core, census, testing, interop-testing, android-interop-testing: move census dependency out of grpc-core (#6577)

Decouples grpc-core with census, while still preserve the default integration of census in grpc-core. Users wishing to enable census needs to add grpc-census to their runtime classpath.

- Created a grpc-census module:
    - Moved CensusStatsModule.java and CensusTracingModule.java into grpc-census from grpc-core. CensusModuleTests.java is also moved. They now belong to io.grpc.census package.
Moved DeprecatedCensusConstants.java into io.grpc.census.internal (is this necessary?) in grpc-census.
    - Created CensusStatsAccessor.java and CensusTracingAccessor.java, which are used to create census ClientInterceptor and ServerStreamTracer.Factory.
    - Everything in grpc-census are package private, except the accessor classes. They only publicly expose ClientInterceptor and ServerStreamTracer.Factory, no Census specific types are exposed.

- Use runtime reflection to load and apply census stats/tracing to channel/server builders, if grpc-census is found in runtime classpath.

- Removed special APIs on AbstractManagedChannelImplBuilder and AbstractServerImplBuilder for overriding census module. They are only used for testing. Now we changed tests to apply Census ClientInterceptor and ServerStreamTracer.Factory just as normal interceptor/stream tracer factory. Test writer is responsible for taking care of the ordering concerns of interceptors and stream tracer factories.

Author: voidzcy

Diff for: android-interop-testing/app/build.gradle

@@ -73,6 +73,7 @@ dependencies {
 
     // You need to build grpc-java to obtain the grpc libraries below.
     implementation 'io.grpc:grpc-auth:1.27.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-census:1.27.0-SNAPSHOT' // CURRENT_GRPC_VERSION
     implementation 'io.grpc:grpc-okhttp:1.27.0-SNAPSHOT' // CURRENT_GRPC_VERSION
     implementation 'io.grpc:grpc-protobuf-lite:1.27.0-SNAPSHOT' // CURRENT_GRPC_VERSION
     implementation 'io.grpc:grpc-stub:1.27.0-SNAPSHOT' // CURRENT_GRPC_VERSION

Diff for: census/BUILD.bazel

@@ -0,0 +1,15 @@
+java_library(
+    name = "census",
+    srcs = glob([
+        "src/main/java/**/*.java",
+    ]),
+    visibility = ["//visibility:public"],
+    deps = [
+            "//api",
+            "//context",
+            "@com_google_code_findbugs_jsr305//jar",
+            "@com_google_guava_guava//jar",
+            "@io_opencensus_opencensus_api//jar",
+            "@io_opencensus_opencensus_contrib_grpc_metrics//jar",
+    ],
+)

Diff for: census/build.gradle

@@ -0,0 +1,43 @@
+plugins {
+    id "java"
+    id "maven-publish"
+}
+
+description = 'gRPC: Census'
+
+evaluationDependsOn(project(':grpc-api').path)
+
+dependencies {
+    compile project(':grpc-api')
+            
+    compile (libraries.opencensus_api) {
+        // prefer 3.0.2 from libraries instead of 3.0.1
+        exclude group: 'com.google.code.findbugs', module: 'jsr305'
+        // prefer 20.0 from libraries instead of 19.0
+        exclude group: 'com.google.guava', module: 'guava'
+        // we'll always be more up-to-date
+        exclude group: 'io.grpc', module: 'grpc-context'
+    }
+    
+    compile (libraries.opencensus_contrib_grpc_metrics) {
+        // prefer 3.0.2 from libraries instead of 3.0.1
+        exclude group: 'com.google.code.findbugs', module: 'jsr305'
+        // we'll always be more up-to-date
+        exclude group: 'io.grpc', module: 'grpc-context'
+        // prefer 20.0 from libraries instead of 19.0
+        exclude group: 'com.google.guava', module: 'guava'
+    }
+
+    testCompile project(':grpc-api').sourceSets.test.output,
+            project(':grpc-context').sourceSets.test.output,
+            project(':grpc-core').sourceSets.test.output,
+            project(':grpc-testing'),
+            libraries.guava_testlib,
+            libraries.opencensus_impl
+}
+
+javadoc {
+    failOnError false  // no public or protected classes found to document
+    exclude 'io/grpc/census/internal/**'
+    exclude 'io/grpc/census/Internal*'
+}

