* glog: add JSON structured logging mode
Add opt-in JSON output format for glog, enabling integration with
log aggregation systems like ELK, Loki, and Datadog.
- Add --log_json flag to enable JSON output at startup
- Add SetJSONMode()/IsJSONMode() for runtime toggle
- Add JSON branches in println, printDepth, printf, printWithFileLine
- Use manual JSON construction (no encoding/json) for performance
- Add jsonEscapeString() for safe string escaping
- Include 8 unit tests and 1 benchmark
Enabled via --log_json flag. Default behavior unchanged.
* glog: prevent lazy flag init from overriding SetJSONMode
If --log_json=true and SetJSONMode(false) was called at runtime,
a subsequent IsJSONMode() call would re-enable JSON mode via the
sync.Once lazy initialization. Mark jsonFlagOnce as done inside
SetJSONMode so the runtime API always takes precedence.
* glog: fix RuneError check to not misclassify valid U+FFFD
The condition r == utf8.RuneError matches both invalid UTF-8
sequences (size=1) and a valid U+FFFD replacement character
(size=3). Without checking size == 1, a valid U+FFFD input
would be incorrectly escaped and only advance by 1 byte,
corrupting the output.
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Co-authored-by: Chris Lu <chris.lu@gmail.com>
JARDEL ALVES