func main() {
region := "us-east-1"
queueName := "example_queue"
numFetchers := 3
// set up an SQS service instance
// note that you can modify the AWS config used - make your own sqsconsumer.AWSConfigOption
// or just depend on ~/.aws/... or environment variables and don't pass any opts at all
s, err := sqsconsumer.SQSServiceForQueue(queueName, sqsconsumer.OptAWSRegion(region))
if err != nil {
log.Fatalf("Could not set up queue '%s': %s", queueName, err)
}
// set up a context which will gracefully cancel the worker on interrupt
fetchCtx, cancelFetch := context.WithCancel(context.Background())
term := make(chan os.Signal, 1)
signal.Notify(term, os.Interrupt, os.Kill)
go func() {
<-term
log.Println("Starting graceful shutdown")
cancelFetch()
}()
// set up metrics - note TrackMetrics does not run the http server, and uses expvar
exposeMetrics()
ms := expvar.NewInt(fmt.Sprintf("%s.success", queueName))
mf := expvar.NewInt(fmt.Sprintf("%s.fail", queueName))
mt := expvar.NewFloat(fmt.Sprintf("%s.time", queueName))
track := middleware.TrackMetrics(ms, mf, mt)
// wrap the handler
handler := middleware.ApplyDecoratorsToHandler(processMessage, track)
// start the consumers
log.Println("Starting queue consumers")
wg := &sync.WaitGroup{}
wg.Add(numFetchers)
for i := 0; i < numFetchers; i++ {
go func() {
// create the consumer and bind it to a queue and processor function
c := sqsconsumer.NewConsumer(s, handler)
// start running the consumer with a context that will be cancelled when a graceful shutdown is requested
c.Run(fetchCtx)
wg.Done()
}()
}
// wait for all the consumers to exit cleanly
wg.Wait()
log.Println("Shutdown complete")
}
// exposeMetrics adds expvar metrics updated every 5 seconds and runs the HTTP server to expose them.
func exposeMetrics() {
goroutines := expvar.NewInt("total_goroutines")
uptime := expvar.NewFloat("process_uptime_seconds")
start := time.Now()
go func() {
for range time.Tick(5 * time.Second) {
goroutines.Set(int64(runtime.NumGoroutine()))
uptime.Set(time.Since(start).Seconds())
}
}()
log.Println("Expvars at http://localhost:8123/debug/vars")
go http.ListenAndServe(":8123", nil)
}
func TestTrackMetricsMiddleware(t *testing.T) {
// given a TrackMetrics with known expvar metric names
successes := expvar.NewInt("success")
fails := expvar.NewInt("fail")
timing := expvar.NewFloat("timing")
m := TrackMetrics(successes, fails, timing)
// when tracking 9 successes, 6 failures with varied runtimes
for i := 0; i < 3; i++ {
m(testHandlerReturnAfterDelay(true, 10*time.Millisecond))(context.Background(), "")
m(testHandlerReturnAfterDelay(true, 20*time.Millisecond))(context.Background(), "")
m(testHandlerReturnAfterDelay(true, 50*time.Millisecond))(context.Background(), "")
m(testHandlerReturnAfterDelay(false, 100*time.Millisecond))(context.Background(), "")
m(testHandlerReturnAfterDelay(false, 110*time.Millisecond))(context.Background(), "")
}
// expvar metrics for success and fail counts should match
assert.Equal(t, "9", successes.String(), "Success count should match")
assert.Equal(t, "6", fails.String(), "Failure count should match")
// expvar metric for timing moving average
avg, _ := strconv.ParseFloat(timing.String(), 64)
assert.InDelta(t, 15, avg, 1.5, "Timing average should match (within 10%)")
}
func main() {
var inerInt int64 = 10
pubInt := expvar.NewInt("Int")
pubInt.Set(inerInt)
pubInt.Add(2)
var inerFloat float64 = 1.2
pubFloat := expvar.NewFloat("Float")
pubFloat.Set(inerFloat)
pubFloat.Add(0.1)
var inerString string = "hello gophers"
pubString := expvar.NewString("String")
pubString.Set(inerString)
pubMap := expvar.NewMap("Map").Init()
pubMap.Set("Int", pubInt)
pubMap.Set("Float", pubFloat)
pubMap.Set("String", pubString)
pubMap.Add("Int", 1)
pubMap.Add("NewInt", 123)
pubMap.AddFloat("Float", 0.5)
pubMap.AddFloat("NewFloat", 0.9)
pubMap.Do(kvfunc)
expvar.Do(kvfunc)
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, "hello gophers")
})
err := http.ListenAndServe(":8080", nil)
if err != nil {
panic(err)
}
}
// check for len(tx.Err) > 0
tx.SetStatus(transaction.StatusIngest)
fallthrough
case transaction.StatusIngest:
tx.Commit(*s.Items, s.FileStore, s.Cache)
}
duration := time.Now().Sub(start)
log.Printf("Finish transaction %s on %s (%s)", tx.ID, tx.ItemID, duration.String())
xTransactionTime.Add(duration.Seconds())
xTransactionCount.Add(1)
}
var (
xTransactionCount = expvar.NewInt("tx.count")
xTransactionTime = expvar.NewFloat("tx.seconds")
)
// TxCleaner will loop forever removing old transactions and old orphened
// uploaded files. That means any finished transactions which are older than a
// few days. Both the transaction and any uploaded files referenced by the
// transaction are deleted. This function will never return.
