[golang-dev] Re: code review 7384048: net: speed up network interface manipulations by caching (issue 7384048)

Thank you for this proposal. I shared Brads concerns that the caching
semantics need to be given some consideration.


https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface.go
File src/pkg/net/interface.go (right):

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface.go#newcode26
src/pkg/net/interface.go:26: )
suggestion (feel free to ignore it)

var interfaceCache = struct {
sync.Mutex
indexMap map[...]...
nameMap map[...]...
}{ indexMap: make(...), nameMap: make(...) }

then (i think) it is clearer in the code (see below)

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface.go#newcode29
src/pkg/net/interface.go:29: interfaceMapLock.RLock()
interfaceCache.Lock()
defer ...
ifi, ok := interfaceCache.indexMap[index]

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface.go#newcode110
src/pkg/net/interface.go:110: // Interfaces returns a list of the
system's network interfaces. It
+1. One day we might not want to use a cache.

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface.go#newcode113
src/pkg/net/interface.go:113: func Interfaces() ([]Interface, error) {
Why does this function always overwrite the cache when called?

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface_test.go
File src/pkg/net/interface_test.go (right):

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface_test.go#newcode16
src/pkg/net/interface_test.go:16: if err != nil {
should this take a *testing.T), then you can t.Fatal(err) ?

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/interface_test.go#newcode132
src/pkg/net/interface_test.go:132: b.Fatalf("loopback interface not
found")
Is b.Skip() of use now ?

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/ipsock.go
File src/pkg/net/ipsock.go (right):

https://codereview.appspot.com/7384048/diff/11001/src/pkg/net/ipsock.go#newcode16
src/pkg/net/ipsock.go:16: Interfaces()
please add a comment

// populate interface cache

https://codereview.appspot.com/7384048/