Implement per-context filtering

[lttng-ust.git] / liblttng-ust / lttng-context.c

diff --git a/liblttng-ust/lttng-context.c b/liblttng-ust/lttng-context.c
index 16894ec1032b722407ce578d43f47051a62bbc60..fc2ab4f570b8182ef69f44a8e3375e5adcde1630 100644 (file)
--- a/liblttng-ust/lttng-context.c
+++ b/liblttng-ust/lttng-context.c
@@ -27,6 +27,11 @@
 #include <string.h>
 #include <assert.h>
 
+/*
+ * The filter implementation requires that two consecutive "get" for the
+ * same context performed by the same thread return the same result.
+ */
+
 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
 {
        unsigned int i;
@@ -41,6 +46,22 @@ int lttng_find_context(struct lttng_ctx *ctx, const char *name)
        return 0;
 }
 
+int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
+{
+       unsigned int i;
+
+       if (!ctx)
+               return -1;
+       for (i = 0; i < ctx->nr_fields; i++) {
+               /* Skip allocated (but non-initialized) contexts */
+               if (!ctx->fields[i].event_field.name)
+                       continue;
+               if (!strcmp(ctx->fields[i].event_field.name, name))
+                       return i;
+       }
+       return -1;
+}
+
 /*
  * Note: as we append context information, the pointer location may change.
  */