57 lines
1005 B
Go
57 lines
1005 B
Go
package mutexes
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type hashmap struct {
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m map[string]*rwmutex
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n int
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}
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func (m *hashmap) init(cap int) {
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m.m = make(map[string]*rwmutex, cap)
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m.n = cap
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}
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func (m *hashmap) Get(key string) *rwmutex { return m.m[key] }
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func (m *hashmap) Put(key string, mu *rwmutex) {
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m.m[key] = mu
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if n := len(m.m); n > m.n {
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m.n = n
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}
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}
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func (m *hashmap) Delete(key string) {
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delete(m.m, key)
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}
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func (m *hashmap) Compact() {
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// Noop when hashmap size
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// is too small to matter.
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if m.n < 2048 {
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return
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}
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// Difference between maximum map
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// size and the current map size.
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diff := m.n - len(m.m)
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// Maximum load factor before
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// runtime allocates new hmap:
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// maxLoad = 13 / 16
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//
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// So we apply the inverse/2, once
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// $maxLoad/2 % of hmap is empty we
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// compact the map to drop buckets.
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if 2*16*diff > m.n*13 {
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// Create new map only as big as required.
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m2 := make(map[string]*rwmutex, len(m.m))
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for k, v := range m.m {
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m2[k] = v
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}
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// Set new.
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m.m = m2
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m.n = len(m2)
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}
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}
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