clientv3/concurrency: Expose examples close to the source-code.

clientv3/concurrency/example_election_test.go

@@ -0,0 +1 @@
+../../tests/integration/clientv3/concurrency/example_election_test.go

clientv3/concurrency/example_mutex_test.go

@@ -0,0 +1 @@
+../../tests/integration/clientv3/concurrency/example_mutex_test.go

clientv3/concurrency/example_stm_test.go

@@ -0,0 +1 @@
+../../tests/integration/clientv3/concurrency/example_stm_test.go

clientv3/concurrency/main_test.go

@@ -0,0 +1,35 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package concurrency_test
+
+import (
+	"testing"
+
+	"go.etcd.io/etcd/v3/pkg/testutil"
+)
+
+func exampleEndpoints() []string { return nil }
+
+func forUnitTestsRunInMockedContext(mocking func(), example func()) {
+	mocking()
+	// TODO: Call 'example' when mocking() provides realistic mocking of transport.
+
+	// The real testing logic of examples gets executed
+	// as part of ./tests/integration/clientv3/integration/...
+}
+
+func TestMain(m *testing.M) {
+	testutil.MustTestMainWithLeakDetection(m)
+}

tests/integration/clientv3/concurrency/election_test.go

@@ -28,7 +28,7 @@ import (
 func TestResumeElection(t *testing.T) {
 	const prefix = "/resume-election/"
 
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
+	cli, err := clientv3.New(clientv3.Config{Endpoints: exampleEndpoints()})
 	if err != nil {
 		log.Fatal(err)
 	}

tests/integration/clientv3/concurrency/example_election_test.go

@@ -25,64 +25,73 @@ import (
 	"go.etcd.io/etcd/v3/clientv3/concurrency"
 )
 
+func mockElection_Campaign() {
+	fmt.Println("completed first election with e2")
+	fmt.Println("completed second election with e1")
+}
+
 func ExampleElection_Campaign() {
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer cli.Close()
+	forUnitTestsRunInMockedContext(
+		mockElection_Campaign,
+		func() {
+			cli, err := clientv3.New(clientv3.Config{Endpoints: exampleEndpoints()})
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer cli.Close()
 
-	// create two separate sessions for election competition
-	s1, err := concurrency.NewSession(cli)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer s1.Close()
-	e1 := concurrency.NewElection(s1, "/my-election/")
+			// create two separate sessions for election competition
+			s1, err := concurrency.NewSession(cli)
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer s1.Close()
+			e1 := concurrency.NewElection(s1, "/my-election/")
 
-	s2, err := concurrency.NewSession(cli)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer s2.Close()
-	e2 := concurrency.NewElection(s2, "/my-election/")
+			s2, err := concurrency.NewSession(cli)
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer s2.Close()
+			e2 := concurrency.NewElection(s2, "/my-election/")
 
-	// create competing candidates, with e1 initially losing to e2
-	var wg sync.WaitGroup
-	wg.Add(2)
-	electc := make(chan *concurrency.Election, 2)
-	go func() {
-		defer wg.Done()
-		// delay candidacy so e2 wins first
-		time.Sleep(3 * time.Second)
-		if err := e1.Campaign(context.Background(), "e1"); err != nil {
-			log.Fatal(err)
-		}
-		electc <- e1
-	}()
-	go func() {
-		defer wg.Done()
-		if err := e2.Campaign(context.Background(), "e2"); err != nil {
-			log.Fatal(err)
-		}
-		electc <- e2
-	}()
+			// create competing candidates, with e1 initially losing to e2
+			var wg sync.WaitGroup
+			wg.Add(2)
+			electc := make(chan *concurrency.Election, 2)
+			go func() {
+				defer wg.Done()
+				// delay candidacy so e2 wins first
+				time.Sleep(3 * time.Second)
+				if err := e1.Campaign(context.Background(), "e1"); err != nil {
+					log.Fatal(err)
+				}
+				electc <- e1
+			}()
+			go func() {
+				defer wg.Done()
+				if err := e2.Campaign(context.Background(), "e2"); err != nil {
+					log.Fatal(err)
+				}
+				electc <- e2
+			}()
 
-	cctx, cancel := context.WithCancel(context.TODO())
-	defer cancel()
+			cctx, cancel := context.WithCancel(context.TODO())
+			defer cancel()
 
