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java.lang.Object org.apache.hadoop.io.CompressedWritable
@InterfaceAudience.Public @InterfaceStability.Stable 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 | |
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CompressedWritable()
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Method Summary | |
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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 |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public CompressedWritable()
Method Detail |
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public final void readFields(DataInput in) throws IOException
Writable
in
.
For efficiency, implementations should attempt to re-use storage in the existing object where possible.
readFields
in interface Writable
in
- DataInput
to deseriablize this object from.
IOException
protected void ensureInflated()
protected abstract void readFieldsCompressed(DataInput in) throws IOException
readFields(DataInput)
.
IOException
public final void write(DataOutput out) throws IOException
Writable
out
.
write
in interface Writable
out
- DataOuput
to serialize this object into.
IOException
protected abstract void writeCompressed(DataOutput out) throws IOException
write(DataOutput)
.
IOException
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