otel tracing: add binary format, grpcTraceBinContextPropagator (#11409)

* otel tracing: add binary format, grpcTraceBinContextPropagator * exception handling, use api base64 encoder omit padding remove binary format abstract class in favor of binary marshaller
grpc · Aug 12, 2024 · 043ba55 · 043ba55
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diff --git a/opentelemetry/src/main/java/io/grpc/opentelemetry/BinaryFormat.java b/opentelemetry/src/main/java/io/grpc/opentelemetry/BinaryFormat.java
@@ -0,0 +1,143 @@
+/*
+ * Copyright 2024 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.opentelemetry;
+
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import io.grpc.Metadata;
+import io.opentelemetry.api.trace.SpanContext;
+import io.opentelemetry.api.trace.SpanId;
+import io.opentelemetry.api.trace.TraceFlags;
+import io.opentelemetry.api.trace.TraceId;
+import io.opentelemetry.api.trace.TraceState;
+import java.util.Arrays;
+
+/**
+ *  Binary encoded {@link SpanContext} for context propagation. This is adapted from OpenCensus
+ *  binary format.
+ *
+ * <p>BinaryFormat format:
+ *
+ * <ul>
+ *   <li>Binary value: &lt;version_id&gt;&lt;version_format&gt;
+ *   <li>version_id: 1-byte representing the version id.
+ *   <li>For version_id = 0:
+ *       <ul>
+ *         <li>version_format: &lt;field&gt;&lt;field&gt;
+ *         <li>field_format: &lt;field_id&gt;&lt;field_format&gt;
+ *         <li>Fields:
+ *             <ul>
+ *               <li>TraceId: (field_id = 0, len = 16, default = &#34;0000000000000000&#34;) -
+ *                   16-byte array representing the trace_id.
+ *               <li>SpanId: (field_id = 1, len = 8, default = &#34;00000000&#34;) - 8-byte array
+ *                   representing the span_id.
+ *               <li>TraceFlags: (field_id = 2, len = 1, default = &#34;0&#34;) - 1-byte array
+ *                   representing the trace_flags.
+ *             </ul>
+ *         <li>Fields MUST be encoded using the field id order (smaller to higher).
+ *         <li>Valid value example:
+ *             <ul>
+ *               <li>{0, 0, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 1, 97,
+ *                   98, 99, 100, 101, 102, 103, 104, 2, 1}
+ *               <li>version_id = 0;
+ *               <li>trace_id = {64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79}
+ *               <li>span_id = {97, 98, 99, 100, 101, 102, 103, 104};
+ *               <li>trace_flags = {1};
+ *             </ul>
+ *       </ul>
+ * </ul>
+ */
+final class BinaryFormat implements Metadata.BinaryMarshaller<SpanContext> {
+  private static final byte VERSION_ID = 0;
+  private static final int VERSION_ID_OFFSET = 0;
+  private static final byte ID_SIZE = 1;
+  private static final byte TRACE_ID_FIELD_ID = 0;
+
+  private static final int TRACE_ID_FIELD_ID_OFFSET = VERSION_ID_OFFSET + ID_SIZE;
+  private static final int TRACE_ID_OFFSET = TRACE_ID_FIELD_ID_OFFSET + ID_SIZE;
+  private static final int TRACE_ID_SIZE = TraceId.getLength() / 2;
+
+  private static final byte SPAN_ID_FIELD_ID = 1;
+  private static final int SPAN_ID_FIELD_ID_OFFSET = TRACE_ID_OFFSET + TRACE_ID_SIZE;
+  private static final int SPAN_ID_OFFSET = SPAN_ID_FIELD_ID_OFFSET + ID_SIZE;
+  private static final int SPAN_ID_SIZE = SpanId.getLength() / 2;
+
+  private static final byte TRACE_FLAG_FIELD_ID = 2;
+  private static final int TRACE_FLAG_FIELD_ID_OFFSET = SPAN_ID_OFFSET + SPAN_ID_SIZE;
+  private static final int TRACE_FLAG_OFFSET = TRACE_FLAG_FIELD_ID_OFFSET + ID_SIZE;
