Author: mduerig
Date: Tue Jul 26 15:13:50 2016
New Revision: 1754139
URL: http://svn.apache.org/viewvc?rev=1754139&view=rev
Log:
OAK-4277: Finalise de-duplication caches
Javadoc
Modified:
jackrabbit/oak/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/WriterCacheManager.java
Modified:
jackrabbit/oak/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/WriterCacheManager.java
URL:
http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/WriterCacheManager.java?rev=1754139&r1=1754138&r2=1754139&view=diff
==============================================================================
---
jackrabbit/oak/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/WriterCacheManager.java
(original)
+++
jackrabbit/oak/trunk/oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/WriterCacheManager.java
Tue Jul 26 15:13:50 2016
@@ -41,7 +41,13 @@ import org.apache.jackrabbit.oak.api.jmx
// FIXME OAK-4277: Finalise de-duplication caches
// implement configuration, monitoring and management
-// document
+/**
+ * Instances of this class manage the deduplication caches used
+ * by the {@link SegmentWriter} to avoid writing multiple copies
+ * of the same record. The caches are striped into generations
+ * with one generation per gc cycle. This avoids records old
+ * generations being reused.
+ */
public abstract class WriterCacheManager {
private static final int DEFAULT_STRING_CACHE_SIZE = getInteger(
"oak.tar.stringsCacheSize", 15000);
@@ -49,12 +55,24 @@ public abstract class WriterCacheManager
private static final int DEFAULT_TEMPLATE_CACHE_SIZE = getInteger(
"oak.tar.templatesCacheSize", 3000);
+ /**
+ * @param generation
+ * @return cache for string records of the given {@code generation}.
+ */
@Nonnull
public abstract RecordCache<String> getStringCache(int generation);
+ /**
+ * @param generation
+ * @return cache for template records of the given {@code generation}.
+ */
@Nonnull
public abstract RecordCache<Template> getTemplateCache(int generation);
+ /**
+ * @param generation
+ * @return cache for node records of the given {@code generation}.
+ */
@Nonnull
public abstract NodeCache getNodeCache(int generation);
@@ -74,7 +92,16 @@ public abstract class WriterCacheManager
return null;
}
+ /**
+ * This implementation of {@link WriterCacheManager} returns empty caches
+ * of size 0.
+ * @see #INSTANCE
+ */
public static class Empty extends WriterCacheManager {
+
+ /**
+ * Singleton instance of {@link Empty}
+ */
public static final WriterCacheManager INSTANCE = new Empty();
private final RecordCache<String> stringCache = newRecordCache(0);
@@ -83,22 +110,36 @@ public abstract class WriterCacheManager
private Empty() {}
+ /**
+ * @return empty cache of size 0
+ */
@Override
public RecordCache<String> getStringCache(int generation) {
return stringCache;
}
+ /**
+ * @return empty cache of size 0
+ */
@Override
public RecordCache<Template> getTemplateCache(int generation) {
return templateCache;
}
+ /**
+ * @return empty cache of size 0
+ */
@Override
public NodeCache getNodeCache(int generation) {
return nodeCache;
}
}
+ /**
+ * This implementation of {@link WriterCacheManager} returns
+ * {@link RecordCache} instances for the string and template cache
+ * and {@link NodeCache} instances for the node cache.
+ */
public static class Default extends WriterCacheManager {
/**
* Cache of recently stored string records, used to avoid storing
duplicates
@@ -118,6 +159,15 @@ public abstract class WriterCacheManager
*/
private final Generations<NodeCache> nodeCaches;
+ /**
+ * New instance using the passed factories for creating cache
instances.
+ * The factories will be invoked exactly once when a generation of a
+ * cache is requested that has not been requested before.
+ *
+ * @param stringCacheFactory factory for the string cache
+ * @param templateCacheFactory factory for the template cache
+ * @param nodeCacheFactory factory for the node cache
+ */
public Default(
@Nonnull Supplier<RecordCache<String>> stringCacheFactory,
@Nonnull Supplier<RecordCache<Template>> templateCacheFactory,
@@ -127,6 +177,10 @@ public abstract class WriterCacheManager
this.nodeCaches = new Generations<>(nodeCacheFactory);
}
+ /**
+ * New instance using the default factories {@link
RecordCache#factory(int)}
+ * and {@link NodeCache#factory(int, int)}.
+ */
public Default() {
this(RecordCache.<String>factory(DEFAULT_STRING_CACHE_SIZE),
RecordCache.<Template>factory(DEFAULT_TEMPLATE_CACHE_SIZE),
@@ -229,6 +283,10 @@ public abstract class WriterCacheManager
};
}
+ /**
+ * Remove all cache generations matching the passed {@code
generations} predicate.
+ * @param generations
+ */
protected final void evictCaches(Predicate<Integer> generations) {
stringCaches.evictGenerations(generations);
templateCaches.evictGenerations(generations);