Diff for: core/src/main/java/io/grpc/internal/CensusStatsModule.java renamed to census/src/main/java/io/grpc/census/CensusStatsModule.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.grpc.internal;
+package io.grpc.census;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
@@ -35,6 +35,7 @@
 import io.grpc.ServerStreamTracer;
 import io.grpc.Status;
 import io.grpc.StreamTracer;
+import io.grpc.census.internal.DeprecatedCensusConstants;
 import io.opencensus.contrib.grpc.metrics.RpcMeasureConstants;
 import io.opencensus.stats.Measure.MeasureDouble;
 import io.opencensus.stats.Measure.MeasureLong;
@@ -67,7 +68,7 @@
  * starts earlier than the ServerCall.  Therefore, only one tracer is created per stream/call and
  * it's the tracer that reports the summary to Census.
  */
-public final class CensusStatsModule {
+final class CensusStatsModule {
   private static final Logger logger = Logger.getLogger(CensusStatsModule.class.getName());
   private static final double NANOS_PER_MILLI = TimeUnit.MILLISECONDS.toNanos(1);
 
@@ -98,7 +99,7 @@ public final class CensusStatsModule {
   /**
    * Creates a {@link CensusStatsModule} with the given OpenCensus implementation.
    */
-  public CensusStatsModule(
+  CensusStatsModule(
       final Tagger tagger,
       final TagContextBinarySerializer tagCtxSerializer,
       StatsRecorder statsRecorder, Supplier<Stopwatch> stopwatchSupplier,

Diff for: core/src/main/java/io/grpc/internal/CensusTracingModule.java renamed to census/src/main/java/io/grpc/census/CensusTracingModule.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.grpc.internal;
+package io.grpc.census;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 

