mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-15 07:27:32 +01:00
107 lines
2.2 KiB
Go
107 lines
2.2 KiB
Go
// Copyright 2024 The Ebitengine Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package text
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import (
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"math"
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"sync"
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"sync/atomic"
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"github.com/hajimehoshi/ebiten/v2/internal/hook"
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)
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var monotonicClock atomic.Int64
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const infTime = math.MaxInt64
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func init() {
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hook.AppendHookOnBeforeUpdate(func() error {
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monotonicClock.Add(1)
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return nil
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})
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}
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type cacheValue[Value any] struct {
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value Value
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// atime is the last time when the value was accessed.
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atime int64
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}
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type cache[Key comparable, Value any] struct {
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// softLimit indicates the soft limit of the number of values in the cache.
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softLimit int
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values map[Key]*cacheValue[Value]
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// atime is the last time when the cache was accessed.
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atime int64
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m sync.Mutex
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}
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func newCache[Key comparable, Value any](softLimit int) *cache[Key, Value] {
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return &cache[Key, Value]{
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softLimit: softLimit,
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}
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}
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func (c *cache[Key, Value]) getOrCreate(key Key, create func() (Value, bool)) Value {
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n := monotonicClock.Load()
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c.m.Lock()
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defer c.m.Unlock()
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e, ok := c.values[key]
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if ok {
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e.atime = n
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return e.value
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}
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if c.values == nil {
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c.values = map[Key]*cacheValue[Value]{}
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}
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ent, canExpire := create()
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e = &cacheValue[Value]{
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value: ent,
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atime: infTime,
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}
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if canExpire {
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e.atime = n
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}
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c.values[key] = e
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// Clean up old entries.
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if c.atime < n {
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// If the number of values exceeds the soft limits, old values are removed.
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// Even after cleaning up the cache, the number of values might still exceed the soft limit,
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// but this is fine.
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if len(c.values) > c.softLimit {
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for key, e := range c.values {
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// 60 is an arbitrary number.
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if e.atime >= n-60 {
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continue
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}
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delete(c.values, key)
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}
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}
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}
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c.atime = n
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return e.value
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}
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