iperf3 exposes a hook for exactly this use — iperf.h describes json_callback
as "allow user apps to receive the JSON strings, instead of writing them to
the output file". Setting it alongside --json-stream's two flags makes iperf3
hand each report ("start", "interval", "end", "error") straight to the bridge
as a JSON string, and test->outfile is never touched.
That removes the pipe, the reader thread, the fdopen/fgets loop, and
AttachCurrentThread from the output path — roughly 90 lines. It also removes
the two constraints that came with them and were both gotten wrong: that the
write end must be closed before joining a reader blocked in fgets(), and that
exactly one side may own the shared state struct. Neither can be violated now
because neither exists.
json_callback carries no user-data pointer, so the run state is reached
through a global published before iperf_run_client() and cleared after it.
Only one test runs at a time, which runIperfLive already enforced. The
callback fires on iperf3's reporting thread, so it resolves a JNIEnv for the
calling thread rather than trusting a stored one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
mikkeli
598a2d99c9