[jira] [Comment Edited] (OAK-7389) Mongo/FileBlobStore does not update timestamp for already existing blobs

["Amit Jain (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-7389?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16595960#comment-16595960 ] 

Amit Jain edited comment on OAK-7389 at 8/29/18 6:39 AM:
---------------------------------------------------------

Backported to:
 * 1.2 with [http://svn.apache.org/viewvc?rev=1839541&view=rev]
 * 1.4 with [http://svn.apache.org/viewvc?rev=1839542&view=rev]


was (Author: amitjain):
Backported to 1.2 with [http://svn.apache.org/viewvc?rev=1839541&view=rev]

> Mongo/FileBlobStore does not update timestamp for already existing blobs
> ------------------------------------------------------------------------
>
>                 Key: OAK-7389
>                 URL: https://issues.apache.org/jira/browse/OAK-7389
>             Project: Jackrabbit Oak
>          Issue Type: Bug
>          Components: blob
>    Affects Versions: 1.2.14, 1.4.20, 1.8.2, 1.6.11
>            Reporter: Amit Jain
>            Assignee: Amit Jain
>            Priority: Critical
>              Labels: candidate_oak_1_0, candidate_oak_1_6, candidate_oak_1_8
>             Fix For: 1.9.0, 1.10, 1.2.30, 1.4.23
>
>         Attachments: OAK-7389-v1.patch, OAK-7389-v2.patch
>
>
> MongoBlobStore uses uses the {{insert}} call and ignores any exceptions which means any existing value won't be updated.
> {code:java}
>     @Override
>     protected void storeBlock(byte[] digest, int level, byte[] data) throws IOException {
>         String id = StringUtils.convertBytesToHex(digest);
>         cache.put(id, data);
>         // Check if it already exists?
>         MongoBlob mongoBlob = new MongoBlob();
>         mongoBlob.setId(id);
>         mongoBlob.setData(data);
>         mongoBlob.setLevel(level);
>         mongoBlob.setLastMod(System.currentTimeMillis());
>         // TODO check the return value
>         // TODO verify insert is fast if the entry already exists
>         try {
>             getBlobCollection().insertOne(mongoBlob);
>         } catch (DuplicateKeyException e) {
>             // the same block was already stored before: ignore
>         } catch (MongoException e) {
>             if (e.getCode() == DUPLICATE_KEY_ERROR_CODE) {
>                 // the same block was already stored before: ignore
>             } else {
>                 throw new IOException(e.getMessage(), e);
>             }
>         }
>     }
> {code}
>  FileBlobStore also returns if there's a file already existing without updating the timestamp
> {code:java}
>     @Override
>     protected synchronized void storeBlock(byte[] digest, int level, byte[] data) throws IOException {
>         File f = getFile(digest, false);
>         if (f.exists()) {
>             return;
>         }
>         .........
> {code}
> The above would cause data loss in DSGC if there are updates to the blob blocks which are re-surrected (stored again at the time of DSGC) because the timestamp would never have been modified.
>  
> cc/ [~tmueller], [~mreutegg], [~chetanm], [~catholicon]



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