Add tracing

pom.xml

@@ -100,6 +100,7 @@
         <immutables.version>2.8.3</immutables.version>
         <powermock.version>2.0.2</powermock.version>
         <objenesis.version>3.0.1</objenesis.version>
+        <opencensus.version>0.26.0</opencensus.version>
 
         <shade.id>${project.groupId}.githubclient.shade</shade.id>
     </properties>
@@ -170,6 +171,11 @@
             <artifactId>jjwt-api</artifactId>
             <version>0.10.5</version>
         </dependency>
+        <dependency>
+            <groupId>io.opencensus</groupId>
+            <artifactId>opencensus-api</artifactId>
+            <version>${opencensus.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.jsonwebtoken</groupId>
             <artifactId>jjwt-impl</artifactId>
@@ -218,6 +224,18 @@
             <version>${mockito-core.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.opencensus</groupId>
+            <artifactId>opencensus-testing</artifactId>
+            <version>${opencensus.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.opencensus</groupId>
+            <artifactId>opencensus-impl</artifactId>
+            <version>${opencensus.version}</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.squareup.okhttp3</groupId>
             <artifactId>mockwebserver</artifactId>

src/main/java/com/spotify/github/Span.java

@@ -0,0 +1,33 @@
+/*-
+ * -\-\-
+ * github-api
+ * --
+ * Copyright (C) 2021 Spotify AB
+ * --
+ * 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 com.spotify.github;
+
+public interface Span extends AutoCloseable {
+
+    Span success();
+
+    Span failure(Throwable t);
+
+    /** Close span. Must be called for any opened span. */
+    @Override
+    void close();
+}
+

src/main/java/com/spotify/github/Tracer.java

@@ -0,0 +1,32 @@
+/*-
+ * -\-\-
+ * github-api
+ * --
+ * Copyright (C) 2021 Spotify AB
+ * --
+ * 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 com.spotify.github;
+
+import java.util.concurrent.CompletionStage;
+
+public interface Tracer {
+
+    /** Create scoped span. Span will be closed when future completes. */
+    Span span(
+            String path, String method, CompletionStage<?> future);
+
+}
+

src/main/java/com/spotify/github/opencensus/OpenCensusSpan.java

@@ -0,0 +1,63 @@
+/*-
+ * -\-\-
+ * github-api
+ * --
+ * Copyright (C) 2016 - 2021 Spotify AB
+ * --
+ * 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 com.spotify.github.opencensus;
+import static java.util.Objects.requireNonNull;
+import com.spotify.github.Span;
+import com.spotify.github.v3.exceptions.RequestNotOkException;
+import io.opencensus.trace.AttributeValue;
+import io.opencensus.trace.Status;
+
+class OpenCensusSpan implements Span {
+
+    public static final int NOT_FOUND = 404;
+    public static final int INTERNAL_SERVER_ERROR = 500;
+    private final io.opencensus.trace.Span span;
+
+    OpenCensusSpan(final io.opencensus.trace.Span span) {
+        this.span = requireNonNull(span);
+    }
+
+    @Override
+    public Span success() {
+        span.setStatus(Status.OK);
+        return this;
+    }
+
+    @Override
+    public Span failure(final Throwable t) {
+        if (t instanceof RequestNotOkException) {
+            RequestNotOkException ex = (RequestNotOkException) t;
+            span.putAttribute("http.status_code", AttributeValue.longAttributeValue(ex.statusCode()));
+            span.putAttribute("message", AttributeValue.stringAttributeValue(ex.getMessage()));
+            if (ex.statusCode() - INTERNAL_SERVER_ERROR >= 0) {
+                span.putAttribute("error", AttributeValue.booleanAttributeValue(true));
+            }
+        }
+        span.setStatus(Status.UNKNOWN);
+        return this;
+    }
+
+    @Override
+    public void close() {
+        span.end();
+    }
+}
+

