Add IntentNameResolverProvider and use it for every new binder Channel.

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

@@ -65,6 +65,15 @@ private Grpc() {
   @Documented
   public @interface TransportAttr {}
 
+  /**
+   * Annotation for Channel attributes. It follows the annotation semantics defined
+   * by {@link Attributes}.
+   */
+  @ExperimentalApi("https://github.com/grpc/grpc-java/issues/5678")
+  @Retention(RetentionPolicy.SOURCE)
+  @Documented
+  public @interface ChannelAttr {}
+
   /**
    * Creates a channel builder with a target string and credentials. The target can be either a
    * valid {@link NameResolver}-compliant URI, or an authority string.

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

@@ -22,6 +22,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
 import com.google.errorprone.annotations.InlineMe;
+import io.grpc.Grpc.ChannelAttr;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -281,6 +282,7 @@ public static final class Args {
     private final ProxyDetector proxyDetector;
     private final SynchronizationContext syncContext;
     private final ServiceConfigParser serviceConfigParser;
+    @Nullable private final Attributes channelAttributes;
     @Nullable private final ScheduledExecutorService scheduledExecutorService;
     @Nullable private final ChannelLogger channelLogger;
     @Nullable private final Executor executor;
@@ -291,6 +293,7 @@ private Args(
         ProxyDetector proxyDetector,
         SynchronizationContext syncContext,
         ServiceConfigParser serviceConfigParser,
+        Attributes channelAttributes,
         @Nullable ScheduledExecutorService scheduledExecutorService,
         @Nullable ChannelLogger channelLogger,
         @Nullable Executor executor,
@@ -299,6 +302,7 @@ private Args(
       this.proxyDetector = checkNotNull(proxyDetector, "proxyDetector not set");
       this.syncContext = checkNotNull(syncContext, "syncContext not set");
       this.serviceConfigParser = checkNotNull(serviceConfigParser, "serviceConfigParser not set");
+      this.channelAttributes = checkNotNull(channelAttributes, "channelAttributes not set");
       this.scheduledExecutorService = scheduledExecutorService;
       this.channelLogger = channelLogger;
       this.executor = executor;
@@ -363,6 +367,15 @@ public ServiceConfigParser getServiceConfigParser() {
       return serviceConfigParser;
     }
 
+    /**
+     * Returns the {@link ServiceConfigParser}.
+     *
+     * @since 1.21.0
+     */
+    public Attributes getChannelAttributes() {
+      return channelAttributes;
+    }
+
     /**
      * Returns the {@link ChannelLogger} for the Channel served by this NameResolver.
      *
@@ -452,6 +465,7 @@ public static final class Builder {
       private ProxyDetector proxyDetector;
       private SynchronizationContext syncContext;
       private ServiceConfigParser serviceConfigParser;
+      private Attributes channelAttributes = Attributes.EMPTY;
       private ScheduledExecutorService scheduledExecutorService;
       private ChannelLogger channelLogger;
       private Executor executor;
@@ -510,6 +524,16 @@ public Builder setServiceConfigParser(ServiceConfigParser parser) {
         return this;
       }
 
+      /**
+       * See {@link Args#getChannelAttributes}.  This is a required field, default empty.
+       *
+       * @since 1.XXX
+       */
+      public Builder setChannelAttributes(@ChannelAttr Attributes channelAttributes) {
+        this.channelAttributes = checkNotNull(channelAttributes);
+        return this;
+      }
+
       /**
        * See {@link Args#getChannelLogger}.
        *
@@ -551,6 +575,7 @@ public Args build() {
         return
             new Args(
                 defaultPort, proxyDetector, syncContext, serviceConfigParser,
+                channelAttributes,
                 scheduledExecutorService, channelLogger, executor, overrideAuthority);
       }
     }

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

@@ -46,6 +46,7 @@ public final class NameResolverRegistry {
   private static final Logger logger = Logger.getLogger(NameResolverRegistry.class.getName());
   private static NameResolverRegistry instance;
 
