectionUtilities] More additions
lorentey Sep 12, 2022
b1cf1ee
[PersistentCollections] Start splitting up _HashPath into _HashValue …
lorentey Sep 12, 2022
77edbef
[_CollectionsUtilities] Restore original debug descriptions
lorentey Sep 14, 2022
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182 changes: 79 additions & 103 deletions Sources/PersistentCollections/PersistentDictionary._Node.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,23 @@ extension _NodeHeader: Equatable {
}
}

extension _NodeHeader {
#if COLLECTIONS_INTERNAL_CHECKS
@inline(never)
func _invariantCheck() {
if isCollisionNode {
precondition(itemMap == childMap)
precondition(!itemMap.isEmpty)
return
}
precondition(itemMap.intersection(childMap).isEmpty)
}
#else
@inline(__always)
func _invariantCheck() {}
#endif
}

extension PersistentDictionary {
internal final class _Node {
typealias Element = (key: Key, value: Value)
Expand Down Expand Up @@ -78,7 +95,7 @@ extension PersistentDictionary {
self.itemCapacity = itemCapacity
self.childCapacity = childCapacity

assert(self.invariant)
_invariantCheck()
}
}
}
Expand Down Expand Up @@ -138,8 +155,8 @@ extension PersistentDictionary._Node {
from: src.childBaseAddress,
count: src.header.childCount)

assert(src.invariant)
assert(dst.invariant)
src._invariantCheck()
dst._invariantCheck()
return dst
}
}
Expand All @@ -152,7 +169,7 @@ extension PersistentDictionary._Node {

self.header = _NodeHeader(itemMap: .empty, childMap: .empty)

assert(self.invariant)
_invariantCheck()
}

convenience init(itemMap: _Bitmap, _ item: Element) {
Expand All @@ -161,7 +178,7 @@ extension PersistentDictionary._Node {
self.header = _NodeHeader(itemMap: itemMap, childMap: .empty)
self.count = 1
self.itemBaseAddress.initialize(to: item)
assert(self.invariant)
_invariantCheck()
}

convenience init(_ item: Element, at bucket: _Bucket) {
Expand All @@ -187,7 +204,7 @@ extension PersistentDictionary._Node {
self.itemBaseAddress.initialize(to: item1)
self.itemBaseAddress.successor().initialize(to: item0)
}
assert(self.invariant)
_invariantCheck()
}

convenience init(_ child: _Node, at bucket: _Bucket) {
Expand All @@ -200,7 +217,7 @@ extension PersistentDictionary._Node {

self.childBaseAddress.initialize(to: child)

assert(self.invariant)
_invariantCheck()
}

convenience init(
Expand All @@ -218,7 +235,7 @@ extension PersistentDictionary._Node {
self.itemBaseAddress.initialize(to: item)
self.childBaseAddress.initialize(to: child)

assert(self.invariant)
_invariantCheck()
}

convenience init<C: Collection>(collisions: C) where C.Element == Element {
Expand All @@ -232,7 +249,7 @@ extension PersistentDictionary._Node {
var (it, c) = self._mutableItems.initialize(from: collisions)
precondition(it.next() == nil && c == self.count)

assert(self.invariant)
_invariantCheck()
}
}

Expand All @@ -259,38 +276,6 @@ extension PersistentDictionary._Node {
header.childMap
}

var invariant: Bool {
guard headerInvariant else {
return false
}

// let recursiveCount = self.reduce(0, { count, _ in count + 1 })
//
// guard recursiveCount == count else {
// return false
// }

guard count - itemCount >= 2 * childCount else {
return false
}

if isCollisionNode {
guard childCount == 0 else { return false }
let hash = _HashValue(_items.first!.key)

guard _items.allSatisfy({ _HashValue($0.key) == hash }) else {
return false
}
}

return true
}

var headerInvariant: Bool {
header.itemMap.intersection(header.childMap).isEmpty
|| (header.itemMap == header.childMap)
}

