Fix: define _LGPL_SOURCE in C files

[lttng-tools.git] / src / bin / lttng-sessiond / ust-metadata.c

diff --git a/src/bin/lttng-sessiond/ust-metadata.c b/src/bin/lttng-sessiond/ust-metadata.c
index 2735169747e9bfc8108cb5e009cd8a922eefffa8..379429285ad6af7f033ce3950c29190eacf706ac 100644 (file)
--- a/src/bin/lttng-sessiond/ust-metadata.c
+++ b/src/bin/lttng-sessiond/ust-metadata.c
@@ -20,6 +20,7 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <stdint.h>
 #include <string.h>
 #include <stdarg.h>
@@ -37,6 +38,13 @@
 #define max_t(type, a, b)      ((type) ((a) > (b) ? (a) : (b)))
 #endif
 
+#define NR_CLOCK_OFFSET_SAMPLES                10
+
+struct offset_sample {
+       uint64_t offset;                /* correlation offset */
+       uint64_t measure_delta;         /* lower is better */
+};
+
 static inline
 int fls(unsigned int x)
 {
@@ -490,37 +498,65 @@ int _lttng_event_header_declare(struct ust_registry_session *session)
        );
 }
 
-/*
- * Approximation of NTP time of day to clock monotonic correlation,
- * taken at start of trace.
- * Yes, this is only an approximation. Yes, we can (and will) do better
- * in future versions.
- */
 static
-uint64_t measure_clock_offset(void)
+int measure_single_clock_offset(struct offset_sample *sample)
 {
-       uint64_t offset, monotonic[2], realtime;
+       uint64_t offset, monotonic[2], measure_delta, realtime;
        struct timespec rts = { 0, 0 };
        int ret;
 
        monotonic[0] = trace_clock_read64();
        ret = clock_gettime(CLOCK_REALTIME, &rts);
-       if (ret < 0)
-               return 0;
+       if (ret < 0) {
+               return ret;
+       }
        monotonic[1] = trace_clock_read64();
+       measure_delta = monotonic[1] - monotonic[0];
+       if (measure_delta > sample->measure_delta) {
+               /*
+                * Discard value if it took longer to read than the best
+                * sample so far.
+                */
+               return 0;
+       }
        offset = (monotonic[0] + monotonic[1]) >> 1;
        realtime = (uint64_t) rts.tv_sec * 1000000000ULL;
        realtime += rts.tv_nsec;
        offset = realtime - offset;
-       return offset;
+       sample->offset = offset;
+       sample->measure_delta = measure_delta;
+       return 0;
 }
 
+/*
+ * Approximation of NTP time of day to clock monotonic correlation,
+ * taken at start of trace. Keep the measurement that took the less time
+ * to complete, thus removing imprecision caused by preemption.
+ */
+static
+uint64_t measure_clock_offset(void)
+{
+       int i;
+       struct offset_sample offset_best_sample = {
+               .offset = 0,
+               .measure_delta = UINT64_MAX,
+       };
+
+       for (i = 0; i < NR_CLOCK_OFFSET_SAMPLES; i++) {
+               if (measure_single_clock_offset(&offset_best_sample)) {
+                       return 0;
+               }
+       }
+       return offset_best_sample.offset;
+}
 
 /*
  * Should be called with session registry mutex held.
  */
 int ust_metadata_session_statedump(struct ust_registry_session *session,
-               struct ust_app *app)
+               struct ust_app *app,
+               uint32_t major,
+               uint32_t minor)
 {
        unsigned char *uuid_c;
        char uuid_s[UUID_STR_LEN],
@@ -529,7 +565,6 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
        char hostname[HOST_NAME_MAX];
 
        assert(session);
-       assert(app);
 
        uuid_c = session->uuid;
 
@@ -585,12 +620,10 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
                "       domain = \"ust\";\n"
                "       tracer_name = \"lttng-ust\";\n"
                "       tracer_major = %u;\n"
-               "       tracer_minor = %u;\n"
-               "       tracer_patchlevel = %u;\n",
+               "       tracer_minor = %u;\n",
                hostname,
-               app->version.major,
-               app->version.minor,
-               app->version.patchlevel
+               major,
+               minor
                );
        if (ret)
                goto end;
@@ -601,8 +634,10 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
         */
        if (app) {
                ret = lttng_metadata_printf(session,
+                       "       tracer_patchlevel = %u;\n"
                        "       vpid = %d;\n"
                        "       procname = \"%s\";\n",
+                       app->version.patchlevel,
                        (int) app->pid,
                        app->name
                        );