WeightedRoundRobinBalancer added. #344

src/main/java/org/redisson/connection/balancer/WeightedRoundRobinBalancer.java

@@ -0,0 +1,158 @@
+/**
+ * Copyright 2014 Nikita Koksharov, Nickolay Borbit
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.redisson.connection.balancer;
+
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.redisson.connection.ClientConnectionsEntry;
+import org.redisson.misc.URIBuilder;
+
+import io.netty.util.internal.PlatformDependent;
+
+/**
+ * Weighted Round Robin balancer.
+ *
+ * @author Nikita Koksharov
+ *
+ */
+public class WeightedRoundRobinBalancer implements LoadBalancer {
+
+    static class WeightEntry {
+
+        final int weight;
+        int weightCounter;
+
+        WeightEntry(int weight) {
+            this.weight = weight;
+            this.weightCounter = weight;
+        }
+
+        public boolean isWeightCounterZero() {
+            return weightCounter == 0;
+        }
+
+        public void decWeightCounter() {
+            weightCounter--;
+        }
+
+        public void resetWeightCounter() {
+            weightCounter = weight;
+        }
+
+    }
+
+    private final AtomicInteger index = new AtomicInteger(-1);
+
+    private final Map<InetSocketAddress, WeightEntry> weights = PlatformDependent.newConcurrentHashMap();
+
+    private final int defaultWeight;
+
+    /**
+     * Creates weighted round robin balancer.
+     *
+     * @param weights - weight mapped by slave node addr in <code>host:port</code> format
+     * @param defaultWeight - default weight value assigns to slaves not defined in weights map
+     */
+    public WeightedRoundRobinBalancer(Map<String, Integer> weights, int defaultWeight) {
+        for (Entry<String, Integer> entry : weights.entrySet()) {
+            URI uri = URIBuilder.create(entry.getKey());
+            InetSocketAddress addr = new InetSocketAddress(uri.getHost(), uri.getPort());
+            if (entry.getValue() <= 0) {
+                throw new IllegalArgumentException("Weight can't be less than or equal zero");
+            }
+            this.weights.put(addr, new WeightEntry(entry.getValue()));
+        }
+        if (defaultWeight <= 0) {
+            throw new IllegalArgumentException("Weight can't be less than or equal zero");
+        }
+
+        this.defaultWeight = defaultWeight;
+    }
+
+    private Set<InetSocketAddress> getAddresses(List<ClientConnectionsEntry> clients) {
+        Set<InetSocketAddress> result = new HashSet<InetSocketAddress>();
+        for (ClientConnectionsEntry entry : clients) {
+            if (entry.isFreezed()) {
+                continue;
+            }
+            result.add(entry.getClient().getAddr());
+        }
+        return result;
+    }
+
+    @Override
+    public ClientConnectionsEntry getEntry(List<ClientConnectionsEntry> clients) {
+        Set<InetSocketAddress> addresses = getAddresses(clients);
+
+        if (!addresses.equals(weights.keySet())) {
+            Set<InetSocketAddress> newAddresses = new HashSet<InetSocketAddress>(addresses);
+            newAddresses.removeAll(weights.keySet());
+            for (InetSocketAddress addr : newAddresses) {
+                weights.put(addr, new WeightEntry(defaultWeight));
+            }
+        }
+
+        Map<InetSocketAddress, WeightEntry> weightsCopy = new HashMap<InetSocketAddress, WeightEntry>(weights);
+
+        List<ClientConnectionsEntry> clientsCopy = new ArrayList<ClientConnectionsEntry>();
+
+        synchronized (this) {
+            for (Iterator<WeightEntry> iterator = weightsCopy.values().iterator(); iterator.hasNext();) {
+                WeightEntry entry = iterator.next();
+
+                if (entry.isWeightCounterZero()) {
+                    iterator.remove();
+                }
+            }
+
+            if (weightsCopy.isEmpty()) {
+                for (WeightEntry entry : weights.values()) {
+                    entry.resetWeightCounter();
+                }
+
+                weightsCopy = weights;
+            }
+
+
+            for (InetSocketAddress addr : weightsCopy.keySet()) {
+                for (ClientConnectionsEntry clientConnectionsEntry : clients) {
+                    if (clientConnectionsEntry.getClient().getAddr().equals(addr)
+                            && !clientConnectionsEntry.isFreezed()) {
+                        clientsCopy.add(clientConnectionsEntry);
+                        break;
+                    }
+                }
+            }
+
+            int ind = Math.abs(index.incrementAndGet() % clientsCopy.size());
+            ClientConnectionsEntry entry = clientsCopy.get(ind);
+            WeightEntry weightEntry = weights.get(entry.getClient().getAddr());
+            weightEntry.decWeightCounter();
+            return entry;
+        }
+    }
+
+}