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-rw-r--r--same/src/main/java/com/orbekk/same/VariableUpdaterTask.java63
1 files changed, 63 insertions, 0 deletions
diff --git a/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java b/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java
new file mode 100644
index 0000000..44f63fe
--- /dev/null
+++ b/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java
@@ -0,0 +1,63 @@
+package com.orbekk.same;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/** Updates a variable on-demand.
+ */
+public class VariableUpdaterTask<T> extends Thread
+ implements Variable.OnChangeListener<T> {
+ private Variable<T> variable;
+ private T newValue;
+ private AtomicBoolean hasNewValue = new AtomicBoolean(false);
+ private AtomicBoolean isReady = new AtomicBoolean(true);
+
+ public VariableUpdaterTask(Variable<T> variable) {
+ this.variable = variable;
+ }
+
+ public synchronized void set(T newValue) {
+ this.newValue = newValue;
+ hasNewValue.set(true);
+ notifyAll();
+ }
+
+ /** Update the variable once. */
+ public void performWork() {
+ boolean shouldDoWork = false;
+ synchronized(this) {
+ shouldDoWork = hasNewValue.get() && isReady.get();
+ hasNewValue.set(false);
+ isReady.set(false);
+ }
+ if (shouldDoWork) {
+ variable.set(newValue);
+ }
+ }
+
+ private synchronized void waitFor(AtomicBoolean v) {
+ while(!v.get()) {
+ try {
+ wait();
+ } catch (InterruptedException e) {
+ return;
+ }
+ }
+ }
+
+ public void run() {
+ while (true) {
+ waitFor(isReady);
+ waitFor(hasNewValue);
+ if (Thread.interrupted()) {
+ break;
+ }
+ performWork();
+ }
+ }
+
+ @Override
+ public synchronized void valueChanged(Variable<T> unused) {
+ isReady.set(true);
+ notifyAll();
+ }
+} \ No newline at end of file