123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264 |
- /*
- * Copyright (C) 2008-2009, Google Inc.
- * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.lib;
-
- import java.io.IOException;
- import java.lang.ref.ReferenceQueue;
- import java.util.concurrent.atomic.AtomicInteger;
- import java.util.concurrent.atomic.AtomicLong;
-
- /**
- * Caches slices of a {@link PackFile} in memory for faster read access.
- * <p>
- * The WindowCache serves as a Java based "buffer cache", loading segments of a
- * PackFile into the JVM heap prior to use. As JGit often wants to do reads of
- * only tiny slices of a file, the WindowCache tries to smooth out these tiny
- * reads into larger block-sized IO operations.
- */
- public class WindowCache extends OffsetCache<ByteWindow, WindowCache.WindowRef> {
- private static final int bits(int newSize) {
- if (newSize < 4096)
- throw new IllegalArgumentException("Invalid window size");
- if (Integer.bitCount(newSize) != 1)
- throw new IllegalArgumentException("Window size must be power of 2");
- return Integer.numberOfTrailingZeros(newSize);
- }
-
- private static volatile WindowCache cache;
-
- static {
- reconfigure(new WindowCacheConfig());
- }
-
- /**
- * Modify the configuration of the window cache.
- * <p>
- * The new configuration is applied immediately. If the new limits are
- * smaller than what what is currently cached, older entries will be purged
- * as soon as possible to allow the cache to meet the new limit.
- *
- * @param packedGitLimit
- * maximum number of bytes to hold within this instance.
- * @param packedGitWindowSize
- * number of bytes per window within the cache.
- * @param packedGitMMAP
- * true to enable use of mmap when creating windows.
- * @param deltaBaseCacheLimit
- * number of bytes to hold in the delta base cache.
- * @deprecated Use {@link WindowCacheConfig} instead.
- */
- public static void reconfigure(final int packedGitLimit,
- final int packedGitWindowSize, final boolean packedGitMMAP,
- final int deltaBaseCacheLimit) {
- final WindowCacheConfig c = new WindowCacheConfig();
- c.setPackedGitLimit(packedGitLimit);
- c.setPackedGitWindowSize(packedGitWindowSize);
- c.setPackedGitMMAP(packedGitMMAP);
- c.setDeltaBaseCacheLimit(deltaBaseCacheLimit);
- reconfigure(c);
- }
-
- /**
- * Modify the configuration of the window cache.
- * <p>
- * The new configuration is applied immediately. If the new limits are
- * smaller than what what is currently cached, older entries will be purged
- * as soon as possible to allow the cache to meet the new limit.
- *
- * @param cfg
- * the new window cache configuration.
- * @throws IllegalArgumentException
- * the cache configuration contains one or more invalid
- * settings, usually too low of a limit.
- */
- public static void reconfigure(final WindowCacheConfig cfg) {
- final WindowCache nc = new WindowCache(cfg);
- final WindowCache oc = cache;
- if (oc != null)
- oc.removeAll();
- cache = nc;
- UnpackedObjectCache.reconfigure(cfg);
- }
-
- static WindowCache getInstance() {
- return cache;
- }
-
- static final ByteWindow get(final PackFile pack, final long offset)
- throws IOException {
- final WindowCache c = cache;
- final ByteWindow r = c.getOrLoad(pack, c.toStart(offset));
- if (c != cache) {
- // The cache was reconfigured while we were using the old one
- // to load this window. The window is still valid, but our
- // cache may think its still live. Ensure the window is removed
- // from the old cache so resources can be released.
- //
- c.removeAll();
- }
- return r;
- }
-
- static final void purge(final PackFile pack) {
- cache.removeAll(pack);
- }
-
- private final int maxFiles;
-
- private final long maxBytes;
-
- private final boolean mmap;
-
- private final int windowSizeShift;
-
- private final int windowSize;
-
- private final AtomicInteger openFiles;
-
- private final AtomicLong openBytes;
-
- private WindowCache(final WindowCacheConfig cfg) {
- super(tableSize(cfg), lockCount(cfg));
- maxFiles = cfg.getPackedGitOpenFiles();
- maxBytes = cfg.getPackedGitLimit();
- mmap = cfg.isPackedGitMMAP();
- windowSizeShift = bits(cfg.getPackedGitWindowSize());
- windowSize = 1 << windowSizeShift;
-
- openFiles = new AtomicInteger();
- openBytes = new AtomicLong();
-
- if (maxFiles < 1)
- throw new IllegalArgumentException("Open files must be >= 1");
- if (maxBytes < windowSize)
- throw new IllegalArgumentException("Window size must be < limit");
- }
-
- int getOpenFiles() {
- return openFiles.get();
- }
-
- long getOpenBytes() {
- return openBytes.get();
- }
-
- @Override
- protected int hash(final int packHash, final long off) {
- return packHash + (int) (off >>> windowSizeShift);
- }
-
- @Override
- protected ByteWindow load(final PackFile pack, final long offset)
- throws IOException {
- if (pack.beginWindowCache())
- openFiles.incrementAndGet();
- try {
- if (mmap)
- return pack.mmap(offset, windowSize);
- return pack.read(offset, windowSize);
- } catch (IOException e) {
- close(pack);
- throw e;
- } catch (RuntimeException e) {
- close(pack);
- throw e;
- } catch (Error e) {
- close(pack);
- throw e;
- }
- }
-
- @Override
- protected WindowRef createRef(final PackFile p, final long o,
- final ByteWindow v) {
- final WindowRef ref = new WindowRef(p, o, v, queue);
- openBytes.addAndGet(ref.size);
- return ref;
- }
-
- @Override
- protected void clear(final WindowRef ref) {
- openBytes.addAndGet(-ref.size);
- close(ref.pack);
- }
-
- private void close(final PackFile pack) {
- if (pack.endWindowCache())
- openFiles.decrementAndGet();
- }
-
- @Override
- protected boolean isFull() {
- return maxFiles < openFiles.get() || maxBytes < openBytes.get();
- }
-
- private long toStart(final long offset) {
- return (offset >>> windowSizeShift) << windowSizeShift;
- }
-
- private static int tableSize(final WindowCacheConfig cfg) {
- final int wsz = cfg.getPackedGitWindowSize();
- final long limit = cfg.getPackedGitLimit();
- if (wsz <= 0)
- throw new IllegalArgumentException("Invalid window size");
- if (limit < wsz)
- throw new IllegalArgumentException("Window size must be < limit");
- return (int) Math.min(5 * (limit / wsz) / 2, 2000000000);
- }
-
- private static int lockCount(final WindowCacheConfig cfg) {
- return Math.max(cfg.getPackedGitOpenFiles(), 32);
- }
-
- static class WindowRef extends OffsetCache.Ref<ByteWindow> {
- final int size;
-
- WindowRef(final PackFile pack, final long position, final ByteWindow v,
- final ReferenceQueue<ByteWindow> queue) {
- super(pack, position, v, queue);
- size = v.size();
- }
- }
- }
|