Allow overriding DfsPackDescription comparator for scanning packs

Provide a factory for comparators that use the default heuristics except
with a different ordering of PackSources.

Change-Id: I0809b64deb3d0486040076946fdbdad650d69240

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackDescriptionTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackDescriptionTest.java
index 6029e9cae8a3ad0b75dfd5ad21a7e127e53b7fda..55e1a9c4cce45652cf795ba9fd5b520a16adad13 100644 (file)
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackDescriptionTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsPackDescriptionTest.java
@@ -46,8 +46,10 @@ package org.eclipse.jgit.internal.storage.dfs;
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.COMPACT;
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.GC;
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.GC_REST;
+import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.GC_TXN;
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.INSERT;
 import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.RECEIVE;
+import static org.eclipse.jgit.internal.storage.dfs.DfsObjDatabase.PackSource.UNREACHABLE_GARBAGE;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.INDEX;
 import static org.eclipse.jgit.internal.storage.pack.PackExt.PACK;
 import static org.junit.Assert.assertEquals;
@@ -101,6 +103,24 @@ public final class DfsPackDescriptionTest {
                assertComparesLessThan(DfsPackDescription.objectLookupComparator(), a, b);
        }
 
+       @Test
+       public void objectLookupComparatorCustomPackSourceComparator()
+                       throws Exception {
+               DfsPackDescription a = create(GC);
+
+               DfsPackDescription b = create(COMPACT);
+
+               assertComparesLessThan(DfsPackDescription.objectLookupComparator(), b, a);
+               assertComparesLessThan(
+                               DfsPackDescription.objectLookupComparator(
+                                       new PackSource.ComparatorBuilder()
+                                               .add(GC)
+                                               .add(INSERT, RECEIVE, GC_REST, GC_TXN, UNREACHABLE_GARBAGE)
+                                               .add(COMPACT)
+                                               .build()),
+                               a, b);
+       }
+
        @Test
        public void objectLookupComparatorGcFileSize() throws Exception {
                // a is older and smaller.

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java
index ce5efd0a853e67ce7d3f9af24026a83a763d9855..09d59376a0159b1d9fb507766a5ae9f17c89d1ff 100644 (file)
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsObjDatabase.java
@@ -240,6 +240,8 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
 
        private DfsReaderOptions readerOptions;
 
+       private Comparator<DfsPackDescription> packComparator;
+
        /**
         * Initialize an object database for our repository.
         *
@@ -253,6 +255,7 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
                this.repository = repository;
                this.packList = new AtomicReference<>(NO_PACKS);
                this.readerOptions = options;
+               this.packComparator = DfsPackDescription.objectLookupComparator();
        }
 
        /**
@@ -264,6 +267,21 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
                return readerOptions;
        }
 
+       /**
+        * Set the comparator used when searching for objects across packs.
+        * <p>
+        * An optimal comparator will find more objects without having to load large
+        * idx files from storage only to find that they don't contain the object.
+        * See {@link DfsPackDescription#objectLookupComparator()} for the default
+        * heuristics.
+        *
+        * @param packComparator
+        *            comparator.
+        */
+       public void setPackComparator(Comparator<DfsPackDescription> packComparator) {
+               this.packComparator = packComparator;
+       }
+
        /** {@inheritDoc} */
        @Override
        public DfsReader newReader() {
@@ -607,7 +625,7 @@ public abstract class DfsObjDatabase extends ObjectDatabase {
                Map<DfsPackDescription, DfsReftable> reftables = reftableMap(old);
 
                List<DfsPackDescription> scanned = listPacks();
-               Collections.sort(scanned, DfsPackDescription.objectLookupComparator());
+               Collections.sort(scanned, packComparator);
 
                List<DfsPackFile> newPacks = new ArrayList<>(scanned.size());
                List<DfsReftable> newReftables = new ArrayList<>(scanned.size());

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackDescription.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackDescription.java
index 53140baf43f8f0c2cf36999dd4a3a6f545ab2ae8..5a1ac02e25c603dad506f26b5ec77bab0e030e7c 100644 (file)
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackDescription.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackDescription.java
@@ -72,13 +72,32 @@ public class DfsPackDescription {
         * with more recent modification dates before older packs, and packs with
         * fewer objects before packs with more objects.
         * <p>
-        * Uses {@link PackSource#DEFAULT_COMPARATOR} for sorting sources.
+        * Uses {@link PackSource#DEFAULT_COMPARATOR} for the portion of comparison
+        * where packs are sorted by source.
         *
         * @return comparator.
         */
        public static Comparator<DfsPackDescription> objectLookupComparator() {
+               return objectLookupComparator(PackSource.DEFAULT_COMPARATOR);
+       }
+
+       /**
+        * Comparator for packs when looking up objects in indexes.
+        * <p>
+        * This comparator tries to position packs in the order readers should examine
+        * them when looking for objects by SHA-1. The default tries to sort packs
+        * with more recent modification dates before older packs, and packs with
+        * fewer objects before packs with more objects.
+        *
+        * @param packSourceComparator
+        *            comparator for the {@link PackSource}, used as the first step in
+        *            comparison.
+        * @return comparator.
+        */
+       public static Comparator<DfsPackDescription> objectLookupComparator(
+                       Comparator<PackSource> packSourceComparator) {
                return Comparator.comparing(
-                                       DfsPackDescription::getPackSource, PackSource.DEFAULT_COMPARATOR)
+                                       DfsPackDescription::getPackSource, packSourceComparator)
                        .thenComparing((a, b) -> {
                                PackSource as = a.getPackSource();
                                PackSource bs = b.getPackSource();