52 lines
1.3 KiB
Go
52 lines
1.3 KiB
Go
package mutexkv
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import (
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"log"
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"sync"
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)
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// MutexKV is a simple key/value store for arbitrary mutexes. It can be used to
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// serialize changes across arbitrary collaborators that share knowledge of the
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// keys they must serialize on.
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//
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// The initial use case is to let aws_security_group_rule resources serialize
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// their access to individual security groups based on SG ID.
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type MutexKV struct {
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lock sync.Mutex
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store map[string]*sync.Mutex
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}
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// Locks the mutex for the given key. Caller is responsible for calling Unlock
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// for the same key
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func (m *MutexKV) Lock(key string) {
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log.Printf("[DEBUG] Locking %q", key)
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m.get(key).Lock()
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log.Printf("[DEBUG] Locked %q", key)
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}
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// Unlock the mutex for the given key. Caller must have called Lock for the same key first
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func (m *MutexKV) Unlock(key string) {
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log.Printf("[DEBUG] Unlocking %q", key)
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m.get(key).Unlock()
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log.Printf("[DEBUG] Unlocked %q", key)
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}
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// Returns a mutex for the given key, no guarantee of its lock status
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func (m *MutexKV) get(key string) *sync.Mutex {
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m.lock.Lock()
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defer m.lock.Unlock()
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mutex, ok := m.store[key]
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if !ok {
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mutex = &sync.Mutex{}
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m.store[key] = mutex
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}
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return mutex
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}
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// Returns a properly initalized MutexKV
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func NewMutexKV() *MutexKV {
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return &MutexKV{
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store: make(map[string]*sync.Mutex),
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}
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}
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