Use a bucket sort for PackReverseIndex.
Previously it took 1200ms to create a reverse index (sorted by offset). Using a simple bucket sort algorithm, that time is reduced to 450ms. The bucket index into the offset array is kept, in order to decrease the binary search window. Don't keep a copy of the offsets. Instead, use nth position to lookup the offset in the PackIndex. Change-Id: If51ab76752622e04a4430d9a14db95ad02f5329d
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@ -44,7 +44,6 @@
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package org.eclipse.jgit.internal.storage.file;
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import java.text.MessageFormat;
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import java.util.Arrays;
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import org.eclipse.jgit.errors.CorruptObjectException;
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import org.eclipse.jgit.internal.JGitText;
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@ -65,21 +64,22 @@ public class PackReverseIndex {
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/** Index we were created from, and that has our ObjectId data. */
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private final PackIndex index;
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/**
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* (offset31, truly) Offsets accommodating in 31 bits.
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*/
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private final int offsets32[];
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/** The number of bytes per entry in the offsetIndex. */
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private final long bucketSize;
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/**
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* Offsets not accommodating in 31 bits.
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* An index into the nth mapping, where the value is the position after the
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* the last index that contains the values of the bucket. For example given
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* offset o (and bucket = o / bucketSize), the offset will be contained in
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* the range nth[offsetIndex[bucket - 1]] inclusive to
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* nth[offsetIndex[bucket]] exclusive.
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*
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* See {@link #binarySearch}
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*/
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private final long offsets64[];
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private final int[] offsetIndex;
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/** Position of the corresponding {@link #offsets32} in {@link #index}. */
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private final int nth32[];
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/** Position of the corresponding {@link #offsets64} in {@link #index}. */
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private final int nth64[];
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/** Mapping from indices in offset order to indices in SHA-1 order. */
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private final int[] nth;
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/**
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* Create reverse index from straight/forward pack index, by indexing all
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@ -92,38 +92,58 @@ public PackReverseIndex(final PackIndex packIndex) {
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index = packIndex;
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final long cnt = index.getObjectCount();
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final long n64 = index.getOffset64Count();
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final long n32 = cnt - n64;
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if (n32 > Integer.MAX_VALUE || n64 > Integer.MAX_VALUE
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|| cnt > 0xffffffffL)
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if (cnt + 1 > Integer.MAX_VALUE)
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throw new IllegalArgumentException(
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JGitText.get().hugeIndexesAreNotSupportedByJgitYet);
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offsets32 = new int[(int) n32];
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offsets64 = new long[(int) n64];
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nth32 = new int[offsets32.length];
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nth64 = new int[offsets64.length];
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int i32 = 0;
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int i64 = 0;
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for (final MutableEntry me : index) {
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final long o = me.getOffset();
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if (o <= Integer.MAX_VALUE)
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offsets32[i32++] = (int) o;
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else
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offsets64[i64++] = o;
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if (cnt == 0) {
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bucketSize = Long.MAX_VALUE;
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offsetIndex = new int[1];
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nth = new int[0];
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return;
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}
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Arrays.sort(offsets32);
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Arrays.sort(offsets64);
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final long[] offsetsBySha1 = new long[(int) cnt];
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int nth = 0;
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long maxOffset = 0;
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int ith = 0;
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for (final MutableEntry me : index) {
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final long o = me.getOffset();
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if (o <= Integer.MAX_VALUE)
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nth32[Arrays.binarySearch(offsets32, (int) o)] = nth++;
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else
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nth64[Arrays.binarySearch(offsets64, o)] = nth++;
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offsetsBySha1[ith++] = o;
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if (o > maxOffset)
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maxOffset = o;
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}
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bucketSize = maxOffset / cnt + 1;
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int[] bucketIndex = new int[(int) cnt];
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int[] bucketValues = new int[(int) cnt + 1];
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for (int oi = 0; oi < offsetsBySha1.length; oi++) {
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final long o = offsetsBySha1[oi];
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final int bucket = (int) (o / bucketSize);
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final int bucketValuesPos = oi + 1;
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final int current = bucketIndex[bucket];
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bucketIndex[bucket] = bucketValuesPos;
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bucketValues[bucketValuesPos] = current;
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}
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int nthByOffset = 0;
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nth = new int[offsetsBySha1.length];
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offsetIndex = bucketIndex; // Reuse the allocation
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for (int bi = 0; bi < bucketIndex.length; bi++) {
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final int start = nthByOffset;
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// Insertion sort of the values in the bucket.
