example/service/s3: add example for file upload with progress (aws#1868)

Adds example for tracking file upload progress.

example/service/s3/putObjectWithProcess/README.md

@@ -0,0 +1,14 @@
+# Example
+
+This is an example using the AWS SDK for Go to upload object with progress.
+We use CustomReader to implement it
+
+
+# Usage
+
+The example uses the bucket name provided, one key for object, and output the progress to stdout.
+The Object size should larger than 5M or your will not see the progress
+
+```sh
+AWS_REGION=<region> go run putObjWithProcess.go <credential> <bucket> <key for object> <local file name>
+```

example/service/s3/putObjectWithProcess/putObjWithProcess.go

@@ -0,0 +1,102 @@
+// +build example
+
+package main
+
+import (
+    "log"
+    "os"
+    "sync/atomic"
+
+    "github.com/aws/aws-sdk-go/aws"
+    "github.com/aws/aws-sdk-go/aws/credentials"
+    "github.com/aws/aws-sdk-go/aws/session"
+    "github.com/aws/aws-sdk-go/service/s3/s3manager"
+)
+
+type CustomReader struct {
+    fp   *os.File
+    size int64
+    read int64
+}
+
+func (r *CustomReader) Read(p []byte) (int, error) {
+    return r.fp.Read(p)
+}
+
+func (r *CustomReader) ReadAt(p []byte, off int64) (int, error) {
+    n, err := r.fp.ReadAt(p, off)
+    if err != nil {
+        return n, err
+    }
+
+    // Got the length have read( or means has uploaded), and you can construct your message
+    atomic.AddInt64(&r.read, int64(n))
+
+    // I have no idea why the read length need to be div 2,
+    // maybe the request read once when Sign and actually send call ReadAt again
+    // It works for me
+    log.Printf("total read:%d    progress:%d%%\n", r.read/2, int(float32(r.read*100/2)/float32(r.size)))
+
+    return n, err
+}
+
+func (r *CustomReader) Seek(offset int64, whence int) (int64, error) {
+    return r.fp.Seek(offset, whence)
+}
+
+func main() {
+    if len(os.Args) < 4 {
+        log.Println("USAGE ERROR: AWS_REGION=us-east-1 go run putObjWithProcess.go <credential> <bucket> <key for object> <local file name>")
+        return
+    }
+
+    credential := os.Args[1]
+    bucket := os.Args[2]
+    key := os.Args[3]
+    fileName := os.Args[4]
+
+    creds := credentials.NewSharedCredentials(credential, "default")
+    if _, err := creds.Get(); err != nil {
+        log.Println("ERROR:", err)
+        return
+    }
+
+    sess := session.New(&aws.Config{
+        Credentials: creds,
+    })
+
+    file, err := os.Open(fileName)
+    if err != nil {
+        log.Println("ERROR:", err)
+        return
+    }
+
+    fileInfo, err := file.Stat()
+    if err != nil {
+        log.Println("ERROR:", err)
+        return
+    }
+
+    reader := &CustomReader{
+        fp:   file,
+        size: fileInfo.Size(),
+    }
+
+    uploader := s3manager.NewUploader(sess, func(u *s3manager.Uploader) {
+        u.PartSize = 5 * 1024 * 1024
+        u.LeavePartsOnError = true
+    })
+
+    output, err := uploader.Upload(&s3manager.UploadInput{
+        Bucket: aws.String(bucket),
+        Key:    aws.String(key),
+        Body:   reader,
+    })
+
+    if err != nil {
+        log.Println("ERROR:", err)
+        return
+    }
+
+    log.Println(output.Location)
+}