Have number of connections limited by channel

Removes previous limit of 1 connection

backend/s3/s3.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"io"
 	"strings"
-	"sync"
 
 	"github.com/mitchellh/goamz/aws"
 	"github.com/mitchellh/goamz/s3"
@@ -14,6 +13,7 @@ import (
 )
 
 const maxKeysInList = 1000
+const connLimit = 10
 
 func s3path(t backend.Type, name string) string {
 	if t == backend.Config {
@@ -23,18 +23,23 @@ func s3path(t backend.Type, name string) string {
 }
 
 type S3 struct {
-	bucket *s3.Bucket
-	mput   sync.Mutex
-	path   string
+	bucket   *s3.Bucket
+	connChan chan struct{}
+	path     string
 }
 
 // Open a backend using an S3 bucket object
 func OpenS3Bucket(bucket *s3.Bucket, bucketname string) *S3 {
-	return &S3{bucket: bucket, path: bucketname}
+	connChan := make(chan struct{}, connLimit)
+	for i := 0; i < connLimit; i++ {
+		connChan <- struct{}{}
+	}
+
+	return &S3{bucket: bucket, path: bucketname, connChan: connChan}
 }
 
 // Open opens the s3 backend at bucket and region.
-func Open(regionname, bucketname string) (*S3, error) {
+func Open(regionname, bucketname string) (backend.Backend, error) {
 	auth, err := aws.EnvAuth()
 	if err != nil {
 		return nil, err
@@ -42,7 +47,7 @@ func Open(regionname, bucketname string) (*S3, error) {
 
 	client := s3.New(auth, aws.Regions[regionname])
 
-	return &S3{bucket: client.Bucket(bucketname), path: bucketname}, nil
+	return OpenS3Bucket(client.Bucket(bucketname), bucketname), nil
 }
 
 // Location returns this backend's location (the bucket name).
@@ -94,9 +99,9 @@ func (bb *s3Blob) Finalize(t backend.Type, name string) error {
 		return errors.New("key already exists!")
 	}
 
-	bb.b.mput.Lock()
+	<-bb.b.connChan
 	err = bb.b.bucket.Put(path, bb.buf.Bytes(), "binary/octet-stream", "private")
-	bb.b.mput.Unlock()
+	bb.b.connChan <- struct{}{}
 	bb.buf.Reset()
 	return err
 }
@@ -118,7 +123,9 @@ func (b *S3) get(t backend.Type, name string) (*s3Blob, error) {
 	}
 
 	path := s3path(t, name)
+	<-b.connChan
 	data, err := b.bucket.Get(path)
+	b.connChan <- struct{}{}
 	blob.buf = bytes.NewBuffer(data)
 	return blob, err
 }