snapshot of https://github.com/ent/ent.git (master, 2026-09-15; blobs > 131072B omitted)

dialect/gremlin/http.go

@@ -0,0 +1,85 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
+package gremlin
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"entgo.io/ent/dialect/gremlin/encoding/graphson"
+
+	jsoniter "github.com/json-iterator/go"
+)
+
+type httpTransport struct {
+	client *http.Client
+	url    string
+}
+
+// NewHTTPTransport returns a new http transport.
+func NewHTTPTransport(urlStr string, client *http.Client) (RoundTripper, error) {
+	u, err := url.Parse(urlStr)
+	if err != nil {
+		return nil, fmt.Errorf("gremlin/http: parsing url: %w", err)
+	}
+	if client == nil {
+		client = http.DefaultClient
+	}
+	return &httpTransport{client, u.String()}, nil
+}
+
+// RoundTrip implements RouterTripper interface.
+func (t *httpTransport) RoundTrip(ctx context.Context, req *Request) (*Response, error) {
+	if req.Operation != OpsEval {
+		return nil, fmt.Errorf("gremlin/http: unsupported operation: %q", req.Operation)
+	}
+	if _, ok := req.Arguments[ArgsGremlin]; !ok {
+		return nil, errors.New("gremlin/http: missing query expression")
+	}
+
+	pr, pw := io.Pipe()
+	defer pr.Close()
+	go func() {
+		err := jsoniter.NewEncoder(pw).Encode(req.Arguments)
+		if err != nil {
+			err = fmt.Errorf("gremlin/http: encoding request: %w", err)
+		}
+		_ = pw.CloseWithError(err)
+	}()
+
+	var br io.Reader
+	{
+		req, err := http.NewRequest(http.MethodPost, t.url, pr)
+		if err != nil {
+			return nil, fmt.Errorf("gremlin/http: creating http request: %w", err)
+		}
+		req.Header.Set("Content-Type", "application/json")
+
+		rsp, err := t.client.Do(req.WithContext(ctx))
+		if err != nil {
+			return nil, fmt.Errorf("gremlin/http: posting http request: %w", err)
+		}
+		defer rsp.Body.Close()
+
+		if rsp.StatusCode < http.StatusOK || rsp.StatusCode > http.StatusPartialContent {
+			body, _ := io.ReadAll(rsp.Body)
+			return nil, fmt.Errorf("gremlin/http: status=%q, body=%q", rsp.Status, body)
+		}
+		if rsp.ContentLength > MaxResponseSize {
+			return nil, errors.New("gremlin/http: context length exceeds limit")
+		}
+		br = rsp.Body
+	}
+
+	var rsp Response
+	if err := graphson.NewDecoder(io.LimitReader(br, MaxResponseSize)).Decode(&rsp); err != nil {
+		return nil, fmt.Errorf("gremlin/http: decoding response: %w", err)
+	}
+	return &rsp, nil
+}