+  private static final int REQUIRED_FORMAT_LENGTH = 3 * ID_SIZE + TRACE_ID_SIZE + SPAN_ID_SIZE;
+  private static final int TRACE_FLAG_SIZE = TraceFlags.getLength() / 2;
+  private static final int ALL_FORMAT_LENGTH = REQUIRED_FORMAT_LENGTH + ID_SIZE + TRACE_FLAG_SIZE;
+
+  private static final BinaryFormat INSTANCE = new BinaryFormat();
+
+  public static BinaryFormat getInstance() {
+    return INSTANCE;
+  }
+
+  @Override
+  public byte[] toBytes(SpanContext spanContext) {
+    checkNotNull(spanContext, "spanContext");
+    byte[] bytes = new byte[ALL_FORMAT_LENGTH];
+    bytes[VERSION_ID_OFFSET] = VERSION_ID;
+    bytes[TRACE_ID_FIELD_ID_OFFSET] = TRACE_ID_FIELD_ID;
+    System.arraycopy(spanContext.getTraceIdBytes(), 0, bytes, TRACE_ID_OFFSET, TRACE_ID_SIZE);
+    bytes[SPAN_ID_FIELD_ID_OFFSET] = SPAN_ID_FIELD_ID;
+    System.arraycopy(spanContext.getSpanIdBytes(), 0, bytes, SPAN_ID_OFFSET, SPAN_ID_SIZE);
+    bytes[TRACE_FLAG_FIELD_ID_OFFSET] = TRACE_FLAG_FIELD_ID;
+    bytes[TRACE_FLAG_OFFSET] = spanContext.getTraceFlags().asByte();
+    return bytes;
+  }
+
+
+  @Override
+  public SpanContext parseBytes(byte[] serialized) {
+    checkNotNull(serialized, "bytes");
+    if (serialized.length == 0 || serialized[0] != VERSION_ID) {
+      throw new IllegalArgumentException("Unsupported version.");
+    }
+    if (serialized.length < REQUIRED_FORMAT_LENGTH) {
+      throw new IllegalArgumentException("Invalid input: truncated");
+    }
+    String traceId;
+    String spanId;
+    TraceFlags traceFlags = TraceFlags.getDefault();
+    int pos = 1;
+    if (serialized[pos] == TRACE_ID_FIELD_ID) {
+      traceId = TraceId.fromBytes(
+          Arrays.copyOfRange(serialized, pos + ID_SIZE, pos + ID_SIZE + TRACE_ID_SIZE));
+      pos += ID_SIZE + TRACE_ID_SIZE;
+    } else {
+      throw new IllegalArgumentException("Invalid input: expected trace ID at offset " + pos);
+    }
+    if (serialized[pos] == SPAN_ID_FIELD_ID) {
+      spanId = SpanId.fromBytes(
+          Arrays.copyOfRange(serialized, pos + ID_SIZE, pos + ID_SIZE + SPAN_ID_SIZE));
+      pos += ID_SIZE + SPAN_ID_SIZE;
+    } else {
+      throw new IllegalArgumentException("Invalid input: expected span ID at offset " + pos);
+    }
+    if (serialized.length > pos && serialized[pos] == TRACE_FLAG_FIELD_ID) {
+      if (serialized.length < ALL_FORMAT_LENGTH) {
+        throw new IllegalArgumentException("Invalid input: truncated");
+      }
+      traceFlags = TraceFlags.fromByte(serialized[pos + ID_SIZE]);
+    }
+    return SpanContext.create(traceId, spanId, traceFlags, TraceState.getDefault());
+  }
+}
diff --git a/opentelemetry/src/main/java/io/grpc/opentelemetry/GrpcTraceBinContextPropagator.java b/opentelemetry/src/main/java/io/grpc/opentelemetry/GrpcTraceBinContextPropagator.java
@@ -0,0 +1,147 @@
+/*
+ * Copyright 2024 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.opentelemetry;
+
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static io.grpc.InternalMetadata.BASE64_ENCODING_OMIT_PADDING;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.io.BaseEncoding;
+import io.grpc.ExperimentalApi;
+import io.grpc.Metadata;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.SpanContext;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.propagation.TextMapGetter;
+import io.opentelemetry.context.propagation.TextMapPropagator;
+import io.opentelemetry.context.propagation.TextMapSetter;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import javax.annotation.Nullable;
+
+/**
+ *  A {@link TextMapPropagator} for transmitting "grpc-trace-bin" span context.
