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https://issues.apache.org/jira/browse/SLING-3737?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14052546#comment-14052546
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ASF GitHub Bot commented on SLING-3737:
---------------------------------------
GitHub user tmaret opened a pull request:
https://github.com/apache/sling/pull/22
SLING-3737 - Instance Sling Identifier may be randomly reset on restart
* add unit test to cover the use case
* read the file completely using org.apache.commons.io.FileUtils
* fix the writeSlingId method not taking the passed identifier into account
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/tmaret/sling SLING-3737a
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/sling/pull/22.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #22
----
commit e29f58cb38ad711f5c7c3b220ab9f2ed41b5b696
Author: tmaret <tma...@adobe.com>
Date: 2014-07-04T16:28:13Z
SLING-3737 - Instance Sling Identifier may be randomly reset on restart
* add unit test to cover the use case
* read the file completely using org.apache.commons.io.FileUtils
* fix the writeSlingId method not taking the passed identifier into account
----
> Instance Sling Identifier may be randomly reset on restart
> ----------------------------------------------------------
>
> Key: SLING-3737
> URL: https://issues.apache.org/jira/browse/SLING-3737
> Project: Sling
> Issue Type: Bug
> Components: Extensions
> Affects Versions: Settings 1.3.0
> Reporter: Timothee Maret
>
> In our Setup, we experience instances which change their Sling identifier
> upon restart.
> We experiences only a few occurrences of this issue, but the effect is really
> bad, turing the services relying on the Sling Identifier into un expected
> state (for instance Sling discovery service).
> We have checked that the sling.id.file was present before the issue occurred.
> We also checked that the value in this file was valid (36 byte long UUID).
> Despite this valid file, the instance reset the Sling ID.
> Looking at the latest code in
> org.apache.sling.settings.impl.SlingSettingsServiceImpl#readSlingId
> it seems there is a bug in the way the sling.id.file file is read.
> {code}
> private String readSlingId(final File idFile) {
> if (idFile.exists() && idFile.length() >= 36) {
> FileInputStream fin = null;
> try {
> fin = new FileInputStream(idFile);
> final byte[] rawBytes = new byte[36];
> if (fin.read(rawBytes) == 36) {
> final String rawString = new String(rawBytes,
> "ISO-8859-1");
> // roundtrip to ensure correct format of UUID value
> final String id = UUID.fromString(rawString).toString();
> logger.debug("Got Sling ID {} from file {}", id, idFile);
> return id;
> }
> } catch (final Throwable t) {
> logger.error("Failed reading UUID from id file " + idFile
> + ", creating new id", t);
> } finally {
> if (fin != null) {
> try {
> fin.close();
> } catch (IOException ignore) {
> }
> }
> }
> }
> return null;
> }
> {code}
> In the line
> {code}
> if (fin.read(rawBytes) == 36) {
> {code}
> The code miss uses the java.io.FileInputStream#read API.
> {code}
> /**
> * Reads up to <code>b.length</code> bytes of data from this input
> * stream into an array of bytes. This method blocks until some input
> * is available.
> *
> * @param b the buffer into which the data is read.
> * @return the total number of bytes read into the buffer, or
> * <code>-1</code> if there is no more data because the end of
> * the file has been reached.
> * @exception IOException if an I/O error occurs.
> */
> {code}
> The API stipulates that the method blocks until if finds *some* data.
> This is a common pattern with Java IO APIs, and indeed, the method may return
> with only one byte read even though the end of the stream was not reached.
> If this is the case, the current logic will treat the slingId as invalid and
> generate a new one.
> A way to fix that is to read the sling id file completely, for instance using
> the org.apache.commons.io.FileUtils API
> We are running on CentOS 6.2, JDK 1.7.
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