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for (int vi = bucketIndex[bi]; vi > 0; vi = bucketValues[vi]) {
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final int nthBySha1 = vi - 1;
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final long o = offsetsBySha1[nthBySha1];
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int insertion = nthByOffset++;
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for (; start < insertion; insertion--) {
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if (o > offsetsBySha1[nth[insertion - 1]])
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break;
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nth[insertion] = nth[insertion - 1];
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}
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nth[insertion] = nthBySha1;
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}
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offsetIndex[bi] = nthByOffset;
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}
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}
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@ -136,17 +156,10 @@ public PackReverseIndex(final PackIndex packIndex) {
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* @return object id for this offset, or null if no object was found.
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*/
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public ObjectId findObject(final long offset) {
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if (offset <= Integer.MAX_VALUE) {
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final int i32 = Arrays.binarySearch(offsets32, (int) offset);
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if (i32 < 0)
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return null;
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return index.getObjectId(nth32[i32]);
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} else {
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final int i64 = Arrays.binarySearch(offsets64, offset);
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if (i64 < 0)
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return null;
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return index.getObjectId(nth64[i64]);
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}
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final int ith = binarySearch(offset);
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if (ith < 0)
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return null;
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return index.getObjectId(nth[ith]);
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}
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/**
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@ -166,52 +179,40 @@ public ObjectId findObject(final long offset) {
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*/
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public long findNextOffset(final long offset, final long maxOffset)
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throws CorruptObjectException {
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if (offset <= Integer.MAX_VALUE) {
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final int i32 = Arrays.binarySearch(offsets32, (int) offset);
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if (i32 < 0)
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throw new CorruptObjectException(
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MessageFormat.format(
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JGitText.get().cantFindObjectInReversePackIndexForTheSpecifiedOffset,
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Long.valueOf(offset)));
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final int ith = binarySearch(offset);
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if (ith < 0)
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throw new CorruptObjectException(
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MessageFormat.format(
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JGitText.get().cantFindObjectInReversePackIndexForTheSpecifiedOffset,
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Long.valueOf(offset)));
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if (i32 + 1 == offsets32.length) {
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if (offsets64.length > 0)
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return offsets64[0];
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return maxOffset;
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}
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return offsets32[i32 + 1];
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} else {
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final int i64 = Arrays.binarySearch(offsets64, offset);
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if (i64 < 0)
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throw new CorruptObjectException(
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MessageFormat.format(
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JGitText.get().cantFindObjectInReversePackIndexForTheSpecifiedOffset,
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Long.valueOf(offset)));
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if (i64 + 1 == offsets64.length)
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return maxOffset;
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return offsets64[i64 + 1];
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}
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if (ith + 1 == nth.length)
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return maxOffset;
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return index.getOffset(nth[ith + 1]);
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}
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int findPostion(long offset) {
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if (offset <= Integer.MAX_VALUE) {
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final int i32 = Arrays.binarySearch(offsets32, (int) offset);
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if (i32 < 0)
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return -1;
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return i32;
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} else {
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final int i64 = Arrays.binarySearch(offsets64, offset);
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if (i64 < 0)
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return -1;
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return nth32.length + i64;
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return binarySearch(offset);
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}
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private int binarySearch(final long offset) {
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int bucket = (int) (offset / bucketSize);
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int low = bucket == 0 ? 0 : offsetIndex[bucket - 1];
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int high = offsetIndex[bucket];
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while (low < high) {
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final int mid = (low + high) >>> 1;
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final long o = index.getOffset(nth[mid]);
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if (offset < o)
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high = mid;
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else if (offset == o)
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return mid;
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else
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low = mid + 1;
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}
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return -1;
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}
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ObjectId findObjectByPosition(int nthPosition) {
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if (nthPosition < nth32.length)
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return index.getObjectId(nth32[nthPosition]);
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final int i64 = nthPosition - nth32.length;
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return index.getObjectId(nth64[i64]);
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return index.getObjectId(nth[nthPosition]);
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}
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}
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