core: enable retry by default (#8402)

Stabilize `enableRetry()` and `disableRetry()`.

Disable retry in `ManagedChannelImplTest` because each call attempt will fork the headers to a new instance, and add a ClientStreamTracer.Factory for bufferSizeLimit in CallOptions, which makes verification not straightforward.

api/src/main/java/io/grpc/ManagedChannelBuilder.java

@@ -467,7 +467,6 @@ public T perRpcBufferLimit(long bytes) {
    * @return this
    * @since 1.11.0
    */
-  @ExperimentalApi("https://github.com/grpc/grpc-java/issues/3982")
   public T disableRetry() {
     throw new UnsupportedOperationException();
   }
@@ -482,7 +481,6 @@ public T disableRetry() {
    * @return this
    * @since 1.11.0
    */
-  @ExperimentalApi("https://github.com/grpc/grpc-java/issues/3982")
   public T enableRetry() {
     throw new UnsupportedOperationException();
   }

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

@@ -142,7 +142,7 @@ public static ManagedChannelBuilder<?> forTarget(String target) {
   int maxHedgedAttempts = 5;
   long retryBufferSize = DEFAULT_RETRY_BUFFER_SIZE_IN_BYTES;
   long perRpcBufferLimit = DEFAULT_PER_RPC_BUFFER_LIMIT_IN_BYTES;
-  boolean retryEnabled = false; // TODO(zdapeng): default to true
+  boolean retryEnabled = true;
 
   InternalChannelz channelz = InternalChannelz.instance();
   int maxTraceEvents;

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

@@ -355,6 +355,7 @@ public void close() throws SecurityException {
 
     channelBuilder = new ManagedChannelImplBuilder(TARGET,
         new UnsupportedClientTransportFactoryBuilder(), new FixedPortProvider(DEFAULT_PORT));
+    channelBuilder.disableRetry();
     configureBuilder(channelBuilder);
   }
 
@@ -1881,6 +1882,7 @@ public void oobChannelHasNoChannelCallCredentials() {
         TARGET, InsecureChannelCredentials.create(),
         new FakeCallCredentials(metadataKey, channelCredValue),
         new UnsupportedClientTransportFactoryBuilder(), new FixedPortProvider(DEFAULT_PORT));
+    channelBuilder.disableRetry();
     configureBuilder(channelBuilder);
     createChannel();
 
@@ -1933,6 +1935,7 @@ public void oobChannelHasNoChannelCallCredentials() {
             new FakeNameResolverFactory.Builder(URI.create("oobauthority")).build())
         .defaultLoadBalancingPolicy(MOCK_POLICY_NAME)
         .idleTimeout(ManagedChannelImplBuilder.IDLE_MODE_MAX_TIMEOUT_DAYS, TimeUnit.DAYS)
+        .disableRetry() // irrelevant to what we test, disable retry to make verification easy
         .build();
     oob.getState(true);
     ArgumentCaptor<Helper> helperCaptor = ArgumentCaptor.forClass(Helper.class);
@@ -1980,6 +1983,7 @@ public SwapChannelCredentialsResult answer(InvocationOnMock invocation) {
         TARGET, InsecureChannelCredentials.create(),
         new FakeCallCredentials(metadataKey, channelCredValue),
         new UnsupportedClientTransportFactoryBuilder(), new FixedPortProvider(DEFAULT_PORT));
+    channelBuilder.disableRetry();
     configureBuilder(channelBuilder);
     createChannel();
 
@@ -2017,6 +2021,7 @@ public SwapChannelCredentialsResult answer(InvocationOnMock invocation) {
             new FakeNameResolverFactory.Builder(URI.create("fake://oobauthority/")).build())
         .defaultLoadBalancingPolicy(MOCK_POLICY_NAME)
         .idleTimeout(ManagedChannelImplBuilder.IDLE_MODE_MAX_TIMEOUT_DAYS, TimeUnit.DAYS)
+        .disableRetry() // irrelevant to what we test, disable retry to make verification easy
         .build();
     oob.getState(true);
     ArgumentCaptor<Helper> helperCaptor = ArgumentCaptor.forClass(Helper.class);