core: Transition to CONNECTING immediately when exiting idle

The name resolver takes some time before it returns addresses. While waiting the channel will be IDLE instead of the proper CONNECTING. This generally doesn't matter since RPCs behave similarly for IDLE and CONNECTING, but is confusing for users when watching channel.getState() closely.

Fixes #10517.

core/src/main/java/io/grpc/internal/ManagedChannelImpl.java

@@ -20,6 +20,7 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 import static io.grpc.ClientStreamTracer.NAME_RESOLUTION_DELAYED;
+import static io.grpc.ConnectivityState.CONNECTING;
 import static io.grpc.ConnectivityState.IDLE;
 import static io.grpc.ConnectivityState.SHUTDOWN;
 import static io.grpc.ConnectivityState.TRANSIENT_FAILURE;
@@ -423,6 +424,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
     // may throw. We don't want to confuse our state, even if we will enter panic mode.
     this.lbHelper = lbHelper;
 
+    channelStateManager.gotoState(CONNECTING);
     NameResolverListener listener = new NameResolverListener(lbHelper, nameResolver);
     nameResolver.start(listener);
     nameResolverStarted = true;

core/src/test/java/io/grpc/internal/ManagedChannelImplTest.java

@@ -2338,7 +2338,7 @@ public class ManagedChannelImplTest {
     channelBuilder.nameResolverFactory(
         new FakeNameResolverFactory.Builder(expectedUri).setResolvedAtStart(false).build());
     createChannel();
-    assertEquals(IDLE, channel.getState(false));
+    assertEquals(CONNECTING, channel.getState(false));
 
     updateBalancingStateSafely(helper, TRANSIENT_FAILURE, mockPicker);
     assertEquals(TRANSIENT_FAILURE, channel.getState(false));
@@ -2395,21 +2395,21 @@ public class ManagedChannelImplTest {
     channelBuilder.nameResolverFactory(
         new FakeNameResolverFactory.Builder(expectedUri).setResolvedAtStart(false).build());
     createChannel();
-    assertEquals(IDLE, channel.getState(false));
+    assertEquals(CONNECTING, channel.getState(false));
 
-    channel.notifyWhenStateChanged(IDLE, onStateChanged);
+    channel.notifyWhenStateChanged(CONNECTING, onStateChanged);
     executor.runDueTasks();
     assertFalse(stateChanged.get());
 
-    // state change from IDLE to CONNECTING
-    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
+    // state change from CONNECTING to IDLE
+    updateBalancingStateSafely(helper, IDLE, mockPicker);
     // onStateChanged callback should run
     executor.runDueTasks();
     assertTrue(stateChanged.get());
 
-    // clear and test form CONNECTING
+    // clear and test form IDLE
     stateChanged.set(false);
-    channel.notifyWhenStateChanged(IDLE, onStateChanged);
+    channel.notifyWhenStateChanged(CONNECTING, onStateChanged);
     // onStateChanged callback should run immediately
     executor.runDueTasks();
     assertTrue(stateChanged.get());
@@ -2428,8 +2428,8 @@ public class ManagedChannelImplTest {
     channelBuilder.nameResolverFactory(
         new FakeNameResolverFactory.Builder(expectedUri).setResolvedAtStart(false).build());
     createChannel();
-    assertEquals(IDLE, channel.getState(false));
-    channel.notifyWhenStateChanged(IDLE, onStateChanged);
+    assertEquals(CONNECTING, channel.getState(false));
+    channel.notifyWhenStateChanged(CONNECTING, onStateChanged);
     executor.runDueTasks();
     assertFalse(stateChanged.get());
 
@@ -2452,9 +2452,6 @@ public class ManagedChannelImplTest {
     long idleTimeoutMillis = 2000L;
     channelBuilder.idleTimeout(idleTimeoutMillis, TimeUnit.MILLISECONDS);
     createChannel();
-    assertEquals(IDLE, channel.getState(false));
-
-    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertEquals(CONNECTING, channel.getState(false));
 
     timer.forwardNanos(TimeUnit.MILLISECONDS.toNanos(idleTimeoutMillis));
@@ -2677,11 +2674,11 @@ public class ManagedChannelImplTest {
 
