Source: index.go in package golang.org/x/pkgsite/internal/index

Package index provides a client for communicating with the module index.

package index

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"go.opencensus.io/plugin/ochttp"
	"golang.org/x/net/context/ctxhttp"
	"golang.org/x/pkgsite/internal"
	"golang.org/x/pkgsite/internal/derrors"
)

A Client is used by the worker service to communicate with the module index.

URL of the module index

	url string

client used for HTTP requests. It is mutable for testing purposes.

	httpClient *http.Client
}

New constructs a *Client using the provided rawurl, which is expected to be an absolute URI that can be directly passed to http.Get.

func New(rawurl string) (_ *Client, err error) {
	defer derrors.Add(&err, "index.New(%q)", rawurl)

	u, err := url.Parse(rawurl)
	if err != nil {
		return nil, fmt.Errorf("url.Parse(%q): %v", rawurl, err)
	}
	if u.Scheme != "https" {
		return nil, fmt.Errorf("scheme must be https (got %s)", u.Scheme)
	}
	return &Client{url: strings.TrimRight(rawurl, "/"), httpClient: &http.Client{Transport: &ochttp.Transport{}}}, nil
}

func (c *Client) pollURL(since time.Time, limit int) string {
	values := url.Values{}
	values.Set("since", since.Format(time.RFC3339))
	if limit > 0 {
		values.Set("limit", strconv.Itoa(limit))
	}
	return fmt.Sprintf("%s?%s", c.url, values.Encode())
}

GetVersions queries the index for new versions.

func (c *Client) GetVersions(ctx context.Context, since time.Time, limit int) (_ []*internal.IndexVersion, err error) {
	defer derrors.Wrap(&err, "index.Client.GetVersions(ctx, %s, %d)", since, limit)

	u := c.pollURL(since, limit)
	r, err := ctxhttp.Get(ctx, c.httpClient, u)
	if err != nil {
		return nil, fmt.Errorf("ctxhttp.Get(ctx, nil, %q): %v", u, err)
	}
	defer r.Body.Close()

	var versions []*internal.IndexVersion
	dec := json.NewDecoder(r.Body)

The module index returns a stream of JSON objects formatted with newline as the delimiter.

	for dec.More() {
		var l internal.IndexVersion
		if err := dec.Decode(&l); err != nil {
			return nil, fmt.Errorf("decoding JSON: %v", err)
		}
		versions = append(versions, &l)
	}
	return versions, nil