+  private final NameResolverRegistry parent;
   private final NameResolver.Factory factory = new NameResolverFactory();
   private static final String UNKNOWN_SCHEME = "unknown";
   @GuardedBy("this")
@@ -58,6 +59,27 @@ public final class NameResolverRegistry {
   @GuardedBy("this")
   private ImmutableMap<String, NameResolverProvider> effectiveProviders = ImmutableMap.of();
 
+  /**
+   * Creates a new empty registry.
+   */
+  public NameResolverRegistry() {
+    this(null);
+  }
+
+  /**
+   * Decorates another {@link NameResolverRegistry} without actually modifying it.
+   *
+   * <p>Lookups will consult both this registry and the parent registry, and will return the highest
+   * priority matching provider between the two of them. This is most useful when 'parent' is the
+   * default registry and modifying that global variable would be inappropriate.
+   *
+   * @param parent another registry to decorate
+   */
+  @Internal
+  public NameResolverRegistry(NameResolverRegistry parent) {
+    this.parent = parent;
+  }
+
   public synchronized String getDefaultScheme() {
     return defaultScheme;
   }
@@ -66,7 +88,14 @@ public NameResolverProvider getProviderForScheme(String scheme) {
     if (scheme == null) {
       return null;
     }
-    return providers().get(scheme.toLowerCase(Locale.US));
+    NameResolverProvider parentResult = (parent != null)
+        ? parent.getProviderForScheme(scheme) : null;
+    NameResolverProvider selfResult = providers().get(scheme.toLowerCase(Locale.US));
+    return (priorityOf(parentResult) >  priorityOf(selfResult)) ? parentResult : selfResult;
+  }
+
+  private static int priorityOf(NameResolverProvider provider) {
+    return provider != null ? provider.priority() : Integer.MIN_VALUE;
   }
 
   /**

binder/src/androidTest/java/io/grpc/binder/BinderChannelSmokeTest.java

@@ -20,6 +20,7 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.junit.Assert.fail;
 
 import android.content.Context;
 import android.content.Intent;
@@ -59,6 +60,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicReference;
 import org.junit.After;
@@ -239,6 +241,21 @@ public void testConnectViaTargetUri() throws Exception {
     assertThat(doCall("Hello").get()).isEqualTo("Hello");
   }
 
+  @Test
+  public void testConnectViaIntentTargetUri() throws Exception {
+    // TODO(jdcormie): Make this test good.
+    channel = BinderChannelBuilder.forTarget("intent://foo/bar", appContext).build();
+    // channel = BinderChannelBuilder.forTarget("android-app://com.foo.bar/authoritaaay", appContext).build();
+    ListenableFuture<String> resultFuture = doCall("Hello");
+    try {
+      resultFuture.get();
+      fail();
+    } catch (ExecutionException ee) {
+      StatusRuntimeException sre = (StatusRuntimeException) ee.getCause();
+      assertThat(sre.getStatus().getCode()).isEqualTo(Code.UNIMPLEMENTED);
+    }
+  }
+
   @Test
   public void testConnectViaIntentFilter() throws Exception {
     // Compare with the <intent-filter> mapping in AndroidManifest.xml.
@@ -263,7 +280,7 @@ public void testUncaughtServerException() throws Exception {
     CallOptions callOptions = CallOptions.DEFAULT.withDeadlineAfter(5, SECONDS);
     try {
       ClientCalls.blockingUnaryCall(interceptedChannel, method, callOptions, "hello");
-      Assert.fail();
+      fail();
     } catch (StatusRuntimeException e) {
       // We don't care how *our* RPC failed, but make sure we didn't have to rely on the deadline.
       assertThat(e.getStatus().getCode()).isNotEqualTo(Code.DEADLINE_EXCEEDED);
@@ -278,7 +295,7 @@ public void testUncaughtClientException() throws Exception {
     CallOptions callOptions = CallOptions.DEFAULT.withDeadlineAfter(5, SECONDS);
     try {
       ClientCalls.blockingUnaryCall(channel, method, callOptions, "hello");
-      Assert.fail();
+      fail();
     } catch (StatusRuntimeException e) {
       // We don't care *how* our RPC failed, but make sure we didn't have to rely on the deadline.
       assertThat(e.getStatus().getCode()).isNotEqualTo(Code.DEADLINE_EXCEEDED);

