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, 13 insertions, 1 deletions

diff --git a/lib/log_vty.h b/lib/log_vty.h
index fa5627e4bd..0fd60e9b07 100644
--- a/lib/log_vty.h
+++ b/lib/log_vty.h
@@ -20,5 +20,17 @@
 
 #ifndef __LOG_VTY_H__
 #define __LOG_VTY_H__
-extern void log_filter_cmd_init(void);
+
+#include "lib/hook.h"
+
+struct vty;
+
+extern void log_cmd_init(void);
+extern void log_config_write(struct vty *vty);
+extern int log_level_match(const char *s);
+extern void log_show_syslog(struct vty *vty);
+
+DECLARE_HOOK(zlog_rotate, (), ())
+extern void zlog_rotate(void);
+
 #endif /* __LOG_VTY_H__ */