An assortment of changes/new things

1 files changed, 81 insertions, 0 deletions

diff --git a/base/src/main/java/bjc/utils/funcutils/Strategy.java b/base/src/main/java/bjc/utils/funcutils/Strategy.java
new file mode 100644
index 0000000..316879f
--- /dev/null
+++ b/base/src/main/java/bjc/utils/funcutils/Strategy.java
@@ -0,0 +1,81 @@
+package bjc.utils.funcutils;
+
+import java.util.concurrent.*;
+import java.util.function.*;
+
+/**
+ * Strategy for dealing with parallel execution.
+ * 
+ * @author Ben Culkin
+ * 
+ * @param <Output> The type returned by the tasks.
+ *
+ */
+public interface Strategy<Output> extends Function<Callable<Output>, Future<Output>>
+{
+	/**
+	 * Convert a function into one which operates concurrently, using this strategy.
+	 * 
+	 * @param <Input> The type of the function argument.
+	 * 
+	 * @param func The type of the function.
+	 * 
+	 * @return A function which executes concurrently.
+	 */
+	public default <Input> Function<Input, Future<Output>> using(Function<Input, Output> func)
+	{
+		return (input) -> this.apply(() -> func.apply(input));
+	}
+	
+	/**
+	 * A strategy which will run tasks in serial.
+	 * 
+	 * @param <Output> The type returned by the task.
+	 * 
+	 * @return A strategy which executes things serially.
+	 */
+	public static <Output> Strategy<Output> serial()
+	{
+		return (call) -> {
+			FutureTask<Output> task = new FutureTask<>(call);
+			task.run();
+			return task;
+		};
+	}
+	/**
+	 * A strategy which creates a fresh thread to execute a task on.
+	 * 
+	 * @param <Output> The type returned by the task.
+	 * 
+	 * @return A strategy which uses threads to create tasks.
+	 */
+	public static <Output> Strategy<Output> simpleThread()
+	{
+		// I leave this as an example as of what is possible with combinators.
+		// return (call) -> invoke(introducing(
+		// 		() -> new FutureTask<>(call),
+		// 		(task, input) -> doWith(
+		// 				(FutureTask<Output> tsk) ->
+		// 					new Thread(task).start()).apply(task)
+		// ));
+		return (call) -> {
+			FutureTask<Output> task = new FutureTask<>(call);
+			new Thread(task).start();
+			return task;
+		};
+	}
+	
+	/**
+	 * A strategy that uses an executor service.
+	 * 
+	 * @param <Output> The type returned by the task.
+	 * 
+	 * @param svc The executor service to use.
+	 * 
+	 * @return A strategy which uses the provided executor.
+	 */
+	public static <Output> Strategy<Output> executorService(ExecutorService svc)
+	{
+		return svc::submit;
+	}
+}