lib: rewrite zlog lock-free & TLS-buffered

This is a full rewrite of the "back end" logging code.  It now uses a
lock-free list to iterate over logging targets, and the targets
themselves are as lock-free as possible.  (syslog() may have a hidden
internal mutex in the C library;  the file/fd targets use a single
write() call which should ensure atomicity kernel-side.)

Note that some functionality is lost in this patch:
- Solaris printstack() backtraces are ditched (unlikely to come back)
- the `log-filter` machinery is gone (re-added in followup commit)
- `terminal monitor` is temporarily stubbed out.  The old code had a
  race condition with VTYs going away.  It'll likely come back rewritten
  and with vtysh support.
- The `zebra_ext_log` hook is gone.  Instead, it's now much easier to
  add a "proper" logging target.

v2: TLS buffer to get some actual performance

Signed-off-by: David Lamparter <equinox@diac24.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/sharpd/sharp_logpump.c b/sharpd/sharp_logpump.c
index d07e2d273f..322d802b8a 100644
--- a/sharpd/sharp_logpump.c
+++ b/sharpd/sharp_logpump.c
@@ -77,6 +77,8 @@ static void *logpump_run(void *arg)
 
 	period = 1000000000L / lp_frequency;
 
+	zlog_tls_buffer_init();
+
 	clock_gettime(CLOCK_MONOTONIC, &start);
 	next = start;
 	do {
@@ -109,6 +111,8 @@ static void *logpump_run(void *arg)
 #endif
 	} while (delta < lp_duration);
 
+	zlog_tls_buffer_fini();
+
 #ifdef RUSAGE_THREAD
 	getrusage(RUSAGE_THREAD, &lp_rusage);
 #else