     // Updating on the old helper (whose balancer has been shutdown) does not change the channel
     // state.
-    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
-    assertEquals(IDLE, channel.getState(false));
-
-    updateBalancingStateSafely(helper2, CONNECTING, mockPicker);
+    updateBalancingStateSafely(helper, IDLE, mockPicker);
     assertEquals(CONNECTING, channel.getState(false));
+
+    updateBalancingStateSafely(helper2, IDLE, mockPicker);
+    assertEquals(IDLE, channel.getState(false));
   }
 
   @Test
@@ -2695,7 +2692,7 @@ public class ManagedChannelImplTest {
             .setServers(Collections.singletonList(new EquivalentAddressGroup(socketAddress)))
             .build());
     createChannel();
-    assertEquals(IDLE, channel.getState(false));
+    assertEquals(CONNECTING, channel.getState(false));
 
     // This call will be buffered in delayedTransport
     ClientCall<String, Integer> call = channel.newCall(method, CallOptions.DEFAULT);
@@ -2790,7 +2787,7 @@ public class ManagedChannelImplTest {
     // enterIdle() will shut down the name resolver and lb policy used to get a pick for the delayed
     // call
     channel.enterIdle();
-    assertEquals(IDLE, channel.getState(false));
+    assertEquals(CONNECTING, channel.getState(false));
 
     // enterIdle() will restart the delayed call by exiting idle. This creates a new helper.
     ArgumentCaptor<Helper> helperCaptor = ArgumentCaptor.forClass(Helper.class);
@@ -2912,14 +2909,14 @@ public class ManagedChannelImplTest {
     channelBuilder.nameResolverFactory(
         new FakeNameResolverFactory.Builder(expectedUri).setResolvedAtStart(false).build());
     createChannel();
-    assertEquals(IDLE, channel.getState(false));
+    assertEquals(CONNECTING, channel.getState(false));
 
     Runnable onStateChanged = mock(Runnable.class);
-    channel.notifyWhenStateChanged(IDLE, onStateChanged);
+    channel.notifyWhenStateChanged(CONNECTING, onStateChanged);
 
     updateBalancingStateSafely(helper, SHUTDOWN, mockPicker);
 
-    assertEquals(IDLE, channel.getState(false));
+    assertEquals(CONNECTING, channel.getState(false));
     executor.runDueTasks();
     verify(onStateChanged, never()).run();
   }
@@ -3222,8 +3219,6 @@ public class ManagedChannelImplTest {
     verify(mockLoadBalancerProvider).newLoadBalancer(helperCaptor.capture());
     helper = helperCaptor.getValue();
 
-    assertEquals(IDLE, getStats(channel).state);
-    updateBalancingStateSafely(helper, CONNECTING, mockPicker);
     assertEquals(CONNECTING, getStats(channel).state);
 
     AbstractSubchannel subchannel =
@@ -3434,7 +3429,7 @@ public class ManagedChannelImplTest {
     assertEquals(READY, getStats(oobChannel).state);
 
     // oobchannel state is separate from the ManagedChannel
-    assertEquals(IDLE, getStats(channel).state);
+    assertEquals(CONNECTING, getStats(channel).state);
     channel.shutdownNow();
     assertEquals(SHUTDOWN, getStats(channel).state);
     assertEquals(SHUTDOWN, getStats(oobChannel).state);

core/src/test/java/io/grpc/internal/ServiceConfigErrorHandlingTest.java

@@ -277,7 +277,7 @@ public class ServiceConfigErrorHandlingTest {
     assertThat(resolvedAddresses.getLoadBalancingPolicyConfig()).isEqualTo("12");
     verify(mockLoadBalancer, never()).handleNameResolutionError(any(Status.class));
 
-    assertThat(channel.getState(true)).isEqualTo(ConnectivityState.IDLE);
+    assertThat(channel.getState(true)).isEqualTo(ConnectivityState.CONNECTING);
 
     reset(mockLoadBalancer);
     nameResolverFactory.servers.clear();
@@ -480,7 +480,7 @@ public class ServiceConfigErrorHandlingTest {
     assertThat(newResolvedAddress.getLoadBalancingPolicyConfig()).isEqualTo("1st raw config");
     assertThat(channel.getConfigSelector()).isSameInstanceAs(configSelector);
     verify(mockLoadBalancer, never()).handleNameResolutionError(any(Status.class));
-    assertThat(channel.getState(false)).isEqualTo(ConnectivityState.IDLE);
+    assertThat(channel.getState(false)).isEqualTo(ConnectivityState.CONNECTING);
   }
 
   @Test