T
- the type of elements of the cursor@API(value=EXPERIMENTAL) public class ConcatCursor<T> extends Object implements RecordCursor<T>
RecordCursor.NoNextReason
Constructor and Description |
---|
ConcatCursor(FDBRecordContext context,
ScanProperties scanProperties,
TriFunction<FDBRecordContext,ScanProperties,byte[],RecordCursor<T>> func1,
TriFunction<FDBRecordContext,ScanProperties,byte[],RecordCursor<T>> func2,
byte[] continuation) |
Modifier and Type | Method and Description |
---|---|
boolean |
accept(RecordCursorVisitor visitor)
Accept a visit from hierarchical visitor, which implements
RecordCursorVisitor . |
void |
close() |
byte[] |
getContinuation()
Deprecated.
|
Executor |
getExecutor() |
RecordCursor.NoNextReason |
getNoNextReason()
Deprecated.
|
T |
next()
Deprecated.
|
CompletableFuture<Boolean> |
onHasNext()
Deprecated.
|
CompletableFuture<RecordCursorResult<T>> |
onNext()
Asynchronously return the next result from this cursor.
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
asIterator, asList, empty, empty, filter, filterAsync, filterAsyncInstrumented, filterAsyncInstrumented, filterInstrumented, filterInstrumented, first, flatMapPipelined, flatMapPipelined, flatMapPipelined, forEach, forEachAsync, forEachResult, forEachResultAsync, fromFuture, fromFuture, fromIterator, fromIterator, fromList, fromList, fromList, fromList, getCount, getNext, hasNext, limitRowsTo, limitTo, map, mapEffect, mapEffect, mapFuture, mapPipelined, orElse, reduce, skip, skipThenLimit
forEachRemaining, remove
@API(value=EXPERIMENTAL) public ConcatCursor(@Nonnull FDBRecordContext context, @Nonnull ScanProperties scanProperties, @Nonnull TriFunction<FDBRecordContext,ScanProperties,byte[],RecordCursor<T>> func1, @Nonnull TriFunction<FDBRecordContext,ScanProperties,byte[],RecordCursor<T>> func2, @Nullable byte[] continuation)
@Nonnull public CompletableFuture<RecordCursorResult<T>> onNext()
RecordCursor
RecordCursorResult
, which represents exactly one of the following:
T
produced by the cursor. In addition to the next record, this result
includes a RecordCursorContinuation
that can be used to continue the cursor after the last record
returned. The returned continuation is guaranteed not to be an "end continuation" representing the end of
the cursor: specifically, RecordCursorContinuation.isEnd()
is always false
on the returned
continuation.
RecordCursor.NoNextReason
that
explains why no record could be produced. The result include a continuation that can be used to continue
the cursor after the last record returned.
If the result's NoNextReason
is anything other than RecordCursor.NoNextReason.SOURCE_EXHAUSTED
, the
returned continuation must not be an end continuation. Conversely, if the result's NoNextReason
is SOURCE_EXHAUSTED
, then the returned continuation must be an an "end continuation".
RecordCursorContinuation
can be serialized to an opaque byte array using
RecordCursorContinuation.toBytes()
. This can be passed back into a new cursor of the same type, with all
other parameters remaining the same.onNext
in interface RecordCursor<T>
RecordCursorResult
,
RecordCursorContinuation
@Nonnull @Deprecated public CompletableFuture<Boolean> onHasNext()
RecordCursor
onHasNext
in interface RecordCursor<T>
true
if RecordCursor.next()
would return a record.AsyncIterator.onHasNext()
@Nullable @Deprecated public T next()
RecordCursor
@Nullable @Deprecated public byte[] getContinuation()
RecordCursor
getContinuation
in interface RecordCursor<T>
null
if the underlying source is completely exhausted, independent of any limit
passed to the cursor creator. Since such creators generally accept null
to mean no continuation,
that is, start from the beginning, one must check for null
from getContinuation
to
keep from starting over.
Result is not always defined if called before onHasNext
or before next
after
onHasNext
has returned true
. That is, a continuation is only guaranteed when called
"between" records from a while (hasNext) next
loop or after its end.@Nonnull @Deprecated public RecordCursor.NoNextReason getNoNextReason()
RecordCursor
false
for RecordCursor.hasNext()
.
If hasNext
was not called or returned true
last time, the result is undefined and
may be an exception.getNoNextReason
in interface RecordCursor<T>
public void close()
close
in interface RecordCursor<T>
close
in interface AutoCloseable
@Nonnull public Executor getExecutor()
getExecutor
in interface RecordCursor<T>
@Nonnull public boolean accept(@Nonnull RecordCursorVisitor visitor)
RecordCursor
RecordCursorVisitor
.
By contract, implementations of this method must return the value of visitor.visitLeave(this)
,
which determines whether or not subsequent siblings of this cursor should be visited.accept
in interface RecordCursor<T>
visitor
- a hierarchical visitortrue
if the subsequent siblings of the cursor
should be visited, and false
otherwise