diff --git a/bucket.go b/bucket.go deleted file mode 100644 index 6a4171c..0000000 --- a/bucket.go +++ /dev/null @@ -1,103 +0,0 @@ -package cuckoo - -type entry[K, V any] struct { - key K - value V -} - -type slot[K, V any] struct { - entry[K, V] - occupied bool -} - -type bucket[K, V any] struct { - hash Hash[K] - slots []slot[K, V] - capacity, size uint64 - compare EqualFunc[K] -} - -// location determines where in the bucket a certain key would be placed. If the -// capacity is 0, this will panic. -func (b bucket[K, V]) location(key K) uint64 { - return b.hash(key) % b.capacity -} - -func (b bucket[K, V]) get(key K) (value V, found bool) { - if b.capacity == 0 { - return - } - - slot := b.slots[b.location(key)] - return slot.value, slot.occupied && b.compare(slot.key, key) -} - -func (b *bucket[K, V]) drop(key K) (occupied bool) { - if b.capacity == 0 { - return - } - - slot := &b.slots[b.location(key)] - - if slot.occupied && b.compare(slot.key, key) { - slot.occupied = false - b.size-- - return true - } - - return false -} - -func (b *bucket[K, V]) resize(capacity uint64) { - b.slots = make([]slot[K, V], capacity) - b.capacity = capacity - b.size = 0 -} - -func (b bucket[K, V]) update(key K, value V) (updated bool) { - if b.capacity == 0 { - return - } - - slot := &b.slots[b.location(key)] - - if slot.occupied && b.compare(slot.key, key) { - slot.value = value - return true - } - - return false -} - -func (b *bucket[K, V]) evict(insertion entry[K, V]) (evicted entry[K, V], eviction bool) { - if b.capacity == 0 { - return insertion, true - } - - slot := &b.slots[b.location(insertion.key)] - - if !slot.occupied { - slot.entry = insertion - slot.occupied = true - b.size++ - return - } - - if b.compare(slot.key, insertion.key) { - slot.value = insertion.value - return - } - - insertion, slot.entry = slot.entry, insertion - return insertion, true -} - -func newBucket[K, V any](capacity uint64, hash Hash[K], compare EqualFunc[K]) bucket[K, V] { - return bucket[K, V]{ - hash: hash, - capacity: capacity, - compare: compare, - size: 0, - slots: make([]slot[K, V], capacity), - } -} diff --git a/compare.go b/compare.go index 57f8b47..953ccd9 100644 --- a/compare.go +++ b/compare.go @@ -2,7 +2,7 @@ package cuckoo // An EqualFunc determines whethers two keys are 'equal'. Keys that are 'equal' // are teated as the same by the [Table]. A good EqualFunc is pure, -// deterministic, and fast. By default, [NewTable] uses [DefaultEqualFunc]. +// deterministic, and fast. By default, [New] uses [DefaultEqualFunc]. // // This function MUST NOT return true if the [Hash] digest of two keys // are different: the [Table] will not work. diff --git a/compare_example_test.go b/compare_example_test.go index b41cb3e..daee291 100644 --- a/compare_example_test.go +++ b/compare_example_test.go @@ -28,7 +28,7 @@ func ExampleEqualFunc_badEqualFunc() { // Two users with the same ID are equal. isEqual := func(a, b User) bool { return a.ID == b.ID } - userbase := cuckoo.NewCustomTable[User, bool](makeHash(1), makeHash(2), isEqual) + userbase := cuckoo.NewCustom[User, bool](makeHash(1), makeHash(2), isEqual) (userbase.Put(User{"1", "Robert Doe"}, true)) diff --git a/cuckoo_fuzz_test.go b/cuckoo_fuzz_test.go index 76bb815..89e4b48 100644 --- a/cuckoo_fuzz_test.go +++ b/cuckoo_fuzz_test.go @@ -56,7 +56,7 @@ func FuzzInsertLookup(f *testing.F) { fmt.Fprintf(os.Stderr, "seedA=%d seedB=%d capacity=%d