Add a concurrent read/write test to plugin.EntryMap

Signed-off-by: Enis Inan <[email protected]>

plugin/entryMap_test.go

@@ -1,7 +1,10 @@
 package plugin
 
 import (
+	"strconv"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/suite"
 )
@@ -67,6 +70,72 @@ func (suite *EntryMapTestSuite) TestRange() {
 	suite.True(count <= 1)
 }
 
+func (suite *EntryMapTestSuite) TestConcurrentReadWrite() {
+	m := newEntryMap()
+
+	var wg sync.WaitGroup
+	var startCh = make(chan struct{})
+	var doneCh = make(chan struct{})
+
+	// Load, Delete, and Range all acquire locks to avoid a concurrent
+	// read/write panic. Thus, this test launches goroutines that invoke
+	// each method concurrently. Idea is that if any one of those methods
+	// fail to acquire a lock (including the right lock, like a Write lock
+	// for Delete), then this test will panic. NumGoroutinesPerMethod is
+	// arbitrary, idea is it should be high enough that we can detect a panic
+	// but low enough that the test won't take too long.
+	//
+	// The test passes if all the goroutines successfully return.
+	//
+	// NOTE: Testing Len() is a bit tricky because a concurrent len(mp) and
+	// delete(mp) does not cause a read/write panic. Since its implementation is
+	// simple enough, we omit Len() to avoid further complicating the tests.
+	NumGoroutinesPerMethod := 40
+	for i := 0; i < NumGoroutinesPerMethod; i++ {
+		key := strconv.Itoa(i)
+		m.mp[key] = nil
+
+		// Load
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			<-startCh
+			m.Load(key)
+		}(i)
+
+		// Delete
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			<-startCh
+			m.Delete(key)
+		}(i)
+
+		// Range
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			<-startCh
+			m.Range(func(_ string, _ Entry) bool {
+				return false
+			})
+		}(i)
+	}
+	time.AfterFunc(5*time.Second, func() {
+		select {
+		case <-doneCh:
+			// Pass-thru
+		default:
+			panic("goroutines did not successfully return after 5 seconds. Did you forget to release a lock?")
+		}
+	})
+
+	// Start the goroutines and wait for them to finish.
+	close(startCh)
+	wg.Wait()
+	close(doneCh)
+}
+
 func TestEntryMap(t *testing.T) {
 	suite.Run(t, new(EntryMapTestSuite))
 }