Other have provided some options. Another option is to use a sentinel value
and check. It is less than ideal for many reasons, but in some cases is
still the best option. In your case it might be to use nil:
var m sync.Mutex
lock := &m
lock.Lock()
defer func() {if lock != nil {lock.Unlock()}}()
if err := performOperation1(); err != nil {
return err
}
lock.Unlock()
lock = nil
performExpensiveOperation2()
On Friday, February 8, 2019 at 1:28:12 PM UTC-5, vincent163 wrote:
>
> I am thinking about how to write programs like this:
> lock1.Lock()
> err = performOperation1()
> if err != nil {
> lock1.Unlock()
> return err
> }
> lock1.Unlock()
> performExpensiveOperation2()
>
> The lock1 must be locked while performing operation1, and I need to use
> its result to perform operation2. Since operation2 is expensive, I don't
> want to hold the lock while performing it, and lock1.Unlock() needs to be
> called before calling operation2.
> Go's defer mechanism doesn't seem to handle this case well since the
> resource is used only within a block and not throughout the function. Is
> there a recommended way to write programs in this case?
> I know I could wrap the lock block in a closure, but that creates a
> completely new scope, so I can't return directly or break out of a loop
> within the closure, etc.
>
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