var _items: UnsafeBufferPointer<Element> {
UnsafeBufferPointer(start: itemBaseAddress, count: header.itemCount)
}
Expand All @@ -313,6 +298,32 @@ extension PersistentDictionary._Node {
}
}

extension PersistentDictionary._Node {
#if COLLECTIONS_INTERNAL_CHECKS
@inline(never)
func _invariantCheck() {
header._invariantCheck()

precondition(itemCount <= itemCapacity)
precondition(childCount <= childCapacity)

precondition(count >= itemCount + 2 * childCount)

let c = self.itemCount + _children.reduce(0) { $0 + $1.count }
precondition(c == self.count)

if isCollisionNode {
precondition(childCount == 0)
let hash = _HashValue(_items.first!.key)
precondition(_items.allSatisfy { _HashValue($0.key) == hash })
}
}
#else
@inline(__always)
func _invariantCheck() {}
#endif
}

extension PersistentDictionary._Node: _NodeProtocol {
var hasChildren: Bool { !header.childMap.isEmpty }

Expand Down Expand Up @@ -418,6 +429,7 @@ extension PersistentDictionary._Node: _DictionaryNodeProtocol {
_ path: _HashPath,
_ effect: inout _DictionaryEffect<Value>
) -> _Node {
defer { _invariantCheck() }

guard isRegularNode else {
return _updateOrUpdatingCollision(isUnique, item, path, &effect)
Expand Down Expand Up @@ -456,7 +468,6 @@ extension PersistentDictionary._Node: _DictionaryNodeProtocol {
isUniqueChild, item, path.descend(), &effect)
guard effect.modified, oldChild !== newChild else {
if effect.previousValue == nil { count += 1 }
assert(self.invariant)
return self
}

Expand Down Expand Up @@ -518,6 +529,7 @@ extension PersistentDictionary._Node: _DictionaryNodeProtocol {
_ path: _HashPath,
_ effect: inout _DictionaryEffect<Value>
) -> _Node {
defer { _invariantCheck() }

guard isRegularNode else {
return _removeOrRemovingCollision(isUnique, key, path, &effect)
Expand All @@ -528,10 +540,7 @@ extension PersistentDictionary._Node: _DictionaryNodeProtocol {
if itemMap.contains(bucket) {
let offset = itemMap.offset(of: bucket)
let item0 = self.item(at: offset)
guard item0.key == key else {
assert(self.invariant)
return self
}
guard item0.key == key else { return self }

effect.setModified(previousValue: item0.value)
if self.itemCount == 2, self.childCount == 0 {
Expand Down Expand Up @@ -569,7 +578,6 @@ extension PersistentDictionary._Node: _DictionaryNodeProtocol {
isChildUnique, key, path.descend(), &effect)
guard effect.modified, oldChild !== newChild else {
if effect.modified { count -= 1 }
assert(self.invariant)
return self
}

Expand All @@ -592,7 +600,6 @@ extension PersistentDictionary._Node: _DictionaryNodeProtocol {
return _copyAndSetTrieNode(
isUnique, bucket, offset, newChild, updateCount: { $0 -= 1 })
}

return self
}

Expand Down Expand Up @@ -750,21 +757,11 @@ extension PersistentDictionary._Node {
func _copyAndSetValue(
_ isUnique: Bool, _ bucket: _Bucket, _ newValue: Value
) -> _Node {
let src: _Node = self
let dst: _Node

if isUnique {
dst = src
} else {
dst = src.copy()
}

let dst = isUnique ? self : self.copy()
let offset = itemMap.offset(of: bucket)

dst.itemBaseAddress[offset].value = newValue

assert(src.invariant)
assert(dst.invariant)
_invariantCheck()
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To be consistent with edits below:

Suggested change
_invariantCheck()
self._invariantCheck()

dst._invariantCheck()
return dst
}

Expand All @@ -775,22 +772,14 @@ extension PersistentDictionary._Node {
_ newNode: _Node,
updateCount: (inout Int) -> Void
) -> _Node {
let src: _Node = self
let dst: _Node

if isUnique {
dst = src
} else {
dst = src.copy()
}

let dst = isUnique ? self : self.copy()
dst.childBaseAddress[offset] = newNode

// update metadata: `itemMap, nodeMap, collMap`
updateCount(&dst.count)

assert(src.invariant)
assert(dst.invariant)
self._invariantCheck()
dst._invariantCheck()
return dst
}

