Author: stefanegli
Date: Wed Jan 27 13:20:04 2016
New Revision: 1727035
URL: http://svn.apache.org/viewvc?rev=1727035&view=rev
Log:
SLING-5458 : support cluster id of discovery lite descriptor to be null - in
which case discovery.oak stores and reads a clusterId property to/from
/var/discovery/oak
Modified:
sling/trunk/bundles/extensions/discovery/oak/src/main/java/org/apache/sling/discovery/oak/cluster/OakClusterViewService.java
Modified:
sling/trunk/bundles/extensions/discovery/oak/src/main/java/org/apache/sling/discovery/oak/cluster/OakClusterViewService.java
URL:
http://svn.apache.org/viewvc/sling/trunk/bundles/extensions/discovery/oak/src/main/java/org/apache/sling/discovery/oak/cluster/OakClusterViewService.java?rev=1727035&r1=1727034&r2=1727035&view=diff
==============================================================================
---
sling/trunk/bundles/extensions/discovery/oak/src/main/java/org/apache/sling/discovery/oak/cluster/OakClusterViewService.java
(original)
+++
sling/trunk/bundles/extensions/discovery/oak/src/main/java/org/apache/sling/discovery/oak/cluster/OakClusterViewService.java
Wed Jan 27 13:20:04 2016
@@ -18,6 +18,7 @@
*/
package org.apache.sling.discovery.oak.cluster;
+import java.util.Calendar;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
@@ -25,11 +26,14 @@ import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
+import java.util.UUID;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.Service;
import org.apache.sling.api.resource.LoginException;
+import org.apache.sling.api.resource.ModifiableValueMap;
+import org.apache.sling.api.resource.PersistenceException;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ResourceResolverFactory;
@@ -42,6 +46,7 @@ import org.apache.sling.discovery.common
import org.apache.sling.discovery.commons.providers.spi.LocalClusterView;
import
org.apache.sling.discovery.commons.providers.spi.base.DiscoveryLiteDescriptor;
import org.apache.sling.discovery.commons.providers.spi.base.IdMapService;
+import org.apache.sling.discovery.commons.providers.util.ResourceHelper;
import org.apache.sling.discovery.oak.Config;
import org.apache.sling.settings.SlingSettingsService;
import org.slf4j.Logger;
@@ -54,6 +59,10 @@ import org.slf4j.LoggerFactory;
@Service(value = ClusterViewService.class)
public class OakClusterViewService implements ClusterViewService {
+ private static final String PROPERTY_CLUSTER_ID = "clusterId";
+ private static final String PROPERTY_CLUSTER_ID_DEFINED_AT =
"clusterIdDefinedAt";
+ private static final String PROPERTY_CLUSTER_ID_DEFINED_BY =
"clusterIdDefinedBy";
+
private final Logger logger = LoggerFactory.getLogger(this.getClass());
@Reference
@@ -130,6 +139,10 @@ public class OakClusterViewService imple
}
logger.trace("asClusterView: start");
String clusterViewId = descriptor.getViewId();
+ if (clusterViewId == null || clusterViewId.length() == 0) {
+ logger.trace("asClusterView: no clusterId provided by
discovery-lite descriptor - reading from repo.");
+ clusterViewId = readOrDefineClusterId(resourceResolver);
+ }
String localClusterSyncTokenId =
/*descriptor.getViewId()+"_"+*/String.valueOf(descriptor.getSeqNum());
if (!descriptor.isFinal()) {
throw new
UndefinedClusterViewException(Reason.NO_ESTABLISHED_VIEW, "descriptor is not
yet final: "+descriptor);
@@ -200,6 +213,75 @@ public class OakClusterViewService imple
}
}
+ /**
+ * oak's discovery-lite can opt to not provide a clusterViewId eg in the
+ * single-VM case. (for clusters discovery-lite normally defines the
+ * clusterViewId, as it is the one responsible for defining the membership
+ * too) Thus if we're not getting an id here we have to define one here.