Diff for: census/src/main/java/io/grpc/census/InternalCensusStatsAccessor.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2019 The gRPC 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 io.grpc.census;
+
+import com.google.common.base.Stopwatch;
+import com.google.common.base.Supplier;
+import io.grpc.ClientInterceptor;
+import io.grpc.Internal;
+import io.grpc.ServerStreamTracer;
+import io.opencensus.stats.StatsRecorder;
+import io.opencensus.tags.Tagger;
+import io.opencensus.tags.propagation.TagContextBinarySerializer;
+
+/**
+ * Accessor for getting {@link ClientInterceptor} or {@link ServerStreamTracer.Factory} with
+ * default Census stats implementation.
+ */
+@Internal
+public final class InternalCensusStatsAccessor {
+
+  private static final Supplier<Stopwatch> STOPWATCH_SUPPLIER = new Supplier<Stopwatch>() {
+    @Override
+    public Stopwatch get() {
+      return Stopwatch.createUnstarted();
+    }
+  };
+
+  // Prevent instantiation.
+  private InternalCensusStatsAccessor() {
+  }
+
+  /**
+   * Returns a {@link ClientInterceptor} with default stats implementation.
+   */
+  public static ClientInterceptor getClientInterceptor(
+      boolean recordStartedRpcs,
+      boolean recordFinishedRpcs,
+      boolean recordRealTimeMetrics) {
+    CensusStatsModule censusStats =
+        new CensusStatsModule(
+            STOPWATCH_SUPPLIER,
+            true, /* propagateTags */
+            recordStartedRpcs,
+            recordFinishedRpcs,
+            recordRealTimeMetrics);
+    return censusStats.getClientInterceptor();
+  }
+
+  /**
+   * Returns a {@link ClientInterceptor} with custom stats implementation.
+   */
+  public static ClientInterceptor getClientInterceptor(
+      Tagger tagger,
+      TagContextBinarySerializer tagCtxSerializer,
+      StatsRecorder statsRecorder,
+      Supplier<Stopwatch> stopwatchSupplier,
+      boolean propagateTags,
+      boolean recordStartedRpcs,
+      boolean recordFinishedRpcs,
+      boolean recordRealTimeMetrics) {
+    CensusStatsModule censusStats =
+        new CensusStatsModule(
+            tagger, tagCtxSerializer, statsRecorder, stopwatchSupplier,
+            propagateTags, recordStartedRpcs, recordFinishedRpcs, recordRealTimeMetrics);
+    return censusStats.getClientInterceptor();
+  }
+
+  /**
+   * Returns a {@link ServerStreamTracer.Factory} with default stats implementation.
+   */
+  public static ServerStreamTracer.Factory getServerStreamTracerFactory(
+      boolean recordStartedRpcs,
+      boolean recordFinishedRpcs,
+      boolean recordRealTimeMetrics) {
+    CensusStatsModule censusStats =
+        new CensusStatsModule(
+            STOPWATCH_SUPPLIER,
+            true, /* propagateTags */
+            recordStartedRpcs,
+            recordFinishedRpcs,
+            recordRealTimeMetrics);
+    return censusStats.getServerTracerFactory();
+  }
+
+  /**
+   * Returns a {@link ServerStreamTracer.Factory} with custom stats implementation.
+   */
+  public static ServerStreamTracer.Factory getServerStreamTracerFactory(
+      Tagger tagger,
+      TagContextBinarySerializer tagCtxSerializer,
+      StatsRecorder statsRecorder,
+      Supplier<Stopwatch> stopwatchSupplier,
+      boolean propagateTags,
+      boolean recordStartedRpcs,
+      boolean recordFinishedRpcs,
+      boolean recordRealTimeMetrics) {
+    CensusStatsModule censusStats =
+        new CensusStatsModule(
+            tagger, tagCtxSerializer, statsRecorder, stopwatchSupplier,
+            propagateTags, recordStartedRpcs, recordFinishedRpcs, recordRealTimeMetrics);
+    return censusStats.getServerTracerFactory();
+  }
+}

Diff for: census/src/main/java/io/grpc/census/InternalCensusTracingAccessor.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2019 The gRPC 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 io.grpc.census;
+
+import io.grpc.ClientInterceptor;
+import io.grpc.Internal;
+import io.grpc.ServerStreamTracer;
+import io.opencensus.trace.Tracing;
+
+/**
+ * Accessor for getting {@link ClientInterceptor} or {@link ServerStreamTracer.Factory} with
+ * default Census tracing implementation.
+ */
+@Internal
+public final class InternalCensusTracingAccessor {
+
+  // Prevent instantiation.
+  private InternalCensusTracingAccessor() {
+  }
+
+  /**
+   * Returns a {@link ClientInterceptor} with default tracing implementation.
+   */
+  public static ClientInterceptor getClientInterceptor() {
+    CensusTracingModule censusTracing =
+        new CensusTracingModule(
+            Tracing.getTracer(),
+            Tracing.getPropagationComponent().getBinaryFormat());
+    return censusTracing.getClientInterceptor();
+  }
+
+  /**
+   * Returns a {@link ServerStreamTracer.Factory} with default stats implementation.
+   */
+  public static ServerStreamTracer.Factory getServerStreamTracerFactory() {
+    CensusTracingModule censusTracing =
+        new CensusTracingModule(
+            Tracing.getTracer(),
+            Tracing.getPropagationComponent().getBinaryFormat());
+    return censusTracing.getServerTracerFactory();
+  }
+}

