Hystrix Metrics Collector for Expvar backend

plugins/expvar_collector.go

@@ -0,0 +1,158 @@
+package plugins
+
+import (
+	"expvar"
+	"github.com/afex/hystrix-go/hystrix/metric_collector"
+	"strings"
+	"time"
+)
+
+var (
+	// We have a collector for every circuit breaker
+	ExpVarCollectors map[string]*ExpvarCollector
+)
+
+func init() {
+	ExpVarCollectors = make(map[string]*ExpvarCollector)
+}
+
+// ExpvarCollector fulfills the metricCollector interface allowing users to ship circuit
+// stats to a Expvar backend. To use users must call InitializeExpvarCollector before
+// circuits are started. Then register NewExpvarCollector with metricCollector.Registry.Register(NewExpvarCollector).
+type ExpvarCollector struct {
+	circuitOpen       *expvar.Int
+	attempts          *expvar.Int
+	errors            *expvar.Int
+	successes         *expvar.Int
+	failures          *expvar.Int
+	rejects           *expvar.Int
+	shortCircuits     *expvar.Int
+	timeouts          *expvar.Int
+	fallbackSuccesses *expvar.Int
+	fallbackFailures  *expvar.Int
+	totalDuration     *expvar.Float
+	runDuration       *expvar.Float
+}
+
+type ExpvarCollectorClient struct {
+	config *ExpvarCollectorConfig
+}
+
+// ExpvarCollectorConfig provides configuration that the Expvar client will need.
+type ExpvarCollectorConfig struct {
+	// Prefix is the prefix that will be prepended to all metrics sent from this collector.
+	Prefix string
+}
+
+// InitializeExpvarCollector should be called before any metrics are recorded.
+func InitializeExpvarCollector(config *ExpvarCollectorConfig) (*ExpvarCollectorClient, error) {
+	return &ExpvarCollectorClient{config: config}, nil
+}
+
+// NewExpvarCollector creates a collector for a specific circuit. The
+// prefix given to this circuit will be {config.Prefix}.{circuit_name}.{metric}.
+// Circuits with "/" in their names will have them replaced with "-".
+func (s *ExpvarCollectorClient) NewExpvarCollector(name string) metricCollector.MetricCollector {
+	name = strings.Replace(name, "/", "-", -1)
+	name = strings.Replace(name, ":", "-", -1)
+	name = strings.Replace(name, ".", "-", -1)
+
+	if s.config.Prefix != "" {
+		name = s.config.Prefix + "." + name
+	}
+
+	collector, ok := ExpVarCollectors[name]
+	if !ok {
+		collector = &ExpvarCollector{
+			circuitOpen:       expvar.NewInt(name + ".circuitOpen"),
+			attempts:          expvar.NewInt(name + ".attempts"),
+			errors:            expvar.NewInt(name + ".errors"),
+			successes:         expvar.NewInt(name + ".successes"),
+			failures:          expvar.NewInt(name + ".failures"),
+			rejects:           expvar.NewInt(name + ".rejects"),
+			shortCircuits:     expvar.NewInt(name + ".shortCircuits"),
+			timeouts:          expvar.NewInt(name + ".timeouts"),
+			fallbackSuccesses: expvar.NewInt(name + ".fallbackSuccesses"),
+			fallbackFailures:  expvar.NewInt(name + ".fallbackFailures"),
+			totalDuration:     expvar.NewFloat(name + ".totalDuration"),
+			runDuration:       expvar.NewFloat(name + ".runDuration"),
+		}
+
+		ExpVarCollectors[name] = collector
+	}
+
+	return collector
+}
+
+// IncrementAttempts increments the number of calls to this circuit.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementAttempts() {
+	g.attempts.Add(1)
+}
+
+// IncrementErrors increments the number of unsuccessful attempts.
+// Attempts minus Errors will equal successes within a time range.
+// Errors are any result from an attempt that is not a success.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementErrors() {
+	g.errors.Add(1)
+}
+
+// IncrementSuccesses increments the number of requests that succeed.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementSuccesses() {
+	g.circuitOpen.Set(0)
+	g.successes.Add(1)
+}
+
+// IncrementFailures increments the number of requests that fail.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementFailures() {
+	g.failures.Add(1)
+}
+
+// IncrementRejects increments the number of requests that are rejected.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementRejects() {
+	g.rejects.Add(1)
+}
+
+// IncrementShortCircuits increments the number of requests that short circuited due to the circuit being open.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementShortCircuits() {
+	g.circuitOpen.Set(1)
+	g.shortCircuits.Add(1)
+}
+
+// IncrementTimeouts increments the number of timeouts that occurred in the circuit breaker.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementTimeouts() {
+	g.timeouts.Add(1)
+}
+
+// IncrementFallbackSuccesses increments the number of successes that occurred during the execution of the fallback function.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementFallbackSuccesses() {
+	g.fallbackSuccesses.Add(1)
+}
+
+// IncrementFallbackFailures increments the number of failures that occurred during the execution of the fallback function.
+// This registers as a counter in the Expvar collector.
+func (g *ExpvarCollector) IncrementFallbackFailures() {
+	g.fallbackFailures.Add(1)
+}
+
+// UpdateTotalDuration updates the internal counter of how long we've run for.
+// This registers as a timer in the Expvar collector.
+func (g *ExpvarCollector) UpdateTotalDuration(timeSinceStart time.Duration) {
+	g.totalDuration.Add(timeSinceStart.Seconds())
+}
+
+// UpdateRunDuration updates the internal counter of how long the last run took.
+// This registers as a timer in the Expvar collector.
+func (g *ExpvarCollector) UpdateRunDuration(runDuration time.Duration) {
+	g.runDuration.Set(runDuration.Seconds())
+}
+
+// Reset is a noop operation in this collector.
+func (g *ExpvarCollector) Reset() {}