Example usage for org.apache.hadoop.mapreduce.lib.map WrappedMapper getMapContext

Introduction

In this page you can find the example usage for org.apache.hadoop.mapreduce.lib.map WrappedMapper getMapContext.

Prototype

public Mapper<KEYIN, VALUEIN, KEYOUT, VALUEOUT>.Context getMapContext(
        MapContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> mapContext) 

Source Link

Document

Get a wrapped Mapper.Context for custom implementations.

Usage

From source file:org.apache.giraph.yarn.GiraphYarnTask.java

License:Apache License

/**
 * Utility to generate dummy Mapper#Context for use in Giraph internals.
 * This is the "key hack" to inject MapReduce-related data structures
 * containing YARN cluster metadata (and our GiraphConf from the AppMaster)
 * into our Giraph BSP task code./*w  ww  .  j  av  a 2 s . co  m*/
 * @param tid the TaskAttemptID to construct this Mapper#Context from.
 * @return sort of a Mapper#Context if you squint just right.
 */
private Context buildProxyMapperContext(final TaskAttemptID tid) {
    MapContext mc = new MapContextImpl<Object, Object, Object, Object>(conf, // our Configuration, populated back at the GiraphYarnClient.
            tid, // our TaskAttemptId, generated w/YARN app, container, attempt IDs
            null, // RecordReader here will never be used by Giraph
            null, // RecordWriter here will never be used by Giraph
            null, // OutputCommitter here will never be used by Giraph
            new TaskAttemptContextImpl.DummyReporter() { // goes in task logs for now
                @Override
                public void setStatus(String msg) {
                    LOG.info("[STATUS: task-" + bspTaskId + "] " + msg);
                }
            }, null); // Input split setting here will never be used by Giraph

    // now, we wrap our MapContext ref so we can produce a Mapper#Context
    WrappedMapper<Object, Object, Object, Object> wrappedMapper = new WrappedMapper<Object, Object, Object, Object>();
    return wrappedMapper.getMapContext(mc);
}

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