api: Add support for DeleteCAS

api/kv.go

@@ -193,27 +193,44 @@ func (k *KV) put(key string, params map[string]string, body []byte, q *WriteOpti
 
 // Delete is used to delete a single key
 func (k *KV) Delete(key string, w *WriteOptions) (*WriteMeta, error) {
-	return k.deleteInternal(key, nil, w)
+	_, qm, err := k.deleteInternal(key, nil, w)
+	return qm, err
+}
+
+// DeleteCAS is used for a Delete Check-And-Set operation. The Key
+// and ModifyIndex are respected. Returns true on success or false on failures.
+func (k *KV) DeleteCAS(p *KVPair, q *WriteOptions) (bool, *WriteMeta, error) {
+	params := map[string]string{
+		"cas": strconv.FormatUint(p.ModifyIndex, 10),
+	}
+	return k.deleteInternal(p.Key, params, q)
 }
 
 // DeleteTree is used to delete all keys under a prefix
 func (k *KV) DeleteTree(prefix string, w *WriteOptions) (*WriteMeta, error) {
-	return k.deleteInternal(prefix, []string{"recurse"}, w)
+	_, qm, err := k.deleteInternal(prefix, map[string]string{"recurse": ""}, w)
+	return qm, err
 }
 
-func (k *KV) deleteInternal(key string, params []string, q *WriteOptions) (*WriteMeta, error) {
+func (k *KV) deleteInternal(key string, params map[string]string, q *WriteOptions) (bool, *WriteMeta, error) {
 	r := k.c.newRequest("DELETE", "/v1/kv/"+key)
 	r.setWriteOptions(q)
-	for _, param := range params {
-		r.params.Set(param, "")
+	for param, val := range params {
+		r.params.Set(param, val)
 	}
 	rtt, resp, err := requireOK(k.c.doRequest(r))
 	if err != nil {
-		return nil, err
+		return false, nil, err
 	}
-	resp.Body.Close()
+	defer resp.Body.Close()
 
 	qm := &WriteMeta{}
 	qm.RequestTime = rtt
-	return qm, nil
+
+	var buf bytes.Buffer
+	if _, err := io.Copy(&buf, resp.Body); err != nil {
+		return false, nil, fmt.Errorf("Failed to read response: %v", err)
+	}
+	res := strings.Contains(string(buf.Bytes()), "true")
+	return res, qm, nil
 }

api/kv_test.go

@@ -117,6 +117,51 @@ func TestClient_List_DeleteRecurse(t *testing.T) {
 	}
 }
 
+func TestClient_DeleteCAS(t *testing.T) {
+	c, s := makeClient(t)
+	defer s.stop()
+
+	kv := c.KV()
+
+	// Put the key
+	key := testKey()
+	value := []byte("test")
+	p := &KVPair{Key: key, Value: value}
+	if work, _, err := kv.CAS(p, nil); err != nil {
+		t.Fatalf("err: %v", err)
+	} else if !work {
+		t.Fatalf("CAS failure")
+	}
+
+	// Get should work
+	pair, meta, err := kv.Get(key, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if pair == nil {
+		t.Fatalf("expected value: %#v", pair)
+	}
+	if meta.LastIndex == 0 {
+		t.Fatalf("unexpected value: %#v", meta)
+	}
+
+	// CAS update with bad index
+	p.ModifyIndex = 1
+	if work, _, err := kv.DeleteCAS(p, nil); err != nil {
+		t.Fatalf("err: %v", err)
+	} else if work {
+		t.Fatalf("unexpected CAS")
+	}
+
+	// CAS update with valid index
+	p.ModifyIndex = meta.LastIndex
+	if work, _, err := kv.DeleteCAS(p, nil); err != nil {
+		t.Fatalf("err: %v", err)
+	} else if !work {
+		t.Fatalf("unexpected CAS failure")
+	}
+}
+
 func TestClient_CAS(t *testing.T) {
 	c, s := makeClient(t)
 	defer s.stop()