growthFactor=%d\n", seedA, seedB, capacity, growthFactor) - actual := cuckoo.NewCustomTable[uint32, uint32]( + actual := cuckoo.NewCustom[uint32, uint32]( offsetHash(seedA), offsetHash(seedB), func(a, b uint32) bool { return a == b }, diff --git a/cuckoo_internal_test.go b/cuckoo_internal_test.go index f2b24a3..461f4d7 100644 --- a/cuckoo_internal_test.go +++ b/cuckoo_internal_test.go @@ -11,7 +11,7 @@ func TestMaxEvictions(t *testing.T) { assert := assert.New(t) for i := 16; i < 116; i++ { - table := NewTable[int, bool](Capacity(i / 2)) + table := New[int, bool](Capacity(i / 2)) expectedEvictions := 3 * math.Floor(math.Log2(float64(i))) assert.Equal(table.maxEvictions(), int(expectedEvictions)) @@ -20,7 +20,7 @@ func TestMaxEvictions(t *testing.T) { func TestLoad(t *testing.T) { assert := assert.New(t) - table := NewTable[int, bool](Capacity(8)) + table := New[int, bool](Capacity(8)) for i := range 16 { err := table.Put(i, true) diff --git a/cuckoo_test.go b/cuckoo_test.go index 56afcde..e9df9f9 100644 --- a/cuckoo_test.go +++ b/cuckoo_test.go @@ -14,7 +14,7 @@ import ( func TestNewTable(t *testing.T) { assert := assert.New(t) - table := cuckoo.NewTable[int, bool]() + table := cuckoo.New[int, bool]() assert.NotNil(table) assert.Zero(table.Size()) @@ -23,7 +23,7 @@ func TestNewTable(t *testing.T) { func TestAddItem(t *testing.T) { assert := assert.New(t) key, value := 0, true - table := cuckoo.NewTable[int, bool]() + table := cuckoo.New[int, bool]() err := table.Put(key, value) @@ -35,7 +35,7 @@ func TestAddItem(t *testing.T) { func TestPutOverwrite(t *testing.T) { assert := assert.New(t) key, value, newValue := 0, 1, 2 - table := cuckoo.NewTable[int, int]() + table := cuckoo.New[int, int]() (table.Put(key, value)) err := table.Put(key, newValue) @@ -50,7 +50,7 @@ func TestPutOverwrite(t *testing.T) { func TestSameHash(t *testing.T) { assert := assert.New(t) hash := func(int) uint64 { return 0 } - table := cuckoo.NewCustomTable[int, bool](hash, hash, cuckoo.DefaultEqualFunc[int]) + table := cuckoo.NewCustom[int, bool](hash, hash, cuckoo.DefaultEqualFunc[int]) errA := table.Put(0, true) errB := table.Put(1, true) @@ -63,14 +63,14 @@ func TestSameHash(t *testing.T) { func TestStartingCapacity(t *testing.T) { assert := assert.New(t) - table := cuckoo.NewTable[int, bool](cuckoo.Capacity(64)) + table := cuckoo.New[int, bool](cuckoo.Capacity(64)) assert.Equal(uint64(128), table.TotalCapacity()) } func TestResizeCapacity(t *testing.T) { assert := assert.New(t) - table := cuckoo.NewTable[int, bool]( + table := cuckoo.New[int, bool]( cuckoo.Capacity(8), cuckoo.GrowthFactor(2), ) @@ -85,7 +85,7 @@ func TestResizeCapacity(t *testing.T) { func TestPutMany(t *testing.T) { assert := assert.New(t) - expected, actual := map[int]bool{}, cuckoo.NewTable[int, bool]() + expected, actual := map[int]bool{}, cuckoo.New[int, bool]() for i := range 1_000 { expected[i] = true @@ -100,7 +100,7 @@ func TestPutMany(t *testing.T) { func TestGetMany(t *testing.T) { assert := assert.New(t) - table := cuckoo.NewTable[int, bool]() + table := cuckoo.New[int, bool]() for i := range 1_000 { err := table.Put(i, true) @@ -121,7 +121,7 @@ func TestGetMany(t *testing.T) { func TestDropExistingItem(t *testing.T) { assert := assert.New(t) key, value := 0, true - table := cuckoo.NewTable[int, bool]() + table := cuckoo.New[int, bool]() (table.Put(key, value)) err := table.Drop(key) @@ -134,7 +134,7 @@ func TestDropExistingItem(t *testing.T) { func