(we
+ * can typically assume that this corresponds to a singleVM case, but
that's
+ * not a 100% requirement). This id must be stored to ensure the contract
+ * that the clusterId is stable across restarts. For that, the id is stored
+ * under /var/discovery/oak (and to account for odd/edgy cases we'll do a
+ * retry when storing the id, in case we'd run into conflicts, even though
+ * they should not occur in singleVM cases)
+ *
+ * @param resourceResolver the ResourceResolver with which to read or write
+ * the clusterId properties under /var/discovery/oak
+ * @return the clusterId to be used - either the one read or defined
+ * at /var/discovery/oak - or the slingId in case of non-fixable exceptions
+ * @throws PersistenceException when /var/discovery/oak could not be
+ * accessed or auto-created
+ */
+ private String readOrDefineClusterId(ResourceResolver resourceResolver)
throws PersistenceException {
+ //TODO: if Config gets a specific, public getDiscoveryResourcePath,
this can be simplified:
+ final String clusterInstancesPath = config.getClusterInstancesPath();
+ final String discoveryResourcePath = clusterInstancesPath.substring(0,
+ clusterInstancesPath.lastIndexOf("/",
clusterInstancesPath.length()-2));
+ final int MAX_RETRIES = 5;
+ for(int retryCnt=0; retryCnt<MAX_RETRIES; retryCnt++) {
+ Resource varDiscoveryOak =
resourceResolver.getResource(discoveryResourcePath);
+ if (varDiscoveryOak == null) {
+ varDiscoveryOak =
ResourceHelper.getOrCreateResource(resourceResolver, discoveryResourcePath);
+ }
+ if (varDiscoveryOak == null) {
+ logger.error("readOrDefinedClusterId: Could not create:
"+discoveryResourcePath);
+ throw new RuntimeException("could not create " +
discoveryResourcePath);
+ }
+ ModifiableValueMap props =
varDiscoveryOak.adaptTo(ModifiableValueMap.class);
+ if (props == null) {
+ logger.error("readOrDefineClusterId: Could not adaptTo
ModifiableValueMap: "+varDiscoveryOak);
+ throw new RuntimeException("could not adaptTo
ModifiableValueMap: " + varDiscoveryOak);
+ }
+ Object clusterIdObj = props.get(PROPERTY_CLUSTER_ID);
+ String clusterId = (clusterIdObj == null) ? null :
String.valueOf(clusterIdObj);
+ if (clusterId != null && clusterId.length() > 0) {
+ logger.trace("readOrDefineClusterId: read clusterId from repo
as {}", clusterId);
+ return clusterId;
+ }
+
+ // must now define a new clusterId and store it under
/var/discovery/oak
+ final String newClusterId = UUID.randomUUID().toString();
+ props.put(PROPERTY_CLUSTER_ID, newClusterId);
+ props.put(PROPERTY_CLUSTER_ID_DEFINED_BY, getSlingId());
+ props.put(PROPERTY_CLUSTER_ID_DEFINED_AT, Calendar.getInstance());
+ try {
+ logger.info("readOrDefineClusterId: storing new clusterId as "
+ newClusterId);
+ resourceResolver.commit();
+ return newClusterId;
+ } catch (PersistenceException e) {
+ logger.warn("readOrDefineClusterId: could not persist
clusterId "
+ + "(retrying in 1 sec max " + (MAX_RETRIES - retryCnt
- 1) + " more times: " + e, e);
+ try {
+ Thread.sleep(1000);
+ } catch (InterruptedException e1) {
+ logger.warn("readOrDefineClusterId: got interrupted: "+e1,
e1);
+ }
+ logger.info("readOrDefineClusterId: retrying now.");
+ }
+ }
+ throw new RuntimeException("failed to write new clusterId (see log
file earlier for more details)");
+ }
+
private String getLeaderElectionId(ResourceResolver resourceResolver,
String slingId) {
if (slingId==null) {
throw new IllegalStateException("slingId must not be null");
