Here is the v2 of the patch which introduces APIs to read controller

specific stats. Added Makefile.am updates which I had missed in the
previous post.

New APIs to read controller specific statistics.

This patch introduces 3 new APIs which can be used to read controller
statistics iteratively. (Eg. stats from memory.stat etc)

Reading of stats is initiated by cgroup_read_stats_begin() API, which
returns the first stat of the requested controller in addition to returing
a handle that should be used in subsequent reads.

cgroup_read_stats_next() API can be used to read the remaining stats
one by one. This needs the handle returned by cgroup_read_stats_begin().

cgroup_read_stats_end() API will terminate the stats reading iteration
initiated by cgroup_read_stats_begin().

Changelog:

v2
- Update tests/Makefile.am so that it generates appropriate rules
  for tests/read_stats.c in the Makefile. This is in addition to
  the manual updates done to the generated file tests/Makefile.in.

v1
- cgroup_read_stats apis now work with relative cgroup path names instead
  of absolute path names.

v0
- Initial post.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/libcgroup.h b/include/libcgroup.h
index 750e36e..efa852b 100644
--- a/include/libcgroup.h
+++ b/include/libcgroup.h
@@ -129,6 +129,11 @@ struct cgroup_file_info {
  */
 #define CG_HIER_MAX  CG_CONTROLLER_MAX
 
+struct cgroup_stat {
+	char name[FILENAME_MAX];
+	char value[CG_VALUE_MAX];
+};
+
 /* Functions and structures that can be used by the application*/
 struct cgroup;
 struct cgroup_controller;
@@ -250,6 +255,25 @@ int cgroup_walk_tree_next(const int depth, void **handle,
 				struct cgroup_file_info *info, int base_level);
 int cgroup_walk_tree_end(void **handle);
 
+/**
+ * Read the statistics values for the specified controller
+ * @controller: Name of the controller for which stats are requested.
+ * @path: cgroup path.
+ * @handle: Handle to be used during iteration.
+ * @stat: Stats values will be filled and returned here.
+ */
+int cgroup_read_stats_begin(char *controller, char *path, void **handle,
+				struct cgroup_stat *stat);
+
+/**
+ * Read the next stat value.
+ * @handle: Handle to be used during iteration.
+ * @stat: Stats values will be filled and returned here.
+ */
+int cgroup_read_stats_next(void **handle, struct cgroup_stat *stat);
+
+int cgroup_read_stats_end(void **handle);
+
 /* The wrappers for filling libcg structures */
 
 struct cgroup *cgroup_new_cgroup(const char *name);