public class PlaceholderStreamStateHandle extends Object implements StreamStateHandle
ByteStreamStateHandle. This class is used in the referenced states of
|Constructor and Description|
|Modifier and Type||Method and Description|
Discards the state referred to and solemnly owned by this handle, to free up resources in the persistent storage.
Returns the size of the state in bytes.
public FSDataInputStream openInputStream()
FSDataInputStreamthat can be used to read back the data that was previously written to the stream.
public void discardState() throws Exception
public long getStateSize()
The values produced by this method are only used for informational purposes and for metrics/monitoring. If this method returns wrong values, the checkpoints and recovery will still behave correctly. However, efficiency may be impacted (wrong space pre-allocation) and functionality that depends on metrics (like monitoring) will be impacted.
Note for implementors: This method should not perform any I/O operations
while obtaining the state size (hence it does not declare throwing an
Instead, the state size should be stored in the state object, or should be computable from
the state stored in this object.
The reason is that this method is called frequently by several parts of the checkpointing
and issuing I/O requests from this method accumulates a heavy I/O load on the storage
system at higher scale.
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