works if response is not too big

lib/svrquery/client.go

@@ -1,6 +1,7 @@
 package svrquery
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -32,26 +33,10 @@ type Client struct {
 	key      string
 	timeout  time.Duration
 	protocol.Queryer
-	Transport Transport
+	transport
 }
 
-func (c *Client) Read(p []byte) (n int, err error) {
-	return c.Transport.Read(p)
-}
-
-func (c *Client) Write(p []byte) (n int, err error) {
-	return c.Transport.Write(p)
-}
-
-func (c *Client) Close() error {
-	return c.Transport.Close()
-}
-
-func (c *Client) Address() string {
-	return c.Transport.Address()
-}
-
-type Transport interface {
+type transport interface {
 	Setup() error
 	Address() string
 	Read(b []byte) (int, error)
@@ -71,7 +56,7 @@ func WithKey(key string) Option {
 // WithTimeout sets the read and write timeout for the client.
 func WithTimeout(t time.Duration) Option {
 	return func(c *Client) error {
-		c.Transport.SetTimeout(t)
+		c.transport.SetTimeout(t)
 		return nil
 	}
 }
@@ -95,12 +80,12 @@ func NewClient(proto, addr string, options ...Option) (*Client, error) {
 		}
 	}
 
-	var t Transport
+	var t transport
 	switch proto {
 	case "sqp":
 		t = &udpTransport{address: addr}
 	case "prom":
-		t = &HTTPTransport{}
+		t = &httpTransport{address: addr}
 	default:
 		return nil, fmt.Errorf("protocol %s not supported", proto)
 	}
@@ -109,7 +94,7 @@ func NewClient(proto, addr string, options ...Option) (*Client, error) {
 		return nil, fmt.Errorf("setup client transport: %w", err)
 	}
 
-	c.Transport = t
+	c.transport = t
 
 	return c, nil
 }
@@ -118,8 +103,8 @@ func (c *Client) Query() (protocol.Responser, error) {
 	return c.Queryer.Query()
 }
 
-var _ Transport = (*udpTransport)(nil)
-var _ Transport = (*HTTPTransport)(nil)
+var _ transport = (*udpTransport)(nil)
+var _ transport = (*httpTransport)(nil)
 
 type udpTransport struct {
 	address    string
@@ -193,36 +178,39 @@ func (c *Client) Protocol() string {
 	return c.protocol
 }
 
-type HTTPTransport struct {
+type httpTransport struct {
 	address    string
-	HttpClient *http.Client
+	httpClient *http.Client
 }
 
-func (h HTTPTransport) Setup() error {
-	h.HttpClient = &http.Client{}
+func (h *httpTransport) Setup() error {
+	h.httpClient = &http.Client{}
 	return nil
 }
 
-func (h HTTPTransport) Address() string {
+func (h *httpTransport) Address() string {
 	return h.address
 }
 
-func (h HTTPTransport) Read(b []byte) (int, error) {
-	//TODO implement me
-	panic("implement me")
+func (h *httpTransport) Read(b []byte) (int, error) {
+	res, err := h.httpClient.Get(h.address)
+	if err != nil {
+		return 0, fmt.Errorf("http get: %w", err)
+	}
+
+	return res.Body.Read(b)
 }
 
-func (h HTTPTransport) Write(b []byte) (int, error) {
-	//TODO implement me
-	panic("implement me")
+func (h *httpTransport) Write(b []byte) (int, error) {
+	return 0, errors.New("httpTransport.Write is unused")
 }
 
 // Close implements io.Closer.
-func (h HTTPTransport) Close() error {
+func (h *httpTransport) Close() error {
 	// no-op
 	return nil
 }
 
-func (h HTTPTransport) SetTimeout(t time.Duration) {
-	h.HttpClient.Timeout = t
+func (h *httpTransport) SetTimeout(t time.Duration) {
+	h.httpClient.Timeout = t
 }

lib/svrquery/protocol/prom/query.go

@@ -1,25 +1,27 @@
 package prom
 
 import (
+	"bytes"
 	"fmt"
-	"github.com/multiplay/go-svrquery/lib/svrquery"
-	"strconv"
-
 	"github.com/multiplay/go-svrquery/lib/svrquery/protocol"
 	"github.com/prometheus/common/expfmt"
+	"io"
+	"strconv"
 )
 
+const defaultBufSize = 4096
+
 type queryer struct {
-	c protocol.Client
+	client protocol.Client
 }
 
 func newCreator(c protocol.Client) protocol.Queryer {
 	return newQueryer(c)
 }
 
-func newQueryer(c protocol.Client) *queryer {
+func newQueryer(client protocol.Client) *queryer {
 	return &queryer{
-		c: c,
+		client: client,
 	}
 }
 
@@ -29,20 +31,17 @@ func (q *queryer) Query() (protocol.Responser, error) {
 }
 
 func (q *queryer) makeQuery() (*QueryResponse, error) {
-	client, ok := q.c.(*svrquery.Client)
-	if !ok {
-		return nil, fmt.Errorf("expected svrquery.Client, got %T", q.c)
-	}
-	httpTransport, ok := client.Transport.(svrquery.HTTPTransport)
-	if !ok {
-		return nil, fmt.Errorf("expected svrquery.HTTPTransport, got %T", q.c)
+	// FIXME: this won't work if the response is larger than defaultBufSize
+	responseBytes := make([]byte, defaultBufSize)
+	n, err := q.client.Read(responseBytes)
+	if n > 0 {
+		responseBytes = responseBytes[:n]
 	}
-	res, err := httpTransport.HttpClient.Get(q.c.Address())
-	if err != nil {
-		return nil, fmt.Errorf("http get: %w", err)
+	if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("query response: %w", err)
 	}
 	var parser expfmt.TextParser
-	metrics, err := parser.TextToMetricFamilies(res.Body)
+	metrics, err := parser.TextToMetricFamilies(bytes.NewReader(responseBytes))
 	if err != nil {
 		return nil, err
 	}