Added resource locking basics.

Author: Bytekeeper

.gitignore

@@ -1,4 +1,4 @@
 /.idea
 /build
 /out
-
+/.gradle

src/main/java/org/bk/ass/FastArrayFill.java renamed to src/main/java/org/bk/ass/collection/FastArrayFill.java

@@ -1,4 +1,4 @@
-package org.bk.ass;
+package org.bk.ass.collection;
 
 public class FastArrayFill {
 

src/main/java/org/bk/ass/collection/UnorderedCollection.java

@@ -1,7 +1,5 @@
 package org.bk.ass.collection;
 
-import org.bk.ass.FastArrayFill;
-
 import java.util.AbstractCollection;
 import java.util.Collection;
 import java.util.Iterator;

src/main/java/org/bk/ass/GMS.java renamed to src/main/java/org/bk/ass/manage/GMS.java

@@ -1,4 +1,4 @@
-package org.bk.ass;
+package org.bk.ass.manage;
 
 import bwapi.TechType;
 import bwapi.UnitType;

src/main/java/org/bk/ass/manage/Lock.java

@@ -0,0 +1,79 @@
+package org.bk.ass.manage;
+
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+
+/**
+ * Holds a lock on a resource. Ie. a unit or {@link GMS}.
+ *
+ * @param <T> the type of resource
+ */
+public class Lock<T> {
+  private boolean satisfied;
+  private boolean satisfiedLater;
+  private boolean changed;
+  private T item;
+  private Predicate<T> criteria = unused -> true;
+  private final Reservation<T> reservation;
+  private final Supplier<T> selector;
+  private int futureFrame;
+
+  public Lock(Reservation<T> reservation, Supplier<T> selector) {
+    this.reservation = reservation;
+    this.selector = selector;
+  }
+
+  public void setFutureFrame(int futureFrame) {
+    this.futureFrame = futureFrame;
+  }
+
+  public T getItem() {
+    return item;
+  }
+
+  public boolean isSatisfied() {
+    return satisfied;
+  }
+
+  public boolean isSatisfiedLater() {
+    return satisfiedLater;
+  }
+
+  public boolean isChanged() {
+    return changed;
+  }
+
+  public void reacquire() {
+    reset();
+    acquire();
+  }
+
+  public void release() {
+    if (item != null) reservation.release(item);
+    item = null;
+    changed = true;
+  }
+
+  public void reset() {
+    item = null;
+    changed = false;
+    satisfied = false;
+  }
+
+  public void acquire() {
+    changed = false;
+    if (item != null && criteria.test(item) && reservation.tryReserve(item)) {
+      satisfied = true;
+      satisfiedLater = true;
+      return;
+    }
+    item = selector.get();
+    satisfied = item != null && criteria.test(item);
+    if (satisfied) {
+      changed = true;
+      satisfiedLater = true;
+      boolean reserved = reservation.tryReserve(item);
+      if (!reserved) throw new IllegalStateException("Could not reserve item that was selected!");
+    } else satisfiedLater = reservation.canBeReservedLater(item, futureFrame);
+  }
+}

src/main/java/org/bk/ass/manage/Reservation.java

@@ -0,0 +1,18 @@
+package org.bk.ass.manage;
+
+/**
+ * Should be implemented by clients to be able to use {@link Lock}.
+ *
+ * @param <T> the type of resource
+ */
+public interface Reservation<T> {
+  /** Returns true if the given item could be reserved, false otherwise. */
+  boolean tryReserve(T item);
+
+  default boolean canBeReservedLater(T item, int futureFrames) {
+    return false;
+  }
+
+  /** Releases the given item. */
+  void release(T item);
+}

src/test/java/org/bk/ass/FastArrayFillTest.java renamed to src/test/java/org/bk/ass/collection/FastArrayFillTest.java

@@ -1,9 +1,10 @@
-package org.bk.ass;
+package org.bk.ass.collection;
 
-import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.jupiter.api.Test;
 
 import java.util.Arrays;
-import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
 
 class FastArrayFillTest {