impl(o11y): introduce `http.response.body_size` by diegomarquezp · Pull Request #4157 · googleapis/sdk-platform-java

diegomarquezp · 2026-03-19T16:48:35Z

Introduces the response size attribute.

Note that the sibling attribute http.request.body_size is not a straightforward implementation since the HTTP libraries don't offer an easy way to access the compressed body size.

…-attr/body-sze

gemini-code-assist · 2026-03-19T16:49:11Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves observability by adding a new http.response.body_size attribute. It integrates the measurement of HTTP response body sizes directly into the gax-httpjson library and extends the existing tracing infrastructure to capture and report this metric. This enhancement provides valuable insights into the data transfer volume for API calls, aiding in performance analysis and debugging. The changes are thoroughly tested to ensure correctness across different communication patterns.

Highlights

Observability: Introduced the http.response.body_size attribute to track the size of HTTP response bodies for enhanced observability.
HTTP JSON Client: Implemented logic within gax-httpjson to accurately measure and record response body sizes for both unary and server-streaming calls.
Tracing Infrastructure: Expanded the tracing framework (ApiTracer, OpenCensus, OpenTelemetry) to support and propagate the new http.response.body_size attribute.
Testing: Added new integration tests to validate the accurate recording of response body sizes in tracing spans.

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Code Review

This pull request introduces observability for HTTP response body size by adding a new attribute http.response.body.size. The changes span across the gax-httpjson and gax modules, introducing new APIs in ApiTracer and implementing the size recording in HttpJsonClientCallImpl. New tests are added to verify the functionality for both unary and server-streaming calls.

My review has identified a few areas for improvement:

A potential logic error in HttpJsonClientCallImpl and OpencensusTracer regarding the incorrect invocation of responseReceived() for unary calls, leading to erroneous tracing data.
A minor documentation issue in the ApiTracer interface.
An incomplete implementation of the new setAttribute method in OpenTelemetryTraceManager, which could lead to non-conformance with OpenTelemetry Semantic Conventions for data types.

Details and suggestions are provided in the specific comments.

I am having trouble creating individual review comments. Click here to see my feedback.

gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpJsonClientCallImpl.java (442-445)

Calling responseReceived() within responseReceived(long responseSize) in OpencensusTracer is problematic. The responseReceived() method is designed to record a message event for streaming RPCs. However, responseReceived(long) is also invoked for unary calls to record the response size. This implementation will incorrectly add a streaming message event to spans for unary calls.

This is also inconsistent with the SpanTracer (OpenTelemetry) implementation, which only sets the size attribute.

To fix this, responseReceived() should not be called in OpencensusTracer.responseReceived(long). Instead, HttpJsonClientCallImpl should be modified to explicitly call tracer.responseReceived() for server-streaming calls, in addition to tracer.responseReceived(responseSize).

    ApiTracer tracer = callOptions.getTracer();
    if (tracer != null) {
      long responseSize = responseBodySizeEnd - responseBodySizeStart;
      tracer.responseReceived(responseSize);
      if (methodDescriptor.getType() == MethodType.SERVER_STREAMING) {
        tracer.responseReceived();
      }
    }

gax-java/gax/src/main/java/com/google/api/gax/tracing/OpencensusTracer.java (411-416)

Calling responseReceived() within responseReceived(long responseSize) is problematic. The responseReceived() method is designed to record a message event for streaming RPCs. However, responseReceived(long) is also invoked for unary calls to record the response size. This implementation will incorrectly add a streaming message event to spans for unary calls.

This is also inconsistent with the SpanTracer (OpenTelemetry) implementation, which only sets the size attribute.

