X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fust-metadata.c;h=f4f273b16cc7021e2f4869e52b42dfd7f14799dd;hp=2735169747e9bfc8108cb5e009cd8a922eefffa8;hb=d7ba13889c8692b14f99238ddf2721ed78df89d2;hpb=7972aab22f74b18faa168c0482216a3dd711a075

diff --git a/src/bin/lttng-sessiond/ust-metadata.c b/src/bin/lttng-sessiond/ust-metadata.c
index 273516974..f4f273b16 100644
--- 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)
 {
@@ -112,6 +120,23 @@ ssize_t metadata_reserve(struct ust_registry_session *session, size_t len)
 	return ret;
 }
 
+static
+int metadata_file_append(struct ust_registry_session *session,
+		const char *str, size_t len)
+{
+	ssize_t written;
+
+	if (session->metadata_fd < 0) {
+		return 0;
+	}
+	/* Write to metadata file */
+	written = lttng_write(session->metadata_fd, str, len);
+	if (written != len) {
+		return -1;
+	}
+	return 0;
+}
+
 /*
  * We have exclusive access to our metadata buffer (protected by the
  * ust_lock), so we can do racy operations such as looking for
@@ -141,6 +166,11 @@ int lttng_metadata_printf(struct ust_registry_session *session,
 		goto end;
 	}
 	memcpy(&session->metadata[offset], str, len);
+	ret = metadata_file_append(session, str, len);
+	if (ret) {
+		PERROR("Error appending to metadata file");
+		goto end;
+	}
 	DBG3("Append to metadata: \"%s\"", str);
 	ret = 0;
 
@@ -490,37 +520,65 @@ 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 +587,6 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
 	char hostname[HOST_NAME_MAX];
 
 	assert(session);
-	assert(app);
 
 	uuid_c = session->uuid;
 
@@ -540,6 +597,15 @@ int ust_metadata_session_statedump(struct ust_registry_session *session,
 		uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
 		uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
 
+	/* For crash ABI */
+	ret = lttng_metadata_printf(session,
+		"/* CTF %u.%u */\n\n",
+		CTF_SPEC_MAJOR,
+		CTF_SPEC_MINOR);
+	if (ret) {
+		goto end;
+	}
+
 	ret = lttng_metadata_printf(session,
 		"typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
 		"typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
@@ -585,12 +651,10 @@ 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 +665,10 @@ 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
 			);