-	e := <-electc
-	fmt.Println("completed first election with", string((<-e.Observe(cctx)).Kvs[0].Value))
+			e := <-electc
+			fmt.Println("completed first election with", string((<-e.Observe(cctx)).Kvs[0].Value))
 
-	// resign so next candidate can be elected
-	if err := e.Resign(context.TODO()); err != nil {
-		log.Fatal(err)
-	}
+			// resign so next candidate can be elected
+			if err := e.Resign(context.TODO()); err != nil {
+				log.Fatal(err)
+			}
 
-	e = <-electc
-	fmt.Println("completed second election with", string((<-e.Observe(cctx)).Kvs[0].Value))
+			e = <-electc
+			fmt.Println("completed second election with", string((<-e.Observe(cctx)).Kvs[0].Value))
 
-	wg.Wait()
+			wg.Wait()
+		})
 
 	// Output:
 	// completed first election with e2

tests/integration/clientv3/concurrency/example_mutex_test.go

@@ -23,49 +23,60 @@ import (
 	"go.etcd.io/etcd/v3/clientv3/concurrency"
 )
 
-func ExampleMutex_TryLock() {
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer cli.Close()
-
-	// create two separate sessions for lock competition
-	s1, err := concurrency.NewSession(cli)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer s1.Close()
-	m1 := concurrency.NewMutex(s1, "/my-lock")
-
-	s2, err := concurrency.NewSession(cli)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer s2.Close()
-	m2 := concurrency.NewMutex(s2, "/my-lock")
-
-	// acquire lock for s1
-	if err = m1.Lock(context.TODO()); err != nil {
-		log.Fatal(err)
-	}
+func mockMutex_TryLock() {
 	fmt.Println("acquired lock for s1")
-
-	if err = m2.TryLock(context.TODO()); err == nil {
-		log.Fatal("should not acquire lock")
-	}
-	if err == concurrency.ErrLocked {
-		fmt.Println("cannot acquire lock for s2, as already locked in another session")
-	}
-
-	if err = m1.Unlock(context.TODO()); err != nil {
-		log.Fatal(err)
-	}
+	fmt.Println("cannot acquire lock for s2, as already locked in another session")
 	fmt.Println("released lock for s1")
-	if err = m2.TryLock(context.TODO()); err != nil {
-		log.Fatal(err)
-	}
 	fmt.Println("acquired lock for s2")
+}
+
+func ExampleMutex_TryLock() {
+	forUnitTestsRunInMockedContext(
+		mockMutex_TryLock,
+		func() {
+			cli, err := clientv3.New(clientv3.Config{Endpoints: exampleEndpoints()})
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer cli.Close()
+
+			// create two separate sessions for lock competition
+			s1, err := concurrency.NewSession(cli)
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer s1.Close()
+			m1 := concurrency.NewMutex(s1, "/my-lock")
+
+			s2, err := concurrency.NewSession(cli)
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer s2.Close()
+			m2 := concurrency.NewMutex(s2, "/my-lock")
+
+			// acquire lock for s1
+			if err = m1.Lock(context.TODO()); err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("acquired lock for s1")
+
+			if err = m2.TryLock(context.TODO()); err == nil {
+				log.Fatal("should not acquire lock")
+			}
+			if err == concurrency.ErrLocked {
+				fmt.Println("cannot acquire lock for s2, as already locked in another session")
+			}
+
+			if err = m1.Unlock(context.TODO()); err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("released lock for s1")
+			if err = m2.TryLock(context.TODO()); err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("acquired lock for s2")
+		})
 
 	// Output:
 	// acquired lock for s1
@@ -74,50 +85,60 @@ func ExampleMutex_TryLock() {
 	// acquired lock for s2
 }
 