src/main/java/com/spotify/github/opencensus/OpenCensusTracer.java

@@ -0,0 +1,71 @@
+/*-
+ * -\-\-
+ * github-api
+ * --
+ * Copyright (C) 2021 Spotify AB
+ * --
+ * 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 com.spotify.github.opencensus;
+
+import com.spotify.github.Span;
+import com.spotify.github.Tracer;
+import io.opencensus.trace.Tracing;
+
+import java.util.concurrent.CompletionStage;
+
+import static io.opencensus.trace.AttributeValue.stringAttributeValue;
+import static io.opencensus.trace.Span.Kind.CLIENT;
+import static java.util.Objects.requireNonNull;
+
+public class OpenCensusTracer implements Tracer {
+
+    private static final io.opencensus.trace.Tracer TRACER = Tracing.getTracer();
+
+    @Override
+    public Span span(final String name, final String method, final CompletionStage<?> future) {
+        return internalSpan(name, method, future);
+    }
+
+    @SuppressWarnings("MustBeClosedChecker")
+    private Span internalSpan(
+            final String path,
+            final String method,
+            final CompletionStage<?> future) {
+        requireNonNull(path);
+        requireNonNull(future);
+
+        final io.opencensus.trace.Span ocSpan =
+                TRACER.spanBuilder("GitHub Request").setSpanKind(CLIENT).startSpan();
+
+        ocSpan.putAttribute("component", stringAttributeValue("github-api-client"));
+        ocSpan.putAttribute("peer.service", stringAttributeValue("github"));
+        ocSpan.putAttribute("http.url", stringAttributeValue(path));
+        ocSpan.putAttribute("method", stringAttributeValue(method));
+        final Span span = new OpenCensusSpan(ocSpan);
+
+        future.whenComplete(
+                (result, t) -> {
+                    if (t == null) {
+                        span.success();
+                    } else {
+                        span.failure(t);
+                    }
+                    span.close();
+                });
+
+        return span;
+    }
+}

src/main/java/com/spotify/github/v3/clients/GitHubClient.java

@@ -24,6 +24,7 @@
 import static okhttp3.MediaType.parse;
 
 import com.fasterxml.jackson.core.type.TypeReference;
+import com.spotify.github.Tracer;
 import com.spotify.github.jackson.Json;
 import com.spotify.github.v3.checks.AccessToken;
 import com.spotify.github.v3.comment.Comment;
@@ -65,6 +66,8 @@
  */
 public class GitHubClient {
 
+  private Tracer tracer = NoopTracer.INSTANCE;
+
   static final Consumer<Response> IGNORE_RESPONSE_CONSUMER = (response) -> {
     if (response.body() != null) {
       response.body().close();
@@ -300,6 +303,11 @@ static String responseBodyUnchecked(final Response response) {
     }
   }
 
+  public GitHubClient withTracer(final Tracer tracer) {
+    this.tracer = tracer;
+    return this;
+  }
+
   public Optional<byte[]> getPrivateKey() {
     return Optional.ofNullable(privateKey);
   }
@@ -724,7 +732,7 @@ public void onResponse(final Call call, final Response response) {
                     });
           }
         });
-
+    tracer.span(request.url().toString(), request.method(), future);
     return future;
   }
 

src/main/java/com/spotify/github/v3/clients/NoopTracer.java

@@ -0,0 +1,57 @@
+/*-
+ * -\-\-
+ * github-api
+ * --
+ * Copyright (C) 2021 Spotify AB
+ * --
+ * 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 com.spotify.github.v3.clients;
+import com.spotify.github.Span;
+import com.spotify.github.Tracer;
+
+import java.util.concurrent.CompletionStage;
+
+public class NoopTracer implements Tracer {
+
+    public static final NoopTracer INSTANCE = new NoopTracer();
+    private static final Span SPAN =
+            new Span() {
+                @Override
+                public Span success() {
+                    return this;
+                }
+
+                @Override
+                public Span failure(final Throwable t) {
+                    return this;
+                }
+
+                @Override
+                public void close() {}
+            };
+
+    private NoopTracer() {}
+
+    @Override
+    public Span span(
+            final String path,
+            final String method,
+            final CompletionStage<?> future) {
+        return SPAN;
+    }
+
+}
+