+ *
+ *  <p>This propagator can transmit the "grpc-trace-bin" context in either binary or Base64-encoded
+ * text format, depending on the capabilities of the provided {@link TextMapGetter} and
+ * {@link TextMapSetter}.
+ *
+ *  <p>If the {@code TextMapGetter} and {@code TextMapSetter} only support text format, Base64
+ *  encoding and decoding will be used when communicating with the carrier API. But gRPC uses
+ *  it with gRPC's metadata-based getter/setter, and the propagator can directly transmit the binary
+ *  header, avoiding the need for Base64 encoding.
+ */
+
+@ExperimentalApi("https://github.com/grpc/grpc-java/issues/11400")
+public final class GrpcTraceBinContextPropagator implements TextMapPropagator {
+  private static final Logger log = Logger.getLogger(GrpcTraceBinContextPropagator.class.getName());
+  public static final String GRPC_TRACE_BIN_HEADER = "grpc-trace-bin";
+  private final Metadata.BinaryMarshaller<SpanContext> binaryFormat;
+  private static final GrpcTraceBinContextPropagator INSTANCE =
+      new GrpcTraceBinContextPropagator(BinaryFormat.getInstance());
+
+  public static GrpcTraceBinContextPropagator defaultInstance() {
+    return INSTANCE;
+  }
+
+  @VisibleForTesting
+  GrpcTraceBinContextPropagator(Metadata.BinaryMarshaller<SpanContext> binaryFormat) {
+    this.binaryFormat = checkNotNull(binaryFormat, "binaryFormat");
+  }
+
+  @Override
+  public Collection<String> fields() {
+    return Collections.singleton(GRPC_TRACE_BIN_HEADER);
+  }
+
+  @Override
+  public <C> void inject(Context context, @Nullable C carrier, TextMapSetter<C> setter) {
+    if (context == null || setter == null) {
+      return;
+    }
+    SpanContext spanContext = Span.fromContext(context).getSpanContext();
+    if (!spanContext.isValid()) {
+      return;
+    }
+    try {
+      byte[] b = binaryFormat.toBytes(spanContext);
+      if (setter instanceof MetadataSetter) {
+        ((MetadataSetter) setter).set((Metadata) carrier, GRPC_TRACE_BIN_HEADER, b);
+      } else {
+        setter.set(carrier, GRPC_TRACE_BIN_HEADER, BASE64_ENCODING_OMIT_PADDING.encode(b));
+      }
+    } catch (Exception e) {
+      log.log(Level.FINE, "Set grpc-trace-bin spanContext failed", e);
+    }
+  }
+
+  @Override
+  public <C> Context extract(Context context, @Nullable C carrier, TextMapGetter<C> getter) {
+    if (context == null) {
+      return Context.root();
+    }
+    if (getter == null) {
+      return context;
+    }
+    byte[] b;
+    if (getter instanceof MetadataGetter) {
+      try {
+        b = ((MetadataGetter) getter).getBinary((Metadata) carrier, GRPC_TRACE_BIN_HEADER);
+        if (b == null) {
+          log.log(Level.FINE, "No grpc-trace-bin present in carrier");
+          return context;
+        }
+      } catch (Exception e) {
+        log.log(Level.FINE, "Get 'grpc-trace-bin' from MetadataGetter failed", e);
+        return context;
+      }
+    } else {
+      String value;
+      try {
+        value = getter.get(carrier, GRPC_TRACE_BIN_HEADER);
+        if (value == null) {
+          log.log(Level.FINE, "No grpc-trace-bin present in carrier");
+          return context;
+        }
+      } catch (Exception e) {
+        log.log(Level.FINE, "Get 'grpc-trace-bin' from getter failed", e);
