jgit/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/WindowCacheConfig.java

/*
 * Copyright (C) 2009, Google Inc.
 * 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.
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 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
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 *
 * - 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
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 *   disclaimer in the documentation and/or other materials provided
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package org.eclipse.jgit.storage.file;

import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.storage.pack.PackConfig;

/** Configuration parameters for {@link WindowCache}. */
public class WindowCacheConfig {
	/** 1024 (number of bytes in one kibibyte/kilobyte) */
	public static final int KB = 1024;

	/** 1024 {@link #KB} (number of bytes in one mebibyte/megabyte) */
	public static final int MB = 1024 * KB;

	private int packedGitOpenFiles;

	private long packedGitLimit;

	private int packedGitWindowSize;

	private boolean packedGitMMAP;

	private int deltaBaseCacheLimit;

	private int streamFileThreshold;

	/** Create a default configuration. */
	public WindowCacheConfig() {
		packedGitOpenFiles = 128;
		packedGitLimit = 10 * MB;
		packedGitWindowSize = 8 * KB;
		packedGitMMAP = false;
		deltaBaseCacheLimit = 10 * MB;
		streamFileThreshold = PackConfig.DEFAULT_BIG_FILE_THRESHOLD;
	}

	/**
	 * @return maximum number of streams to open at a time. Open packs count
	 *         against the process limits. <b>Default is 128.</b>
	 */
	public int getPackedGitOpenFiles() {
		return packedGitOpenFiles;
	}

	/**
	 * @param fdLimit
	 *            maximum number of streams to open at a time. Open packs count
	 *            against the process limits
	 */
	public void setPackedGitOpenFiles(final int fdLimit) {
		packedGitOpenFiles = fdLimit;
	}

	/**
	 * @return maximum number bytes of heap memory to dedicate to caching pack
	 *         file data. <b>Default is 10 MB.</b>
	 */
	public long getPackedGitLimit() {
		return packedGitLimit;
	}

	/**
	 * @param newLimit
	 *            maximum number bytes of heap memory to dedicate to caching
	 *            pack file data.
	 */
	public void setPackedGitLimit(final long newLimit) {
		packedGitLimit = newLimit;
	}

	/**
	 * @return size in bytes of a single window mapped or read in from the pack
	 *         file. <b>Default is 8 KB.</b>
	 */
	public int getPackedGitWindowSize() {
		return packedGitWindowSize;
	}

	/**
	 * @param newSize
	 *            size in bytes of a single window read in from the pack file.
	 */
	public void setPackedGitWindowSize(final int newSize) {
		packedGitWindowSize = newSize;
	}

	/**
	 * @return true enables use of Java NIO virtual memory mapping for windows;
	 *         false reads entire window into a byte[] with standard read calls.
	 *         <b>Default false.</b>
	 */
	public boolean isPackedGitMMAP() {
		return packedGitMMAP;
	}

	/**
	 * @param usemmap
	 *            true enables use of Java NIO virtual memory mapping for
	 *            windows; false reads entire window into a byte[] with standard
	 *            read calls.
	 */
	public void setPackedGitMMAP(final boolean usemmap) {
		packedGitMMAP = usemmap;
	}

	/**
	 * @return maximum number of bytes to cache in {@link DeltaBaseCache}
	 *         for inflated, recently accessed objects, without delta chains.
	 *         <b>Default 10 MB.</b>
	 */
	public int getDeltaBaseCacheLimit() {
		return deltaBaseCacheLimit;
	}

	/**
	 * @param newLimit
	 *            maximum number of bytes to cache in
	 *            {@link DeltaBaseCache} for inflated, recently accessed
	 *            objects, without delta chains.
	 */
	public void setDeltaBaseCacheLimit(final int newLimit) {
		deltaBaseCacheLimit = newLimit;
	}

	/** @return the size threshold beyond which objects must be streamed. */
	public int getStreamFileThreshold() {
		return streamFileThreshold;
	}

	/**
	 * @param newLimit
	 *            new byte limit for objects that must be streamed. Objects
	 *            smaller than this size can be obtained as a contiguous byte
	 *            array, while objects bigger than this size require using an
	 *            {@link org.eclipse.jgit.lib.ObjectStream}.
	 */
	public void setStreamFileThreshold(final int newLimit) {
		streamFileThreshold = newLimit;
	}

	/**
	 * Update properties by setting fields from the configuration.
	 * <p>
	 * If a property is not defined in the configuration, then it is left
	 * unmodified.
	 *
	 * @param rc configuration to read properties from.
	 */
	public void fromConfig(final Config rc) {
		setPackedGitOpenFiles(rc.getInt("core", null, "packedgitopenfiles", getPackedGitOpenFiles()));
		setPackedGitLimit(rc.getLong("core", null, "packedgitlimit", getPackedGitLimit()));
		setPackedGitWindowSize(rc.getInt("core", null, "packedgitwindowsize", getPackedGitWindowSize()));
		setPackedGitMMAP(rc.getBoolean("core", null, "packedgitmmap", isPackedGitMMAP()));
		setDeltaBaseCacheLimit(rc.getInt("core", null, "deltabasecachelimit", getDeltaBaseCacheLimit()));

		long maxMem = Runtime.getRuntime().maxMemory();
		long sft = rc.getLong("core", null, "streamfilethreshold", getStreamFileThreshold());
		sft = Math.min(sft, maxMem / 4); // don't use more than 1/4 of the heap
		sft = Math.min(sft, Integer.MAX_VALUE); // cannot exceed array length
		setStreamFileThreshold((int) sft);
	}
}