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/*
* Javolution - Java(TM) Solution for Real-Time and Embedded Systems
* Copyright (C) 2007 - Javolution (http://javolution.org/)
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software is
* freely granted, provided that this notice is preserved.
*/
package javolution.context;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.DoubleBuffer;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import java.nio.LongBuffer;
import java.nio.ShortBuffer;
import javolution.lang.Configurable;
import javolution.osgi.internal.OSGiServices;
/**
* A context for executing and chaining calculations in parallel
* on computing devices such as CPUs/GPUs. ComputeContext keeps its
* {@link Buffer buffers} in device memory unless a buffer is
* {@link Buffer#export exported} (to the heap). Device operations
* are asynchronous and performed in parallel whenever possible
* (based on inputs parameters dependencies).
* Synchronization with host (java) is performed when buffers
* are read/exported (typically to retrieve the calculations results).
* [code]
* FloatVector result;
* ComputeContext ctx = ComputeContext.enter();
* try {
* FloatVector x = new FloatVector(1.0, 2.0, 3.0);
* FloatVector y = new FloatVector(1.0, 2.0, 3.0);
* FloatVector z = new FloatVector(1.0, 2.0, 3.0);
*
* FloatVector sumXYZ = x.plus(y).plus(z); // Both sum and product calculations
* FloatVector productXYZ = x.times(y).times(z); // are performed in parallel.
*
* result = sumXYZ.plus(productXYZ);
* result.export(); // Moves result to global memory (heap).
* } finally {
* ctx.exit(); // Release all local resources (e.g. device buffers).
* }
*
* class FloatVector implements ComputeContext.Local {
* private final ComputeContext.Buffer buffer;
* public FloatVector(double... elements) {
* buffer = ComputeContext.newBuffer(DoubleBuffer.wrap(elements));
* }
* private FloatVector(int length) {
* buffer = ComputeContext.newBuffer(length * 8L); // Size in bytes.
* }
* FloatVector plus(FloatVector that) {
* if (this.length() != that.length()) throw new DimensionMismatch();
* FloatVector result = new FloatVector(this.length());
* ComputeContext.Kernel sum = ComputeContext.newKernel(VectorFP64.class, "sum");
* sum.setArguments(this.buffer.readOnly(), that.buffer.readOnly(), result.buffer);
* sum.setGlobalWorkSize(length()); // Number of work-items.
* sum.execute(); // Executes in parallel with others kernels.
* return result;
* }
* @Override
* public void export() { // Moves to global memory.
* buffer.export();
* }
* public int length() { return (int) buffer.getByteCount() / 8; }
* }
* class VectorFP64 implements Program { // All programs published as OSGi services are
* // automatically loaded/compiled by Javolution.
* public String toOpenCL() {
* return "__kernel void sum(__global const double *a, __global const double *b, __global double *c) {" +
* " int gid = get_global_id(0);" +
* " c[gid] = a[gid] + b[gid];" + "}";
* }
* [/code]
*
* By default, the best GPU device with support for {@link
* ComputeContext#DOUBLE_PRECISION_REQUIRED double precision
* floating-point} is selected. If your GPU does not have such support,
* the CPU device is chosen. For complex data structures shared between
* OpenCL and Java, {@link javolution.io.Struct} is recommended.
*
* Thread-Safety: As for any {@link AbstractContext context},
* compute contexts are inherently thread-safe (each thread entering
* a context has its own context instance); but nesting a
* {@link ConcurrentContext} within a {@link ComputeContext}
* (already intrinsically parallel) is ill-advised
* (the reverse is fine though).
*
* @author Jean-Marie Dautelle
* @version 6.1, December 22, 2013
* @see Wikipedia: OpenCL
*/
public abstract class ComputeContext extends AbstractContext {
/**
* A high speed memory buffer which can be created on a device.
*/
public interface Buffer extends Local {
/**
* Returns this buffer as a {@link ByteBuffer}.
*/
ByteBuffer asByteBuffer();
/**
* Returns this buffer as a {@link CharBuffer}.
*/
CharBuffer asCharBuffer();
/**
* Returns this buffer as a {@link DoubleBuffer}.
*
* @throws UnsupportedOperationException if
* {@link ComputeContext#DOUBLE_PRECISION_REQUIRED} is
* configured to {@code false}
*/
DoubleBuffer asDoubleBuffer();
/**
* Returns this buffer as a {@link FloatBuffer}.
