public abstract class ChunksIntEncoder extends IntEncoder
IntEncoderwhich encodes values in chunks. Implementations of this class assume the data which needs encoding consists of small, consecutive values, and therefore the encoder is able to compress them better. You can read more on the two implementations
Extensions of this class need to implement
IntEncoder.encode(int) in order to
build the proper indicator (flags). When enough values were accumulated
(typically the batch size), extensions can call
flush the indicator and the rest of the values.
NOTE: flags encoders do not accept values ≤ 0 (zero) in their
IntEncoder.encode(int). For performance reasons they do not check that
condition, however if such value is passed the result stream may be corrupt
or an exception will be thrown. Also, these encoders perform the best when
there are many consecutive small values (depends on the encoder
implementation). If that is not the case, the encoder will occupy 1 more byte
for every batch number of integers, over whatever
VInt8IntEncoder would have occupied. Therefore make sure to check
whether your data fits into the conditions of the specific encoder.
For the reasons mentioned above, these encoders are usually chained with
DGapIntEncoder in the following
IntEncoder fourFlags =
new SortingEncoderFilter(new UniqueValuesIntEncoder(new DGapIntEncoder(new FlagsIntEncoderImpl())));
|Modifier and Type||Field and Description|
Holds the values which must be encoded, outside the indicator.
Encoder used to encode values outside the indicator.
Represents bits flag byte.
Counts the current ordinal of the encoded value.
|Modifier||Constructor and Description|
|Modifier and Type||Method and Description|
Instructs the encoder to finish the encoding process.
Encodes the values of the current chunk.
Reinitializes the encoder with the give
protected final int encodeQueue
protected int encodeQueueSize
protected final IntEncoder encoder
protected int indicator
protected byte ordinal
protected void encodeChunk() throws IOException
public void close() throws IOException
reInit. An implementation may do here additional cleanup required to complete the encoding, such as flushing internal buffers, etc.
encodeshould be made before first calling
NOTE: overriding classes should make sure they either call
super.close() or close the output stream themselves.
public void reInit(OutputStream out)
OutputStream. For re-usability it can be changed without the need to reconstruct a new object.
NOTE: after calling
IntEncoder.close(), one must call
this method even if the output stream itself hasn't changed. An example
case is that the output stream wraps a byte, and the output stream itself
is reset, but its instance hasn't changed. Some implementations of
IntEncoder may write some metadata about themselves to the output
stream, and therefore it is imperative that one calls this method before
encoding any data.
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