+        return context;
+      }
+      try {
+        b = BaseEncoding.base64().decode(value);
+      } catch (Exception e) {
+        log.log(Level.FINE, "Base64-decode spanContext bytes failed", e);
+        return context;
+      }
+    }
+
+    SpanContext spanContext;
+    try {
+      spanContext = binaryFormat.parseBytes(b);
+    } catch (Exception e) {
+      log.log(Level.FINE, "Failed to parse tracing header", e);
+      return context;
+    }
+    if (!spanContext.isValid()) {
+      return context;
+    }
+    return context.with(Span.wrap(spanContext));
+  }
+}
diff --git a/opentelemetry/src/main/java/io/grpc/opentelemetry/MetadataGetter.java b/opentelemetry/src/main/java/io/grpc/opentelemetry/MetadataGetter.java
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2024 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.opentelemetry;
+
+
+import static io.grpc.InternalMetadata.BASE64_ENCODING_OMIT_PADDING;
+
+import io.grpc.Metadata;
+import io.opentelemetry.context.propagation.TextMapGetter;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import javax.annotation.Nullable;
+
+/**
+ *  A TextMapGetter that reads value from gRPC {@link Metadata}. Supports both text and binary
+ *  headers. Supporting binary header is an optimization path for GrpcTraceBinContextPropagator
+ *  to work around the lack of binary propagator API and thus avoid
+ *  base64 (de)encoding when passing data between propagator API interfaces.
+ */
+final class MetadataGetter implements TextMapGetter<Metadata> {
+  private static final Logger logger = Logger.getLogger(MetadataGetter.class.getName());
+  private static final MetadataGetter INSTANCE = new MetadataGetter();
+
+  public static MetadataGetter getInstance() {
+    return INSTANCE;
+  }
+
+  @Override
+  public Iterable<String> keys(Metadata carrier) {
+    return carrier.keys();
+  }
+
+  @Nullable
+  @Override
+  public String get(@Nullable Metadata carrier, String key) {
+    if (carrier == null) {
+      logger.log(Level.FINE, "Carrier is null, getting no data");
+      return null;
+    }
+    try {
+      if (key.equals("grpc-trace-bin")) {
+        byte[] value = carrier.get(Metadata.Key.of(key, Metadata.BINARY_BYTE_MARSHALLER));
+        if (value == null) {
+          return null;
+        }
+        return BASE64_ENCODING_OMIT_PADDING.encode(value);
+      } else {
+        return carrier.get(Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER));
+      }
+    } catch (Exception e) {
+      logger.log(Level.FINE, String.format("Failed to get metadata key %s", key), e);
+      return null;
+    }
+  }
+
+  @Nullable
+  public byte[] getBinary(@Nullable Metadata carrier, String key) {
+    if (carrier == null) {
+      logger.log(Level.FINE, "Carrier is null, getting no data");
+      return null;
+    }
+    if (!key.equals("grpc-trace-bin")) {
+      logger.log(Level.FINE, "Only support 'grpc-trace-bin' binary header. Get no data");
+      return null;
+    }
+    try {
+      return carrier.get(Metadata.Key.of(key, Metadata.BINARY_BYTE_MARSHALLER));
+    } catch (Exception e) {
+      logger.log(Level.FINE, String.format("Failed to get metadata key %s", key), e);
+      return null;
+    }
+  }
+}