Add healthchecker to check broker connection

healthcheck_test.go

@@ -0,0 +1,101 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
+package asynq
+
+import (
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/hibiken/asynq/internal/rdb"
+	"github.com/hibiken/asynq/internal/testbroker"
+)
+
+func TestHealthChecker(t *testing.T) {
+	r := setup(t)
+	rdbClient := rdb.NewRDB(r)
+
+	var (
+		// mu guards called and e variables.
+		mu     sync.Mutex
+		called int
+		e      error
+	)
+	checkFn := func(err error) {
+		mu.Lock()
+		defer mu.Unlock()
+		called++
+		e = err
+	}
+
+	hc := newHealthChecker(healthcheckerParams{
+		logger:          testLogger,
+		broker:          rdbClient,
+		interval:        1 * time.Second,
+		healthcheckFunc: checkFn,
+	})
+
+	hc.start(&sync.WaitGroup{})
+
+	time.Sleep(2 * time.Second)
+
+	mu.Lock()
+	if called == 0 {
+		t.Errorf("Healthchecker did not call the provided HealthCheckFunc")
+	}
+	if e != nil {
+		t.Errorf("HealthCheckFunc was called with non-nil error: %v", e)
+	}
+	mu.Unlock()
+
+	hc.terminate()
+}
+
+func TestHealthCheckerWhenRedisDown(t *testing.T) {
+	// Make sure that healthchecker goroutine doesn't panic
+	// if it cannot connect to redis.
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("panic occurred: %v", r)
+		}
+	}()
+	r := rdb.NewRDB(setup(t))
+	testBroker := testbroker.NewTestBroker(r)
+	var (
+		// mu guards called and e variables.
+		mu     sync.Mutex
+		called int
+		e      error
+	)
+	checkFn := func(err error) {
+		mu.Lock()
+		defer mu.Unlock()
+		called++
+		e = err
+	}
+
+	hc := newHealthChecker(healthcheckerParams{
+		logger:          testLogger,
+		broker:          testBroker,
+		interval:        1 * time.Second,
+		healthcheckFunc: checkFn,
+	})
+
+	testBroker.Sleep()
+	hc.start(&sync.WaitGroup{})
+
+	time.Sleep(2 * time.Second)
+
+	mu.Lock()
+	if called == 0 {
+		t.Errorf("Healthchecker did not call the provided HealthCheckFunc")
+	}
+	if e == nil {
+		t.Errorf("HealthCheckFunc was called with nil; want non-nil error")
+	}
+	mu.Unlock()
+
+	hc.terminate()
+}