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java.lang.Objectorg.apache.hadoop.io.CompressedWritable
public abstract class CompressedWritable
A base-class for Writables which store themselves compressed and lazily inflate on field access. This is useful for large objects whose fields are not be altered during a map or reduce operation: leaving the field data compressed makes copying the instance from one file to another much faster.
| Constructor Summary | |
|---|---|
CompressedWritable()
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| Method Summary | |
|---|---|
protected void |
ensureInflated()
Must be called by all methods which access fields to ensure that the data has been uncompressed. |
void |
readFields(DataInput in)
Deserialize the fields of this object from in. |
protected abstract void |
readFieldsCompressed(DataInput in)
Subclasses implement this instead of readFields(DataInput). |
void |
write(DataOutput out)
Serialize the fields of this object to out. |
protected abstract void |
writeCompressed(DataOutput out)
Subclasses implement this instead of write(DataOutput). |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
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public CompressedWritable()
| Method Detail |
|---|
public final void readFields(DataInput in)
throws IOException
Writablein.
For efficiency, implementations should attempt to re-use storage in the existing object where possible.
readFields in interface Writablein - DataInput to deseriablize this object from.
IOExceptionprotected void ensureInflated()
protected abstract void readFieldsCompressed(DataInput in)
throws IOException
readFields(DataInput).
IOException
public final void write(DataOutput out)
throws IOException
Writableout.
write in interface Writableout - DataOuput to serialize this object into.
IOException
protected abstract void writeCompressed(DataOutput out)
throws IOException
write(DataOutput).
IOException
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