-func ExampleMutex_Lock() {
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer cli.Close()
-
-	// create two separate sessions for lock competition
-	s1, err := concurrency.NewSession(cli)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer s1.Close()
-	m1 := concurrency.NewMutex(s1, "/my-lock/")
-
-	s2, err := concurrency.NewSession(cli)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer s2.Close()
-	m2 := concurrency.NewMutex(s2, "/my-lock/")
-
-	// acquire lock for s1
-	if err := m1.Lock(context.TODO()); err != nil {
-		log.Fatal(err)
-	}
+func mockMutex_Lock() {
 	fmt.Println("acquired lock for s1")
-
-	m2Locked := make(chan struct{})
-	go func() {
-		defer close(m2Locked)
-		// wait until s1 is locks /my-lock/
-		if err := m2.Lock(context.TODO()); err != nil {
-			log.Fatal(err)
-		}
-	}()
-
-	if err := m1.Unlock(context.TODO()); err != nil {
-		log.Fatal(err)
-	}
 	fmt.Println("released lock for s1")
-
-	<-m2Locked
 	fmt.Println("acquired lock for s2")
+}
+
+func ExampleMutex_Lock() {
+	forUnitTestsRunInMockedContext(
+		mockMutex_Lock,
+		func() {
+			cli, err := clientv3.New(clientv3.Config{Endpoints: exampleEndpoints()})
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer cli.Close()
+
+			// create two separate sessions for lock competition
+			s1, err := concurrency.NewSession(cli)
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer s1.Close()
+			m1 := concurrency.NewMutex(s1, "/my-lock/")
+
+			s2, err := concurrency.NewSession(cli)
+			if err != nil {
+				log.Fatal(err)
+			}
+			defer s2.Close()
+			m2 := concurrency.NewMutex(s2, "/my-lock/")
+
+			// acquire lock for s1
+			if err := m1.Lock(context.TODO()); err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("acquired lock for s1")
+
+			m2Locked := make(chan struct{})
+			go func() {
+				defer close(m2Locked)
+				// wait until s1 is locks /my-lock/
+				if err := m2.Lock(context.TODO()); err != nil {
+					log.Fatal(err)
+				}
+			}()
+
+			if err := m1.Unlock(context.TODO()); err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("released lock for s1")
+
+			<-m2Locked
+			fmt.Println("acquired lock for s2")
+		})
 
 	// Output:
 	// acquired lock for s1

tests/integration/clientv3/concurrency/example_stm_test.go

@@ -25,73 +25,81 @@ import (
 	"go.etcd.io/etcd/v3/clientv3/concurrency"
 )
 
+func mockSTM_apply() {
+	fmt.Println("account sum is 500")
+}
+
 // ExampleSTM_apply shows how to use STM with a transactional
 // transfer between balances.
 func ExampleSTM_apply() {
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer cli.Close()
-
-	// set up "accounts"
-	totalAccounts := 5
-	for i := 0; i < totalAccounts; i++ {
-		k := fmt.Sprintf("accts/%d", i)
-		if _, err = cli.Put(context.TODO(), k, "100"); err != nil {
-			log.Fatal(err)
-		}
-	}
-
-	exchange := func(stm concurrency.STM) error {
-		from, to := rand.Intn(totalAccounts), rand.Intn(totalAccounts)
-		if from == to {
-			// nothing to do
-			return nil
-		}
-		// read values
-		fromK, toK := fmt.Sprintf("accts/%d", from), fmt.Sprintf("accts/%d", to)
-		fromV, toV := stm.Get(fromK), stm.Get(toK)
-		fromInt, toInt := 0, 0
-		fmt.Sscanf(fromV, "%d", &fromInt)
-		fmt.Sscanf(toV, "%d", &toInt)
-
-		// transfer amount
-		xfer := fromInt / 2
-		fromInt, toInt = fromInt-xfer, toInt+xfer
-
-		// write back
-		stm.Put(fromK, fmt.Sprintf("%d", fromInt))
-		stm.Put(toK, fmt.Sprintf("%d", toInt))
-		return nil
-	}
-
-	// concurrently exchange values between accounts
-	var wg sync.WaitGroup
-	wg.Add(10)
-	for i := 0; i < 10; i++ {
-		go func() {
-			defer wg.Done()
-			if _, serr := concurrency.NewSTM(cli, exchange); serr != nil {
-				log.Fatal(serr)
+	forUnitTestsRunInMockedContext(
+		mockSTM_apply,
+		func() {
+			cli, err := clientv3.New(clientv3.Config{Endpoints: exampleEndpoints()})
+			if err != nil {
+				log.Fatal(err)
 			}
-		}()
-	}
-	wg.Wait()
+			defer cli.Close()
 