*/
FloatBuffer asFloatBuffer();
/**
* Returns this buffer as a {@link IntBuffer}.
*/
IntBuffer asIntBuffer();
/**
* Returns this buffer as a {@link LongBuffer}.
*/
LongBuffer asLongBuffer();
/**
* Returns this buffer as a {@link ShortBuffer}.
*/
ShortBuffer asShortBuffer();
/**
* Returns the size in bytes of this buffer.
*/
long getByteCount();
/**
* Returns an unmodifiable view over this buffer.
*/
Buffer readOnly();
}
/**
* A function which can be executed on a device.
*/
public interface Kernel {
/**
* Executes this kernel possibly in parallel with other kernels
* executions. This kernel can be reused with new sets of arguments
* immediately after this call.
*/
void execute();
/**
* Sets the arguments of this kernel.
*/
void setArguments(Object... args);
/**
* Sets the number of global work-items for each dimension.
*/
void setGlobalWorkSize(int... gws);
/**
* Sets the number of work-items which makes up a work-group for
* each dimension.
*/
void setLocalWorkSize(int... lws);
}
/**
* An object which may be partially allocated in local device memory.
* Local memory is used to enable coalesced accesses, to share data between
* work items in a work group, and to reduce accesses to lower bandwidth
* global memory.
*/
public interface Local {
/**
* Exports this object to global memory (heap).
*/
void export();
}
/**
* A program which can be loaded/compiled on a device.
* Any OSGi published instance of this class is automatically
* loaded and compiled by Javolution.
*/
public interface Program {
/**
* Returns the OpenCL image of this program.
*/
String toOpenCL();
}
/**
* Indicates if support for double precision floating-point is required
* (default {@code true}). Running with the option {@code
* -Djavolution.context.ComputeContext#DOUBLE_PRECISION_REQUIRED=false}
* disables the requirement to select a device supporting
* double precision.
*/
public static final Configurable DOUBLE_PRECISION_REQUIRED = new Configurable() {
@Override
protected Boolean getDefault() {
return true;
}
};
/**
* Returns the current computational context.
*/
private static ComputeContext currentComputeContext() {
ComputeContext ctx = current(ComputeContext.class);
if (ctx != null)
return ctx;
return OSGiServices.getComputeContext();
}
/**
* Enters the scope of a local computing context; all the resources
* (kernels, buffers) allocated while in this context scope are
* released upon {@link AbstractContext#exit() exit}.
*/
public static ComputeContext enter() {
ComputeContext ctx = currentComputeContext();
return (ComputeContext) ctx.enterInner();
}
/**
* Explicitly loads the specified program.
*/
public static void load(Program program) {
currentComputeContext().loadAndBuild(program);
}
/**
* Returns a memory buffer having the specified initial data.
* Once created the buffer returned as no further link to the specified
* NIO buffer.
*/
public static Buffer newBuffer(java.nio.Buffer init) {
return currentComputeContext().createBuffer(init);
}
/**
* Returns a memory buffer having the specified capacity.
*/
public static Buffer newBuffer(long byteCount) {
return currentComputeContext().createBuffer(byteCount);
}
/**
* Returns a kernel from the current context having the specified name.
* If the program has not yet been loaded, a new instance is allocated
* using the class default constructor and then loaded.
*/
public static Kernel newKernel(Class program,
String kernelName) {
return currentComputeContext().createKernel(program, kernelName);
}
/**
* Explicitly unloads the specified program.
*/
public static void unload(Program program) {
currentComputeContext().unloadAndFree(program);
}
/**
* Default constructor.
*/
protected ComputeContext() {
}
/**
* Creates a buffer having the specified initial data in this context.
*/
protected abstract Buffer createBuffer(java.nio.Buffer init);
/**
* Creates a memory buffer having the specified capacity in this context.
*/
protected abstract Buffer createBuffer(long byteCount);
/**
* Creates the kernel from the specified program having the specified name
* in this context. If the specified program has not yet been loaded
* in this context or a parent context, a new instance is allocated
* using the class default constructor and then loaded in this context.
*/
protected abstract Kernel createKernel(Class program,
String kernelName);
/**
* Loads and builds the specified program.
*/
protected abstract void loadAndBuild(Program program);
/**
* Unloads and free the specified program.
*/
protected abstract void unloadAndFree(Program program);
}