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, 5 insertions, 0 deletions

diff --git a/lib/frr_pthread.c b/lib/frr_pthread.c
index 55f0b55ed6..e237934f81 100644
--- a/lib/frr_pthread.c
+++ b/lib/frr_pthread.c
@@ -27,6 +27,7 @@
 #include "frr_pthread.h"
 #include "memory.h"
 #include "linklist.h"
+#include "zlog.h"
 
 DEFINE_MTYPE_STATIC(LIB, FRR_PTHREAD, "FRR POSIX Thread")
 DEFINE_MTYPE_STATIC(LIB, PTHREAD_PRIM, "POSIX sync primitives")
@@ -273,6 +274,8 @@ static void *fpt_run(void *arg)
 	struct frr_pthread *fpt = arg;
 	fpt->master->owner = pthread_self();
 
+	zlog_tls_buffer_init();
+
 	int sleeper[2];
 	pipe(sleeper);
 	thread_add_read(fpt->master, &fpt_dummy, NULL, sleeper[0], NULL);
@@ -294,5 +297,7 @@ static void *fpt_run(void *arg)
 	close(sleeper[1]);
 	close(sleeper[0]);
 
+	zlog_tls_buffer_fini();
+
 	return NULL;
 }