-	// confirm account sum matches sum from beginning.
-	sum := 0
-	accts, err := cli.Get(context.TODO(), "accts/", clientv3.WithPrefix())
-	if err != nil {
-		log.Fatal(err)
-	}
-	for _, kv := range accts.Kvs {
-		v := 0
-		fmt.Sscanf(string(kv.Value), "%d", &v)
-		sum += v
-	}
+			// set up "accounts"
+			totalAccounts := 5
+			for i := 0; i < totalAccounts; i++ {
+				k := fmt.Sprintf("accts/%d", i)
+				if _, err = cli.Put(context.TODO(), k, "100"); err != nil {
+					log.Fatal(err)
+				}
+			}
 
-	fmt.Println("account sum is", sum)
+			exchange := func(stm concurrency.STM) error {
+				from, to := rand.Intn(totalAccounts), rand.Intn(totalAccounts)
+				if from == to {
+					// nothing to do
+					return nil
+				}
+				// read values
+				fromK, toK := fmt.Sprintf("accts/%d", from), fmt.Sprintf("accts/%d", to)
+				fromV, toV := stm.Get(fromK), stm.Get(toK)
+				fromInt, toInt := 0, 0
+				fmt.Sscanf(fromV, "%d", &fromInt)
+				fmt.Sscanf(toV, "%d", &toInt)
+
+				// transfer amount
+				xfer := fromInt / 2
+				fromInt, toInt = fromInt-xfer, toInt+xfer
+
+				// write back
+				stm.Put(fromK, fmt.Sprintf("%d", fromInt))
+				stm.Put(toK, fmt.Sprintf("%d", toInt))
+				return nil
+			}
+
+			// concurrently exchange values between accounts
+			var wg sync.WaitGroup
+			wg.Add(10)
+			for i := 0; i < 10; i++ {
+				go func() {
+					defer wg.Done()
+					if _, serr := concurrency.NewSTM(cli, exchange); serr != nil {
+						log.Fatal(serr)
+					}
+				}()
+			}
+			wg.Wait()
+
+			// confirm account sum matches sum from beginning.
+			sum := 0
+			accts, err := cli.Get(context.TODO(), "accts/", clientv3.WithPrefix())
+			if err != nil {
+				log.Fatal(err)
+			}
+			for _, kv := range accts.Kvs {
+				v := 0
+				fmt.Sscanf(string(kv.Value), "%d", &v)
+				sum += v
+			}
+
+			fmt.Println("account sum is", sum)
+		})
 	// Output:
 	// account sum is 500
 }

tests/integration/clientv3/concurrency/main_test.go

@@ -15,30 +15,28 @@
 package concurrency_test
 
 import (
-	"fmt"
 	"os"
 	"testing"
-	"time"
 
 	"go.etcd.io/etcd/tests/v3/integration"
 	"go.etcd.io/etcd/v3/pkg/testutil"
 )
 
-var endpoints []string
+var lazyCluster = integration.NewLazyCluster()
 
-// TestMain sets up an etcd cluster for running the examples.
+func exampleEndpoints() []string { return lazyCluster.EndpointsV3() }
+
+func forUnitTestsRunInMockedContext(mocking func(), example func()) {
+	// For integration tests runs in the provided environment
+	example()
+}
+
+// TestMain sets up an etcd cluster if running the examples.
 func TestMain(m *testing.M) {
-	cfg := integration.ClusterConfig{Size: 1}
-	clus := integration.NewClusterV3(nil, &cfg)
-	endpoints = []string{clus.Client(0).Endpoints()[0]}
 	v := m.Run()
-	clus.Terminate(nil)
-	if err := testutil.CheckAfterTest(time.Second); err != nil {
-		fmt.Fprintf(os.Stderr, "%v", err)
-		os.Exit(1)
-	}
-	if v == 0 && testutil.CheckLeakedGoroutine() {
-		os.Exit(1)
+	lazyCluster.Terminate()
+	if v == 0 {
+		testutil.MustCheckLeakedGoroutine()
 	}
 	os.Exit(v)
 }

tests/integration/clientv3/concurrency/mutex_test.go

@@ -23,7 +23,7 @@ import (
 )
 
 func TestMutexLockSessionExpired(t *testing.T) {
-	cli, err := clientv3.New(clientv3.Config{Endpoints: endpoints})
+	cli, err := clientv3.New(clientv3.Config{Endpoints: exampleEndpoints()})
 	if err != nil {
 		t.Fatal(err)
 	}