зеркало из https://github.com/microsoft/docker.git
46 строки
1.1 KiB
Go
46 строки
1.1 KiB
Go
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package graph
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import "sync"
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// imageMutex provides a lock per image id to protect shared resources in the
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// graph. This is only used with registration but should be used when
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// manipulating the layer store.
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type imageMutex struct {
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mus map[string]*sync.Mutex // mutexes by image id.
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mu sync.Mutex // protects lock map
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// NOTE(stevvooe): The map above will grow to the size of all images ever
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// registered during a daemon run. To free these resources, we must
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// deallocate after unlock. Doing this safely is non-trivial in the face
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// of a very minor leak.
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}
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// Lock the provided id.
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func (im *imageMutex) Lock(id string) {
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im.getImageLock(id).Lock()
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}
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// Unlock the provided id.
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func (im *imageMutex) Unlock(id string) {
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im.getImageLock(id).Unlock()
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}
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// getImageLock returns the mutex for the given id. This method will never
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// return nil.
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func (im *imageMutex) getImageLock(id string) *sync.Mutex {
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im.mu.Lock()
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defer im.mu.Unlock()
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if im.mus == nil { // lazy
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im.mus = make(map[string]*sync.Mutex)
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}
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mu, ok := im.mus[id]
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if !ok {
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mu = new(sync.Mutex)
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im.mus[id] = mu
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}
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return mu
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}
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