listObjects: list objects minor optimization.

Minor optimization.

- Add 1000 entries buffered channel for walkerCh.
- Reset marker after the lexical order has reached and
  compare only if the marker is set.

generic-handlers.go

@@ -176,7 +176,7 @@ func setIgnoreResourcesHandler(h http.Handler) http.Handler {
 
 // Resource handler ServeHTTP() wrapper
 func (h resourceHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	// Skip the first element which is usally '/' and split the rest.
+	// Skip the first element which is usually '/' and split the rest.
 	splits := strings.SplitN(r.URL.Path[1:], "/", 2)
 
 	// Save bucketName and objectName extracted from url Path.

pkg/fs/fs-bucket-listobjects.go

@@ -56,11 +56,11 @@ type listWorkerReq struct {
 	respCh chan ListObjectsResult
 }
 
-// listObjects - list objects lists objects upto maxKeys for a given prefix.
+// listObjects - list objects lists objects up to maxKeys for a given prefix.
 func (fs Filesystem) listObjects(bucket, prefix, marker, delimiter string, maxKeys int) (chan<- listWorkerReq, *probe.Error) {
 	quitWalker := make(chan bool)
 	reqCh := make(chan listWorkerReq)
-	walkerCh := make(chan ObjectMetadata)
+	walkerCh := make(chan ObjectMetadata, 1000)
 	go func() {
 		defer close(walkerCh)
 		var walkPath string
@@ -144,8 +144,14 @@ func (fs Filesystem) listObjects(bucket, prefix, marker, delimiter string, maxKe
 				for object := range walkerCh {
 					// Verify if the object is lexically smaller than
 					// the marker, we will skip those objects.
-					if marker >= object.Object {
+					if marker != "" {
-						continue
+						if marker >= object.Object {
+							continue
+						} else {
+							// Reset marker so that we avoid comparing
+							// again and again in a loop unecessarily.
+							marker = ""
+						}
 					}
 					if delimiter != "" {
 						// Prefixes are only valid wth delimiters, and
@@ -275,7 +281,7 @@ func (fs *Filesystem) listObjectsService() *probe.Error {
 	return nil
 }
 
-// ListObjects - lists all objects for a given prefix, returns upto
+// ListObjects - lists all objects for a given prefix, returns up to
 // maxKeys number of objects per call.
 func (fs Filesystem) ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsResult, *probe.Error) {
 	// Input validation.

pkg/fs/signature.go

@@ -346,7 +346,7 @@ func (r *Signature) DoesPresignedSignatureMatch() (bool, *probe.Error) {
 //     - http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
 // returns true if matches, false otherwise. if error is not nil then it is always false
 func (r *Signature) DoesSignatureMatch(hashedPayload string) (bool, *probe.Error) {
-	// set new calulated payload
+	// set new calculated payload
 	r.Request.Header.Set("X-Amz-Content-Sha256", hashedPayload)
 
 	// Add date if not present throw error