dfs: Use special ForReverseIndex DfsStreamKey wrapper instead of derive
While implementing a custom subclass of DfsStreamKey it became obvious
the required derive(String) was making it impossible to construct an
efficient key in all cases.
Instead, use a special wrapper type ForReverseIndex around the INDEX's
own DfsStreamKey to denote the reverse index stream in the
DfsBlockCache. This adds a smaller layer of boxing, but eliminates
weird issues for DFS implementors using specialized DfsStreamKey
implementations for space efficiency reasons.
Now that DfsStreamKey is reasonably light-weight, avoid allocating the
index and reverse index keys until necessary. DfsPackFile mostly
holds the DfsBlockCache.Ref handle to the object, and only needs the
DfsStreamKey when its looking up the handle.
Change-Id: Icea78e8f7f1514087b94ef5f525d9573ea2913f2
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
index b4a8828..5620df4 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
@@ -88,10 +88,6 @@
* objects are similar.
*/
public final class DfsPackFile extends BlockBasedFile {
- final DfsStreamKey idxKey;
- final DfsStreamKey reverseIdxKey;
- DfsStreamKey bitmapKey;
-
/**
* Lock for initialization of {@link #index} and {@link #corruptObjects}.
* <p>
@@ -127,8 +123,6 @@
*/
DfsPackFile(DfsBlockCache cache, DfsPackDescription desc) {
super(cache, desc, PACK);
- idxKey = desc.getStreamKey(INDEX);
- reverseIdxKey = idxKey.derive("r"); //$NON-NLS-1$
length = desc.getFileSize(PACK);
if (length <= 0)
length = -1;
@@ -151,7 +145,7 @@
long objCnt = idx.getObjectCount();
int recSize = Constants.OBJECT_ID_LENGTH + 8;
int sz = (int) Math.min(objCnt * recSize, Integer.MAX_VALUE);
- index = cache.put(idxKey, 0, sz, idx);
+ index = cache.put(desc.getStreamKey(INDEX), 0, sz, idx);
}
/**
@@ -254,9 +248,7 @@
if (idx != null)
return idx;
}
- if (bitmapKey == null) {
- bitmapKey = desc.getStreamKey(BITMAP_INDEX);
- }
+
long size;
PackBitmapIndex idx;
try {
@@ -294,8 +286,9 @@
throw e2;
}
- bitmapIndex = cache.put(bitmapKey, 0,
- (int) Math.min(size, Integer.MAX_VALUE), idx);
+ bitmapIndex = cache.put(
+ desc.getStreamKey(BITMAP_INDEX),
+ 0, (int) Math.min(size, Integer.MAX_VALUE), idx);
return idx;
}
}
@@ -320,7 +313,9 @@
PackReverseIndex revidx = new PackReverseIndex(idx);
int sz = (int) Math.min(
idx.getObjectCount() * 8, Integer.MAX_VALUE);
- reverseIndex = cache.put(reverseIdxKey, 0, sz, revidx);
+ reverseIndex = cache.put(
+ new DfsStreamKey.ForReverseIndex(desc.getStreamKey(INDEX)),
+ 0, sz, revidx);
return revidx;
}
}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsStreamKey.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsStreamKey.java
index 5106666..f0a5da0 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsStreamKey.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsStreamKey.java
@@ -80,15 +80,6 @@
this.hash = hash * 31;
}
- /**
- * Derive a new StreamKey based on this existing key.
- *
- * @param suffix
- * a derivation suffix.
- * @return derived stream key.
- */
- public abstract DfsStreamKey derive(String suffix);
-
@Override
public int hashCode() {
return hash;
@@ -112,14 +103,6 @@
}
@Override
- public DfsStreamKey derive(String suffix) {
- byte[] s = suffix.getBytes(UTF_8);
- byte[] n = Arrays.copyOf(name, name.length + s.length);
- System.arraycopy(s, 0, n, name.length, s.length);
- return new ByteArrayDfsStreamKey(n);
- }
-
- @Override
public boolean equals(Object o) {
if (o instanceof ByteArrayDfsStreamKey) {
ByteArrayDfsStreamKey k = (ByteArrayDfsStreamKey) o;
@@ -128,4 +111,19 @@
return false;
}
}
+
+ static final class ForReverseIndex extends DfsStreamKey {
+ private final DfsStreamKey idxKey;
+
+ ForReverseIndex(DfsStreamKey idxKey) {
+ super(idxKey.hash + 1);
+ this.idxKey = idxKey;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ return o instanceof ForReverseIndex
+ && idxKey.equals(((ForReverseIndex) o).idxKey);
+ }
+ }
}
