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, 15 deletions

diff --git a/lib/clippy.c b/lib/clippy.c
index cd8067f5eb..2e09c24c66 100644
--- a/lib/clippy.c
+++ b/lib/clippy.c
@@ -107,21 +107,11 @@ int main(int argc, char **argv)
 #include "log.h"
 #include "zassert.h"
 
-#define ZLOG_FUNC(FUNCNAME)                                                    \
-	void FUNCNAME(const char *format, ...)                                 \
-	{                                                                      \
-		va_list args;                                                  \
-		va_start(args, format);                                        \
-		vfprintf(stderr, format, args);                                \
-		fputs("\n", stderr);                                           \
-		va_end(args);                                                  \
-	}
-
-ZLOG_FUNC(zlog_err)
-ZLOG_FUNC(zlog_warn)
-ZLOG_FUNC(zlog_info)
-ZLOG_FUNC(zlog_notice)
-ZLOG_FUNC(zlog_debug)
+void vzlog(int prio, const char *format, va_list args)
+{
+	vfprintf(stderr, format, args);
+	fputs("\n", stderr);
+}
 
 void _zlog_assert_failed(const char *assertion, const char *file,
 			 unsigned int line, const char *function)