ccache/item_test.go

package ccache

import (
	"github.com/karlseguin/gspec"
	"testing"
)

func TestItemPromotability(t *testing.T) {
	spec := gspec.New(t)
	item := &Item{promotions: 4}
	spec.Expect(item.shouldPromote(5)).ToEqual(true)
	spec.Expect(item.shouldPromote(5)).ToEqual(false)
}
initial tests 2013-10-19 14:36:33 +02:00			`package ccache`

			`import (`
The cache can now do reference counting so that the LRU algorithm is aware of long-lived objects and won't clean them up. Oftentimes, the value returned from a cache hit is short-lived. As a silly example: func GetUser(http.responseWrite) { user := cache.Get("user:1") response.Write(serialize(user)) } It's fine if the cache's GC cleans up "user:1" while the user variable has a reference to the object..the cache's reference is removed and the real GC will clean it up at some point after the user variable falls out of scope. However, what if user is long-lived? Possibly stored as a reference to another cached object? Normally (without this commit) the next time you call cache.Get("user:1"), you'll get a miss and will need to refetch the object; even though the original user object is still somewhere in memory - you just lost your reference to it from the cache. By enabling the Track() configuration flag, and calling TrackingGet() (instead of Get), the cache will track that the object is in-use and won't GC it (even if there's great memory pressure (what's the point? something else is holding on to it anyways). Calling item.Release() will decrement the number of references. When the count is 0, the item can be pruned from the cache. The returned value is a TrackedItem which exposes: - Value() interface{} (to get the actual cached value) - Release() to release the item back in the cache 2014-02-28 13:10:42 +01:00			`"github.com/karlseguin/gspec"`
			`"testing"`
initial tests 2013-10-19 14:36:33 +02:00			`)`

			`func TestItemPromotability(t *testing.T) {`
The cache can now do reference counting so that the LRU algorithm is aware of long-lived objects and won't clean them up. Oftentimes, the value returned from a cache hit is short-lived. As a silly example: func GetUser(http.responseWrite) { user := cache.Get("user:1") response.Write(serialize(user)) } It's fine if the cache's GC cleans up "user:1" while the user variable has a reference to the object..the cache's reference is removed and the real GC will clean it up at some point after the user variable falls out of scope. However, what if user is long-lived? Possibly stored as a reference to another cached object? Normally (without this commit) the next time you call cache.Get("user:1"), you'll get a miss and will need to refetch the object; even though the original user object is still somewhere in memory - you just lost your reference to it from the cache. By enabling the Track() configuration flag, and calling TrackingGet() (instead of Get), the cache will track that the object is in-use and won't GC it (even if there's great memory pressure (what's the point? something else is holding on to it anyways). Calling item.Release() will decrement the number of references. When the count is 0, the item can be pruned from the cache. The returned value is a TrackedItem which exposes: - Value() interface{} (to get the actual cached value) - Release() to release the item back in the cache 2014-02-28 13:10:42 +01:00			`spec := gspec.New(t)`
			`item := &Item{promotions: 4}`
			`spec.Expect(item.shouldPromote(5)).ToEqual(true)`
			`spec.Expect(item.shouldPromote(5)).ToEqual(false)`
initial tests 2013-10-19 14:36:33 +02:00			`}`