Added more unit tests for SessionPool (#1862)

Author: vkedia

google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolTest.java

@@ -32,6 +32,7 @@
 import com.google.cloud.GrpcTransportOptions.ExecutorFactory;
 import com.google.cloud.spanner.SessionPool.Clock;
 import com.google.cloud.spanner.SessionPool.PooledSession;
+import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.Uninterruptibles;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -114,6 +115,123 @@ public void poolClosure() throws Exception {
     pool.closeAsync().get();
   }
 
+  @Test
+  public void poolClosureFailsPendingReadWaiters() throws Exception {
+    final CountDownLatch insideCreation = new CountDownLatch(1);
+    final CountDownLatch releaseCreation = new CountDownLatch(1);
+    when(client.createSession(db))
+        .thenReturn(mock(Session.class))
+        .thenAnswer(
+            new Answer<Session>() {
+              @Override
+              public Session answer(InvocationOnMock invocation) throws Throwable {
+                insideCreation.countDown();
+                releaseCreation.await();
+                return mock(Session.class);
+              }
+            });
+    pool = createPool();
+    pool.getReadSession();
+    AtomicBoolean failed = new AtomicBoolean(false);
+    CountDownLatch latch = new CountDownLatch(1);
+    getSessionAsync(latch, failed);
+    insideCreation.await();
+    pool.closeAsync();
+    releaseCreation.countDown();
+    latch.await();
+    assertThat(failed.get()).isTrue();
+  }
+
+  @Test
+  public void poolClosureFailsPendingWriteWaiters() throws Exception {
+    final CountDownLatch insideCreation = new CountDownLatch(1);
+    final CountDownLatch releaseCreation = new CountDownLatch(1);
+    when(client.createSession(db))
+        .thenReturn(mock(Session.class))
+        .thenAnswer(
+            new Answer<Session>() {
+              @Override
+              public Session answer(InvocationOnMock invocation) throws Throwable {
+                insideCreation.countDown();
+                releaseCreation.await();
+                return mock(Session.class);
+              }
+            });
+    pool = createPool();
+    pool.getReadSession();
+    AtomicBoolean failed = new AtomicBoolean(false);
+    CountDownLatch latch = new CountDownLatch(1);
+    getReadWriteSessionAsync(latch, failed);
+    insideCreation.await();
+    pool.closeAsync();
+    releaseCreation.countDown();
+    latch.await();
+    assertThat(failed.get()).isTrue();
+  }
+
+  @Test
+  public void poolClosesEvenIfCreationFails() throws Exception {
+    final CountDownLatch insideCreation = new CountDownLatch(1);
+    final CountDownLatch releaseCreation = new CountDownLatch(1);
+    when(client.createSession(db))
+        .thenAnswer(
+            new Answer<Session>() {
+              @Override
+              public Session answer(InvocationOnMock invocation) throws Throwable {
+                insideCreation.countDown();
+                releaseCreation.await();
+                throw SpannerExceptionFactory.newSpannerException(new RuntimeException());
+              }
+            });
+    pool = createPool();
+    AtomicBoolean failed = new AtomicBoolean(false);
+    CountDownLatch latch = new CountDownLatch(1);
+    getSessionAsync(latch, failed);
+    insideCreation.await();
+    ListenableFuture<Void> f = pool.closeAsync();
+    releaseCreation.countDown();
+    f.get();
+    assertThat(f.isDone()).isTrue();
+  }
+
+  @Test
+  public void poolClosesEvenIfPreparationFails() throws Exception {
+    Session session = mock(Session.class);
+    when(client.createSession(db)).thenReturn(session);
+    final CountDownLatch insidePrepare = new CountDownLatch(1);
+    final CountDownLatch releasePrepare = new CountDownLatch(1);
+    doAnswer(
+            new Answer<Session>() {
+              @Override
+              public Session answer(InvocationOnMock invocation) throws Throwable {
+                insidePrepare.countDown();
+                releasePrepare.await();
+                throw SpannerExceptionFactory.newSpannerException(new RuntimeException());
+              }
+            })
+        .when(session)
+        .prepareReadWriteTransaction();
+    pool = createPool();
+    AtomicBoolean failed = new AtomicBoolean(false);
+    CountDownLatch latch = new CountDownLatch(1);
+    getReadWriteSessionAsync(latch, failed);
+    insidePrepare.await();
+    ListenableFuture<Void> f = pool.closeAsync();
+    releasePrepare.countDown();
+    f.get();
+    assertThat(f.isDone()).isTrue();
+  }
+
+  @Test
+  public void poolClosureFailsNewRequests() throws Exception {
+    when(client.createSession(db)).thenReturn(mock(Session.class));
+    pool = createPool();
+    pool.getReadSession();
+    pool.closeAsync();
+    expectedException.expect(IllegalStateException.class);
+    pool.getReadSession();
+  }
+
   @Test
   public void atMostMaxSessionsCreated() {
     AtomicBoolean failed = new AtomicBoolean(false);
@@ -243,6 +361,35 @@ public Void answer(InvocationOnMock arg0) throws Throwable {
     writeSession.close();
   }
 
