Feature: Provide new libcgroup walk tree API

From: Balbir Singh <balbir@linux.vnet.ibm.com>

Changelog v3..v4

1. Add _end() method for the iterator

Changelog v3..v2

1. Move to iterator based design

Changelog v2..v1

1. Add base path and depth semantics for walking

This patch adds the capability to walk cgroups by providing a new API
called cgroup_walk_tree. The API accepts the controller to walk and the
order in which the directories and files must be visited. The code is
implemented as an iterator, the begin function starts the walk and
we have depth control. The next function gets the following node
and returns ECGEOF when done.

libcgroup.map has been updated to reflect the same change and the prototype
is exported in libcgroup.h.

I've also added test cases (tests/walk_test.c). Sample output is show

root is /cgroup/cpu///
path , parent , relative /, full /cgroup/cpu///
path l3, parent , relative /l3, full /cgroup/cpu///l3
path ll1, parent l3, relative /l3/ll1, full /cgroup/cpu///l3/ll1
path lll1, parent ll1, relative /l3/ll1/lll1, full /cgroup/cpu///l3/ll1/lll1
path l2, parent , relative /l2, full /cgroup/cpu///l2
path ll1, parent l2, relative /l2/ll1, full /cgroup/cpu///l2/ll1
path lll1, parent ll1, relative /l2/ll1/lll1, full /cgroup/cpu///l2/ll1/lll1
path l1, parent , relative /l1, full /cgroup/cpu///l1
path ll1, parent l1, relative /l1/ll1, full /cgroup/cpu///l1/ll1
path lll1, parent ll1, relative /l1/ll1/lll1, full /cgroup/cpu///l1/ll1/lll1
path a, parent , relative /a, full /cgroup/cpu///a
path e, parent a, relative /a/e, full /cgroup/cpu///a/e
path f, parent e, relative /a/e/f, full /cgroup/cpu///a/e/f
path f, parent a, relative /a/f, full /cgroup/cpu///a/f
path x, parent a, relative /a/x, full /cgroup/cpu///a/x
path b, parent a, relative /a/b, full /cgroup/cpu///a/b
path c, parent b, relative /a/b/c, full /cgroup/cpu///a/b/c
path d, parent c, relative /a/b/c/d, full /cgroup/cpu///a/b/c/d
path default, parent , relative /default, full /cgroup/cpu///default
root is /cgroup/cpu//a/
path , parent , relative /, full /cgroup/cpu//a/
path e, parent , relative /e, full /cgroup/cpu//a/e
path f, parent e, relative /e/f, full /cgroup/cpu//a/e/f
path f, parent , relative /f, full /cgroup/cpu//a/f
path x, parent , relative /x, full /cgroup/cpu//a/x
path b, parent , relative /b, full /cgroup/cpu//a/b
path c, parent b, relative /b/c, full /cgroup/cpu//a/b/c
Walking the first 5 nodes
root is /cgroup/cpu///
path , parent , relative /, full /cgroup/cpu///
path l3, parent , relative /l3, full /cgroup/cpu///l3
path ll1, parent l3, relative /l3/ll1, full /cgroup/cpu///l3/ll1
path lll1, parent ll1, relative /l3/ll1/lll1, full /cgroup/cpu///l3/ll1/lll1


NOTE: Parent directory is represented by an empty (not NULL) string "".
The length of the string is 0.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>



git-svn-id: https://libcg.svn.sourceforge.net/svnroot/libcg/trunk@356 4f4bb910-9a46-0410-90c8-c897d4f1cd53

2 files changed, 95 insertions, 1 deletions

diff --git a/tests/Makefile b/tests/Makefile
index 00bfe3d..9ebadac 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -8,7 +8,8 @@ TARGET= libtest_functions.a \
 	libcgrouptest01 \
 	libcg_ba \
 	setuid \
-	pathtest
+	pathtest \
+	walk_test
 
 all:	$(TARGET)
 
@@ -30,5 +31,8 @@ setuid: setuid.c
 pathtest: pathtest.c
 	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS) $(LIBS)
 
+walk_test: walk_test.c
+	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS) $(LIBS)
+
 clean:
 	\rm -f $(TARGET) test_functions.o
diff --git a/tests/walk_test.c b/tests/walk_test.c
new file mode 100644
index 0000000..2e16ecd
--- /dev/null
+++ b/tests/walk_test.c
@@ -0,0 +1,90 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string.h>
+#include <libcgroup.h>
+
+void visit_node(struct cgroup_file_info *info, char *root)
+{
+	if (info->type == CGROUP_FILE_TYPE_DIR) {
+		printf("path %s, parent %s, relative %s, full %s\n",
+			info->path, info->parent, info->full_path +
+				+ strlen(root) - 1,
+				info->full_path);
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+	char *controller;
+	void *handle;
+	struct cgroup_file_info info;
+	char root[FILENAME_MAX];
+	int lvl, i;
+
+	if (argc < 2) {
+		fprintf(stderr, "Usage %s: <controller name>\n",
+			argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	controller = argv[1];
+
+	cgroup_init();
+
+	ret = cgroup_walk_tree_begin(controller, "/", 0, &handle, &info, &lvl);
+
+	if (ret != 0) {
+		fprintf(stderr, "Walk failed\n");
+		exit(EXIT_FAILURE);
+	}
+	strcpy(root, info.full_path);
+	printf("root is %s\n", root);
+	visit_node(&info, root);
+	while ((ret = cgroup_walk_tree_next(0, &handle, &info, lvl)) !=
+			ECGEOF) {
+		visit_node(&info, root);
+	}
+	cgroup_walk_tree_end(&handle);
+
+	ret = cgroup_walk_tree_begin(controller, "/a", 2, &handle, &info, &lvl);
+
+	if (ret != 0) {
+		fprintf(stderr, "Walk failed\n");
+		exit(EXIT_FAILURE);
+	}
+	strcpy(root, info.full_path);
+	printf("root is %s\n", root);
+	visit_node(&info, root);
+	while ((ret = cgroup_walk_tree_next(2, &handle, &info, lvl)) !=
+			ECGEOF) {
+		visit_node(&info, root);
+	}
+	cgroup_walk_tree_end(&handle);
+
+	/*
+	 * Walk only the first five nodes
+	 */
+	i = 0;
+	printf("Walking the first 5 nodes\n");
+	ret = cgroup_walk_tree_begin(controller, "/", 0, &handle, &info, &lvl);
+
+	if (ret != 0) {
+		fprintf(stderr, "Walk failed\n");
+		exit(EXIT_FAILURE);
+	}
+	strcpy(root, info.full_path);
+	printf("root is %s\n", root);
+	visit_node(&info, root);
+	i++;
+	while ((ret = cgroup_walk_tree_next(0, &handle, &info, lvl)) !=
+			ECGEOF) {
+		visit_node(&info, root);
+		if (++i >= 5)
+			break;
+	}
+	cgroup_walk_tree_end(&handle);
+	return EXIT_SUCCESS;
+}