core: add a property that shows the current memory usage of a unit

This is exposed the memory.usage_in_bytes cgroup property on the bus,
and makes "systemctl status" show it in its default output.

2 files changed, 12 insertions, 0 deletions

diff --git a/src/shared/cgroup-util.c b/src/shared/cgroup-util.c
index 86729f14bf..0d3cc53517 100644
--- a/src/shared/cgroup-util.c
+++ b/src/shared/cgroup-util.c
@@ -1592,6 +1592,17 @@ int cg_set_attribute(const char *controller, const char *path, const char *attri
         return write_string_file_no_create(p, value);
 }
 
+int cg_get_attribute(const char *controller, const char *path, const char *attribute, char **ret) {
+        _cleanup_free_ char *p = NULL;
+        int r;
+
+        r = cg_get_path(controller, path, attribute, &p);
+        if (r < 0)
+                return r;
+
+        return read_one_line_file(p, ret);
+}
+
 static const char mask_names[] =
         "cpu\0"
         "cpuacct\0"
diff --git a/src/shared/cgroup-util.h b/src/shared/cgroup-util.h
index 89dc2b1135..96a3d3bafa 100644
--- a/src/shared/cgroup-util.h
+++ b/src/shared/cgroup-util.h
@@ -85,6 +85,7 @@ int cg_attach_fallback(const char *controller, const char *path, pid_t pid);
 int cg_create_and_attach(const char *controller, const char *path, pid_t pid);
 
 int cg_set_attribute(const char *controller, const char *path, const char *attribute, const char *value);
+int cg_get_attribute(const char *controller, const char *path, const char *attribute, char **ret);
 
 int cg_set_group_access(const char *controller, const char *path, mode_t mode, uid_t uid, gid_t gid);
 int cg_set_task_access(const char *controller, const char *path, mode_t mode, uid_t uid, gid_t gid);