Expand All @@ -799,16 +788,13 @@ extension PersistentDictionary._Node {
_ bucket: _Bucket,
_ item: Element
) -> _Node {
let src: _Node = self
let dst: _Node

let hasRoomForItem = header.itemCount < itemCapacity

if isUnique && hasRoomForItem {
dst = src
} else {
dst = src.copy(itemCapacityGrowthFactor: hasRoomForItem ? 1 : 2)
}
let dst = (
isUnique && hasRoomForItem
? self
: self.copy(itemCapacityGrowthFactor: hasRoomForItem ? 1 : 2))
assert(dst.itemCount < dst.itemCapacity)

let offset = dst.itemMap.offset(of: bucket)
Expand All @@ -818,21 +804,14 @@ extension PersistentDictionary._Node {
dst.header.itemMap.insert(bucket)
dst.count += 1

assert(src.invariant)
assert(dst.invariant)
self._invariantCheck()
dst._invariantCheck()
return dst
}

func _copyAndRemoveValue(_ isUnique: Bool, _ bucket: _Bucket) -> _Node {
assert(itemMap.contains(bucket))
let src: _Node = self
let dst: _Node

if isUnique {
dst = src
} else {
dst = src.copy()
}
let dst = isUnique ? self : self.copy()

let dataOffset = dst.itemMap.offset(of: bucket)
_rangeRemove(
Expand All @@ -842,22 +821,21 @@ extension PersistentDictionary._Node {
dst.header.itemMap.remove(bucket)
dst.count -= 1

assert(src.invariant)
assert(dst.invariant)
self._invariantCheck()
dst._invariantCheck()
return dst
}

func _copyAndMigrateFromInlineToNode(
_ isUnique: Bool, _ bucket: _Bucket, _ node: _Node
) -> _Node {
assert(itemMap.contains(bucket))
let src: _Node = self
let dst: _Node

let hasRoomForChild = header.childCount < childCapacity

if isUnique && hasRoomForChild {
dst = src
dst = self
} else {
// TODO reconsider the details of the heuristic
//
Expand All @@ -868,7 +846,7 @@ extension PersistentDictionary._Node {
// slots.
let itemsNeedShrinking = Swift.max(header.itemCount * 2 - 1, 4) < itemCapacity

dst = src.copy(
dst = self.copy(
itemCapacityShrinkFactor: itemsNeedShrinking ? 2 : 1,
childCapacityGrowthFactor: hasRoomForChild ? 1 : 2)
}
Expand All @@ -887,24 +865,22 @@ extension PersistentDictionary._Node {
dst.header.childMap.insert(bucket)
dst.count += 1 // assuming that `node.count == 2`

assert(src.invariant)
assert(dst.invariant)
self._invariantCheck()
dst._invariantCheck()
return dst
}

func _copyAndMigrateFromNodeToInline(
_ isUnique: Bool, _ bucket: _Bucket, _ item: Element
) -> _Node {
assert(childMap.contains(bucket))
let src: _Node = self
let dst: _Node

let hasRoomForItem = header.itemCount < itemCapacity

let dst: _Node
if isUnique && hasRoomForItem {
dst = src
dst = self
} else {
dst = src.copy(itemCapacityGrowthFactor: hasRoomForItem ? 1 : 2)
dst = self.copy(itemCapacityGrowthFactor: hasRoomForItem ? 1 : 2)
}

let childOffset = dst.childMap.offset(of: bucket)
Expand All @@ -921,8 +897,8 @@ extension PersistentDictionary._Node {
dst.header.childMap.remove(bucket)
dst.count -= 1 // assuming that updated `node.count == 1`

assert(src.invariant)
assert(dst.invariant)
self._invariantCheck()
dst._invariantCheck()
return dst
}
}
Expand Down
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