Implement UST clock override plugin support

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/ust-clock.h b/src/bin/lttng-sessiond/ust-clock.h
index 7d9c99a66a19c3b55209b86fa91d97f062dcf5bf..8493737634a72d8656e6ddb155aa68d6452c33ea 100644 (file)
--- a/src/bin/lttng-sessiond/ust-clock.h
+++ b/src/bin/lttng-sessiond/ust-clock.h
@@ -25,12 +25,26 @@
 #include <stdint.h>
 #include <stddef.h>
 #include <stdio.h>
-#include <errno.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+#include <lttng/ust-clock.h>
 
 #include <common/compat/uuid.h>
 
 /* TRACE CLOCK */
 
+struct lttng_trace_clock {
+       uint64_t (*read64)(void);
+       uint64_t (*freq)(void);
+       int (*uuid)(char *uuid);
+       const char *(*name)(void);
+       const char *(*description)(void);
+};
+
+extern struct lttng_trace_clock *lttng_trace_clock;
+
+void lttng_ust_clock_init(void);
+
 /*
  * Currently using the kernel MONOTONIC clock, waiting for kernel-side
  * LTTng to implement mmap'd trace clock.
@@ -39,7 +53,7 @@
 /* Choosing correct trace clock */
 
 static __inline__
-uint64_t trace_clock_read64(void)
+uint64_t trace_clock_read64_monotonic(void)
 {
        struct timespec ts;
 
@@ -48,13 +62,13 @@ uint64_t trace_clock_read64(void)
 }
 
 static __inline__
-uint64_t trace_clock_freq(void)
+uint64_t trace_clock_freq_monotonic(void)
 {
        return 1000000000ULL;
 }
 
 static __inline__
-int trace_clock_uuid(char *uuid)
+int trace_clock_uuid_monotonic(char *uuid)
 {
        int ret = 0;
        size_t len;
@@ -69,15 +83,93 @@ int trace_clock_uuid(char *uuid)
        if (!fp) {
                return -ENOENT;
        }
-       len = fread(uuid, 1, UUID_STR_LEN - 1, fp);
-       if (len < UUID_STR_LEN - 1) {
+       len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp);
+       if (len < LTTNG_UST_UUID_STR_LEN - 1) {
                ret = -EINVAL;
                goto end;
        }
-       uuid[UUID_STR_LEN - 1] = '\0';
+       uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0';
 end:
        fclose(fp);
        return ret;
 }
 
+static __inline__
+const char *trace_clock_name_monotonic(void)
+{
+       return "monotonic";
+}
+
+static __inline__
+const char *trace_clock_description_monotonic(void)
+{
+       return "Monotonic Clock";
+}
+
+static __inline__
+uint64_t trace_clock_read64(void)
+{
+       struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+       if (caa_likely(!ltc)) {
+               return trace_clock_read64_monotonic();
+       } else {
+               cmm_read_barrier_depends();     /* load ltc before content */
+               return ltc->read64();
+       }
+}
+
+static __inline__
+uint64_t trace_clock_freq(void)
+{
+       struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+       if (!ltc) {
+               return trace_clock_freq_monotonic();
+       } else {
+               cmm_read_barrier_depends();     /* load ltc before content */
+               return ltc->freq();
+       }
+}
+
+static __inline__
+int trace_clock_uuid(char *uuid)
+{
+       struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+       cmm_read_barrier_depends();     /* load ltc before content */
+       /* Use default UUID cb when NULL */
+       if (!ltc || !ltc->uuid) {
+               return trace_clock_uuid_monotonic(uuid);
+       } else {
+               return ltc->uuid(uuid);
+       }
+}
+
+static __inline__
+const char *trace_clock_name(void)
+{
+       struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+       if (!ltc) {
+               return trace_clock_name_monotonic();
+       } else {
+               cmm_read_barrier_depends();     /* load ltc before content */
+               return ltc->name();
+       }
+}
+
+static __inline__
+const char *trace_clock_description(void)
+{
+       struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock);
+
+       if (!ltc) {
+               return trace_clock_description_monotonic();
+       } else {
+               cmm_read_barrier_depends();     /* load ltc before content */
+               return ltc->description();
+       }
+}
+
 #endif /* _UST_CLOCK_H */

diff --git a/src/bin/lttng-sessiond/ust-metadata.c b/src/bin/lttng-sessiond/ust-metadata.c
index f4f273b16cc7021e2f4869e52b42dfd7f14799dd..b67921ef81b88c2712aea27365a694a8dcc113c0 100644 (file)
--- a/src/bin/lttng-sessiond/ust-metadata.c
+++ b/src/bin/lttng-sessiond/ust-metadata.c
@@ -524,6 +524,7 @@ static
 int measure_single_clock_offset(struct offset_sample *sample)
 {
        uint64_t offset, monotonic[2], measure_delta, realtime;
+       uint64_t tcf = trace_clock_freq();
        struct timespec rts = { 0, 0 };
        int ret;
 
@@ -544,6 +545,9 @@ int measure_single_clock_offset(struct offset_sample *sample)
        offset = (monotonic[0] + monotonic[1]) >> 1;
        realtime = (uint64_t) rts.tv_sec * 1000000000ULL;
        realtime += rts.tv_nsec;
+       if (tcf != 1000000000ULL) {
+               realtime /= 1000000000ULL / tcf;
+       }
        offset = realtime - offset;
        sample->offset = offset;
        sample->measure_delta = measure_delta;
@@ -685,8 +689,8 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
 
        ret = lttng_metadata_printf(session,
                "clock {\n"
-               "       name = %s;\n",
-               "monotonic"
+               "       name = \"%s\";\n",
+               trace_clock_name()
                );
        if (ret)
                goto end;
@@ -701,11 +705,12 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
        }
 
        ret = lttng_metadata_printf(session,
-               "       description = \"Monotonic Clock\";\n"
+               "       description = \"%s\";\n"
                "       freq = %" PRIu64 "; /* Frequency, in Hz */\n"
                "       /* clock value offset from Epoch is: offset * (1/freq) */\n"
                "       offset = %" PRIu64 ";\n"
                "};\n\n",
+               trace_clock_description(),
                trace_clock_freq(),
                measure_clock_offset()
                );
@@ -715,20 +720,23 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
        ret = lttng_metadata_printf(session,
                "typealias integer {\n"
                "       size = 27; align = 1; signed = false;\n"
-               "       map = clock.monotonic.value;\n"
+               "       map = clock.%s.value;\n"
                "} := uint27_clock_monotonic_t;\n"
                "\n"
                "typealias integer {\n"
                "       size = 32; align = %u; signed = false;\n"
-               "       map = clock.monotonic.value;\n"
+               "       map = clock.%s.value;\n"
                "} := uint32_clock_monotonic_t;\n"
                "\n"
                "typealias integer {\n"
                "       size = 64; align = %u; signed = false;\n"
-               "       map = clock.monotonic.value;\n"
+               "       map = clock.%s.value;\n"
                "} := uint64_clock_monotonic_t;\n\n",
+               trace_clock_name(),
                session->uint32_t_alignment,
-               session->uint64_t_alignment
+               trace_clock_name(),
+               session->uint64_t_alignment,
+               trace_clock_name()
                );
        if (ret)
                goto end;