adds display package

mempool/mempool.go

@@ -0,0 +1,81 @@
+package mempool
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/url"
+
+	"github.com/gorilla/websocket"
+)
+
+var (
+	ErrNotWebsocket = errors.New("provided addr was not websocket")
+)
+
+type mempool struct {
+	addr string
+	ws   *websocket.Conn
+}
+
+func New(addr string) *mempool {
+	return &mempool{
+		addr: addr,
+	}
+}
+
+func (m *mempool) Init() error {
+	u, err := url.Parse(m.addr)
+	if err != nil {
+		return err
+	}
+
+	if u.Scheme != "wss" && u.Scheme != "ws" {
+		return fmt.Errorf("%w: got %s", ErrNotWebsocket, u.Scheme)
+	}
+
+	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
+	if err != nil {
+		return err
+	}
+
+	m.ws = c
+	return nil
+}
+
+func (m *mempool) Listen(ctx context.Context, blocks chan Block, errs chan error, done chan struct{}) {
+	for {
+		select {
+		case <-ctx.Done():
+			close(blocks)
+			close(errs)
+			close(done)
+			return
+		default:
+			_, message, err := m.ws.ReadMessage()
+			if err != nil {
+				errs <- err
+				continue
+			}
+
+			var b Block
+			err = json.Unmarshal(message, &b)
+			if err != nil {
+				errs <- err
+				continue
+			}
+
+			blocks <- b
+		}
+	}
+}
+
+func (m *mempool) Shutdown(ctx context.Context) error {
+	err := m.ws.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
+	if err != nil {
+		return err
+	}
+	m.ws.Close()
+	return nil
+}