69 lines
1.4 KiB
Go
69 lines
1.4 KiB
Go
// Copyright 2018 Google LLC
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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 p9
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import (
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"sync"
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)
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// pool is a simple allocator.
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//
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// It is used for both tags and FIDs.
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type pool struct {
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mu sync.Mutex
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// cache is the set of returned values.
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cache []uint64
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// start is the starting value (if needed).
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start uint64
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// max is the current maximum issued.
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max uint64
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// limit is the upper limit.
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limit uint64
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}
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// Get gets a value from the pool.
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func (p *pool) Get() (uint64, bool) {
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p.mu.Lock()
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defer p.mu.Unlock()
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// Anything cached?
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if len(p.cache) > 0 {
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v := p.cache[len(p.cache)-1]
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p.cache = p.cache[:len(p.cache)-1]
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return v, true
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}
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// Over the limit?
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if p.start == p.limit {
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return 0, false
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}
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// Generate a new value.
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v := p.start
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p.start++
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return v, true
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}
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// Put returns a value to the pool.
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func (p *pool) Put(v uint64) {
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p.mu.Lock()
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p.cache = append(p.cache, v)
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p.mu.Unlock()
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}
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