Presently working on a Data Race and have some questions on how to proceed.
The code example is a hypothetical mock up of the actual code under review,
but is a fair representation.
The struct used by both functions is named Foo.
In the hypothetical, SomeFunc() reads variable from foo.bar, checking for
nil,
if nil SomeFunc() calls a Foo method Refresh().
Foo method Refresh() calls function DoSomeCalc() assigned to foo.bar and
returned back to method SomeFunc()
The race detector flags the read of foo.bar in method SomeFunc() in the if
statement,
and flags the write of foo.bar in method Refresh().
The problem I see is that in method SomeFunc() the if statement does a read,
but it too also does an assignment to foo.bar.
My initial thought is to add a sync.Lock() at the beginning of method
SomeFunc(),
followed by a defer sync.UnLock(),
that will be held until method SomeFunc() exists.
I state this because method SomeFunc() also does an assignment to variable
foo.bar.
So, a sync.RLock() would be insufficient to protect variable foo.bar
My only concern is the call to method Refresh(), which also writes to
foo.bar.
If my understanding is correct, this should work, because the lock is
initiated in method SomeFunc(), held to the exit of the method.
With the call to method Refresh() occurring within method SomeFunc() the
lock should protect variable foo.bar from other goroutines trying to update
this variable.
Asking this question to confirm my thought process is correct.
If there is an edge case I missed, please advise.
func (foo *Foo) SomeFunc() fields.SomeVariable {
if foo.bar == nil { <=== Race detector flags this
read
foo.bar = foo.ReFresh()
}
return foo.bar
}
func (foo *Foo) ReFresh() fields.SomeVariable {
foo.bar = DoSomeCalc(foo) <=== Race detector flags this
write
return foo.bar
}
THANX(MKD).
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