binder/src/main/java/io/grpc/binder/ApiConstants.java

@@ -17,7 +17,10 @@
 package io.grpc.binder;
 
 import android.content.Intent;
+import android.os.UserHandle;
+import io.grpc.Attributes;
 import io.grpc.ExperimentalApi;
+import io.grpc.Grpc.ChannelAttr;
 
 /** Constant parts of the gRPC binder transport public API. */
 @ExperimentalApi("https://github.com/grpc/grpc-java/issues/8022")
@@ -29,4 +32,8 @@ private ApiConstants() {}
    * themselves in a {@link android.app.Service#onBind(Intent)} call.
    */
   public static final String ACTION_BIND = "grpc.io.action.BIND";
+
+  @ChannelAttr
+  public static final Attributes.Key<UserHandle> CHANNEL_ATTR_TARGET_USER =
+      Attributes.Key.create("io.grpc.binder.CHANNEL_ATTR_TARGET_USER");
 }

binder/src/main/java/io/grpc/binder/BinderChannelBuilder.java

@@ -23,6 +23,7 @@
 import android.os.UserHandle;
 import androidx.annotation.RequiresApi;
 import com.google.errorprone.annotations.DoNotCall;
+import io.grpc.Attributes;
 import io.grpc.ExperimentalApi;
 import io.grpc.ForwardingChannelBuilder;
 import io.grpc.ManagedChannel;
@@ -159,6 +160,7 @@ public static BinderChannelBuilder forTarget(String target) {
 
   private final ManagedChannelImplBuilder managedChannelImplBuilder;
   private final BinderClientTransportFactory.Builder transportFactoryBuilder;
+  private final Attributes.Builder channelAttrBuilder = Attributes.newBuilder();
 
   private boolean strictLifecycleManagement;
 
@@ -179,6 +181,13 @@ private BinderChannelBuilder(
     } else {
       managedChannelImplBuilder =
           new ManagedChannelImplBuilder(target, transportFactoryBuilder, null);
+      if (target.startsWith("intent:")) {
+        // We register our resolver here instead of using SPI:
+        // 1) So the 99% of Android apps that don't use grpc-binder and don't use indirect
+        // addressing don't have to pay to load our classes.
+        // 2) It's our first opportunity to access the Application Context.
+        IntentNameResolverProvider.createAndRegisterSingletonOnce(sourceContext.getApplicationContext());
+      }
     }
     idleTimeout(60, TimeUnit.SECONDS);
   }
@@ -250,6 +259,7 @@ public BinderChannelBuilder securityPolicy(SecurityPolicy securityPolicy) {
   @RequiresApi(30)
   public BinderChannelBuilder bindAsUser(UserHandle targetUserHandle) {
     transportFactoryBuilder.setTargetUserHandle(targetUserHandle);
+    channelAttrBuilder.set(ApiConstants.CHANNEL_ATTR_TARGET_USER, targetUserHandle);
     return this;
   }
 
@@ -284,6 +294,7 @@ public BinderChannelBuilder idleTimeout(long value, TimeUnit unit) {
   public ManagedChannel build() {
     transportFactoryBuilder.setOffloadExecutorPool(
         managedChannelImplBuilder.getOffloadExecutorPool());
+    managedChannelImplBuilder.setChannelAttributes(channelAttrBuilder.build());
     return super.build();
   }
 }