To fix this, responseReceived() should not be called here. Instead, HttpJsonClientCallImpl should be modified to explicitly call tracer.responseReceived() for server-streaming calls, in addition to tracer.responseReceived(responseSize).

  public void responseReceived(long responseSize) {
    span.putAttribute(
        ObservabilityAttributes.HTTP_RESPONSE_BODY_SIZE,
        AttributeValue.longAttributeValue(responseSize));
  }

gax-java/gax/src/main/java/com/google/api/gax/tracing/ApiTracer.java (182-184)

The Javadoc for responseReceived(long) states it's for a "streaming response". This is a bit misleading as the method is also used for unary calls to record the response body size. To avoid confusion, could you please make the documentation more generic?

  /** Adds an annotation for the size of a received response body in bytes. */
  default void responseReceived(long responseSize) {}
  ;

gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTraceManager.java (80-90)

The new setAttribute method only handles Long, Integer, and String explicitly, falling back to value.toString() for all other types. This could lead to incorrect attribute types for other common types like Double or Boolean, which would be converted to strings instead of being stored as their native types. To ensure conformance with OpenTelemetry Semantic Conventions for data types, please consider handling more primitive wrapper types directly.

    public void setAttribute(String key, Object value) {
      if (value instanceof Long) {
        span.setAttribute(key, (Long) value);
      } else if (value instanceof Integer) {
        span.setAttribute(key, ((Integer) value).longValue());
      } else if (value instanceof Double) {
        span.setAttribute(key, (Double) value);
      } else if (value instanceof Boolean) {
        span.setAttribute(key, (Boolean) value);
      } else if (value instanceof String) {
        span.setAttribute(key, (String) value);
      } else {
        span.setAttribute(key, value.toString());
      }
    }

References

When defining OpenTelemetry attributes, conform to the Semantic Conventions (SemConv) for data types.

diegomarquezp · 2026-03-19T17:35:12Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces a new observability attribute http.response.body_size to track the size of HTTP response bodies. The implementation correctly uses a CountingInputStream to measure the bytes read from the response stream for both unary and server-streaming calls. The changes span across the tracing interfaces and implementations (OpenCensus, OpenTelemetry) to support this new attribute. New unit and integration tests are added to verify the functionality. The changes are well-implemented and improve the observability of the HTTP client. The suggestion to enhance the setAttribute method for better OpenTelemetry type conformity is noted.

gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTraceManager.java

diegomarquezp · 2026-03-19T18:48:42Z

/gcbrun

blakeli0 · 2026-03-19T20:47:48Z

gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpJsonClientCallImpl.java

    }

+    if (responseCountingStream == null) {
+      responseCountingStream = new CountingInputStream(runnableResult.getResponseContent());


This does not seem to be an intuitive approach, can we rely on the ContentLength header instead? See discussion.

blakeli0 · 2026-03-19T20:58:43Z

gax-java/gax/src/main/java/com/google/api/gax/tracing/ApiTracer.java

  ;

+  /** Adds an annotation that a streaming response has been received with size. */
+  default void recordResponseSize(long responseSize) {}


If we go with the header approach, I think we can make this new method more generic and pass all headers to the tracer. Maybe something like "headersReceived".

…in tracing refactor)

sonarqubecloud · 2026-03-20T21:55:20Z

Quality Gate failed for 'gapic-generator-java-root'

Failed conditions
27.1% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

sonarqubecloud · 2026-03-20T21:59:35Z

Quality Gate failed for 'java_showcase_integration_tests'

Failed conditions
68.8% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

blakeli0 · 2026-03-20T21:57:05Z

gax-java/gax/src/main/java/com/google/api/gax/tracing/SpanTracer.java

+    try {
+      String contentLengthStr =
+          value instanceof java.util.List
+              ? ((java.util.List<?>) value).get(0).toString()


Is this an edge case? I'm not sure we want to consider this edge case even if it could happen. I think it's OK to parseLong directly and consider other scenarios invalid.

