From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 28 Sep 2011 01:16:19 +0000 (-0400)
Subject: Add procname context
X-Git-Tag: v1.9.1~171
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=4847e9bbec5a73140193185073437d95fdf15f30;p=lttng-ust.git

Add procname context

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/ust/lttng-events.h b/include/ust/lttng-events.h
index 0439ea7a..e09443f1 100644
--- a/include/ust/lttng-events.h
+++ b/include/ust/lttng-events.h
@@ -323,6 +323,7 @@ void lttng_destroy_context(struct lttng_ctx *ctx);
 int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx);
 int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx);
 int lttng_add_pthread_id_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_procname_to_ctx(struct lttng_ctx **ctx);
 void lttng_context_vtid_reset(void);
 void lttng_context_vpid_reset(void);
 
diff --git a/include/ust/lttng-ust-abi.h b/include/ust/lttng-ust-abi.h
index c967fb11..303493ee 100644
--- a/include/ust/lttng-ust-abi.h
+++ b/include/ust/lttng-ust-abi.h
@@ -69,6 +69,7 @@ enum lttng_ust_context_type {
 	LTTNG_UST_CONTEXT_VTID			= 0,
 	LTTNG_UST_CONTEXT_VPID			= 1,
 	LTTNG_UST_CONTEXT_PTHREAD_ID		= 2,
+	LTTNG_UST_CONTEXT_PROCNAME		= 3,
 };
 
 struct lttng_ust_context {
diff --git a/libust/Makefile.am b/libust/Makefile.am
index cb00e179..9295d6b7 100644
--- a/libust/Makefile.am
+++ b/libust/Makefile.am
@@ -22,6 +22,7 @@ libust_la_SOURCES = \
 	lttng-context-vtid.c \
 	lttng-context-vpid.c \
 	lttng-context-pthread-id.c \
+	lttng-context-procname.c \
 	ltt-context.c
 
 libust_la_LDFLAGS = -no-undefined -version-info 0:0:0
diff --git a/libust/lttng-context-procname.c b/libust/lttng-context-procname.c
new file mode 100644
index 00000000..2056d194
--- /dev/null
+++ b/libust/lttng-context-procname.c
@@ -0,0 +1,88 @@
+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng UST procname context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <sys/prctl.h>
+#include <ust/lttng-events.h>
+#include <ust/lttng-tracer.h>
+#include <ust/ringbuffer-config.h>
+#include <assert.h>
+
+#define PROCNAME_LEN	17	/* includes \0 */
+
+/*
+ * We cache the result to ensure we don't trigger a system call for
+ * each event.
+ * Upon exec, procname changes, but exec takes care of throwing away
+ * this cached version.
+ */
+static char cached_procname[17];
+
+static inline
+char *wrapper_getprocname(void)
+{
+	int ret;
+
+	if (unlikely(!cached_procname[0])) {
+		ret = prctl(PR_GET_NAME, (unsigned long) cached_procname,
+			0, 0, 0);
+		assert(!ret);
+	}
+	return cached_procname;
+}
+
+void lttng_context_procname_reset(void)
+{
+	cached_procname[0] = '\0';
+}
+
+static
+size_t procname_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += PROCNAME_LEN;
+	return size;
+}
+
+static
+void procname_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct ltt_channel *chan)
+{
+	char *procname;
+
+	procname = wrapper_getprocname();
+	chan->ops->event_write(ctx, procname, PROCNAME_LEN);
+}
+
+int lttng_add_procname_to_ctx(struct lttng_ctx **ctx)
+{
+	struct lttng_ctx_field *field;
+
+	field = lttng_append_context(ctx);
+	if (!field)
+		return -ENOMEM;
+	if (lttng_find_context(*ctx, "procname")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "procname";
+	field->event_field.type.atype = atype_array;
+	field->event_field.type.u.array.elem_type.atype = atype_integer;
+	field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT;
+	field->event_field.type.u.array.elem_type.u.basic.integer.alignment = lttng_alignof(char) * CHAR_BIT;
+	field->event_field.type.u.array.elem_type.u.basic.integer.signedness = lttng_is_signed_type(char);
+	field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0;
+	field->event_field.type.u.array.elem_type.u.basic.integer.base = 10;
+	field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8;
+	field->event_field.type.u.array.length = PROCNAME_LEN;
+	field->get_size = procname_get_size;
+	field->record = procname_record;
+	return 0;
+}
diff --git a/libust/lttng-ust-abi.c b/libust/lttng-ust-abi.c
index e125ac6d..1d32e777 100644
--- a/libust/lttng-ust-abi.c
+++ b/libust/lttng-ust-abi.c
@@ -278,6 +278,8 @@ long lttng_abi_add_context(int objd,
 		return lttng_add_vtid_to_ctx(ctx);
 	case LTTNG_UST_CONTEXT_VPID:
 		return lttng_add_vpid_to_ctx(ctx);
+	case LTTNG_UST_CONTEXT_PROCNAME:
+		return lttng_add_procname_to_ctx(ctx);
 	default:
 		return -EINVAL;
 	}
diff --git a/tests/ust-basic-tracing/ust-basic-tracing.c b/tests/ust-basic-tracing/ust-basic-tracing.c
index d200b4f9..e97552a1 100644
--- a/tests/ust-basic-tracing/ust-basic-tracing.c
+++ b/tests/ust-basic-tracing/ust-basic-tracing.c
@@ -571,6 +571,8 @@ int send_app_msgs(int sock, const char *outputpath,
 	lum.cmd = LTTNG_UST_CONTEXT;
 	lum.u.context.ctx = LTTNG_UST_CONTEXT_VTID;
 	//lum.u.context.ctx = LTTNG_UST_CONTEXT_PTHREAD_ID;
+	//lum.u.context.ctx = LTTNG_UST_CONTEXT_VPID;
+	//lum.u.context.ctx = LTTNG_UST_CONTEXT_PROCNAME;
 	ret = send_app_cmd(sock, &lum, &lur);
 	if (ret)
 		return ret;