Move liblttng-ust to 'src/lib/'

[lttng-ust.git] / src / lib / lttng-ust / lttng-context-cpu-id.c

diff --git a/src/lib/lttng-ust/lttng-context-cpu-id.c b/src/lib/lttng-ust/lttng-context-cpu-id.c
new file mode 100644 (file)
index 0000000..900b3c2
--- /dev/null
+++ b/src/lib/lttng-ust/lttng-context-cpu-id.c
@@ -0,0 +1,83 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng UST CPU id context.
+ *
+ * Note: threads can be migrated at any point while executing the
+ * tracepoint probe. This means the CPU id field (and filter) is only
+ * statistical. For instance, even though a user might select a
+ * cpu_id==1 filter, there may be few events recorded into the channel
+ * appearing from other CPUs, due to migration.
+ */
+
+#define _LGPL_SOURCE
+#include <stddef.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <limits.h>
+#include <lttng/ust-events.h>
+#include <lttng/ust-tracer.h>
+#include "common/ringbuffer/getcpu.h"
+#include <lttng/ringbuffer-context.h>
+
+#include "context-internal.h"
+
+static
+size_t cpu_id_get_size(void *priv __attribute__((unused)),
+               size_t offset)
+{
+       size_t size = 0;
+
+       size += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(int));
+       size += sizeof(int);
+       return size;
+}
+
+static
+void cpu_id_record(void *priv __attribute__((unused)),
+                struct lttng_ust_lib_ring_buffer_ctx *ctx,
+                struct lttng_ust_channel_buffer *chan)
+{
+       int cpu;
+
+       cpu = lttng_ust_get_cpu();
+       chan->ops->event_write(ctx, &cpu, sizeof(cpu), lttng_ust_rb_alignof(cpu));
+}
+
+static
+void cpu_id_get_value(void *priv __attribute__((unused)),
+               struct lttng_ust_ctx_value *value)
+{
+       value->u.s64 = lttng_ust_get_cpu();
+}
+
+static const struct lttng_ust_ctx_field *ctx_field = lttng_ust_static_ctx_field(
+       lttng_ust_static_event_field("cpu_id",
+               lttng_ust_static_type_integer(sizeof(int) * CHAR_BIT,
+                               lttng_ust_rb_alignof(int) * CHAR_BIT,
+                               lttng_ust_is_signed_type(int),
+                               BYTE_ORDER, 10),
+               false, false),
+       cpu_id_get_size,
+       cpu_id_record,
+       cpu_id_get_value,
+       NULL, NULL);
+
+int lttng_add_cpu_id_to_ctx(struct lttng_ust_ctx **ctx)
+{
+       int ret;
+
+       if (lttng_find_context(*ctx, ctx_field->event_field->name)) {
+               ret = -EEXIST;
+               goto error_find_context;
+       }
+       ret = lttng_ust_context_append(ctx, ctx_field);
+       if (ret)
+               return ret;
+       return 0;
+
+error_find_context:
+       return ret;
+}