gistfile1.txt

func readPath(name string) {
    p := GetPolicy(name)
    DoSomething(p)
}

func writePath(name string) {
    p := GetPolicy(name)
    LockManager.Lock(name, func() {
        DoSomethign(p)
    })
}


func GetPolicy(name string) *Policy {
    p := GetCachedPolicy(name)
    if p == nil {
        p = GetStoredPolicy(name)
    }
    if p != nil && p.NeedsUpgrade() {
        LockManager.Lock(name, func() {
            // Check if the lock was upgraded in a race
            p := GetPolicy(name)
            if !p.NeedsUpgrade() {
                return p
            }
        
            // Do the upgrade
            p.Upgrade()

            // Update the cache
            SetCachedPolicy(p)
            return p
        })
    }
    return p
}

func GetCachedPolicy(name) *Policy {
    if cacheDisabled {
        return nil
    }
    cache.RLock()
    defer cache.RUnlock()
    return cache[name]
}

func SetCachedPolicy(name, p *Policy) {
    if cacheDisabled {
        return 
    }
    cache.Lock()
    defer cache.Unlock()
    cache[name] = p
}