consul/state: adding KVSList for listing a given prefix

consul/state/state_store.go

@@ -755,6 +755,32 @@ func (s *StateStore) KVSGet(key string) (*structs.DirEntry, error) {
 	return entry.(*structs.DirEntry), nil
 }
 
+// KVSList is used to list out all keys under a given prefix. If the
+// prefix is left empty, all keys in the KVS will be returned. The
+// returned index is the max index of the returned kvs entries.
+func (s *StateStore) KVSList(prefix string) (uint64, []string, error) {
+	tx := s.db.Txn(false)
+	defer tx.Abort()
+
+	// Query the prefix and list the available keys
+	entries, err := tx.Get("kvs", "id_prefix", prefix)
+	if err != nil {
+		return 0, nil, fmt.Errorf("failed kvs lookup: %s", err)
+	}
+
+	// Gather all of the keys found in the store
+	var keys []string
+	var lindex uint64
+	for entry := entries.Next(); entry != nil; entry = entries.Next() {
+		e := entry.(*structs.DirEntry)
+		keys = append(keys, e.Key)
+		if e.ModifyIndex > lindex {
+			lindex = e.ModifyIndex
+		}
+	}
+	return lindex, keys, nil
+}
+
 // KVSDelete is used to perform a shallow delete on a single key in the
 // the state store.
 func (s *StateStore) KVSDelete(idx uint64, key string) error {

consul/state/state_store_test.go

@@ -883,3 +883,59 @@ func TestStateStore_KVSDelete(t *testing.T) {
 		t.Fatalf("bad index: %d", idx)
 	}
 }
+
+func TestStateStore_KVSList(t *testing.T) {
+	s := testStateStore(t)
+
+	// Listing an empty KVS returns nothing
+	idx, keys, err := s.KVSList("")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if idx != 0 {
+		t.Fatalf("bad index: %d", idx)
+	}
+	if keys != nil {
+		t.Fatalf("expected nil, got: %#v", keys)
+	}
+
+	// Create some KVS entries
+	testSetKey(t, s, 1, "foo", "foo")
+	testSetKey(t, s, 2, "foo/bar", "bar")
+	testSetKey(t, s, 3, "foo/bar/zip", "zip")
+	testSetKey(t, s, 4, "foo/bar/zip/zorp", "zorp")
+	testSetKey(t, s, 5, "foo/bar/baz", "baz")
+
+	// List out all of the keys
+	idx, keys, err = s.KVSList("")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Check the index
+	if idx != 5 {
+		t.Fatalf("bad index: %d", idx)
+	}
+
+	// Check that all of the keys were returned
+	if n := len(keys); n != 5 {
+		t.Fatalf("expected 5 kvs entries, got: %d", n)
+	}
+
+	// Try listing with a provided prefix
+	idx, keys, err = s.KVSList("foo/bar/zip")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if idx != 4 {
+		t.Fatalf("bad index: %d", idx)
+	}
+
+	// Check that only the keys in the prefix were returned
+	if n := len(keys); n != 2 {
+		t.Fatalf("expected 2 kvs entries, got: %d", n)
+	}
+	if keys[0] != "foo/bar/zip" || keys[1] != "foo/bar/zip/zorp" {
+		t.Fatalf("bad: %#v", keys)
+	}
+}