public abstract class DocValuesFormat extends Object implements NamedSPILoader.NamedSPI
Note, when extending this class, the name (getName()
) may
written into the index in certain configurations. In order for the segment
to be read, the name must resolve to your implementation via forName(String)
.
This method uses Java's
Service Provider Interface
(SPI) to resolve format names.
If you implement your own format, make sure that it has a no-arg constructor so SPI can load it.
ServiceLoader
Modifier | Constructor and Description |
---|---|
protected |
DocValuesFormat(String name)
Creates a new docvalues format.
|
Modifier and Type | Method and Description |
---|---|
static Set<String> |
availableDocValuesFormats()
returns a list of all available format names
|
abstract DocValuesConsumer |
fieldsConsumer(SegmentWriteState state)
Returns a
DocValuesConsumer to write docvalues to the
index. |
abstract DocValuesProducer |
fieldsProducer(SegmentReadState state)
Returns a
DocValuesProducer to read docvalues from the index. |
static DocValuesFormat |
forName(String name)
looks up a format by name
|
String |
getName() |
static void |
reloadDocValuesFormats(ClassLoader classloader)
Reloads the DocValues format list from the given
ClassLoader . |
String |
toString() |
protected DocValuesFormat(String name)
The provided name will be written into the index segment in some configurations
(such as when using PerFieldDocValuesFormat
): in such configurations,
for the segment to be read this class should be registered with Java's
SPI mechanism (registered in META-INF/ of your jar file, etc).
name
- must be all ascii alphanumeric, and less than 128 characters in length.public abstract DocValuesConsumer fieldsConsumer(SegmentWriteState state) throws IOException
DocValuesConsumer
to write docvalues to the
index.IOException
public abstract DocValuesProducer fieldsProducer(SegmentReadState state) throws IOException
DocValuesProducer
to read docvalues from the index.
NOTE: by the time this call returns, it must hold open any files it will need to use; else, those files may be deleted. Additionally, required files may be deleted during the execution of this call before there is a chance to open them. Under these circumstances an IOException should be thrown by the implementation. IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.
IOException
public final String getName()
getName
in interface NamedSPILoader.NamedSPI
public static DocValuesFormat forName(String name)
public static Set<String> availableDocValuesFormats()
public static void reloadDocValuesFormats(ClassLoader classloader)
ClassLoader
.
Changes to the docvalues formats are visible after the method ends, all
iterators (availableDocValuesFormats()
,...) stay consistent.
NOTE: Only new docvalues formats are added, existing ones are never removed or replaced.
This method is expensive and should only be called for discovery of new docvalues formats on the given classpath/classloader!
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