Files
JARDEL ALVES 1413822424 glog: add JSON structured logging mode (#8708)
* 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.

---------

Co-authored-by: Chris Lu <chris.lu@gmail.com>
2026-03-19 22:01:09 -07:00
..

glog
====

Leveled execution logs for Go.

This is an efficient pure Go implementation of leveled logs in the
manner of the open source C++ package
	http://code.google.com/p/google-glog

By binding methods to booleans it is possible to use the log package
without paying the expense of evaluating the arguments to the log.
Through the -vmodule flag, the package also provides fine-grained
control over logging at the file level.

The comment from glog.go introduces the ideas:

	Package glog implements logging analogous to the Google-internal
	C++ INFO/ERROR/V setup.  It provides functions Info, Warning,
	Error, Fatal, plus formatting variants such as Infof. It
	also provides V-style logging controlled by the -v and
	-vmodule=file=2 flags.
	
	Basic examples:
	
		glog.Info("Prepare to repel boarders")
	
		glog.Fatalf("Initialization failed: %s", err)
	
	See the documentation for the V function for an explanation
	of these examples:
	
		if glog.V(2) {
			glog.Info("Starting transaction...")
		}
	
		glog.V(2).Infoln("Processed", nItems, "elements")


The repository contains an open source version of the log package
used inside Google. The master copy of the source lives inside
Google, not here. The code in this repo is for export only and is not itself
under development. Feature requests will be ignored.

Send bug reports to golang-nuts@googlegroups.com.