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E
- The type of entity accepted by this writer.@NotThreadSafe public interface DatasetWriter<E>
A stream-oriented dataset writer.
Implementations of this interface write data to a Dataset
.
Writers are use-once objects that serialize entities of type E
and
write them to the underlying storage system. Normally, you are
not expected to instantiate implementations directly. Instead, use the
containing dataset's View.newWriter()
method to get an appropriate
implementation. You should receive an instance of this interface from a
dataset, invoke write(Object)
and flush()
as necessary,
and close()
when they are done, or no more data exists.
Implementations can hold system resources until the close()
method
is called, so you must follow the normal try / finally
pattern to ensure these resources are properly freed when the writer is no
longer needed. Do not rely on implementations automatically invoking the
close()
method upon object finalization (implementations must not do
so). All implementations must silently ignore multiple invocations of
close()
as well as a close of an unopened writer.
If any method throws an exception, the writer is no longer valid, and the
only method that can be subsequently called is close()
.
Implementations of DatasetWriter
are typically not thread-safe; that
is, the behavior when accessing a single instance from multiple threads is
undefined.
Method Summary | |
---|---|
void |
close()
Close the writer and release any system resources. |
void |
flush()
Force or commit any outstanding data to storage. |
boolean |
isOpen()
|
void |
open()
Deprecated. will be removed in 0.16.0; no longer required |
void |
write(E entity)
Write an entity of type E to the associated dataset. |
Method Detail |
---|
@Deprecated void open()
Open the writer, allocating any necessary resources required to store entities.
This method must be invoked prior to any calls of
write(Object)
or flush()
.
DatasetWriterException
void write(E entity)
Write an entity of type E
to the associated dataset.
Implementations can buffer entities internally (see the flush()
method). All instances of entity
must conform to the dataset's
schema. If they don't, implementations should throw an exception, although
this is not required.
entity
- The entity to write
DatasetWriterException
void flush()
Force or commit any outstanding data to storage.
Implementations of this interface must declare their durability guarantees.
flush
in interface Flushable
DatasetWriterException
void close()
Close the writer and release any system resources.
No further operations of this interface (other than additional calls to this method) can be performed; however, implementations can choose to permit other method calls. See implementation documentation for details.
close
in interface Closeable
DatasetWriterException
boolean isOpen()
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