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This new base class has the minimum set of properties and methods necessary for DfsBlockCache to manage blocks of a file in the cache. Subclasses can use DfsBlockCache for any content. This refactoring opens the door for additional PackExt types other than PACK to be stored on a block-by-block basis by the DfsBlockCache. Change-Id: I307228fc805c3ff0c596783beb24fd52bec35ba8stable-4.9
Shawn Pearce
7 years ago
4 changed files with 234 additions and 174 deletions
@ -0,0 +1,207 @@
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/* |
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* Copyright (C) 2017, Google Inc. |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.internal.storage.dfs; |
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import java.io.EOFException; |
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import java.io.IOException; |
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import java.nio.ByteBuffer; |
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import java.text.MessageFormat; |
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import org.eclipse.jgit.annotations.Nullable; |
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import org.eclipse.jgit.errors.PackInvalidException; |
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import org.eclipse.jgit.internal.storage.pack.PackExt; |
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/** Block based file stored in {@link DfsBlockCache}. */ |
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public abstract class BlockBasedFile { |
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/** Cache that owns this file and its data. */ |
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final DfsBlockCache cache; |
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/** Unique identity of this file while in-memory. */ |
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final DfsStreamKey key; |
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/** Description of the associated pack file's storage. */ |
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final DfsPackDescription packDesc; |
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final PackExt ext; |
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/** |
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* Preferred alignment for loading blocks from the backing file. |
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* <p> |
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* It is initialized to 0 and filled in on the first read made from the |
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* file. Block sizes may be odd, e.g. 4091, caused by the underling DFS |
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* storing 4091 user bytes and 5 bytes block metadata into a lower level |
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* 4096 byte block on disk. |
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*/ |
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volatile int blockSize; |
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/** |
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* Total number of bytes in this pack file. |
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* <p> |
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* This field initializes to -1 and gets populated when a block is loaded. |
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*/ |
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volatile long length; |
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/** True once corruption has been detected that cannot be worked around. */ |
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volatile boolean invalid; |
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BlockBasedFile(DfsBlockCache cache, DfsStreamKey key, |
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DfsPackDescription packDesc, PackExt ext) { |
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this.cache = cache; |
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this.key = key; |
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this.packDesc = packDesc; |
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this.ext = ext; |
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} |
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String getFileName() { |
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return packDesc.getFileName(ext); |
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} |
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boolean invalid() { |
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return invalid; |
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} |
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void setInvalid() { |
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invalid = true; |
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} |
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void setBlockSize(int newSize) { |
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blockSize = newSize; |
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} |
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long alignToBlock(long pos) { |
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int size = blockSize; |
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if (size == 0) |
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size = cache.getBlockSize(); |
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return (pos / size) * size; |
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} |
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int blockSize(ReadableChannel rc) { |
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// If the block alignment is not yet known, discover it. Prefer the
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// larger size from either the cache or the file itself.
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int size = blockSize; |
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if (size == 0) { |
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size = rc.blockSize(); |
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if (size <= 0) |
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size = cache.getBlockSize(); |
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else if (size < cache.getBlockSize()) |
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size = (cache.getBlockSize() / size) * size; |
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blockSize = size; |
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} |
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return size; |
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} |
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DfsBlock readOneBlock(long pos, DfsReader ctx, |
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@Nullable ReadableChannel fileChannel) throws IOException { |
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if (invalid) |
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throw new PackInvalidException(getFileName()); |
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ctx.stats.readBlock++; |
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long start = System.nanoTime(); |
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ReadableChannel rc = fileChannel != null ? fileChannel |
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: ctx.db.openFile(packDesc, ext); |
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try { |
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int size = blockSize(rc); |
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pos = (pos / size) * size; |
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// If the size of the file is not yet known, try to discover it.
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// Channels may choose to return -1 to indicate they don't
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// know the length yet, in this case read up to the size unit
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// given by the caller, then recheck the length.
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long len = length; |
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if (len < 0) { |
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len = rc.size(); |
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if (0 <= len) |
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length = len; |
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} |
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if (0 <= len && len < pos + size) |
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size = (int) (len - pos); |
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if (size <= 0) |
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throw new EOFException(MessageFormat.format( |
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DfsText.get().shortReadOfBlock, Long.valueOf(pos), |
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getFileName(), Long.valueOf(0), Long.valueOf(0))); |
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byte[] buf = new byte[size]; |
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rc.position(pos); |
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int cnt = read(rc, ByteBuffer.wrap(buf, 0, size)); |
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ctx.stats.readBlockBytes += cnt; |
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if (cnt != size) { |
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if (0 <= len) { |
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throw new EOFException(MessageFormat.format( |
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DfsText.get().shortReadOfBlock, Long.valueOf(pos), |
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getFileName(), Integer.valueOf(size), |
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Integer.valueOf(cnt))); |
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} |
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// Assume the entire thing was read in a single shot, compact
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// the buffer to only the space required.
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byte[] n = new byte[cnt]; |
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System.arraycopy(buf, 0, n, 0, n.length); |
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buf = n; |
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} else if (len < 0) { |
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// With no length at the start of the read, the channel should
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// have the length available at the end.
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length = len = rc.size(); |
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} |
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return new DfsBlock(key, pos, buf); |
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} finally { |
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if (rc != fileChannel) { |
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rc.close(); |
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} |
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ctx.stats.readBlockMicros += elapsedMicros(start); |
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} |
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} |
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static int read(ReadableChannel rc, ByteBuffer buf) throws IOException { |
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int n; |
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do { |
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n = rc.read(buf); |
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} while (0 < n && buf.hasRemaining()); |
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return buf.position(); |
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} |
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static long elapsedMicros(long start) { |
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return (System.nanoTime() - start) / 1000L; |
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} |
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} |
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