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, 60 insertions, 0 deletions

diff --git a/lib/zlog_targets.h b/lib/zlog_targets.h
new file mode 100644
index 0000000000..7d7b26e32b
--- /dev/null
+++ b/lib/zlog_targets.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2015-19  David Lamparter, for NetDEF, Inc.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef _FRR_ZLOG_TARGETS_H
+#define _FRR_ZLOG_TARGETS_H
+
+#include <pthread.h>
+
+#include "zlog.h"
+
+/* multiple file log targets can be active */
+
+struct zlt_fd;
+
+struct zlog_cfg_file {
+	struct zlt_fd *active;
+
+	pthread_mutex_t cfg_mtx;
+
+	/* call zlog_file_set_other() to apply these */
+	int prio_min;
+	char ts_subsec;
+	bool record_priority;
+
+	/* call zlog_file_set_filename/fd() to change this */
+	char *filename;
+	int fd;
+};
+
+extern void zlog_file_init(struct zlog_cfg_file *zcf);
+extern void zlog_file_fini(struct zlog_cfg_file *zcf);
+
+extern void zlog_file_set_other(struct zlog_cfg_file *zcf);
+extern bool zlog_file_set_filename(struct zlog_cfg_file *zcf, const char *name);
+extern bool zlog_file_set_fd(struct zlog_cfg_file *zcf, int fd);
+extern bool zlog_file_rotate(struct zlog_cfg_file *zcf);
+
+/* syslog is always limited to one target */
+
+extern void zlog_syslog_set_facility(int facility);
+extern int zlog_syslog_get_facility(void);
+
+/* use ZLOG_DISABLED to disable */
+extern void zlog_syslog_set_prio_min(int prio_min);
+extern int zlog_syslog_get_prio_min(void);
+
+#endif /* _FRR_ZLOG_TARGETS_H */