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Added another lock to protect broker stats

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Added another lock to the metrics struct to synchronize accesses to the
broker stats. There's a possible race condition if stats are updated at
the same time they are being logged.
This commit is contained in:
Cecylia Bocovich 2019-12-02 13:22:05 -05:00
parent 42e16021c4
commit 06298eec73
2 changed files with 14 additions and 1 deletions
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10
broker/broker.go
View file

@ -38,7 +38,7 @@ type BrokerContext struct {
// Map keeping track of snowflakeIDs required to match SDP answers from
// the second http POST.
idToSnowflake map[string]*Snowflake
// Synchronization for the
// Synchronization for the snowflake map and heap
snowflakeLock sync.Mutex
proxyPolls chan *ProxyPoll
metrics *Metrics
@ -181,14 +181,18 @@ func proxyPolls(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
if err != nil {
log.Println("Error processing proxy IP: ", err.Error())
} else {
ctx.metrics.lock.Lock()
ctx.metrics.UpdateCountryStats(remoteIP, proxyType)
ctx.metrics.lock.Unlock()
}
// Wait for a client to avail an offer to the snowflake, or timeout if nil.
offer := ctx.RequestOffer(sid, proxyType)
var b []byte
if nil == offer {
ctx.metrics.lock.Lock()
ctx.metrics.proxyIdleCount++
ctx.metrics.lock.Unlock()
b, err = messages.EncodePollResponse("", false)
if err != nil {
@ -227,7 +231,9 @@ func clientOffers(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
numSnowflakes := ctx.snowflakes.Len()
ctx.snowflakeLock.Unlock()
if numSnowflakes <= 0 {
ctx.metrics.lock.Lock()
ctx.metrics.clientDeniedCount++
ctx.metrics.lock.Unlock()
w.WriteHeader(http.StatusServiceUnavailable)
return
}
@ -241,7 +247,9 @@ func clientOffers(ctx *BrokerContext, w http.ResponseWriter, r *http.Request) {
// Wait for the answer to be returned on the channel or timeout.
select {
case answer := <-snowflake.answerChannel:
ctx.metrics.lock.Lock()
ctx.metrics.clientProxyMatchCount++
ctx.metrics.lock.Unlock()
if _, err := w.Write(answer); err != nil {
log.Printf("unable to write answer with error: %v", err)
}

5
broker/metrics.go
View file

@ -39,6 +39,9 @@ type Metrics struct {
proxyIdleCount uint
clientDeniedCount uint
clientProxyMatchCount uint
//synchronization for access to snowflake metrics
lock sync.Mutex
}
func (s CountryStats) Display() string {
@ -161,6 +164,7 @@ func (m *Metrics) logMetrics() {
}
func (m *Metrics) printMetrics() {
m.lock.Lock()
m.logger.Println("snowflake-stats-end", time.Now().UTC().Format("2006-01-02 15:04:05"), fmt.Sprintf("(%d s)", int(metricsResolution.Seconds())))
m.logger.Println("snowflake-ips", m.countryStats.Display())
m.logger.Println("snowflake-ips-total", len(m.countryStats.standalone)+
@ -171,6 +175,7 @@ func (m *Metrics) printMetrics() {
m.logger.Println("snowflake-idle-count", binCount(m.proxyIdleCount))
m.logger.Println("client-denied-count", binCount(m.clientDeniedCount))
m.logger.Println("client-snowflake-match-count", binCount(m.clientProxyMatchCount))
m.lock.Unlock()
}
// Restores all metrics to original values