Merge lp:~songofacandy/goamz/s3head into lp:goamz

[methane]

Unmerged revisions

36. By methane on 2013-03-23

s3: Support HEAD request.

=== modified file 's3/s3.go'
--- s3/s3.go	2013-02-11 17:15:59 +0000
+++ s3/s3.go	2013-03-23 08:19:21 +0000
@@ -168,6 +168,30 @@
 	panic("unreachable")
 }
 
+// Exists checks an object is on S3 bucket with HEAD request.
+func (b *Bucket) Exists(path string) (exists bool, err error) {
+	req := &request{
+		method: "HEAD",
+		bucket: b.Name,
+		path:   path,
+	}
+	err = b.S3.prepare(req)
+	if err != nil {
+		return
+	}
+	for attempt := attempts.Start(); attempt.Next(); {
+		resp, err := b.S3.run(req, nil)
+		if shouldRetry(err) && attempt.HasNext() {
+			continue
+		}
+		if resp.StatusCode/100 == 2 {
+			exists = true
+		}
+		return exists, err
+	}
+	panic("unreachable")
+}
+
 // Put inserts an object into the S3 bucket.
 //
 // See http://goo.gl/FEBPD for details.