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Reduce allocations

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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().
This commit is contained in:
Ryan Slade 2014-12-16 08:18:07 +00:00
parent f391194b96
commit 505a8b21f5
1 changed files with 23 additions and 12 deletions
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35
http.go
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@ -17,8 +17,9 @@ limitations under the License.
package groupcache
import (
"bytes"
"fmt"
"io/ioutil"
"io"
"net/http"
"net/url"
"strings"
@ -51,8 +52,9 @@ type HTTPPool struct {
// 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 @@ func NewHTTPPoolOpts(self string, o *HTTPPoolOptions) *HTTPPool {
}
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 @@ func (p *HTTPPool) Set(peers ...string) {
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 @@ func (p *HTTPPool) PickPeer(key string) (ProtoGetter, bool) {
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 @@ type httpGetter struct {
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 @@ func (h *httpGetter) Get(context Context, in *pb.GetRequest, out *pb.GetResponse
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)
}