perf: use byteLength property for binary body chunks

[trivikr]

This relates to...

Improves HTTP/1 body writer chunk-size handling for binary chunks

Rationale

AsyncWriter.write() used Buffer.byteLength(chunk) for every body chunk.

For Buffer and Uint8Array chunks, chunk.byteLength is cheaper and avoids the string-oriented logic in Buffer.byteLength(). String chunks still need Buffer.byteLength() to preserve byte-accurate content-length and chunked framing behavior.

Changes

• Use chunk.byteLength when body writer chunks are Uint8Array instances, including Buffer.
• Keep Buffer.byteLength(chunk) for string chunks and invalid non-binary values.

Features

N/A

Bug Fixes

N/A

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

Assisted-by: openai:gpt-5.5

[trivikr]

Benchmarks

benchmark                      avg (min … max) p75 / p99    (min … top 1%)
---------------------------------------------- -------------------------------
• body writer chunk length
---------------------------------------------- -------------------------------
Buffer.byteLength(buffer)         9.21 ns/iter   9.12 ns █                    
                          (9.05 ns … 38.91 ns)  12.80 ns █                    
                       (  0.10  b …  57.16  b)   0.15  b █▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

buffer.byteLength               362.41 ps/iter 356.20 ps           █          
                        (325.44 ps … 14.06 ns) 386.47 ps           █          
                       (  0.09  b …  32.11  b)   0.09  b ▁▁▁▁▁▁▁▅▁▁█▁▁▂▁▁▁▁▁▁▁

Buffer.byteLength(uint8Array)     9.60 ns/iter   9.35 ns █                    
                          (9.30 ns … 47.80 ns)  14.59 ns █                    
                       (  0.10  b …  56.11  b)   0.14  b █▃▁▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

uint8Array.byteLength           396.28 ps/iter 396.73 ps             █        
                        (366.21 ps … 14.03 ns) 416.99 ps         █   █        
                       (  0.09  b …  84.19  b)   0.09  b ▁▁▁▁▁▁▁▁█▁▁▁█▁▁▁▂▁▁▁▁

Buffer.byteLength(string)         2.54 µs/iter   2.54 µs █ ▅                  
                           (2.52 µs … 2.60 µs)   2.59 µs █▇█                  
                       (  0.10  b …   1.12  b)   0.13  b ███▇▄▇▄▇▄▆▄▄▁▁▁▁▁▁▁▁▃

• body writer chunk length helper
---------------------------------------------- -------------------------------
previousChunkLength(buffer)      12.99 ns/iter  12.93 ns  █                   
                         (12.87 ns … 36.76 ns)  14.23 ns ▄█                   
                       (  0.09  b …  44.11  b)   0.17  b ██▁▁▁▁▁▁▁▁▁▂▁▁▁▁▁▁▁▁▁

currentChunkLength(buffer)      399.13 ps/iter 396.73 ps             █        
                        (366.21 ps … 14.01 ns) 417.24 ps             █        
                       (  0.09  b …  44.73  b)   0.09  b ▁▁▁▁▁▁▁▁▆▁▁▁█▁▁▁▂▁▁▁▁

previousChunkLength(uint8Array)   9.30 ns/iter   9.26 ns █                    
                          (9.22 ns … 24.05 ns)  10.66 ns ██                   
                       (  0.10  b …  56.10  b)   0.15  b ██▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

currentChunkLength(uint8Array)    1.96 ns/iter   1.94 ns    █                 
                          (1.92 ns … 15.85 ns)   2.04 ns    █                 
                       (  0.09  b …  52.10  b)   0.11  b ▁▁▃█▁▅▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

previousChunkLength(string)       2.55 µs/iter   2.54 µs █▂                   
                           (2.52 µs … 2.70 µs)   2.69 µs ██                   
                       (  0.10  b …   2.01  b)   0.14  b ██▇▅▁▂▁▂▁▁▂▃▁▅▁▁▁▁▁▁▂

currentChunkLength(string)        2.53 µs/iter   2.54 µs █  ▂                 
                           (2.53 µs … 2.60 µs)   2.56 µs █▇▃█                 
                       (  0.10  b …   0.74  b)   0.12  b ████▁▂▁▂▅▄▁▄▄▂▁▁▁▂▂▅▂

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.14%. Comparing base (9a6e313) to head (24e4790).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5126   +/-   ##
=======================================
  Coverage   93.14%   93.14%           
=======================================
  Files         110      110           
  Lines       36117    36117           
=======================================
  Hits        33642    33642           
  Misses       2475     2475           

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