17339: remove unnecessary memory allocation when reading from Keep with

       the S3 v2 driver. Also fix a few incorrect calls to log.Error()

Arvados-DCO-1.1-Signed-off-by: Ward Vandewege <ward@curii.com>

diff --git a/services/keepstore/handlers.go b/services/keepstore/handlers.go
index 52683d97162c448c82a694641943f1fad07063c5..63a23687ece8f8a60213791006a78712bd19a67b 100644 (file)
--- a/services/keepstore/handlers.go
+++ b/services/keepstore/handlers.go
@@ -709,7 +709,7 @@ func GetBlock(ctx context.Context, volmgr *RRVolumeManager, hash string, buf []b
                if filehash != hash {
                        // TODO: Try harder to tell a sysadmin about
                        // this.
-                       log.Error("checksum mismatch for block %s (actual %s) on %s", hash, filehash, vol)
+                       log.Errorf("checksum mismatch for block %s (actual %s), size %d on %s", hash, filehash, size, vol)
                        errorToCaller = DiskHashError
                        continue
                }
@@ -976,7 +976,7 @@ func CompareAndTouch(ctx context.Context, volmgr *RRVolumeManager, hash string,
                        // to tell which one is wanted if we have
                        // both, so there's no point writing it even
                        // on a different volume.)
-                       log.Error("collision in Compare(%s) on volume %s", hash, mnt.Volume)
+                       log.Errorf("collision in Compare(%s) on volume %s", hash, mnt.Volume)
                        return CollisionError
                } else if os.IsNotExist(err) {
                        // Block does not exist. This is the only

diff --git a/services/keepstore/s3aws_volume.go b/services/keepstore/s3aws_volume.go
index e6b4d6453037bcce7f272faddf641ee0b838da77..4064809d5dd3d983d23453b524fe3457c906036a 100644 (file)
--- a/services/keepstore/s3aws_volume.go
+++ b/services/keepstore/s3aws_volume.go
@@ -463,52 +463,24 @@ func (v *S3AWSVolume) head(key string) (result *s3.HeadObjectOutput, err error)
 // Get a block: copy the block data into buf, and return the number of
 // bytes copied.
 func (v *S3AWSVolume) Get(ctx context.Context, loc string, buf []byte) (int, error) {
-       return getWithPipe(ctx, loc, buf, v)
+       // Do not use getWithPipe here: the BlockReader interface does not pass
+       // through 'buf []byte', and we don't want to allocate two buffers for each
+       // read request. Instead, use a version of ReadBlock that accepts 'buf []byte'
+       // as an input.
+       return v.ReadBlock(ctx, loc, buf)
 }
 
-func (v *S3AWSVolume) readWorker(ctx context.Context, key string) (rdr io.ReadCloser, err error) {
-       buf := make([]byte, 0, 67108864)
-       awsBuf := aws.NewWriteAtBuffer(buf)
-
-       downloader := s3manager.NewDownloaderWithClient(v.bucket.svc, func(u *s3manager.Downloader) {
-               u.PartSize = PartSize
-               u.Concurrency = ReadConcurrency
-       })
-
-       v.logger.Debugf("Partsize: %d; Concurrency: %d\n", downloader.PartSize, downloader.Concurrency)
-
-       _, err = downloader.DownloadWithContext(ctx, awsBuf, &s3.GetObjectInput{
-               Bucket: aws.String(v.bucket.bucket),
-               Key:    aws.String(key),
-       })
-       v.bucket.stats.TickOps("get")
-       v.bucket.stats.Tick(&v.bucket.stats.Ops, &v.bucket.stats.GetOps)
-       v.bucket.stats.TickErr(err)
-       if err != nil {
-               return nil, v.translateError(err)
-       }
-       buf = awsBuf.Bytes()
-
-       rdr = NewCountingReader(bytes.NewReader(buf), v.bucket.stats.TickInBytes)
-       return
-}
-
-// ReadBlock implements BlockReader.
-func (v *S3AWSVolume) ReadBlock(ctx context.Context, loc string, w io.Writer) error {
+func (v *S3AWSVolume) ReadBlock(ctx context.Context, loc string, buf []byte) (int, error) {
        key := v.key(loc)
-       rdr, err := v.readWorker(ctx, key)
-
+       count, err := v.readWorker(ctx, key, buf)
        if err == nil {
-               _, err2 := io.Copy(w, rdr)
-               if err2 != nil {
-                       return err2
-               }
-               return err
+               v.bucket.stats.TickInBytes(uint64(count))
+               return count, err
        }
 
        err = v.translateError(err)
        if !os.IsNotExist(err) {
-               return err
+               return 0, err
        }
 
        _, err = v.head("recent/" + key)
@@ -516,23 +488,45 @@ func (v *S3AWSVolume) ReadBlock(ctx context.Context, loc string, w io.Writer) er
        if err != nil {
                // If we can't read recent/X, there's no point in
                // trying fixRace. Give up.
-               return err
+               return 0, err
        }
        if !v.fixRace(key) {
                err = os.ErrNotExist
-               return err
+               return 0, err
        }
 
-       rdr, err = v.readWorker(ctx, key)
+       count, err = v.readWorker(ctx, key, buf)
        if err != nil {
                v.logger.Warnf("reading %s after successful fixRace: %s", loc, err)
                err = v.translateError(err)
-               return err
+               return 0, err
        }
+       v.bucket.stats.TickInBytes(uint64(count))
+       return count, err
+}
 
-       _, err = io.Copy(w, rdr)
+func (v *S3AWSVolume) readWorker(ctx context.Context, key string, buf []byte) (int, error) {
+       awsBuf := aws.NewWriteAtBuffer(buf)
+       downloader := s3manager.NewDownloaderWithClient(v.bucket.svc, func(u *s3manager.Downloader) {
+               u.PartSize = PartSize
+               u.Concurrency = ReadConcurrency
+       })
 
-       return err
+       v.logger.Debugf("Partsize: %d; Concurrency: %d\n", downloader.PartSize, downloader.Concurrency)
+
+       count, err := downloader.DownloadWithContext(ctx, awsBuf, &s3.GetObjectInput{
+               Bucket: aws.String(v.bucket.bucket),
+               Key:    aws.String(key),
+       })
+       v.bucket.stats.TickOps("get")
+       v.bucket.stats.Tick(&v.bucket.stats.Ops, &v.bucket.stats.GetOps)
+       v.bucket.stats.TickErr(err)
+       if err != nil {
+               return 0, v.translateError(err)
+       }
+       buf = awsBuf.Bytes()
+
+       return int(count), err
 }
 
 func (v *S3AWSVolume) writeObject(ctx context.Context, key string, r io.Reader) error {