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cache.go
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cache.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package main
import (
"bytes"
"context"
"fmt"
"io/ioutil"
"go.uber.org/yarpc/api/middleware"
"go.uber.org/yarpc/api/transport"
)
// CacheOutboundMiddleware is a OutboundMiddleware
type CacheOutboundMiddleware interface {
middleware.UnaryOutbound
Invalidate()
}
type entry struct {
Headers transport.Headers
Body []byte
}
type cacheOutboundMiddleware map[string]entry
// NewCacheOutboundMiddleware builds a new CacheOutboundMiddleware.
func NewCacheOutboundMiddleware() CacheOutboundMiddleware {
cache := make(cacheOutboundMiddleware)
return &cache
}
func (c *cacheOutboundMiddleware) Invalidate() {
fmt.Println("invalidating")
*c = make(cacheOutboundMiddleware)
}
func (c *cacheOutboundMiddleware) Call(ctx context.Context, request *transport.Request, out transport.UnaryOutbound) (*transport.Response, error) {
data := *c
// Read the entire request body to match against the cache
body, err := ioutil.ReadAll(request.Body)
if err != nil {
return nil, err
}
request.Body = ioutil.NopCloser(bytes.NewReader(body))
if v, ok := data[string(body)]; ok {
fmt.Println("cache hit")
return &transport.Response{
Headers: v.Headers,
Body: ioutil.NopCloser(bytes.NewReader(v.Body)),
}, nil
}
fmt.Println("cache miss")
res, err := out.Call(ctx, request)
if err != nil {
return nil, err
}
defer res.Body.Close()
resBody, err := ioutil.ReadAll(res.Body)
if err != nil {
return nil, err
}
data[string(body)] = entry{Headers: res.Headers, Body: resBody}
res.Body = ioutil.NopCloser(bytes.NewReader(resBody))
return res, nil
}