TestDropNoItem(t *testing.T) { assert := assert.New(t) key := 0 - table := cuckoo.NewTable[int, bool]() + table := cuckoo.New[int, bool]() err := table.Drop(key) @@ -146,7 +146,7 @@ func TestDropNoItem(t *testing.T) { func TestDropItemCapacity(t *testing.T) { assert := assert.New(t) key := 0 - table := cuckoo.NewTable[int, bool]( + table := cuckoo.New[int, bool]( cuckoo.Capacity(64), cuckoo.GrowthFactor(2), ) @@ -164,7 +164,7 @@ func TestDropItemCapacity(t *testing.T) { func TestPutNoCapacity(t *testing.T) { assert := assert.New(t) key, value := 0, true - table := cuckoo.NewTable[int, bool]( + table := cuckoo.New[int, bool]( cuckoo.Capacity(0), ) @@ -177,7 +177,7 @@ func TestPutNoCapacity(t *testing.T) { func TestBadHashCapacity(t *testing.T) { assert := assert.New(t) - table := cuckoo.NewCustomTable[int, bool]( + table := cuckoo.NewCustom[int, bool]( func(int) uint64 { return 0 }, func(int) uint64 { return 0 }, func(a, b int) bool { return a == b }, @@ -197,7 +197,7 @@ func TestBadHashCapacity(t *testing.T) { func TestDropResizeCapacity(t *testing.T) { assert := assert.New(t) - table := cuckoo.NewTable[int, bool]( + table := cuckoo.New[int, bool]( cuckoo.Capacity(10), ) @@ -217,9 +217,7 @@ func TestNewTableBy(t *testing.T) { } assert := assert.New(t) - table := cuckoo.NewTableBy[User, bool]( - func(u User) string { return u.id }, - ) + table := cuckoo.NewBy[User, bool](func(u User) string { return u.id }) err := table.Put(User{nil, "1", "Robert"}, true) diff --git a/doc.go b/doc.go index 11f8cda..3be8bfc 100644 --- a/doc.go +++ b/doc.go @@ -1,8 +1,8 @@ // Package cuckoo provides a hash table that uses cuckoo hashing to achieve // a worst-case O(1) lookup time. // -// While a [NewTable] only supports comparable keys by default, you can create -// a table with any key type using [NewCustomTable]. Custom [Hash] functions and +// While a [New] only supports comparable keys by default, you can create +// a table with any key type using [NewCustom]. Custom [Hash] functions and // key comparison are also supported. // // See more: https://en.wikipedia.org/wiki/Cuckoo_hashing diff --git a/doc_example_test.go b/doc_example_test.go index da8d62a..3671857 100644 --- a/doc_example_test.go +++ b/doc_example_test.go @@ -8,7 +8,7 @@ import ( ) func Example_basic() { - table := cuckoo.NewTable[int, string]() + table := cuckoo.New[int, string]() if err := table.Put(1, "Hello, World!"); err != nil { fmt.Println("Put error:", err) diff --git a/settings.go b/settings.go index fe0408f..97c6e0a 100644 --- a/settings.go +++ b/settings.go @@ -9,7 +9,7 @@ import "fmt" const DefaultCapacity uint64 = 16 // DefaultGrowthFactor is the standard resize multiplier for a [Table]. Most -// hash table implementations use 2. +// implementations use 2. const DefaultGrowthFactor uint64 = 2 // defaultMinimumLoad is the default lowest acceptable occupancy of a [Table]. @@ -26,10 +26,10 @@ type settings struct { } // An Option modifies the settings of a [Table]. It is used in its constructors -// like [NewTable], for example. +// like [New], for example. type Option func(*settings) -// Capacity modifies the starting capacity of each bucket of the [Table]. The +// Capacity modifies the starting capacity of each subtable of the [Table]. The // value must be non-negative. func Capacity(value int) Option { if value < 0 { diff --git a/subtable.go b/subtable.go new file mode 100644 index 0000000..749d16d --- /dev/null +++ b/subtable.go @@ -0,0 +1,103 @@ +package cuckoo + +type entry[K, V any] struct { + key K + value V +} + +type slot[K, V any] struct { + entry[K, V] + occupied bool +} + +type subtable[K, V any] struct { + hash Hash[K] + slots []slot[K, V] + capacity, size uint64 + compare EqualFunc[K] +} + +// location determines where in the subtable a certain key would be placed. If +// the capacity is 0, this will panic. +func (t subtable[K, V]) location(key K) uint64 { + return t.hash(key) % t.capacity +} + +func (t subtable[K, V]) get(key K) (value V, found bool) { + if t.capacity == 0 { + return + } + + slot := t.slots[t.location(key)] + return slot.value, slot.occupied && t.compare(slot.key, key) +} + +func (t *subtable[K, V]) drop(key K) (occupied bool) { + if t.capacity == 0 { + return + } + + slot := &t.slots[t.location(key)] + + if slot.occupied && t.compare(slot.key, key) { + slot.occupied = false + t.size-- + return true + } + + return false +} + +func (t *subtable[K, V]) resize(capacity uint64) { + t.slots = make([]slot[K, V], capacity) + t.capacity = capacity + t.size = 0 +} + +func (t subtable[K, V]) update(key K, value V) (updated bool) { + if t.capacity == 0 { + return + } + + slot := &t.slots[t.location(key)] + + if slot.occupied && t.compare(slot.key, key) { + slot.value = value + return true + } + + return false +} + +func (t *subtable[K, V]) evict(insertion entry[K, V]) (evicted entry[K, V], eviction bool) { + if t.capacity == 0 { + return insertion, true + } + + slot := &t.slots[t.location(insertion.key)] + + if !slot.occupied { + slot.entry = insertion + slot.occupied = true + t.size++ + return + } + + if t.compare(slot.key, insertion.key) { + slot.value = insertion.value + return + } + + insertion, slot.entry = slot.entry, insertion + return insertion, true +} + +func newSubtable[K, V any](capacity uint64, hash Hash[K], compare EqualFunc[K]) subtable[K, V] { + return subtable[K, V]{ + hash: hash, + capacity: capacity, + compare: compare, + size: 0, + slots: make([]slot[K, V], capacity), + } +} diff --git a/table.go b/table.go index 8b4967d..b5619fb 100644 --- a/table.go +++ b/table.go @@ -16,35 +16,35 @@ import ( // 2. A different [Hash] algorithm. var ErrBadHash = errors.New("bad hash") -// A Table is hash table that uses cuckoo hashing to resolve collision. Create -// one with [NewTable]. Or if you want more granularity, use [NewTableBy] or -// [NewCustomTable]. +// A Table which uses cuckoo hashing to resolve collision. Create +// one with [New]. Or if you want more granularity, use [NewBy] or +// [NewCustom]. type Table[K, V any] struct { - bucketA, bucketB bucket[K, V] - growthFactor uint64 - minLoadFactor float64 + tableA, tableB subtable[K, V] + growthFactor uint64 + minLoadFactor float64 } // TotalCapacity returns the number of slots allocated for the [Table]. To get the // number of slots filled, look at [Table.Size]. -func (t Table[K, V]) TotalCapacity() uint64 { - return t.bucketA.capacity + t.bucketB.capacity +func (t *Table[K, V]) TotalCapacity() uint64 { + return t.tableA.capacity + t.tableB.capacity } // Size returns how many slots are filled in the [Table]. -func (t Table[K, V]) Size() int { - return int(t.bucketA.size + t.bucketB.size) +func (t *Table[K, V]) Size() int { + return int(t.tableA.size + t.tableB.size) } func log2(n uint64) (m int) { return max(0, bits.Len64(n)-1) } -func (t Table[K, V]) maxEvictions() int { +func (t *Table[K, V]) maxEvictions() int { return 3 * log2(t.TotalCapacity()) } -func (t Table[K, V]) load() float64 { +func (t *Table[K, V]) load() float64 { // When there are no slots in the table, we still treat the load as 100%. // Every slot in the table is full. if t.TotalCapacity() == 0 { @@ -54,7 +54,7 @@ func (t Table[K, V]) load() float64 { return float64(t.Size()) / float64(t.TotalCapacity()) } -// resize clears all buckets, changes the sizes of them to a specific capacity, +// resize clears all tables, changes the sizes of them to a specific capacity, // and fills them back up again. It is a helper function for [Table.grow] and // [Table.shrink]; use them instead. func (t *Table[K, V]) resize(capacity uint64) error { @@ -63,8 +63,8 @@ func (t *Table[K, V]) resize(capacity uint64) error { entries = append(entries, entry[K, V]{k, v}) } - t.bucketA.resize(capacity) - t.bucketB.resize(capacity) + t.tableA.resize(capacity) + t.tableB.resize(capacity) for _, entry := range entries { if err := t.Put(entry.key, entry.value); err != nil { @@ -75,7 +75,7 @@ func (t *Table[K, V]) resize(capacity uint64) error { return nil } -// grow increases the table's capacity by the [Table.growthFactor]. If the +// grow increases the table's capacity by the growth factor. If the // capacity is 0, it increases it to 1. func (t *Table[K, V]) grow() error { var newCapacity uint64 @@ -83,26 +83,26 @@ func (t *Table[K, V]) grow() error { if t.TotalCapacity() == 0 { newCapacity = 1 } else { - newCapacity = t.bucketA.capacity * t.growthFactor + newCapacity = t.tableA.capacity * t.growthFactor } return t.resize(newCapacity) } -// shrink reduces the table's capacity by the [Table.growthFactor]. It may +// shrink reduces the table's capacity by the growth factor. It may // reduce it down to 0. func (t *Table[K, V]) shrink() error { - return t.resize(t.bucketA.capacity / t.growthFactor) + return t.resize(t.tableA.capacity / t.growthFactor) } // Get fetches the value for a key in the [Table]. Matches the comma-ok pattern // of a builtin map; see [Table.Find] for plain indexing. func (t Table[K, V]) Get(key K) (value V, ok bool) { - if item, ok := t.bucketA.get(key); ok { + if item, ok := t.tableA.get(key); ok { return item, true } - if item, ok := t.bucketB.get(key); ok { + if item, ok := t.tableB.get(key); ok { return item, true } @@ -124,21 +124,21 @@ func (t Table[K, V]) Has(key K) (exists bool) { // Put sets the value for a key. Returns error if its value cannot be set. func (t *Table[K, V]) Put(key K, value V) (err error) { - if t.bucketA.update(key, value) { + if t.tableA.update(key, value) { return nil } - if t.bucketB.update(key, value) { + if t.tableB.update(key, value) { return nil } entry, eviction := entry[K, V]{key, value}, false for range t.maxEvictions() { - if entry, eviction = t.bucketA.evict(entry); !eviction { + if entry, eviction = t.tableA.evict(entry); !eviction { return nil } - if entry, eviction = t.bucketB.evict(entry); !eviction { + if entry, eviction = t.tableB.evict(entry); !eviction { return nil } } @@ -157,8 +157,8 @@ func (t *Table[K, V]) Put(key K, value V) (err error) { // Drop removes a value for a key in the table. Returns an error if its value // cannot be removed. func (t *Table[K, V]) Drop(key K) (err error) { - t.bucketA.drop(key) - t.bucketB.drop(key) + t.tableA.drop(key) + t.tableB.drop(key) if t.load() < t.minLoadFactor { return t.shrink() @@ -168,9 +168,9 @@ func (t *Table[K, V]) Drop(key K) (err