/
eventqueue.go
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/
eventqueue.go
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package eventqueue
import (
"sync"
"github.com/PagerDuty/go-pdagent/pkg/common"
"github.com/PagerDuty/go-pdagent/pkg/eventsapi"
"go.uber.org/zap"
)
const DefaultBufferSize = 1000
// EventQueues are a basic thread-safe queue for processing PagerDuty events.
//
// Each EventQueue is internally composed of several individual queues
// segmented by routing key, ensuring that events are in-order on a per
// routing key basis. Each of these queues has a single dedicated worker.
//
// All responses occur through a single user-provided channel when enqueuing
// events.
//
// EventQueues also have a configurable, synchronous processor. By default this
// processor sends events to PagerDuty's events API..
//
// Example usage:
//
// queue := eventqueue.NewEventQueue()
//
// event := eventsapi.EventV2{
// RoutingKey: "NN2EZIJQPVVQF3KIKN2MDMSUV7E6GLFN",
// EventAction: "trigger",
// Payload: eventsapi.PayloadV2{
// Summary: "Test summary",
// Source: "Test source",
// Severity: "Error",
// },
// }
//
// rawEvent, _ := json.Marshal(event)
//
// eventContainer := eventsapi.EventContainer{
// EventVersion: event.Version(),
// EventData: rawEvent,
// }
//
// respChan = make(chan eventqueue.Response)
//
// queue.Enqueue(&eventContainer, respChan)
//
// resp := <-respChan
//
// // When you're done with the queue.
// queue.Shutdown()
type EventQueue struct {
Processor Processor
logger *zap.SugaredLogger
mu sync.Mutex
queues map[string]chan Job
stop chan bool
wg sync.WaitGroup
}
// NewEventQueue initializes a new default EventQueue.
func NewEventQueue() *EventQueue {
logger := common.Logger.Named("EventQueue")
logger.Info("Creating new EventQueue.")
return &EventQueue{
Processor: DefaultProcessor,
logger: logger,
queues: make(map[string]chan Job),
stop: make(chan bool),
}
}
// Shutdown the queue and all associated workers.
//
// There may be a blocking delay while any running workers or processors
// attempt to complete their current tasks.
func (q *EventQueue) Shutdown() {
q.logger.Info("Shutting down EventQueue.")
for _, w := range q.queues {
close(w)
}
q.wg.Wait()
close(q.stop)
q.logger.Info("Shut down EventQueue.")
}
// Enqueue a PagerDuty event for processing.
//
// Accepts an event and a channel over which to communicate responses. Errors
// come in two flavors: Synchronous errors (e.g. event is invalid and never
// queued) as a return value and asynchronous errors (e.g. server error) that
// are part of the channel Response.
func (q *EventQueue) Enqueue(eventContainer *eventsapi.EventContainer, respChan chan<- Response) error {
event, err := eventContainer.UnmarshalEvent()
if err != nil {
return err
}
if err := event.Validate(); err != nil {
return err
}
key := event.GetRoutingKey()
q.ensureWorker(key)
select {
case q.queues[key] <- Job{eventContainer, respChan, q.logger.Named(key)}:
return nil
default:
respChan <- Response{Error: &ErrBufferOverflow{key, DefaultBufferSize}}
return nil
}
}
func (q *EventQueue) ensureWorker(key string) {
q.mu.Lock()
defer q.mu.Unlock()
if q.queues[key] != nil {
return
}
c := make(chan Job, DefaultBufferSize)
q.wg.Add(1)
go q.worker(key, c)
q.queues[key] = c
}
func (q *EventQueue) worker(key string, c <-chan Job) {
defer q.wg.Done()
logger := q.logger.Named(key)
logger.Infof("Worker started.")
for job := range c {
logger.Infof("Job started, %v pending.", len(c))
q.Processor(job, q.stop)
}
logger.Infof("Worker stopped.")
}
type Job struct {
EventContainer *eventsapi.EventContainer
ResponseChan chan<- Response
Logger *zap.SugaredLogger
}
type Response struct {
Response eventsapi.Response
Error error
}