haproxy/dev/haring/README

This needs to be built from the top makefile, for example :

  make dev/haring/haring

If HAProxy is built with special options such -DDEBUG_THREAD or with
multi-threading support enabled (which changes the ring's header size),
it can be worth reusing the same build options for haring, usually they
will remain compatible, and will simplify the handling of different file
layouts, at the expense of dragging more dependencies into the executable.
DEV: haring: add a simple utility to read file-backed rings With the ability to back a memory ring into an mmapped file, it makes sense to be able to dump these files. That's what this utility does. The entire ring is dumped to stdout. It's well suited to large dumps, it converts roughly 6 GB of logs per second. The utility is really meant for developers at the moment. It might evolve into a more general tool but at the moment it's still possible that it might need to be run under gdb to process certain crash dumps. Also at the moment it must not be used on a ring being actively written to or it will dump garbage. The code is made so that we can envision later to attach to a live ring and dump live contents, but this requires that the utility is built with the exact same options (threads etc), and that the file is opened read-write. For now these parts have been commented out, waiting for a reasonably balanced and non-intrusive solution to be found (e.g. signals must be intercepted so that the tool cannot leave the ring with a watcher present). If it is detected that the memory layout of the ring struct differs, a warning is emitted. At the end, if an error occurs, a warning is printed as well (this does happen when the process is not cleanly stopped, but it indicates the end was reached). 2022-08-12 05:23:59 -04:00			`This needs to be built from the top makefile, for example :`

			`make dev/haring/haring`

DEV: haring: update readme to suggest using the same build options for haring It's not necessarily obvious so better suggest it there to use the same build options, and indicate the tradeoffs (e.g. depend on more libs). 2023-05-04 02:13:44 -04:00			`If HAProxy is built with special options such -DDEBUG_THREAD or with`
			`multi-threading support enabled (which changes the ring's header size),`
			`it can be worth reusing the same build options for haring, usually they`
			`will remain compatible, and will simplify the handling of different file`
			`layouts, at the expense of dragging more dependencies into the executable.`