September 2017 Update

2017-09-23 10:01:46 +02:00 · 2017-09-23 10:01:46 +02:00 · ba8067c3b7
commit ba8067c3b7
parent bba7bfd280
14570 changed files with 153136 additions and 63871 deletions
--- a/Task/Atomic-updates/Java/atomic-updates.java
+++ b/Task/Atomic-updates/Java/atomic-updates.java
@ -0,0 +1,106 @@
+import java.util.Arrays;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class AtomicUpdates {
+
+    private static final int NUM_BUCKETS = 10;
+
+    public static class Buckets {
+        private final int[] data;
+
+        public Buckets(int[] data) {
+            this.data = data.clone();
+        }
+
+        public int getBucket(int index) {
+            synchronized (data) {
+                return data[index];
+            }
+        }
+
+        public int transfer(int srcIndex, int dstIndex, int amount) {
+            if (amount < 0)
+                throw new IllegalArgumentException("negative amount: " + amount);
+            if (amount == 0)
+                return 0;
+
+            synchronized (data) {
+                if (data[srcIndex] - amount < 0)
+                    amount = data[srcIndex];
+                if (data[dstIndex] + amount < 0)
+                    amount = Integer.MAX_VALUE - data[dstIndex];
+                if (amount < 0)
+                    throw new IllegalStateException();
+                data[srcIndex] -= amount;
+                data[dstIndex] += amount;
+                return amount;
+            }
+        }
+
+        public int[] getBuckets() {
+            synchronized (data) {
+                return data.clone();
+            }
+        }
+    }
+
+    private static long getTotal(int[] values) {
+        long total = 0;
+        for (int value : values) {
+            total += value;
+        }
+        return total;
+    }
+
+    public static void main(String[] args) {
+        ThreadLocalRandom rnd = ThreadLocalRandom.current();
+
+        int[] values = new int[NUM_BUCKETS];
+        for (int i = 0; i < values.length; i++)
+            values[i] = rnd.nextInt() & Integer.MAX_VALUE;
+        System.out.println("Initial Array: " + getTotal(values) + " " + Arrays.toString(values));
+
+        Buckets buckets = new Buckets(values);
+        new Thread(() -> equalize(buckets), "equalizer").start();
+        new Thread(() -> transferRandomAmount(buckets), "transferrer").start();
+        new Thread(() -> print(buckets), "printer").start();
+    }
+
+    private static void transferRandomAmount(Buckets buckets) {
+        ThreadLocalRandom rnd = ThreadLocalRandom.current();
+        while (true) {
+            int srcIndex = rnd.nextInt(NUM_BUCKETS);
+            int dstIndex = rnd.nextInt(NUM_BUCKETS);
+            int amount = rnd.nextInt() & Integer.MAX_VALUE;
+            buckets.transfer(srcIndex, dstIndex, amount);
+        }
+    }
+
+    private static void equalize(Buckets buckets) {
+        ThreadLocalRandom rnd = ThreadLocalRandom.current();
+        while (true) {
+            int srcIndex = rnd.nextInt(NUM_BUCKETS);
+            int dstIndex = rnd.nextInt(NUM_BUCKETS);
+            int amount = (buckets.getBucket(srcIndex) - buckets.getBucket(dstIndex)) / 2;
+            if (amount >= 0)
+                buckets.transfer(srcIndex, dstIndex, amount);
+        }
+    }
+
+    private static void print(Buckets buckets) {
+        while (true) {
+            long nextPrintTime = System.currentTimeMillis() + 3000;
+            long now;
+            while ((now = System.currentTimeMillis()) < nextPrintTime) {
+                try {
+                    Thread.sleep(nextPrintTime - now);
+                } catch (InterruptedException e) {
+                    return;
+                }
+            }
+
+            int[] bucketValues = buckets.getBuckets();
+            System.out.println("Current values: " + getTotal(bucketValues) + " " + Arrays.toString(bucketValues));
+        }
+    }
+}