error) { } // Entries returns an unordered sequence of all key-value pairs in the table. -func (t Table[K, V]) Entries() iter.Seq2[K, V] { +func (t *Table[K, V]) Entries() iter.Seq2[K, V] { return func(yield func(K, V) bool) { - for _, slot := range t.bucketA.slots { + for _, slot := range t.tableA.slots { if slot.occupied { if !yield(slot.key, slot.value) { return @@ -178,7 +178,7 @@ func (t Table[K, V]) Entries() iter.Seq2[K, V] { } } - for _, slot := range t.bucketB.slots { + for _, slot := range t.tableB.slots { if slot.occupied { if !yield(slot.key, slot.value) { return @@ -189,8 +189,8 @@ func (t Table[K, V]) Entries() iter.Seq2[K, V] { } // String returns the entries of the table as a string in the format: -// "table[k1:v1 h2:v2 ...]". -func (t Table[K, V]) String() string { +// "table[k1:v1 k2:v2 ...]". +func (t *Table[K, V]) String() string { var sb strings.Builder sb.WriteString("table[") @@ -208,9 +208,9 @@ func (t Table[K, V]) String() string { return sb.String() } -// NewCustomTable creates a [Table] with custom [Hash] and [EqualFunc] +// NewCustom creates a [Table] with custom [Hash] and [EqualFunc] // functions, along with any [Option] the user provides. -func NewCustomTable[K, V any](hashA, hashB Hash[K], compare EqualFunc[K], options ...Option) *Table[K, V] { +func NewCustom[K, V any](hashA, hashB Hash[K], compare EqualFunc[K], options ...Option) *Table[K, V] { settings := &settings{ growthFactor: DefaultGrowthFactor, bucketSize: DefaultCapacity, @@ -224,8 +224,8 @@ func NewCustomTable[K, V any](hashA, hashB Hash[K], compare EqualFunc[K], option return &Table[K, V]{ growthFactor: settings.growthFactor, minLoadFactor: settings.minLoadFactor, - bucketA: newBucket[K, V](settings.bucketSize, hashA, compare), - bucketB: newBucket[K, V](settings.bucketSize, hashB, compare), + tableA: newSubtable[K, V](settings.bucketSize, hashA, compare), + tableB: newSubtable[K, V](settings.bucketSize, hashB, compare), } } @@ -233,10 +233,10 @@ func pipe[X, Y, Z any](a func(X) Y, b func(Y) Z) func(X) Z { return func(x X) Z { return b(a(x)) } } -// NewTableBy creates a [Table] for any key type by using keyFunc to derive a +// NewBy creates a [Table] for any key type by using keyFunc to derive a // comparable key. Two keys with the same derived key are treated as equal. -func NewTableBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *Table[K, V] { - return NewCustomTable[K, V]( +func NewBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *Table[K, V] { + return NewCustom[K, V]( pipe(keyFunc, NewDefaultHash[C]()), pipe(keyFunc, NewDefaultHash[C]()), func(a, b K) bool { return keyFunc(a) == keyFunc(b) }, @@ -244,10 +244,10 @@ func NewTableBy[K, V any, C comparable](keyFunc func(K) C, options ...Option) *T ) } -// NewTable creates a [Table] using the default [Hash] and [EqualFunc]. Use +// New creates a [Table] using the default [Hash] and [EqualFunc]. Use // the [Option] functions to configure its behavior. Note that this constructor // is only provided for comparable keys. For arbitrary keys, consider -// [NewTableBy] or [NewCustomTable]. -func NewTable[K comparable, V any](options ...Option) *Table[K, V] { - return NewCustomTable[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...) +// [NewBy] or [NewCustom]. +func New[K comparable, V any](options ...Option) *Table[K, V] { + return NewCustom[K, V](NewDefaultHash[K](), NewDefaultHash[K](), DefaultEqualFunc[K], options...) }