Merge pull request hector-client#555 from hector-client/row_clear

Row clear

core/src/main/java/me/prettyprint/cassandra/service/ClearCounterRow.java

@@ -0,0 +1,99 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package me.prettyprint.cassandra.service;
+
+import me.prettyprint.hector.api.Keyspace;
+import me.prettyprint.hector.api.Serializer;
+import me.prettyprint.hector.api.beans.HCounterColumn;
+import me.prettyprint.hector.api.factory.HFactory;
+import me.prettyprint.hector.api.mutation.Mutator;
+import me.prettyprint.hector.api.query.SliceCounterQuery;
+
+/**
+ * Resets each counter counter column in the row to zero.  This class is subject to the limitations of counter columns.
+ * See the <a href="http://wiki.apache.org/cassandra/Counters">Cassandra Wiki</a> for more information on the
+ * limitations.
+ *
+ * @author thrykol
+ */
+public class ClearCounterRow<K, N> {
+	private Keyspace keyspace;
+	private Serializer<K> keySerializer;
+	private Serializer<N> nameSerializer;
+	private K rowKey;
+	private String cf;
+	private int mutateInterval = 100;
+	private int count = 100;
+
+	public ClearCounterRow(Keyspace keyspace, Serializer<K> keySerializer, Serializer<N> nameSerializer) {
+		this.keyspace = keyspace;
+		this.keySerializer =keySerializer;
+		this.nameSerializer = nameSerializer;
+	}
+
+	/**
+	 * Column family the row is part of.
+	 *
+	 * @param cf Column family name
+	 * @return <code>this</code>
+	 */
+	public ClearCounterRow setColumnFamily(String cf) {
+		this.cf = cf;
+		return this;
+	}
+
+	/**
+	 * Key of the source row.
+	 *
+	 * @param rowKey Row key
+	 * @return <code>this</code>
+	 */
+	public ClearCounterRow setRowKey(K rowKey) {
+		this.rowKey = rowKey;
+		return this;
+	}
+
+	/**
+	 * Set the mutate interval.
+	 *
+	 * @param interval Mutation interval
+	 * @return <code>this</code>
+	 */
+	public ClearCounterRow setMutateInterval(int interval) {
+		this.mutateInterval = interval;
+		return this;
+	}
+
+	/**
+	 * Set the number of columns to retrieve per slice.
+	 *
+	 * @param count The number of columns to retrieve per slice
+	 * @return &lt;this&gt;
+	 */
+	public ClearCounterRow setCount(int count) {
+		this.count = count;
+		return this;
+	}
+	/**
+	 * Clear the counter columns.
+	 */
+	public void clear() {
+		Mutator<K> mutator = HFactory.createMutator(this.keyspace, this.keySerializer, new BatchSizeHint(1, this.mutateInterval));
+
+		SliceCounterQuery<K, N> query = HFactory.createCounterSliceQuery(this.keyspace, this.keySerializer, this.nameSerializer).
+						setColumnFamily(this.cf).
+						setKey(this.rowKey);
+
+		SliceCounterIterator<K, N> iterator =
+						new SliceCounterIterator<K, N>(query, null, (N) null, false, this.count);
+
+		while(iterator.hasNext()) {
+			HCounterColumn<N> column = iterator.next();
+			mutator.incrementCounter(this.rowKey, this.cf, column.getName(), column.getValue() * -1);
+		}
+
+		mutator.execute();
+	}
+}

core/src/test/java/me/prettyprint/cassandra/service/ClearCounterRowTest.java

@@ -0,0 +1,69 @@
+package me.prettyprint.cassandra.service;
+
+import me.prettyprint.cassandra.BaseEmbededServerSetupTest;
+import me.prettyprint.cassandra.serializers.StringSerializer;
+import me.prettyprint.hector.api.Cluster;
+import me.prettyprint.hector.api.Keyspace;
+import me.prettyprint.hector.api.beans.HCounterColumn;
+import me.prettyprint.hector.api.factory.HFactory;
+import static me.prettyprint.hector.api.factory.HFactory.*;
+import me.prettyprint.hector.api.mutation.Mutator;
+import me.prettyprint.hector.api.query.SliceCounterQuery;
+import org.junit.After;
+import static org.junit.Assert.assertEquals;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ClearCounterRowTest extends BaseEmbededServerSetupTest {
+
+	private static final StringSerializer ss = new StringSerializer();
+	private static final String cf = "Counter1";
+	private static final String key = "key";
+	private Cluster cluster;
+	private Keyspace keyspace;
+
+	@Before
+	public void setUp() {
+    cluster = getOrCreateCluster("Test Cluster", "127.0.0.1:9170");
+    keyspace = createKeyspace("Keyspace1", cluster);
+
+		Mutator<String> m = createMutator(keyspace, ss);
+	}
+
+	@After
+	public void tearDown() {
+    keyspace = null;
+    cluster = null;
+	}
+
+	@Test
+	public void testClear() {
+    Mutator<String> mutator = createMutator(keyspace, ss);
+    for (int i = 1; i <= 10; i++) {
+    	mutator.addCounter(key, cf, createCounterColumn("" + i, i));
+    }
+    mutator.execute();
+
+		SliceCounterQuery query = HFactory.createCounterSliceQuery(keyspace, ss, ss);
+		query.setColumnFamily(cf);
+		query.setKey(key);
+
+		SliceCounterIterator<String, String> iterator = new SliceCounterIterator<String, String>(query, null, (String) null, false, 10);
+		while(iterator.hasNext()) {
+			HCounterColumn<String> column = iterator.next();
+
+			long expected = Long.parseLong(column.getName());
+			assertEquals(expected, (long) column.getValue());
+		}
+
+		new ClearCounterRow(keyspace, ss, ss).setColumnFamily(cf).setRowKey(key).clear();
+
+		iterator = new SliceCounterIterator<String, String>(query, null, (String) null, false, 10);
+		while(iterator.hasNext()) {
+			HCounterColumn<String> column = iterator.next();
+
+			long expected = 0;
+			assertEquals(expected, (long) column.getValue());
+		}
+	}
+}