sync: add Counter and Cache

sync: add Counter and Cache

[bradfitz, 2013-03-11 00:41:23]

Nice.

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go
File src/pkg/sync/cache.go (right):

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go#newcode30
src/pkg/sync/cache.go:30: // Returns false if the case cache is full.
case cache?

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go#newcode31
src/pkg/sync/cache.go:31: func (c *Cache) Put(v interface{}) bool {
maybe also a Clear method, to clear all procs' cache?

[dvyukov, 2013-03-11 05:58:33]

On 2013/03/11 00:41:23, bradfitz wrote:
> Nice.
> 
> https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go
> File src/pkg/sync/cache.go (right):
> 
>
https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go#newcode30
> src/pkg/sync/cache.go:30: // Returns false if the case cache is full.
> case cache?
> 
>
https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go#newcode31
> src/pkg/sync/cache.go:31: func (c *Cache) Put(v interface{}) bool {
> maybe also a Clear method, to clear all procs' cache?

Yes, I am going to add:
func (c *Cache) Drain() []interface{} {
The cache will support use case when a user needs to explicitly Close all
resources. Put() returns false on failure, and Drain() returns all the cached
resources.

Also I am going to add:
func (c *Cache) SetCapacity(local, global int) {

[james4k, 2013-06-04 17:36:30]

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go
File src/pkg/sync/cache.go (right):

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go#newcode9
src/pkg/sync/cache.go:9: Mutex
Is this mutex needed?

[dvyukov, 2013-06-04 17:46:41]

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go
File src/pkg/sync/cache.go (right):

https://codereview.appspot.com/7686043/diff/6001/src/pkg/sync/cache.go#newcode9
src/pkg/sync/cache.go:9: Mutex
On 2013/06/04 17:36:30, james4k wrote:
> Is this mutex needed?

It would be needed for Drain/SetCapacity methods.
This is a draft CL, little sense in looking at it.