Allow the user to configure the GPU render bucket size (#220)

* Feature: user defined render bucket size when using GPUs

src/com/sheepit/client/hardware/gpu/GPUDevice.java

@@ -19,10 +19,14 @@
 
 package com.sheepit.client.hardware.gpu;
 
+import com.sheepit.client.hardware.gpu.nvidia.Nvidia;
+import com.sheepit.client.hardware.gpu.opencl.OpenCL;
+
 public class GPUDevice {
 	private String type;
 	private String model;
 	private long memory; // in B
+	private int renderBucketSize;
 	
 	private String id;
 	
@@ -33,6 +37,7 @@ public class GPUDevice {
 		this.model = model;
 		this.memory = ram;
 		this.id = id;
+		this.renderBucketSize = 32;
 	}
 	
 	public GPUDevice(String type, String model, long ram, String id, String oldId) {
@@ -80,8 +85,43 @@ public class GPUDevice {
 		this.oldId = id;
 	}
 	
+	public int getRenderbucketSize() {
+		return this.renderBucketSize;
+	}
+	
+	public void setRenderbucketSize(int proposedRenderbucketSize) {
+		int renderBucketSize = 32;
+		GPULister gpu;
+		
+		if (type.equals("CUDA")) {
+			gpu = new Nvidia();
+		}
+		else if (type.equals("OPENCL")) {
+			gpu = new OpenCL();
+		}
+		else {
+			// If execution takes this branch is because we weren't able to detect the proper GPU technology or
+			// because is a new one (different from CUDA and OPENCL). In that case, move into the safest position
+			// of 32x32 pixel tile sizes
+			System.out.println("GPUDevice::setRenderbucketSize Unable to detect GPU technology. Render bucket size set to 32x32 pixels");
+			this.renderBucketSize = 32;
+			return;
+		}
+		
+		if (proposedRenderbucketSize >= 32) {
+			if (proposedRenderbucketSize <= gpu.getMaximumRenderBucketSize(getMemory())) {
+				renderBucketSize = proposedRenderbucketSize;
+			}
+			else {
+				renderBucketSize = gpu.getRecommendedRenderBucketSize(getMemory());
+			}
+		}
+		
+		this.renderBucketSize = renderBucketSize;
+	}
+	
 	@Override
 	public String toString() {
-		return "GPUDevice [type=" + type + ", model='" + model + "', memory=" + memory + ", id=" + id + "]";
+		return "GPUDevice [type=" + type + ", model='" + model + "', memory=" + memory + ", id=" + id + ", renderbucketSize=" + renderBucketSize + "]";
 	}
 }

src/com/sheepit/client/hardware/gpu/GPULister.java

@@ -4,4 +4,8 @@ import java.util.List;
 
 public interface GPULister {
 	public abstract List<GPUDevice> getGpus();
+	
+	public abstract int getRecommendedRenderBucketSize(long memory);
+	
+	public abstract int getMaximumRenderBucketSize(long memory);
 }

src/com/sheepit/client/hardware/gpu/nvidia/Nvidia.java

@@ -127,4 +127,14 @@ public class Nvidia implements GPULister {
 		return devices;
 	}
 	
+	@Override
+	public int getRecommendedRenderBucketSize(long memory) {
+		// Optimal CUDA-based GPUs Renderbucket algorithm
+		return (memory > 1073741824L) ? 256 : 128;
+	}
+	
+	@Override
+	public int getMaximumRenderBucketSize(long memory) {
+		return (memory > 1073741824L) ? 512 : 128;
+	}
 }

src/com/sheepit/client/hardware/gpu/opencl/OpenCL.java

@@ -123,6 +123,17 @@ public class OpenCL implements GPULister {
 		return available_devices;
 	}
 	
+	@Override
+	public int getRecommendedRenderBucketSize(long memory) {
+		// Optimal CUDA-based GPUs Renderbucket algorithm
+		return (memory > 1073741824L) ? 256 : 128;
+	}
+	
+	@Override
+	public int getMaximumRenderBucketSize(long memory) {
+		return (memory > 1073741824L) ? 2048 : 128;
+	}
+	
 	private static String getInfodeviceString(OpenCLLib lib, CLDeviceId.ByReference device, int type) {
 		byte name[] = new byte[256];