[otelfiber] fix: when body is stream middleware read everything into memory first, no streaming to client

[Alantoo]

Bug Description
When application stream some file middleware reads all the streamed data into the memory to calculate response size which can consume all the available memory.

How to Reproduce
Steps to reproduce the behavior:

• Stream some binary data from handler

Expected Behavior
The middleware should skip response/request body size calculation when body is stream

Summary by CodeRabbit

• New Features
  • Enhanced request and response body size handling, including stream management for improved performance and resource utilization.
• Tests
  • Implemented new tests for streaming response body functionalities to ensure reliability and efficiency.

[ReneWerner87]

@Alantoo could you pls provide a unittest for this case?

[ReneWerner87]

@Alantoo friendly ping

[coderabbitai]

Walkthrough

The recent modifications introduce enhancements in handling request and response body sizes, particularly focusing on stream handling. This includes the introduction of a new struct for reading body stream sizes and improvements in testing capabilities for streamed response bodies by implementing a fake file interface and its concrete counterpart.

Changes

File(s)	Summary
otelfiber/fiber.go	- Added import for github.com/valyala/fasthttp and io - Added bodyStreamSizeReader struct and Read method - Modified handling of request and response body sizes, including stream handling
otelfiber/otelfiber_test/fiber_test.go	- Added a new fakeFile interface and its implementation fakeFileImpl with a Read method for streaming response body testing in the TestStreamedResponseBody function

🐇✨
In the realm of code, where streams do flow,
A rabbit hopped, with changes in tow.
"Let's measure," it said, "the size of the stream,
And test with a fake, a coder's dream."
With a hop and a skip, improvements were sown,
In the land of the fibers, where speed is grown.
🚀📈

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[coderabbitai]

Review Status

Actionable comments generated: 0

Configuration used: CodeRabbit UI

Commits

Files that changed from the base of the PR and between 8f79f35 and 391cb9c.

Files selected for processing (2)

• otelfiber/fiber.go (6 hunks)
• otelfiber/otelfiber_test/fiber_test.go (2 hunks)

Additional comments: 7

otelfiber/fiber.go (5)

• 5-6: The addition of imports for github.com/valyala/fasthttp and io is appropriate given the context of the changes. These imports are necessary for the new functionality introduced to handle streamed data more efficiently.
• 36-55: The introduction of the bodyStreamSizeReader struct and its Read method is a key part of the solution to handle streamed data without excessive memory consumption. This implementation correctly adheres to the io.Reader interface, ensuring compatibility and proper functionality within the Go ecosystem. The method's logic to record the histogram upon reaching EOF is a clever way to measure the streamed data size without reading it entirely into memory. However, it's important to ensure that the histogram.Record method is thread-safe if Read can be called concurrently.
• 164-181: The logic to handle request bodies that are streams is correctly implemented by checking request.IsBodyStream(). Creating a copy of the request and setting the body stream to an instance of bodyStreamSizeReader is a smart approach to integrate the new streaming handling mechanism. However, it's crucial to ensure that the CopyTo method and the SetBodyStream method do not introduce any side effects or memory leaks, especially in long-running applications. Additionally, setting the body length to -1 in SetBodyStream correctly indicates an unknown length, aligning with the streaming context.
• 183-199: Similar to the request handling, the logic for response bodies follows the same pattern and correctly checks if the body is a stream. The use of bodyStreamSizeReader for the response stream and the careful handling of copying the response to avoid issues with closed streams are well thought out. Again, it's important to verify the absence of side effects or memory leaks with the CopyTo and SetBodyStream methods in this context as well.
• 209-215: The conditional recording of request and response sizes based on whether they are streams or not is a good practice. It ensures that the middleware does not attempt to calculate the size of streamed data, aligning with the PR's objectives. This approach effectively addresses the issue of excessive memory consumption when handling large streamed data. It's essential to ensure that the metrics recorded here accurately reflect the actual sizes for non-streamed data and that the absence of size recording for streamed data is documented and understood by users of the middleware.

otelfiber/otelfiber_test/fiber_test.go (2)

• 450-483: The introduction of the fakeFile interface and its implementation fakeFileImpl is a strategic addition for testing the middleware's handling of streamed response bodies. The Read method's logic, simulating a finite stream of data, is well-designed for testing purposes. It's important to ensure that the test adequately covers various scenarios, including partial reads and reaching EOF, to fully validate the middleware's behavior with streamed data. Additionally, resetting f.done and f.pos upon reaching EOF might not be necessary unless the intention is to reuse the fakeFileImpl instance in multiple reads, which is not typical for most streaming use cases.
• 485-525: The TestStreamedResponseBody function is a crucial addition to the test suite, ensuring that the middleware's new behavior with streamed response bodies is correctly implemented. The use of fakeFileImpl to simulate a streamed response and the validation of the recorded metrics for the response size are well-executed. It's important to ensure comprehensive coverage by including tests for various stream sizes and potential edge cases, such as empty streams or streams that trigger multiple reads. Additionally, verifying that no unexpected metrics are recorded and that the middleware's behavior remains consistent across different streaming scenarios would strengthen the test suite.

[coderabbitai]

Review Status

Actionable comments generated: 0

Configuration used: CodeRabbit UI

Commits

Files that changed from the base of the PR and between 391cb9c and 19642fb.

Files selected for processing (2)

• otelfiber/fiber.go (6 hunks)
• otelfiber/otelfiber_test/fiber_test.go (2 hunks)

Files skipped from review as they are similar to previous changes (2)

• otelfiber/fiber.go
• otelfiber/otelfiber_test/fiber_test.go

[Alantoo]

@Alantoo friendly ping

Hey. Sorry for long delay. Unfortunately had no time to work on it. I've pushed test to make sure response size computed in lazy way correctly. Please let me know if its fine or I should fix anything else.
Thank you

[ReneWerner87]

@Alantoo pls fix this

[ReneWerner87]

@Alantoo

but we still support go 1.19.x