Reduce allocations
Store temporary buffers in a sync.Pool.
Create one httpGetter per peer when Set() is called so we don't
allocate a new one on each call PickPeer().
diff --git a/http.go b/http.go
index abc25a3..8f637d7 100644
--- a/http.go
+++ b/http.go
@@ -17,8 +17,9 @@
package groupcache
import (
+ "bytes"
"fmt"
- "io/ioutil"
+ "io"
"net/http"
"net/url"
"strings"
@@ -51,8 +52,9 @@
// this peer's base URL, e.g. "https://example.net:8000"
self string
- mu sync.Mutex
- peers *consistenthash.Map
+ mu sync.Mutex // guards peers and httpGetters
+ peers *consistenthash.Map
+ httpGetters map[string]*httpGetter // keyed by e.g. "http://10.0.0.2:8008"
}
// HTTPPoolOptions are the configurations of a HTTPPool.
@@ -103,9 +105,10 @@
}
p := &HTTPPool{
- basePath: opts.BasePath,
- self: self,
- peers: consistenthash.New(opts.Replicas, opts.HashFn),
+ basePath: opts.BasePath,
+ self: self,
+ peers: consistenthash.New(opts.Replicas, opts.HashFn),
+ httpGetters: make(map[string]*httpGetter),
}
RegisterPeerPicker(func() PeerPicker { return p })
return p
@@ -119,6 +122,10 @@
defer p.mu.Unlock()
p.peers = consistenthash.New(defaultReplicas, nil)
p.peers.Add(peers...)
+ p.httpGetters = make(map[string]*httpGetter, len(peers))
+ for _, peer := range peers {
+ p.httpGetters[peer] = &httpGetter{transport: p.Transport, baseURL: peer + p.basePath}
+ }
}
func (p *HTTPPool) PickPeer(key string) (ProtoGetter, bool) {
@@ -128,9 +135,7 @@
return nil, false
}
if peer := p.peers.Get(key); peer != p.self {
- // TODO: pre-build a slice of *httpGetter when Set()
- // is called to avoid these two allocations.
- return &httpGetter{p.Transport, peer + p.basePath}, true
+ return p.httpGetters[peer], true
}
return nil, false
}
@@ -182,6 +187,10 @@
baseURL string
}
+var bufferPool = sync.Pool{
+ New: func() interface{} { return new(bytes.Buffer) },
+}
+
func (h *httpGetter) Get(context Context, in *pb.GetRequest, out *pb.GetResponse) error {
u := fmt.Sprintf(
"%v%v/%v",
@@ -205,12 +214,14 @@
if res.StatusCode != http.StatusOK {
return fmt.Errorf("server returned: %v", res.Status)
}
- // TODO: avoid this garbage.
- b, err := ioutil.ReadAll(res.Body)
+ b := bufferPool.Get().(*bytes.Buffer)
+ b.Reset()
+ defer bufferPool.Put(b)
+ _, err = io.Copy(b, res.Body)
if err != nil {
return fmt.Errorf("reading response body: %v", err)
}
- err = proto.Unmarshal(b, out)
+ err = proto.Unmarshal(b.Bytes(), out)
if err != nil {
return fmt.Errorf("decoding response body: %v", err)
}