Diff for: core/src/main/java/io/grpc/internal/DeprecatedCensusConstants.java renamed to census/src/main/java/io/grpc/census/internal/DeprecatedCensusConstants.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.grpc.internal;
+package io.grpc.census.internal;
 
 import com.google.common.annotations.VisibleForTesting;
 import io.opencensus.contrib.grpc.metrics.RpcMeasureConstants;

Diff for: core/src/test/java/io/grpc/internal/CensusModulesTest.java renamed to census/src/test/java/io/grpc/census/CensusModulesTest.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.grpc.internal;
+package io.grpc.census;
 
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
@@ -56,7 +56,10 @@
 import io.grpc.ServerCallHandler;
 import io.grpc.ServerServiceDefinition;
 import io.grpc.ServerStreamTracer;
+import io.grpc.ServerStreamTracer.ServerCallInfo;
 import io.grpc.Status;
+import io.grpc.census.internal.DeprecatedCensusConstants;
+import io.grpc.internal.FakeClock;
 import io.grpc.internal.testing.StatsTestUtils;
 import io.grpc.internal.testing.StatsTestUtils.FakeStatsRecorder;
 import io.grpc.internal.testing.StatsTestUtils.FakeTagContextBinarySerializer;
@@ -95,6 +98,7 @@
 import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.Nullable;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
@@ -1044,7 +1048,7 @@ public void serverBasicTracingNoHeaders() {
     assertSame(spyServerSpan, ContextUtils.getValue(filteredContext));
 
     serverStreamTracer.serverCallStarted(
-        new ServerCallInfoImpl<>(method, Attributes.EMPTY, null));
+        new CallInfo<>(method, Attributes.EMPTY, null));
 
     verify(spyServerSpan, never()).end(any(EndSpanOptions.class));
 
@@ -1087,7 +1091,7 @@ public void serverTracingSampledToLocalSpanStore() {
     serverStreamTracer.filterContext(Context.ROOT);
 
     serverStreamTracer.serverCallStarted(
-        new ServerCallInfoImpl<>(sampledMethod, Attributes.EMPTY, null));
+        new CallInfo<>(sampledMethod, Attributes.EMPTY, null));
 
     serverStreamTracer.streamClosed(Status.CANCELLED);
 
@@ -1250,8 +1254,39 @@ public Long apply(LastValueDataLong arg) {
         new Function<AggregationData, Long>() {
           @Override
           public Long apply(AggregationData arg) {
-            return ((io.opencensus.stats.AggregationData.MeanData) arg).getCount();
+            return ((AggregationData.MeanData) arg).getCount();
           }
         });
   }
+
+  private static class CallInfo<ReqT, RespT> extends ServerCallInfo<ReqT, RespT> {
+    private final MethodDescriptor<ReqT, RespT> methodDescriptor;
+    private final Attributes attributes;
+    private final String authority;
+
+    CallInfo(
+        MethodDescriptor<ReqT, RespT> methodDescriptor,
+        Attributes attributes,
+        @Nullable String authority) {
+      this.methodDescriptor = methodDescriptor;
+      this.attributes = attributes;
+      this.authority = authority;
+    }
+
+    @Override
+    public MethodDescriptor<ReqT, RespT> getMethodDescriptor() {
+      return methodDescriptor;
+    }
+
+    @Override
+    public Attributes getAttributes() {
+      return attributes;
+    }
+
+    @Nullable
+    @Override
+    public String getAuthority() {
+      return authority;
+    }
+  }
 }

Diff for: core/BUILD.bazel

@@ -38,8 +38,6 @@ java_library(
         "@com_google_errorprone_error_prone_annotations//jar",
         "@com_google_guava_guava//jar",
         "@com_google_j2objc_j2objc_annotations//jar",
-        "@io_opencensus_opencensus_api//jar",
-        "@io_opencensus_opencensus_contrib_grpc_metrics//jar",
         "@io_perfmark_perfmark_api//jar",
         "@org_codehaus_mojo_animal_sniffer_annotations//jar",
     ],