Anton Kaliaev
6 years ago
No known key found for this signature in database
GPG Key ID: 7B6881D965918214
5 changed files with 241 additions and 166 deletions
Split View
Diff Options
-
+2 -3libs/pubsub/example_test.go
-
+91 -115libs/pubsub/pubsub.go
-
+56 -48libs/pubsub/pubsub_test.go
-
+60 -0libs/pubsub/subscription.go
-
+32 -0libs/pubsub/tag_map.go
+ 2
- 3
libs/pubsub/example_test.go
View File
+ 91
- 115
libs/pubsub/pubsub.go
View File
+ 56
- 48
libs/pubsub/pubsub_test.go
View File
+ 60
- 0
libs/pubsub/subscription.go
View File
| @ -0,0 +1,60 @@ | |||
| package pubsub | |||
| import ( | |||
| "errors" | |||
| "sync" | |||
| ) | |||
| var ( | |||
| // ErrUnsubscribed is returned by Err when a client unsubscribes. | |||
| ErrUnsubscribed = errors.New("client unsubscribed") | |||
| // ErrOutOfCapacity is returned by Err when a client is not pulling messages | |||
| // fast enough. Note the client's subscription will be terminated. | |||
| ErrOutOfCapacity = errors.New("client is not pulling messages fast enough") | |||
| ) | |||
| // A Subscription represents a client subscription for a particular query and | |||
| // consists of three things: | |||
| // 1) channel onto which messages and tags are published | |||
| // 2) channel which is closed if a client is too slow or choose to unsubscribe | |||
| // 3) err indicating the reason for (2) | |||
| type Subscription struct { | |||
| out chan MsgAndTags | |||
| cancelled chan struct{} | |||
| mtx sync.RWMutex | |||
| err error | |||
| } | |||
| // Out returns a channel onto which messages and tags are published. | |||
| // Unsubscribe/UnsubscribeAll does not close the channel to avoid clients from | |||
| // receiving a nil message. | |||
| func (s *Subscription) Out() <-chan MsgAndTags { | |||
| return s.out | |||
| } | |||
| // Cancelled returns a channel that's closed when the subscription is | |||
| // terminated and supposed to be used in a select statement. | |||
| func (s *Subscription) Cancelled() <-chan struct{} { | |||
| return s.cancelled | |||
| } | |||
| // Err returns nil if the channel returned by Cancelled is not yet closed. | |||
| // If the channel is closed, Err returns a non-nil error explaining why: | |||
| // - ErrUnsubscribed if the subscriber choose to unsubscribe, | |||
| // - ErrOutOfCapacity if the subscriber is not pulling messages fast enough | |||
| // and the channel returned by Out became full, | |||
| // After Err returns a non-nil error, successive calls to Err return the same | |||
| // error. | |||
| func (s *Subscription) Err() error { | |||
| s.mtx.RLock() | |||
| defer s.mtx.RUnlock() | |||
| return s.err | |||
| } | |||
| // MsgAndTags glues a message and tags together. | |||
| type MsgAndTags struct { | |||
| Msg interface{} | |||
| Tags TagMap | |||
| } | |||
+ 32
- 0
libs/pubsub/tag_map.go
View File
| @ -0,0 +1,32 @@ | |||
| package pubsub | |||
| // TagMap is used to associate tags to a message. | |||
| // They can be queried by subscribers to choose messages they will received. | |||
| type TagMap interface { | |||
| // Get returns the value for a key, or nil if no value is present. | |||
| // The ok result indicates whether value was found in the tags. | |||
| Get(key string) (value string, ok bool) | |||
| // Len returns the number of tags. | |||
| Len() int | |||
| } | |||
| type tagMap map[string]string | |||
| var _ TagMap = (*tagMap)(nil) | |||
| // NewTagMap constructs a new immutable tag set from a map. | |||
| func NewTagMap(data map[string]string) TagMap { | |||
| return tagMap(data) | |||
| } | |||
| // Get returns the value for a key, or nil if no value is present. | |||
| // The ok result indicates whether value was found in the tags. | |||
| func (ts tagMap) Get(key string) (value string, ok bool) { | |||
| value, ok = ts[key] | |||
| return | |||
| } | |||
| // Len returns the number of tags. | |||
| func (ts tagMap) Len() int { | |||
| return len(ts) | |||
| } | |||