Actually I meant that we don't have to check if it is a list, but it's still better to do a try catch.

gax-java/gax/src/main/java/com/google/api/gax/tracing/BaseApiTracer.java

gax-java/gax/src/main/java/com/google/api/gax/tracing/ApiTracer.java

gax-java/gax/src/main/java/com/google/api/gax/tracing/SpanTracer.java

…Tracer

…nd simplify parseContentLength

blakeli0 · 2026-03-21T02:13:44Z

gax-java/gax/src/main/java/com/google/api/gax/tracing/SpanTracer.java

+   * @return the content length in bytes, or -1 if the header is missing or malformed.
+   */
+  private long extractContentLength(java.util.Map<String, Object> headers) {
+    if (headers == null) {


I think the logic in this method and the next method can be simplified to

if (headers == null || headers.get(CONTENT_LENGTH_KEY) == null) { return -1; } return Long.parseLong(String.valueOf(headers.get(CONTENT_LENGTH_KEY)));

Add try catch as I mentioned in another comment though.

diegomarquezp added 4 commits March 18, 2026 23:13

impl(o11y): introduce body size attributes

4ef3d9f

impl(httpjson): record response and request sizes

c00e49a

test: expand tests

c6da324

fix revert request size attribute

72be770

product-auto-label bot added the size: l Pull request size is large. label Mar 19, 2026

Merge remote-tracking branch 'origin/main' into observability/tracing…

7865574

…-attr/body-sze

chore: cleanup

1265da3

gemini-code-assist bot reviewed Mar 19, 2026

View reviewed changes

fix: use separate logic for unary resposne body size

94e55db

gemini-code-assist bot reviewed Mar 19, 2026

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gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTraceManager.java Outdated Show resolved Hide resolved

test: improvements

2cb0479

diegomarquezp marked this pull request as ready for review March 19, 2026 18:06

diegomarquezp marked this pull request as draft March 19, 2026 18:13

diegomarquezp added 3 commits March 19, 2026 14:24

test: improve coverage

dc84757

fix: revert changes in opencensus

cba2159

test: cover baseapitracer

9435824

test: test setAttribute

0ae245d

diegomarquezp marked this pull request as ready for review March 19, 2026 20:10

fix: address code quality flags

9f1bcd8

blakeli0 reviewed Mar 19, 2026

View reviewed changes

diegomarquezp added 5 commits March 20, 2026 16:34

refactor: use content lenght header

eb959bb

Merge origin/main into observability/tracing-attr/body-sze (accept ma…

7bc8aa0

…in tracing refactor)

fix(tracing): add body_size tracking to OpenTelemetry SpanTracer

11950af

chore(tracing): revert HttpJson tracing and merge test files

6e8b311

chore: format

6035f29

blakeli0 reviewed Mar 20, 2026

View reviewed changes

diegomarquezp added 5 commits March 20, 2026 19:21

refactor(o11y): remove redundant responseHeadersReceived from BaseApi…

960ddd1

…Tracer

refactor: update responseHeadersReceived to use Map<String, Object> a…

097e5ee

…nd simplify parseContentLength

test: add responseHeadersReceived tests to SpanTracerTest

ab61cbb

refactor: extract CONTENT_LENGTH_KEY to static final string

869bd2a

refactor: remove NumberFormatException handling in tracers

c721960

blakeli0 reviewed Mar 21, 2026

View reviewed changes

diegomarquezp added 4 commits March 23, 2026 11:07

fix: simplify logic of header getter

53117a3

fix: use number format exception

247f871

merge: resolve conflicts with origin/main

fad817a

chore: format code

c2fdd2a

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Summary of Changes

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gax-java/gax-httpjson/src/main/java/com/google/api/gax/httpjson/HttpJsonClientCallImpl.java (442-445)

gax-java/gax/src/main/java/com/google/api/gax/tracing/OpencensusTracer.java (411-416)

gax-java/gax/src/main/java/com/google/api/gax/tracing/ApiTracer.java (182-184)

gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTraceManager.java (80-90)

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sonarqubecloud bot commented Mar 20, 2026

Quality Gate failed for 'gapic-generator-java-root'

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Quality Gate failed for 'java_showcase_integration_tests'

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diegomarquezp commented Mar 19, 2026 •

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