T - the type of elements returned by this cursor@API(value=EXPERIMENTAL) public class AutoContinuingCursor<T> extends Object implements RecordCursor<T>
AutoContinuingCursor is also exhausted.
AutoContinuingCursor is responsible for all FDBRecordContext management, so all reads it does are in
the scope of transactions that it controls.
The AutoContinuingCursor has no visibility into the ScanProperties of
the underlying cursor and, therefore, will not be involved in enforcing any limits that may be individually
applied to the underlying cursor. For example, if the generator returns an underlying cursor that
specified, say, a record scan limit of 10 records, the AutoContinuingCursor will scan all data until it is
exhausted, at most 10 records at a transaction.
RecordCursor.NoNextReason| Constructor and Description |
|---|
AutoContinuingCursor(FDBDatabaseRunner runner,
BiFunction<FDBRecordContext,byte[],RecordCursor<T>> nextCursorGenerator)
Creates a new
AutoContinuingCursor. |
| 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() |
RecordCursorResult<T> |
getNext()
Get the next result from this cursor.
|
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, waitasIterator, 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, hasNext, limitRowsTo, limitTo, map, mapEffect, mapEffect, mapFuture, mapPipelined, orElse, reduce, skip, skipThenLimitforEachRemaining, removepublic AutoContinuingCursor(@Nonnull FDBDatabaseRunner runner, @Nonnull BiFunction<FDBRecordContext,byte[],RecordCursor<T>> nextCursorGenerator)
AutoContinuingCursor.runner - the runner from which it can open new contextsnextCursorGenerator - the method which can generate the underlying cursor given a record context and a
continuation@Nonnull public CompletableFuture<RecordCursorResult<T>> onNext()
RecordCursorRecordCursorResult, 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 public RecordCursorResult<T> getNext()
RecordCursorRecordCursor.onNext(), should
be preferred in such circumstances.getNext in interface RecordCursor<T>RecordCursor.onNext(),
RecordCursorResult,
RecordCursorContinuation@Nonnull @Deprecated public CompletableFuture<Boolean> onHasNext()
RecordCursoronHasNext 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()
RecordCursorgetContinuation 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()
RecordCursorfalse 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>public boolean accept(@Nonnull RecordCursorVisitor visitor)
RecordCursorRecordCursorVisitor.
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