Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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.apache.tez.common.counters; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.WritableUtils; /** * A generic counter implementation */ @InterfaceAudience.Private public class GenericCounter extends AbstractCounter { private String name; private String displayName; private long value = 0; public GenericCounter() { // mostly for readFields } public GenericCounter(String name, String displayName) { this.name = name; this.displayName = displayName; } public GenericCounter(String name, String displayName, long value) { this.name = name; this.displayName = displayName; this.value = value; } @Override @Deprecated public synchronized void setDisplayName(String displayName) { this.displayName = displayName; } @Override public synchronized void readFields(DataInput in) throws IOException { name = Text.readString(in); displayName = in.readBoolean() ? Text.readString(in) : name; value = WritableUtils.readVLong(in); } /** * GenericCounter ::= keyName isDistinctDisplayName [displayName] value */ @Override public synchronized void write(DataOutput out) throws IOException { Text.writeString(out, name); boolean distinctDisplayName = !name.equals(displayName); out.writeBoolean(distinctDisplayName); if (distinctDisplayName) { Text.writeString(out, displayName); } WritableUtils.writeVLong(out, value); } @Override public synchronized String getName() { return name; } @Override public synchronized String getDisplayName() { return displayName; } @Override public synchronized long getValue() { return value; } @Override public synchronized void setValue(long value) { this.value = value; } @Override public synchronized void increment(long incr) { value += incr; } @Override public TezCounter getUnderlyingCounter() { return this; } }