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79 lines
1.8 KiB
Go
79 lines
1.8 KiB
Go
// Copyright (C) 2015 Space Monkey, Inc.
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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 monkit
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import (
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"sync"
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)
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// funcSet is a set data structure (keeps track of unique functions). funcSet
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// has a fast path for dealing with cases where the set only has one element.
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//
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// to reduce memory usage for functions, funcSet exposes its mutex for use in
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// other contexts
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type funcSet struct {
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// sync/atomic things
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first *Func
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// protected by mtx
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sync.Mutex
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rest map[*Func]struct{}
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}
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var (
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// used to signify that we've specifically added a nil function, since nil is
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// used internally to specify an empty set.
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nilFunc = &Func{}
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)
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func (s *funcSet) Add(f *Func) {
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if f == nil {
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f = nilFunc
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}
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if loadFunc(&s.first) == f {
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return
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}
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if compareAndSwapFunc(&s.first, nil, f) {
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return
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}
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s.Mutex.Lock()
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if s.rest == nil {
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s.rest = map[*Func]struct{}{}
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}
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s.rest[f] = struct{}{}
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s.Mutex.Unlock()
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}
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// Iterate loops over all unique elements of the set.
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func (s *funcSet) Iterate(cb func(f *Func)) {
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s.Mutex.Lock()
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uniq := make(map[*Func]struct{}, len(s.rest)+1)
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for f := range s.rest {
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uniq[f] = struct{}{}
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}
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s.Mutex.Unlock()
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f := loadFunc(&s.first)
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if f != nil {
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uniq[f] = struct{}{}
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}
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for f := range uniq {
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if f == nilFunc {
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cb(nil)
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} else {
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cb(f)
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}
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}
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}
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