- All Known Implementing Classes:
DisposableResultCursorImpl
,ResultCursorImpl
records
.
Result can be eagerly fetched in a list using listAsync()
or navigated lazily using
forEachAsync(Consumer)
or nextAsync()
.
Results are valid until the next query is run or until the end of the current transaction,
whichever comes first. To keep a result around while further queries are run, or to use a result outside the scope
of the current transaction, see listAsync()
.
Important note on semantics
In order to handle very large results, and to minimize memory overhead and maximize
performance, results are retrieved lazily. Please see AsyncQueryRunner
for
important details on the effects of this.
The short version is that, if you want a hard guarantee that the underlying query
has completed, you need to either call AsyncTransaction.commitAsync()
on the transaction
or AsyncSession.closeAsync()
on the session
that created this result, or you need to use
the result.
Note: Every returned CompletionStage
can be completed by an IO thread which should never block.
Otherwise IO operations on this and potentially other network connections might deadlock. Please do not chain
blocking operations like CompletableFuture.get()
on the returned stages. Consider using asynchronous calls
throughout the chain or offloading blocking operation to a different Executor
. This can be done using
methods with "Async" suffix like CompletionStage.thenApplyAsync(java.util.function.Function)
or
CompletionStage.thenApplyAsync(java.util.function.Function, Executor)
.
- Since:
- 1.5
-
Method Summary
Modifier and TypeMethodDescriptionAsynchronously retrieve the result summary.forEachAsync
(Consumer<Record> action) Asynchronously apply the givenaction
to every record in the result, yielding a summary of it.Determine if result is open.keys()
Retrieve the keys of the records this result cursor contains.Asynchronously retrieve and store the entire result stream.<T> CompletionStage<List<T>>
Asynchronously retrieve and store a projection of the entire result.Asynchronously navigate to and retrieve the nextRecord
in this result.Asynchronously investigate the next upcomingRecord
without moving forward in the result.Asynchronously return the first record in the result, failing if there is not exactly one record left in the stream.
-
Method Details
-
keys
Retrieve the keys of the records this result cursor contains.- Returns:
- list of all keys.
-
consumeAsync
CompletionStage<ResultSummary> consumeAsync()Asynchronously retrieve the result summary.If the records in the result is not fully consumed, then calling this method will exhausts the result.
If you want to access unconsumed records after summary, you shall use
Result.list()
to buffer all records into memory before summary.- Returns:
- a
CompletionStage
completed with a summary for the whole query result. Stage can also be completed exceptionally if query execution fails.
-
nextAsync
CompletionStage<Record> nextAsync()Asynchronously navigate to and retrieve the nextRecord
in this result. Returned stage can containnull
if end of records stream has been reached.- Returns:
- a
CompletionStage
completed with a record ornull
. Stage can also be completed exceptionally if query execution fails.
-
peekAsync
CompletionStage<Record> peekAsync()Asynchronously investigate the next upcomingRecord
without moving forward in the result. Returned stage can containnull
if end of records stream has been reached.- Returns:
- a
CompletionStage
completed with a record ornull
. Stage can also be completed exceptionally if query execution fails.
-
singleAsync
CompletionStage<Record> singleAsync()Asynchronously return the first record in the result, failing if there is not exactly one record left in the stream.- Returns:
- a
CompletionStage
completed with the first and only record in the stream. Stage will be completed exceptionally withNoSuchRecordException
if there is not exactly one record left in the stream. It can also be completed exceptionally if query execution fails.
-
forEachAsync
Asynchronously apply the givenaction
to every record in the result, yielding a summary of it.- Parameters:
action
- the function to be applied to every record in the result. Provided function should not block.- Returns:
- a
CompletionStage
completed with a summary for the whole query result. Stage can also be completed exceptionally if query execution or provided function fails.
-
listAsync
CompletionStage<List<Record>> listAsync()Asynchronously retrieve and store the entire result stream. This can be used if you want to iterate over the stream multiple times or to store the whole result for later use.Note that this method can only be used if you know that the query that yielded this result returns a finite stream. Some queries can yield infinite results, in which case calling this method will lead to running out of memory.
Calling this method exhausts the result.
- Returns:
- a
CompletionStage
completed with a list of all remaining immutable records. Stage can also be completed exceptionally if query execution fails.
-
listAsync
Asynchronously retrieve and store a projection of the entire result. This can be used if you want to iterate over the stream multiple times or to store the whole result for later use.Note that this method can only be used if you know that the query that yielded this result returns a finite stream. Some queries can yield infinite results, in which case calling this method will lead to running out of memory.
Calling this method exhausts the result.
- Type Parameters:
T
- the type of result list elements- Parameters:
mapFunction
- a function to map from Record to T. SeeRecords
for some predefined functions.- Returns:
- a
CompletionStage
completed with a list of all remaining immutable records. Stage can also be completed exceptionally if query execution or provided function fails.
-
isOpenAsync
CompletionStage<Boolean> isOpenAsync()Determine if result is open.Result is considered to be open if it has not been consumed (
consumeAsync()
) and its creator object (e.g. session or transaction) has not been closed (including committed or rolled back).Attempts to access data on closed result will produce
ResultConsumedException
.- Returns:
- a
CompletionStage
completed withtrue
if result is open andfalse
otherwise.
-