Revise thread-safety logic

src/main/java/net/imglib2/blocks/FallbackPrimitiveBlocks.java

@@ -40,6 +40,7 @@
 import net.imglib2.loops.LoopBuilder;
 import net.imglib2.type.NativeType;
 import net.imglib2.type.NativeTypeFactory;
+import net.imglib2.util.Cast;
 import net.imglib2.util.Util;
 import net.imglib2.view.Views;
 
@@ -66,8 +67,8 @@ public FallbackPrimitiveBlocks( final RandomAccessible< T > source, final T type
 		if ( type.getEntitiesPerPixel().getRatio() != 1 )
 			throw new IllegalArgumentException( "Types with entitiesPerPixel != 1 are not supported" );
 
-		nativeTypeFactory = ( NativeTypeFactory< T, A > ) type.getNativeTypeFactory();
-		primitiveTypeProperties = ( PrimitiveTypeProperties< ?, A > ) PrimitiveTypeProperties.get( nativeTypeFactory.getPrimitiveType() );
+		nativeTypeFactory = Cast.unchecked( type.getNativeTypeFactory() );
+		primitiveTypeProperties = Cast.unchecked( PrimitiveTypeProperties.get( nativeTypeFactory.getPrimitiveType() ) );
 	}
 
 	@Override
@@ -85,6 +86,13 @@ public void copy( final long[] srcPos, final Object dest, final int[] size )
 		LoopBuilder.setImages( Views.interval( source, interval ), img ).forEachPixel( ( a, b ) -> b.set( a ) );
 	}
 
+	@Override
+	public PrimitiveBlocks< T > independentCopy()
+	{
+		// NB FallbackPrimitiveBlocks is stateless
+		return this;
+	}
+
 	@Override
 	public PrimitiveBlocks< T > threadSafe()
 	{

src/main/java/net/imglib2/blocks/PrimitiveBlocks.java

@@ -33,13 +33,13 @@
  */
 package net.imglib2.blocks;
 
+import static net.imglib2.blocks.PrimitiveBlocks.OnFallback.FAIL;
+import static net.imglib2.blocks.PrimitiveBlocks.OnFallback.WARN;
+
 import net.imglib2.RandomAccessible;
 import net.imglib2.type.NativeType;
 import net.imglib2.util.Util;
 
-import static net.imglib2.blocks.PrimitiveBlocks.OnFallback.FAIL;
-import static net.imglib2.blocks.PrimitiveBlocks.OnFallback.WARN;
-
 
 /**
  * Copy blocks of data out of a {@code NativeType<T>} source into primitive
@@ -77,7 +77,7 @@
  * If a source {@code RandomAccessible} cannot be understood, {@link
  * PrimitiveBlocks#of(RandomAccessible) PrimitiveBlocks.of} will return a
  * fall-back implementation (based on {@code LoopBuilder}).
- *
+ * <p>
  * With the optional {@link OnFallback OnFallback} argument to {@link
  * PrimitiveBlocks#of(RandomAccessible, OnFallback) PrimitiveBlocks.of} it can
  * be configured, whether
@@ -144,6 +144,8 @@ default void copy( int[] srcPos, Object dest, int[] size )
 	 */
 	PrimitiveBlocks< T > threadSafe();
 
+	PrimitiveBlocks< T > independentCopy();
+
 	enum OnFallback
 	{
 		ACCEPT,
@@ -197,11 +199,11 @@ static < T extends NativeType< T > > PrimitiveBlocks< T > of(
 	 * @return a {@code PrimitiveBlocks} accessor for {@code ra}.
 	 * @param <T> pixel type
 	 */
-	static < T extends NativeType< T >, R extends NativeType< R > > PrimitiveBlocks< T > of(
+	static < T extends NativeType< T > > PrimitiveBlocks< T > of(
 			RandomAccessible< T > ra,
 			OnFallback onFallback )
 	{
-		final ViewPropertiesOrError< T, R > props = ViewAnalyzer.getViewProperties( ra );
+		final ViewPropertiesOrError< T, ? > props = ViewAnalyzer.getViewProperties( ra );
 		if ( props.isFullySupported() )
 		{
 			return new ViewPrimitiveBlocks<>( props.getViewProperties() );

