[PATCH v18 09/18] trace-cmd: Add new API to generate a unique ID of the tracing session

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

A new libtracecmd API is implemented:
	unsigned long long tracecmd_generate_traceid(void);
At trace-cmd init phase a unique ID, used for the current tracing session.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h  |  1 +
 lib/trace-cmd/trace-util.c     | 37 ++++++++++++++++++++++++++++++++++
 tracecmd/include/trace-local.h |  1 +
 tracecmd/trace-record.c        |  1 +
 4 files changed, 40 insertions(+)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 9a2b7db..ad69313 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -441,6 +441,7 @@ void tracecmd_plog_error(const char *fmt, ...);
 int tracecmd_set_logfile(char *logfile);
 
 /* --- System --- */
+unsigned long long tracecmd_generate_traceid(void);
 int tracecmd_count_cpus(void);
 
 /* --- Hack! --- */
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 75ec5a3..fabd558 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -18,6 +18,8 @@
 #include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/sysinfo.h>
+#include <time.h>
 
 #include "trace-cmd.h"
 #include "event-utils.h"
@@ -1309,3 +1311,38 @@ error:
 	tracecmd_put_tracing_file(path);
 	return ret;
 }
+
+#define FNV_64_PRIME 0x100000001b3ULL
+/*
+ * tracecmd_generate_traceid - Generate a unique ID, used to identify
+ *			       the current tracing session
+ *
+ * Returns unique ID
+ */
+unsigned long long tracecmd_generate_traceid(void)
+{
+	unsigned long long hash = 0;
+	unsigned char *ustr;
+	struct sysinfo sinfo;
+	struct timespec ts;
+	char *str = NULL;
+
+	clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
+	sysinfo(&sinfo);
+	asprintf(&str, "%ld %ld %ld %ld %ld %ld %ld %ld %d",
+		 ts.tv_sec, ts.tv_nsec,
+		 sinfo.loads[0], sinfo.loads[1], sinfo.loads[2],
+		 sinfo.freeram, sinfo.sharedram, sinfo.freeswap,
+		 sinfo.procs);
+	if (!str)
+		return 0;
+	ustr = (unsigned char *)str;
+	hash = 0;
+	while (*ustr) {
+		hash ^= (unsigned long long)*ustr++;
+		hash *= FNV_64_PRIME;
+	}
+
+	free(str);
+	return hash;
+}
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 51abef1..6203e0d 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -182,6 +182,7 @@ struct pid_addr_maps {
 struct buffer_instance {
 	struct buffer_instance	*next;
 	struct tracecmd_instance	*ftrace;
+	unsigned long long	trace_id;
 	char			*cpumask;
 	struct event_list	*events;
 	struct event_list	**event_next;
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 7a3d687..7089f7b 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -5061,6 +5061,7 @@ void init_top_instance(void)
 		top_instance.ftrace = tracecmd_alloc_instance(NULL);
 	top_instance.cpu_count = tracecmd_count_cpus();
 	top_instance.flags = BUFFER_FL_KEEP;
+	top_instance.trace_id = tracecmd_generate_traceid();
 	tracecmd_init_instance(&top_instance);
 }
 
-- 
2.23.0