forked from Shiloh/githaven
7f8e3192cd
* Allow common redis and leveldb connections Prevents multiple reopening of redis and leveldb connections to the same place by sharing connections. Further allows for more configurable redis connection type using the redisURI and a leveldbURI scheme. Signed-off-by: Andrew Thornton <art27@cantab.net> * add unit-test Signed-off-by: Andrew Thornton <art27@cantab.net> * as per @lunny Signed-off-by: Andrew Thornton <art27@cantab.net> * add test Signed-off-by: Andrew Thornton <art27@cantab.net> * Update modules/cache/cache_redis.go * Update modules/queue/queue_disk.go * Update modules/cache/cache_redis.go * Update modules/cache/cache_redis.go * Update modules/queue/unique_queue_disk.go * Update modules/queue/queue_disk.go * Update modules/queue/unique_queue_disk.go * Update modules/session/redis.go Co-authored-by: techknowlogick <techknowlogick@gitea.io> Co-authored-by: Lauris BH <lauris@nix.lv>
61 lines
1.7 KiB
Go
Vendored
61 lines
1.7 KiB
Go
Vendored
/*
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Copyright 2014 The Camlistore Authors
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package internal
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import (
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"sync"
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"sync/atomic"
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)
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// A Once will perform a successful action exactly once.
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//
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// Unlike a sync.Once, this Once's func returns an error
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// and is re-armed on failure.
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type Once struct {
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m sync.Mutex
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done uint32
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}
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// Do calls the function f if and only if Do has not been invoked
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// without error for this instance of Once. In other words, given
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// var once Once
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// if once.Do(f) is called multiple times, only the first call will
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// invoke f, even if f has a different value in each invocation unless
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// f returns an error. A new instance of Once is required for each
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// function to execute.
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//
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// Do is intended for initialization that must be run exactly once. Since f
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// is niladic, it may be necessary to use a function literal to capture the
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// arguments to a function to be invoked by Do:
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// err := config.once.Do(func() error { return config.init(filename) })
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func (o *Once) Do(f func() error) error {
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if atomic.LoadUint32(&o.done) == 1 {
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return nil
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}
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// Slow-path.
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o.m.Lock()
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defer o.m.Unlock()
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var err error
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if o.done == 0 {
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err = f()
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if err == nil {
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atomic.StoreUint32(&o.done, 1)
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}
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}
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return err
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}
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