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, 1 insertions, 0 deletions

diff --git a/bfdd/bfdd.c b/bfdd/bfdd.c
index 69f268ab0..6190be917 100644
--- a/bfdd/bfdd.c
+++ b/bfdd/bfdd.c
@@ -25,6 +25,7 @@
 #include "bfd.h"
 #include "bfdd_nb.h"
 #include "lib/version.h"
+#include "lib/command.h"
 
 
 /*