src/main/java/net/imglib2/blocks/PrimitiveBlocksUtils.java

@@ -34,41 +34,15 @@
 package net.imglib2.blocks;
 
 import java.util.Arrays;
-import java.util.function.Supplier;
+
 import net.imglib2.img.array.ArrayImg;
 import net.imglib2.img.array.ArrayImgFactory;
 import net.imglib2.img.basictypeaccess.array.ArrayDataAccess;
 import net.imglib2.transform.integer.MixedTransform;
 import net.imglib2.type.NativeType;
-import net.imglib2.util.CloseableThreadLocal;
 
 class PrimitiveBlocksUtils
 {
-	static < T extends NativeType< T > > PrimitiveBlocks< T > threadSafe( final Supplier< PrimitiveBlocks< T > > supplier )
-	{
-		final CloseableThreadLocal< PrimitiveBlocks< T > > tl = CloseableThreadLocal.withInitial( supplier );
-		return new PrimitiveBlocks< T >()
-		{
-			@Override
-			public T getType()
-			{
-				return tl.get().getType();
-			}
-
-			@Override
-			public void copy( final long[] srcPos, final Object dest, final int[] size )
-			{
-				tl.get().copy( srcPos, dest, size );
-			}
-
-			@Override
-			public PrimitiveBlocks< T > threadSafe()
-			{
-				return this;
-			}
-		};
-	}
-
 	static < T extends NativeType< T > > Object extractOobValue( final T type, final Extension extension )
 	{
 		if ( extension.type() == Extension.Type.CONSTANT )

src/main/java/net/imglib2/blocks/ViewPrimitiveBlocks.java

@@ -33,15 +33,17 @@
  */
 package net.imglib2.blocks;
 
-import net.imglib2.img.basictypeaccess.nio.BufferAccess;
+import static net.imglib2.blocks.PrimitiveBlocksUtils.extractOobValue;
+
+import java.util.function.Supplier;
+
 import net.imglib2.transform.integer.MixedTransform;
 import net.imglib2.type.NativeType;
 import net.imglib2.type.PrimitiveType;
 import net.imglib2.util.Cast;
+import net.imglib2.util.CloseableThreadLocal;
 import net.imglib2.util.Intervals;
 
-import static net.imglib2.blocks.PrimitiveBlocksUtils.extractOobValue;
-
 class ViewPrimitiveBlocks< T extends NativeType< T >, R extends NativeType< R > > implements PrimitiveBlocks< T >
 {
 	private final ViewProperties< T, R > props;
@@ -59,6 +61,8 @@ class ViewPrimitiveBlocks< T extends NativeType< T >, R extends NativeType< R >
 
 	private final Convert convert;
 
+	private Supplier< PrimitiveBlocks< T > > threadSafeSupplier;
+
 	public ViewPrimitiveBlocks( final ViewProperties< T, R > props )
 	{
 		this.props = props;
@@ -157,10 +161,38 @@ else if ( doConvert )
 	@Override
 	public PrimitiveBlocks< T > threadSafe()
 	{
-		return PrimitiveBlocksUtils.threadSafe( this::newInstance );
+		if ( threadSafeSupplier == null )
+			threadSafeSupplier = CloseableThreadLocal.withInitial( this::independentCopy )::get;
+		return new PrimitiveBlocks< T >()
+		{
+			@Override
+			public T getType()
+			{
+				return props.getViewType();
+			}
+
+			@Override
+			public void copy( final long[] srcPos, final Object dest, final int[] size )
+			{
+				threadSafeSupplier.get().copy( srcPos, dest, size );
+			}
+
+			@Override
+			public PrimitiveBlocks< T > independentCopy()
+			{
+				return ViewPrimitiveBlocks.this.independentCopy().threadSafe();
+			}
+
+			@Override
+			public PrimitiveBlocks< T > threadSafe()
+			{
+				return this;
+			}
+		};
 	}
 
-	ViewPrimitiveBlocks< T, R > newInstance()
+	@Override
+	public PrimitiveBlocks< T > independentCopy()
 	{
 		return new ViewPrimitiveBlocks<>( this );
 	}