github/containerd
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 2 Wiki Activity

Support simultaneous unpacking of same layer

Browse Source 
Prevent unpack failures due to id collision or the need to
wait for another process to finish unpacking. Always attempt
to unpack a layer and handle collisions on commit. Commit
collisions are easily handled as it could be considered the
same as a successful unpack.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan 2017-09-06 14:45:07 -07:00
parent 843b35c9f2
commit 597d0d76ae
No known key found for this signature in database
GPG Key ID: F58C5D0A4405ACDB
1 changed files with 22 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
rootfs/apply.go
View File

@ -1,7 +1,10 @@
package rootfs
import (
"crypto/rand"
"encoding/base64"
"fmt"
"time"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/log"
@ -63,7 +66,7 @@ func ApplyLayer(ctx context.Context, layer Layer, chain []digest.Digest, sn snap
return false, errors.Wrap(err, "failed to stat snapshot")
}
key := fmt.Sprintf("extract %s", chainID)
key := fmt.Sprintf("extract-%s %s", uniquePart(), chainID)
// Prepare snapshot with from parent
mounts, err := sn.Prepare(ctx, key, parent.String())
@ -90,8 +93,25 @@ func ApplyLayer(ctx context.Context, layer Layer, chain []digest.Digest, sn snap
}
if err = sn.Commit(ctx, chainID.String(), key); err != nil {
return false, errors.Wrapf(err, "failed to commit snapshot %s", parent)
if !errdefs.IsAlreadyExists(err) {
return false, errors.Wrapf(err, "failed to commit snapshot %s", parent)
}
// Destination already exists, cleanup key and return without error
err = nil
if err := sn.Remove(ctx, key); err != nil {
return false, errors.Wrapf(err, "failed to cleanup aborted apply %s", key)
}
return false, nil
}
return true, nil
}
func uniquePart() string {
t := time.Now()
var b [3]byte
// Ignore read failures, just decreases uniqueness
rand.Read(b[:])
return fmt.Sprintf("%d-%s", t.Nanosecond(), base64.URLEncoding.EncodeToString(b[:]))
}