+  @Test
+  public void getReadSessionFallsBackToWritePreparedSession() throws Exception {
+    Session mockSession1 = mock(Session.class);
+    final CountDownLatch prepareLatch = new CountDownLatch(2);
+    doAnswer(
+            new Answer<Void>() {
+              @Override
+              public Void answer(InvocationOnMock arg0) throws Throwable {
+                prepareLatch.countDown();
+                return null;
+              }
+            })
+        .when(mockSession1)
+        .prepareReadWriteTransaction();
+    when(client.createSession(db)).thenReturn(mockSession1);
+    options =
+        SessionPoolOptions.newBuilder()
+            .setMinSessions(minSessions)
+            .setMaxSessions(1)
+            .setWriteSessionsFraction(1.0f)
+            .build();
+    pool = createPool();
+    pool.getReadWriteSession().close();
+    prepareLatch.await();
+    // This session should also be write prepared.
+    PooledSession readSession = (PooledSession) pool.getReadSession();
+    verify(readSession.delegate, times(2)).prepareReadWriteTransaction();
+  }
+
   @Test
   public void failOnPoolExhaustion() {
     options =
@@ -262,6 +409,18 @@ public void failOnPoolExhaustion() {
     session1.close();
   }
 
+  @Test
+  public void poolWorksWhenSessionNotFound() {
+    Session mockSession1 = mock(Session.class);
+    Session mockSession2 = mock(Session.class);
+    doThrow(SpannerExceptionFactory.newSpannerException(ErrorCode.NOT_FOUND, "Session not found"))
+        .when(mockSession1)
+        .prepareReadWriteTransaction();
+    when(client.createSession(db)).thenReturn(mockSession1).thenReturn(mockSession2);
+    pool = createPool();
+    assertThat(((PooledSession) pool.getReadWriteSession()).delegate).isEqualTo(mockSession2);
+  }
+
   @Test
   public void idleSessionCleanup() throws Exception {
     options =
@@ -366,6 +525,9 @@ public void run() {
                 try (Session session = pool.getReadSession()) {
                   failed.compareAndSet(false, session == null);
                   Uninterruptibles.sleepUninterruptibly(10, TimeUnit.MILLISECONDS);
+                } catch (SpannerException e) {
+                  failed.compareAndSet(false, true);
+                } finally {
                   latch.countDown();
                 }
               }
@@ -381,6 +543,9 @@ public void run() {
                 try (Session session = pool.getReadWriteSession()) {
                   failed.compareAndSet(false, session == null);
                   Uninterruptibles.sleepUninterruptibly(2, TimeUnit.MILLISECONDS);
+                } catch (SpannerException e) {
+                  failed.compareAndSet(false, true);
+                } finally {
                   latch.countDown();
                 }
               }