func (s *RESTServer) TxCleaner() {
for {
err := s.transactionCleaner()
if err == nil {
err = s.fileCleaner()
}
if err != nil {
log.Println("TxCleaner:", err)
}
// NewGauge returns a new Gauge backed by an expvar with the given name. It
// should be updated manually; for a callback-based approach, see
// PublishCallbackGauge. Fields are ignored.
func NewGauge(name string) metrics.Gauge {
return &gauge{expvar.NewFloat(name)}
}
BytesReceived: expvar.NewInt("sys.broker.load.bytes_received"),
},
SubscriptionsCount: expvar.NewInt("sys.broker.subscriptions.count"),
},
},
// for debug
NumGoroutine: expvar.NewInt("numgoroutine"),
NumCgoCall: expvar.NewInt("numcgocall"),
Uptime: expvar.NewInt("uptime"),
MemFree: expvar.NewInt("memfree"),
MemUsed: expvar.NewInt("memused"),
MemActualFree: expvar.NewInt("memactualfree"),
MemActualUsed: expvar.NewInt("memactualused"),
MemTotal: expvar.NewInt("memtotal"),
LoadOne: expvar.NewFloat("loadone"),
LoadFive: expvar.NewFloat("loadfive"),
LoadFifteen: expvar.NewFloat("loadfifteen"),
CpuUser: expvar.NewFloat("cpuuser"),
CpuNice: expvar.NewFloat("cpunice"),
CpuSys: expvar.NewFloat("cpusys"),
CpuIdle: expvar.NewFloat("cpuidle"),
CpuWait: expvar.NewFloat("cpuwait"),
CpuIrq: expvar.NewFloat("cpuirq"),
CpuSoftIrq: expvar.NewFloat("cpusoftirq"),
CpuStolen: expvar.NewFloat("cpustolen"),
CpuTotal: expvar.NewFloat("cputotal"),
MessageSentPerSec: myexpvar.NewDiffInt("msg_sent_per_sec"),
ConnectPerSec: myexpvar.NewDiffInt("connect_per_sec"),
GoroutinePerConn: expvar.NewFloat("goroutine_per_conn"),
// SetCheck takes an item id and schedules another fixity check at the
// given time in the future (or past).
SetCheck(id string, when time.Time) error
// LookupCheck takes an item id and returns the time of earliest pending
// fixity check for that item. If no fixity check is pending, returns
// the zero time.
LookupCheck(id string) (time.Time, error)
}
var (
xFixityRunning = expvar.NewInt("fixity.running")
xFixityItemsChecked = expvar.NewInt("fixity.check.count")
xFixityBytesChecked = expvar.NewInt("fixity.check.bytes")
xFixityDuration = expvar.NewFloat("fixity.check.seconds")
xFixityError = expvar.NewInt("fixity.check.error")
xFixityMismatch = expvar.NewInt("fixity.check.mismatch")
)
// StartFixity starts the background goroutines to check item fixity. It
// returns immediately and does not block.
func (s *RESTServer) StartFixity() {
xFixityRunning.Add(1)
go s.fixity()
// should scanfixity run periodically? or only at startup?
// this will keep running it in a loop with 24 hour rest in between.
go func() {
for {
// NewGauge returns a new Gauge backed by an expvar with the given name. It
// should be updated manually; for a callback-based approach, see
// PublishCallbackGauge. Fields are ignored.
func NewGauge(name string) metrics.Gauge {
return &gauge{
name: name,
v: expvar.NewFloat(name),
}
}