| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.jackrabbit.oak.plugins.document; |
| |
| import java.util.Collections; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| |
| import org.apache.jackrabbit.oak.cache.CacheStats; |
| import org.apache.jackrabbit.oak.plugins.document.util.StringValue; |
| import org.jetbrains.annotations.NotNull; |
| import org.jetbrains.annotations.Nullable; |
| |
| import com.google.common.cache.Cache; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| import static org.apache.jackrabbit.oak.commons.PathUtils.denotesRoot; |
| import static org.apache.jackrabbit.oak.commons.PathUtils.getName; |
| import static org.apache.jackrabbit.oak.commons.PathUtils.getParentPath; |
| |
| /** |
| * An in-memory diff cache implementation. |
| */ |
| public class MemoryDiffCache extends DiffCache { |
| |
| /** |
| * Cache entry Strings with a length more than this limit are not put into |
| * the cache. |
| */ |
| static final int CACHE_VALUE_LIMIT = Integer.getInteger( |
| "oak.memoryDiffCache.limit", 8 * 1024 * 1024); |
| |
| private static final Logger LOG = LoggerFactory.getLogger(MemoryDiffCache.class); |
| |
| /** |
| * Diff cache. |
| * |
| * Key: PathRev, value: StringValue |
| */ |
| protected final Cache<PathRev, StringValue> diffCache; |
| protected final CacheStats diffCacheStats; |
| |
| |
| protected MemoryDiffCache(DocumentNodeStoreBuilder<?> builder) { |
| diffCache = builder.buildMemoryDiffCache(); |
| diffCacheStats = new CacheStats(diffCache, "Document-MemoryDiff", |
| builder.getWeigher(), builder.getMemoryDiffCacheSize()); |
| } |
| |
| @Nullable |
| @Override |
| public String getChanges(@NotNull final RevisionVector from, |
| @NotNull final RevisionVector to, |
| @NotNull final String path, |
| @Nullable final Loader loader) { |
| PathRev key = diffCacheKey(path, from, to); |
| StringValue diff; |
| if (loader == null) { |
| diff = diffCache.getIfPresent(key); |
| if (diff == null && isUnchanged(from, to, path)) { |
| diff = new StringValue(""); |
| } |
| } else { |
| try { |
| diff = diffCache.get(key, new Callable<StringValue>() { |
| @Override |
| public StringValue call() throws Exception { |
| if (isUnchanged(from, to, path)) { |
| return new StringValue(""); |
| } else { |
| return new StringValue(loader.call()); |
| } |
| } |
| }); |
| } catch (ExecutionException e) { |
| // try again with loader directly |
| diff = new StringValue(loader.call()); |
| } |
| } |
| return diff != null ? diff.toString() : null; |
| } |
| |
| @NotNull |
| @Override |
| public Entry newEntry(@NotNull RevisionVector from, |
| @NotNull RevisionVector to, |
| boolean local /*ignored*/) { |
| return new MemoryEntry(from, to); |
| } |
| |
| @NotNull |
| @Override |
| public Iterable<CacheStats> getStats() { |
| return Collections.singleton(diffCacheStats); |
| } |
| |
| protected class MemoryEntry implements Entry { |
| |
| private final RevisionVector from; |
| private final RevisionVector to; |
| |
| protected MemoryEntry(RevisionVector from, RevisionVector to) { |
| this.from = checkNotNull(from); |
| this.to = checkNotNull(to); |
| } |
| |
| @Override |
| public void append(@NotNull String path, @NotNull String changes) { |
| PathRev key = diffCacheKey(path, from, to); |
| if (changes.length() > CACHE_VALUE_LIMIT) { |
| LOG.warn("Not caching entry for {} from {} to {}. Length of changes is {}.", |
| path, from, to, changes.length()); |
| } else { |
| LOG.debug("Adding cache entry for {} from {} to {}", path, from, to); |
| diffCache.put(key, new StringValue(changes)); |
| } |
| } |
| |
| @Override |
| public boolean done() { |
| return true; |
| } |
| } |
| |
| private static PathRev diffCacheKey(@NotNull String path, |
| @NotNull RevisionVector from, |
| @NotNull RevisionVector to) { |
| return new PathRev(from + path, to); |
| } |
| |
| /** |
| * Returns {@code true} if it can be inferred from cache entries on |
| * ancestors of the given {@code path} that the node was not changed between |
| * the two revisions. This method returns {@code false} if there are no |
| * matching cache entries for the given revision range or one of them |
| * indicates that the node at the given path may have been modified. |
| * |
| * @param from the from revision. |
| * @param to the to revision. |
| * @param path the path of the node to check. |
| * @return {@code true} if there are cache entries that indicate the node |
| * at the given path was modified between the two revisions. |
| */ |
| private boolean isUnchanged(@NotNull final RevisionVector from, |
| @NotNull final RevisionVector to, |
| @NotNull final String path) { |
| return !denotesRoot(path) |
| && isChildUnchanged(from, to, getParentPath(path), getName(path)); |
| } |
| |
| private boolean isChildUnchanged(@NotNull final RevisionVector from, |
| @NotNull final RevisionVector to, |
| @NotNull final String parent, |
| @NotNull final String name) { |
| PathRev parentKey = diffCacheKey(parent, from, to); |
| StringValue parentCachedEntry = diffCache.getIfPresent(parentKey); |
| boolean unchanged; |
| if (parentCachedEntry == null) { |
| if (denotesRoot(parent)) { |
| // reached root and we don't know whether name |
| // changed between from and to |
| unchanged = false; |
| } else { |
| // recurse down |
| unchanged = isChildUnchanged(from, to, |
| getParentPath(parent), getName(parent)); |
| } |
| } else { |
| unchanged = parseJsopDiff(parentCachedEntry.asString(), new Diff() { |
| @Override |
| public boolean childNodeAdded(String n) { |
| return !name.equals(n); |
| } |
| |
| @Override |
| public boolean childNodeChanged(String n) { |
| return !name.equals(n); |
| } |
| |
| @Override |
| public boolean childNodeDeleted(String n) { |
| return !name.equals(n); |
| } |
| }); |
| } |
| return unchanged; |
| } |
| } |