Merge pull request #5807 from xiang90/gproxy

*: initial implementation of grpc-proxy

proxy/grpcproxy/cache/store.go

@@ -15,6 +15,7 @@
 package cache
 
 import (
+	"errors"
 	"sync"
 
 	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
@@ -45,7 +46,8 @@ func keyFunc(req *pb.RangeRequest) string {
 
 func NewCache(maxCacheEntries int) Cache {
 	return &cache{
-		lru: lru.New(maxCacheEntries),
+		lru:          lru.New(maxCacheEntries),
+		compactedRev: -1,
 	}
 }
 
@@ -76,7 +78,7 @@ func (c *cache) Get(req *pb.RangeRequest) (*pb.RangeResponse, error) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	if req.Revision > c.compactedRev {
+	if req.Revision < c.compactedRev {
 		c.lru.Remove(key)
 		return nil, ErrCompacted
 	}
@@ -84,7 +86,7 @@ func (c *cache) Get(req *pb.RangeRequest) (*pb.RangeResponse, error) {
 	if resp, ok := c.lru.Get(key); ok {
 		return resp.(*pb.RangeResponse), nil
 	}
-	return nil, nil
+	return nil, errors.New("not exist")
 }
 
 // Compact invalidate all caching response before the given rev.

proxy/grpcproxy/kv.go

@@ -18,6 +18,7 @@ import (
 	"github.com/coreos/etcd/clientv3"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 	"github.com/coreos/etcd/proxy/grpcproxy/cache"
+
 	"golang.org/x/net/context"
 )
 
@@ -36,17 +37,23 @@ func NewKvProxy(c *clientv3.Client) *kvProxy {
 func (p *kvProxy) Range(ctx context.Context, r *pb.RangeRequest) (*pb.RangeResponse, error) {
 	// if request set Serializable, serve it from local cache first
 	if r.Serializable {
-		if resp, err := p.cache.Get(r); err == nil || err == cache.ErrCompacted {
-			return resp, err
+		resp, err := p.cache.Get(r)
+		switch err {
+		case nil:
+			return resp, nil
+		case cache.ErrCompacted:
+			return nil, err
 		}
 	}
 
 	resp, err := p.client.Do(ctx, RangeRequestToOp(r))
 	if err != nil {
-		p.cache.Add(r, (*pb.RangeResponse)(resp.Get()))
+		return nil, err
 	}
 
-	return (*pb.RangeResponse)(resp.Get()), err
+	p.cache.Add(r, (*pb.RangeResponse)(resp.Get()))
+
+	return (*pb.RangeResponse)(resp.Get()), nil
 }
 
 func (p *kvProxy) Put(ctx context.Context, r *pb.PutRequest) (*pb.PutResponse, error) {