add http lock implementation

sync/lock/http/http.go

@@ -0,0 +1,135 @@
+// Package http adds a http lock implementation
+package http
+
+import (
+	"errors"
+	"fmt"
+	"hash/crc32"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"strings"
+
+	"github.com/micro/go-micro/sync/lock"
+)
+
+var (
+	DefaultPath    = "/sync/lock"
+	DefaultAddress = "localhost:8080"
+)
+
+type httpLock struct {
+	opts lock.Options
+}
+
+func (h *httpLock) url(id string) (string, error) {
+	sum := crc32.ChecksumIEEE([]byte(id))
+	node := h.opts.Nodes[sum%uint32(len(h.opts.Nodes))]
+
+	// parse the host:port or whatever
+	uri, err := url.Parse(node)
+	if err != nil {
+		return "", err
+	}
+
+	if len(uri.Scheme) == 0 {
+		uri.Scheme = "http"
+	}
+
+	// set path
+	// build path
+	path := filepath.Join(DefaultPath, h.opts.Prefix, id)
+	uri.Path = path
+
+	// return url
+	return uri.String(), nil
+}
+
+func (h *httpLock) Acquire(id string, opts ...lock.AcquireOption) error {
+	var options lock.AcquireOptions
+	for _, o := range opts {
+		o(&options)
+	}
+
+	uri, err := h.url(id)
+	if err != nil {
+		return err
+	}
+
+	ttl := fmt.Sprintf("%d", int64(options.TTL.Seconds()))
+	wait := fmt.Sprintf("%d", int64(options.Wait.Seconds()))
+
+	rsp, err := http.PostForm(uri, url.Values{
+		"id":   {id},
+		"ttl":  {ttl},
+		"wait": {wait},
+	})
+	if err != nil {
+		return err
+	}
+	defer rsp.Body.Close()
+
+	b, err := ioutil.ReadAll(rsp.Body)
+	if err != nil {
+		return err
+	}
+
+	// success
+	if rsp.StatusCode == 200 {
+		return nil
+	}
+
+	// return error
+	return errors.New(string(b))
+}
+
+func (h *httpLock) Release(id string) error {
+	uri, err := h.url(id)
+	if err != nil {
+		return err
+	}
+
+	vals := url.Values{
+		"id": {id},
+	}
+
+	req, err := http.NewRequest("DELETE", uri, strings.NewReader(vals.Encode()))
+	if err != nil {
+		return err
+	}
+
+	rsp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer rsp.Body.Close()
+
+	b, err := ioutil.ReadAll(rsp.Body)
+	if err != nil {
+		return err
+	}
+
+	// success
+	if rsp.StatusCode == 200 {
+		return nil
+	}
+
+	// return error
+	return errors.New(string(b))
+}
+
+func NewLock(opts ...lock.Option) lock.Lock {
+	var options lock.Options
+	for _, o := range opts {
+		o(&options)
+	}
+
+	if len(options.Nodes) == 0 {
+		options.Nodes = []string{DefaultAddress}
+	}
+
+	return &httpLock{
+		opts: options,
+	}
+}