Add functions for clearing specific cache entries. (#96)

goon.go

@@ -412,6 +412,80 @@ func (g *Goon) FlushLocalCache() {
  g.cache.Flush()
 }
 
+// ClearCache removes the provided entity from cache.
+// Takes either *S or *datastore.Key.
+// The 'mem' and 'local' booleans dictate the type of caches to clear.
+func (g *Goon) ClearCache(src interface{}, mem, local bool) error {
+ if !mem && !local {
+ // Nothing to clear ..
+ return nil
+ }
+ var srcs interface{}
+ if key, ok := src.(*datastore.Key); ok {
+ srcs = []*datastore.Key{key}
+ } else {
+ v := reflect.ValueOf(src)
+ if v.Kind() != reflect.Ptr {
+ return fmt.Errorf("goon: expected pointer to a struct, got %#v", src)
+ }
+ srcs = []interface{}{src}
+ }
+ err := g.ClearCacheMulti(srcs, mem, local)
+ if err != nil {
+ // Look for an embedded error if it's multi
+ if me, ok := err.(appengine.MultiError); ok {
+ return me[0]
+ }
+ }
+ return err
+}
+
+// ClearCacheMulti removes the provided entities from cache.
+// Takes either []*S or []*datastore.Key.
+// The 'mem' and 'local' booleans dictate the type of caches to clear.
+func (g *Goon) ClearCacheMulti(src interface{}, mem, local bool) error {
+ if !mem && !local {
+ // Nothing to clear ..
+ return nil
+ }
+ keys, ok := src.([]*datastore.Key)
+ if !ok {
+ var err error
+ keys, err = g.extractKeys(src, false) // don't allow incomplete keys on a Clear request
+ if err != nil {
+ return err
+ }
+ }
+ if len(keys) == 0 {
+ return nil
+ // not an error, and it was "successful", so return nil
+ }
+ cachekeys := make([]string, 0, len(keys))
+ for _, key := range keys {
+ cachekeys = append(cachekeys, cacheKey(key))
+ }
+ if g.inTransaction {
+ g.txnCacheLock.Lock()
+ for _, ck := range cachekeys {
+ if local {
+ g.toDelete[ck] = struct{}{}
+ }
+ if mem {
+ g.toDeleteMC[ck] = struct{}{}
+ }
+ }
+ g.txnCacheLock.Unlock()
+ } else {
+ if local {
+ g.cache.DeleteMulti(cachekeys)
+ }
+ if mem {
+ g.memcacheDeleteError(memcache.DeleteMulti(g.Context, cachekeys))
+ }
+ }
+ return nil
+}
+
 type memcacheTask struct {
  items []*memcache.Item
  size int

goon_test.go

@@ -1865,6 +1865,63 @@ func TestCaches(t *testing.T) {
  if !reflect.DeepEqual(*phid, ghids[0]) {
  t.Fatalf("Invalid result!\n%s", getDiff(*phid, ghids[0], "*phid", "ghids[0]"))
  }
+
+ // Do a sneaky save straight to the datastore
+ mhid := &HasId{Id: phid.Id, Name: "modified"}
+ if _, err := datastore.Put(c, datastore.NewKey(c, "HasId", "", phid.Id, nil), mhid); err != nil {
+ t.Fatalf("Unexpected error on datastore.Put: %v", err)
+ }
+
+ // Clear the memcache entry specifically
+ if err := g.ClearCache(phid, true, false); err != nil {
+ t.Fatalf("Failed to clear cache: %v", err)
+ }
+
+ // fetch *struct{} from cache
+ ghid = &HasId{Id: phid.Id}
+ err = g.Get(ghid)
+ if err != nil {
+ t.Fatalf("Unexpected error on get - %v", err)
+ }
+ if !reflect.DeepEqual(phid, ghid) {
+ t.Fatalf("Invalid result!\n%s", getDiff(phid, ghid, "phid", "ghid"))
+ }
+
+ // Clear the local cache entry specifically
+ if err := g.ClearCache(phid, false, true); err != nil {
+ t.Fatalf("Failed to clear cache: %v", err)
+ }
+
+ // fetch *struct{} from datastore
+ ghid = &HasId{Id: phid.Id}
+ err = g.Get(ghid)
+ if err != nil {
+ t.Fatalf("Unexpected error on get - %v", err)
+ }
+ if !reflect.DeepEqual(mhid, ghid) {
+ t.Fatalf("Invalid result!\n%s", getDiff(mhid, ghid, "mhid", "ghid"))
+ }
+
+ // Do a sneaky save straight to the datastore
+ nhid := &HasId{Id: phid.Id, Name: "nudged"}
+ if _, err := datastore.Put(c, datastore.NewKey(c, "HasId", "", phid.Id, nil), nhid); err != nil {
+ t.Fatalf("Unexpected error on datastore.Put: %v", err)
+ }
+
+ // Clear the local cache entry specifically
+ if err := g.ClearCache(phid, false, true); err != nil {
+ t.Fatalf("Failed to clear cache: %v", err)
+ }
+
+ // fetch *struct{} from memcache
+ ghid = &HasId{Id: phid.Id}
+ err = g.Get(ghid)
+ if err != nil {
+ t.Fatalf("Unexpected error on get - %v", err)
+ }
+ if !reflect.DeepEqual(mhid, ghid) {
+ t.Fatalf("Invalid result!\n%s", getDiff(mhid, ghid, "mhid", "ghid"))
+ }
 }
 
 func TestGoon(t *testing.T) {