Move ObjectDirectory streaming limit to WindowCacheConfig

IDEs like Eclipse offer up the settings in WindowCacheConfig to the
user as a global set of options that are configured for the entire
JVM process, not per-repository, as the cache is shared across the
entire JVM.  The limit on how much we are willing to allocate for
an object buffer is similar to the limit on how much we can use for
data caches, allocating that much space impacts the entire JVM and
not just a single repository, so it should be a global limit.

Change-Id: I22eafb3e223bf8dea57ece82cd5df8bfe5badebc
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

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

@@ -218,9 +218,4 @@ class CachedObjectDirectory extends FileObjectDatabase {
 			WindowCursor curs) throws IOException {
 		wrapped.selectObjectRepresentation(packer, otp, curs);
 	}
-
-	@Override
-	int getStreamFileThreshold() {
-		return wrapped.getStreamFileThreshold();
-	}
 }

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

@@ -248,8 +248,6 @@ abstract class FileObjectDatabase extends ObjectDatabase {
 
 	abstract FileObjectDatabase newCachedFileObjectDatabase();
 
-	abstract int getStreamFileThreshold();
-
 	static class AlternateHandle {
 		final FileObjectDatabase db;
 

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

@@ -170,7 +170,6 @@ public class FileRepository extends Repository {
 				options.getObjectDirectory(), //
 				options.getAlternateObjectDirectories(), //
 				getFS());
-		getListenerList().addConfigChangedListener(objectDatabase);
 
 		if (objectDatabase.exists()) {
 			final String repositoryFormatVersion = getConfig().getString(

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

@@ -63,13 +63,10 @@ import java.util.concurrent.atomic.AtomicReference;
 
 import org.eclipse.jgit.JGitText;
 import org.eclipse.jgit.errors.PackMismatchException;
-import org.eclipse.jgit.events.ConfigChangedEvent;
-import org.eclipse.jgit.events.ConfigChangedListener;
 import org.eclipse.jgit.lib.AbbreviatedObjectId;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Constants;
-import org.eclipse.jgit.lib.CoreConfig;
 import org.eclipse.jgit.lib.ObjectDatabase;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
@@ -98,8 +95,7 @@ import org.eclipse.jgit.util.FS;
  * searched (recursively through all alternates) before the slow half is
  * considered.
  */
-public class ObjectDirectory extends FileObjectDatabase implements
-		ConfigChangedListener {
+public class ObjectDirectory extends FileObjectDatabase {
 	private static final PackList NO_PACKS = new PackList(-1, -1, new PackFile[0]);
 
 	/** Maximum number of candidates offered as resolutions of abbreviation. */
@@ -121,8 +117,6 @@ public class ObjectDirectory extends FileObjectDatabase implements
 
 	private final AtomicReference<AlternateHandle[]> alternates;
 
-	private int streamFileThreshold;
-
 	/**
 	 * Initialize a reference to an on-disk object directory.
 	 *
@@ -157,13 +151,6 @@ public class ObjectDirectory extends FileObjectDatabase implements
 				alt[i] = openAlternate(alternatePaths[i]);
 			alternates.set(alt);
 		}
-
-		onConfigChanged(new ConfigChangedEvent());
-	}
-
-	public void onConfigChanged(ConfigChangedEvent event) {
-		CoreConfig core = config.get(CoreConfig.KEY);
-		streamFileThreshold = core.getStreamFileThreshold();
 	}
 
 	/**
@@ -744,9 +731,4 @@ public class ObjectDirectory extends FileObjectDatabase implements
 	FileObjectDatabase newCachedFileObjectDatabase() {
 		return new CachedObjectDirectory(this);
 	}
-
-	@Override
-	int getStreamFileThreshold() {
-		return streamFileThreshold;
-	}
 }

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

@@ -133,6 +133,8 @@ public class WindowCache {
 
 	private static volatile WindowCache cache;
 
+	private static volatile int streamFileThreshold;
+
 	static {
 		reconfigure(new WindowCacheConfig());
 	}
@@ -184,9 +186,14 @@ public class WindowCache {
 		if (oc != null)
 			oc.removeAll();
 		cache = nc;
+		streamFileThreshold = cfg.getStreamFileThreshold();
 		UnpackedObjectCache.reconfigure(cfg);
 	}
 
+	static int getStreamFileThreshold() {
+		return streamFileThreshold;
+	}
+
 	static WindowCache getInstance() {
 		return cache;
 	}

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

@@ -44,6 +44,7 @@
 package org.eclipse.jgit.storage.file;
 
 import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.lib.ObjectLoader;
 
 /** Configuration parameters for {@link WindowCache}. */
 public class WindowCacheConfig {
@@ -63,6 +64,8 @@ public class WindowCacheConfig {
 
 	private int deltaBaseCacheLimit;
 
+	private int streamFileThreshold;
+
 	/** Create a default configuration. */
 	public WindowCacheConfig() {
 		packedGitOpenFiles = 128;
@@ -70,6 +73,7 @@ public class WindowCacheConfig {
 		packedGitWindowSize = 8 * KB;
 		packedGitMMAP = false;
 		deltaBaseCacheLimit = 10 * MB;
+		streamFileThreshold = ObjectLoader.STREAM_THRESHOLD;
 	}
 
 	/**
@@ -160,6 +164,22 @@ public class WindowCacheConfig {
 		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>
@@ -174,5 +194,11 @@ public class WindowCacheConfig {
 		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);
 	}
 }

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

@@ -267,9 +267,7 @@ final class WindowCursor extends ObjectReader implements ObjectReuseAsIs {
 	}
 
 	int getStreamFileThreshold() {
-		if (db == null)
-			return ObjectLoader.STREAM_THRESHOLD;
-		return db.getStreamFileThreshold();
+		return WindowCache.getStreamFileThreshold();
 	}
 
 	/** Release the current window cursor. */