PackBitmapIndex/StoredBitmap: Expose size and counts

PackBitmapIndex holds a collection of StoredBitmaps. StoredBitmaps can
be either base bitmaps (ready) or an XOR over another bitmap. XOR
bitmaps are replaced with a resolved version on demand. Bitmaps
can use a significant amount of memory but we don't have detailed
visibility about it.

Add methods to PackBitmapIndex to know how many xor/bases we have and
their sizes.

Change-Id: I57aa80a1f07ddf9223eb34cfda85aab85529ea9c

3 files changed, 129 insertions, 1 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BasePackBitmapIndex.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BasePackBitmapIndex.java
index 906faded81..c2b3926309 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BasePackBitmapIndex.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BasePackBitmapIndex.java
@@ -35,6 +35,50 @@ abstract class BasePackBitmapIndex extends PackBitmapIndex {
 		return bitmaps;
 	}
 
+	@Override
+	public int getBaseBitmapCount() {
+		int bases = 0;
+		for (StoredBitmap sb : getBitmaps()) {
+			if (sb.isBase()) {
+				bases += 1;
+			}
+		}
+		return bases;
+	}
+
+	@Override
+	public long getBaseBitmapSizeInBytes() {
+		long baseSize = 0;
+		for (StoredBitmap sb : getBitmaps()) {
+			if (sb.isBase()) {
+				baseSize += sb.getCurrentSizeInBytes();
+			}
+		}
+		return baseSize;
+	}
+
+	@Override
+	public int getXorBitmapCount() {
+		int xored = 0;
+		for (StoredBitmap sb : getBitmaps()) {
+			if (!sb.isBase()) {
+				xored += 1;
+			}
+		}
+		return xored;
+	}
+
+	@Override
+	public long getXorBitmapSizeInBytes() {
+		long xorSize = 0;
+		for (StoredBitmap sb : getBitmaps()) {
+			if (!sb.isBase()) {
+				xorSize += sb.getCurrentSizeInBytes();
+			}
+		}
+		return xorSize;
+	}
+
 	/**
 	 * Data representation of the bitmap entry restored from a pack index. The
 	 * commit of the bitmap is the map key.
@@ -74,8 +118,9 @@ abstract class BasePackBitmapIndex extends PackBitmapIndex {
 		EWAHCompressedBitmap getBitmapWithoutCaching() {
 			// Fast path to immediately return the expanded result.
 			Object r = bitmapContainer;
-			if (r instanceof EWAHCompressedBitmap)
+			if (r instanceof EWAHCompressedBitmap) {
 				return (EWAHCompressedBitmap) r;
+			}
 
 			// Expand the bitmap but not cache the result.
 			XorCompressedBitmap xb = (XorCompressedBitmap) r;
@@ -100,10 +145,38 @@ abstract class BasePackBitmapIndex extends PackBitmapIndex {
 		int getFlags() {
 			return flags;
 		}
+
+		/**
+		 * This bitmap is (currently) a base or a XOR mask
+		 *
+		 * @return true if this bitmap is a base (a ready map).
+		 */
+		boolean isBase() {
+			return bitmapContainer instanceof EWAHCompressedBitmap;
+		}
+
+		/**
+		 * Size in bytes of this bitmap in its current representation
+		 *
+		 * If this is a XOR'ed bitmap, size is different before/after
+		 * {@link #getBitmap()}. Before is the byte size of the xor mask,
+		 * afterwards is the size of the "ready" bitmap
+		 *
+		 * @return size in bytes of the bitmap in its current representation
+		 */
+		long getCurrentSizeInBytes() {
+			Object r = bitmapContainer;
+			if (r instanceof EWAHCompressedBitmap) {
+				return ((EWAHCompressedBitmap) r).sizeInBytes();
+			}
+			XorCompressedBitmap xor = ((XorCompressedBitmap) r);
+			return xor.bitmap.sizeInBytes();
+		}
 	}
 
 	private static final class XorCompressedBitmap {
 		final EWAHCompressedBitmap bitmap;
+
 		final StoredBitmap xorBitmap;
 
 		XorCompressedBitmap(EWAHCompressedBitmap b, StoredBitmap xb) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java
index 2334bd4851..def4f3dc11 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java
@@ -196,6 +196,41 @@ public abstract class PackBitmapIndex {
 	public abstract int getBitmapCount();
 
 	/**
+	 * Returns the number of bitmaps in this bitmap index ready to use, not
+	 * XOR'ed against other entries.
+	 *
+	 * @return the number of bitmaps in this bitmap index ready to use.
+	 */
+	public abstract int getBaseBitmapCount();
+
+	/**
+	 * Current size in bytes of all base bitmaps in the index.
+	 *
+	 * Resolving xors for bitmaps can affect this size.
+	 *
+	 * @return Current size (in bytes) of all base bitmaps in this index.
+	 */
+	public abstract long getBaseBitmapSizeInBytes();
+
+	/**
+	 * Returns the number of bitmaps in this bitmap index XOR'ed against other
+	 * entries.
+	 *
+	 * @return the number of bitmaps in this bitmap index represented as XOR
+	 *         masks.
+	 */
+	public abstract int getXorBitmapCount();
+
+	/**
+	 * Current size in bytes of all XOR'ed bitmaps in the index.
+	 *
+	 * Resolving xors for bitmaps can affect this size.
+	 *
+	 * @return Current size (in bytes) of all xor bitmaps in this index.
+	 */
+	public abstract long getXorBitmapSizeInBytes();
+
+	/**
 	 * Supplier that propagates IOException.
 	 *
 	 * @param <T>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexRemapper.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexRemapper.java
index 91c3683501..bb7cfd0464 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexRemapper.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndexRemapper.java
@@ -95,6 +95,26 @@ public class PackBitmapIndexRemapper extends PackBitmapIndex
 	}
 
 	@Override
+	public int getBaseBitmapCount() {
+		return newPackIndex.getBaseBitmapCount();
+	}
+
+	@Override
+	public long getBaseBitmapSizeInBytes() {
+		return newPackIndex.getBaseBitmapSizeInBytes();
+	}
+
+	@Override
+	public int getXorBitmapCount() {
+		return newPackIndex.getXorBitmapCount();
+	}
+
+	@Override
+	public long getXorBitmapSizeInBytes() {
+		return newPackIndex.getXorBitmapSizeInBytes();
+	}
+
+	@Override
 	public EWAHCompressedBitmap ofObjectType(
 			EWAHCompressedBitmap bitmap, int type) {
 		return newPackIndex.ofObjectType(bitmap, type);