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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,113 @@ | ||
| // Copyright 2024 Blink Labs Software | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package event | ||
|
|
||
| import ( | ||
| "sync" | ||
| "time" | ||
| ) | ||
|
|
||
| const ( | ||
| EventQueueSize = 20 | ||
| ) | ||
|
|
||
| type EventType string | ||
|
|
||
| type EventSubscriberId int | ||
|
|
||
| type EventHandlerFunc func(Event) | ||
|
|
||
| type Event struct { | ||
| Type EventType | ||
| Timestamp time.Time | ||
| Data any | ||
| } | ||
|
|
||
| func NewEvent(eventType EventType, eventData any) Event { | ||
| return Event{ | ||
| Type: eventType, | ||
| Timestamp: time.Now(), | ||
| Data: eventData, | ||
| } | ||
| } | ||
|
|
||
| type EventBus struct { | ||
| sync.Mutex | ||
| subscribers map[EventType]map[EventSubscriberId]chan Event | ||
| lastSubId EventSubscriberId | ||
| } | ||
|
|
||
| // NewEventBus creates a new EventBus | ||
| func NewEventBus() *EventBus { | ||
| return &EventBus{ | ||
| subscribers: make(map[EventType]map[EventSubscriberId]chan Event), | ||
| } | ||
| } | ||
|
|
||
| // Subscribe allows a consumer to receive events of a particular type via a channel | ||
| func (e *EventBus) Subscribe(eventType EventType) (EventSubscriberId, <-chan Event) { | ||
| e.Lock() | ||
| defer e.Unlock() | ||
| // Create event channel | ||
| evtCh := make(chan Event, EventQueueSize) | ||
| // Increment subscriber ID | ||
| subId := e.lastSubId + 1 | ||
| e.lastSubId = subId | ||
| // Add new subscriber | ||
| if _, ok := e.subscribers[eventType]; !ok { | ||
| e.subscribers[eventType] = make(map[EventSubscriberId]chan Event) | ||
| } | ||
| evtTypeSubs := e.subscribers[eventType] | ||
| evtTypeSubs[subId] = evtCh | ||
| return subId, evtCh | ||
| } | ||
|
|
||
| // SubscribeFunc allows a consumer to receive events of a particular type via a callback function | ||
| func (e *EventBus) SubscribeFunc(eventType EventType, handlerFunc EventHandlerFunc) EventSubscriberId { | ||
| subId, evtCh := e.Subscribe(eventType) | ||
| go func(evtCh <-chan Event, handlerFunc EventHandlerFunc) { | ||
| for { | ||
| evt, ok := <-evtCh | ||
| if !ok { | ||
| return | ||
| } | ||
| handlerFunc(evt) | ||
| } | ||
| }(evtCh, handlerFunc) | ||
| return subId | ||
| } | ||
|
|
||
| // Unsubscribe stops delivery of events for a particular type for an existing subscriber | ||
| func (e *EventBus) Unsubscribe(eventType EventType, subId EventSubscriberId) { | ||
| e.Lock() | ||
| defer e.Unlock() | ||
| if evtTypeSubs, ok := e.subscribers[eventType]; ok { | ||
| delete(evtTypeSubs, subId) | ||
| } | ||
| } | ||
|
|
||
| // Publish allows a producer to send an event of a particular type to all subscribers | ||
| func (e *EventBus) Publish(eventType EventType, evt Event) { | ||
| e.Lock() | ||
| defer e.Unlock() | ||
| if subs, ok := e.subscribers[eventType]; ok { | ||
| for _, subCh := range subs { | ||
| // NOTE: this is purposely a blocking operation to prevent dropping data | ||
| // XXX: do we maybe want to detect a blocked channel and temporarily set it aside | ||
| // to get the event sent to the other subscribers? | ||
| subCh <- evt | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,115 @@ | ||
| // Copyright 2024 Blink Labs Software | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package event_test | ||
|
|
||
| import ( | ||
| "testing" | ||
| "time" | ||
|
|
||
| "github.com/blinklabs-io/node/event" | ||
| ) | ||
|
|
||
| func TestEventBusSingleSubscriber(t *testing.T) { | ||
| var testEvtData int = 999 | ||
| var testEvtType event.EventType = "test.event" | ||
| eb := event.NewEventBus() | ||
| _, subCh := eb.Subscribe(testEvtType) | ||
| eb.Publish(testEvtType, event.NewEvent(testEvtType, testEvtData)) | ||
| select { | ||
| case evt, ok := <-subCh: | ||
| if !ok { | ||
| t.Fatalf("event channel closed unexpectedly") | ||
| } | ||
| switch v := evt.Data.(type) { | ||
| case int: | ||
| if v != testEvtData { | ||
| t.Fatalf("did not get expected event") | ||
| } | ||
| default: | ||
| t.Fatalf("event data was not of expected type, expected int, got %T", evt.Data) | ||
| } | ||
| case <-time.After(1 * time.Second): | ||
| t.Fatalf("timeout waiting for event") | ||
| } | ||
| } | ||
|
|
||
| func TestEventBusMultipleSubscribers(t *testing.T) { | ||
| var testEvtData int = 999 | ||
| var testEvtType event.EventType = "test.event" | ||
| eb := event.NewEventBus() | ||
| _, sub1Ch := eb.Subscribe(testEvtType) | ||
| _, sub2Ch := eb.Subscribe(testEvtType) | ||
| eb.Publish(testEvtType, event.NewEvent(testEvtType, testEvtData)) | ||
| var gotVal1, gotVal2 bool | ||
| for { | ||
| if gotVal1 && gotVal2 { | ||
| break | ||
| } | ||
| select { | ||
| case evt, ok := <-sub1Ch: | ||
| if !ok { | ||
| t.Fatalf("event channel closed unexpectedly") | ||
| } | ||
| if gotVal1 { | ||
| t.Fatalf("received unexpected event") | ||
| } | ||
| switch v := evt.Data.(type) { | ||
| case int: | ||
| if v != testEvtData { | ||
| t.Fatalf("did not get expected event") | ||
| } | ||
| default: | ||
| t.Fatalf("event data was not of expected type, expected int, got %T", evt.Data) | ||
| } | ||
| gotVal1 = true | ||
| case evt, ok := <-sub2Ch: | ||
| if !ok { | ||
| t.Fatalf("event channel closed unexpectedly") | ||
| } | ||
| if gotVal2 { | ||
| t.Fatalf("received unexpected event") | ||
| } | ||
| switch v := evt.Data.(type) { | ||
| case int: | ||
| if v != testEvtData { | ||
| t.Fatalf("did not get expected event") | ||
| } | ||
| default: | ||
| t.Fatalf("event data was not of expected type, expected int, got %T", evt.Data) | ||
| } | ||
| gotVal2 = true | ||
| case <-time.After(1 * time.Second): | ||
| t.Fatalf("timeout waiting for event") | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func TestEventBusUnsubscribe(t *testing.T) { | ||
| var testEvtData int = 999 | ||
| var testEvtType event.EventType = "test.event" | ||
| eb := event.NewEventBus() | ||
| subId, subCh := eb.Subscribe(testEvtType) | ||
| eb.Unsubscribe(testEvtType, subId) | ||
| eb.Publish(testEvtType, event.NewEvent(testEvtType, testEvtData)) | ||
| select { | ||
| case _, ok := <-subCh: | ||
| if !ok { | ||
| t.Fatalf("event channel closed unexpectedly") | ||
| } | ||
| t.Fatalf("received unexpected event") | ||
| case <-time.After(1 * time.Second): | ||
| // NOTE: this is the expected way for the test to end | ||
| } | ||
| } |
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