ChangeStream
public class ChangeStream<T> : CursorProtocol where T : Decodable, T : Encodable
A MongoDB change stream.
-
The
ResumeToken
associated with the most recent event seen by the change stream.Declaration
Swift
public var resumeToken: ResumeToken? { get }
-
Indicates whether this change stream has the potential to return more data.
This change stream will be dead after
next
returnsnil
, but it may still be alive aftertryNext
returnsnil
.After either of
next
ortryNext
return a non-DecodingError
error, this change stream will be dead. It may still be alive after either returns aDecodingError
, however.Declaration
Swift
public func isAlive() -> Bool
-
Get the next
T
from this change stream.This method will block until an event is returned from the server, an error occurred, or the change stream is killed. Each attempt to retrieve results will wait server-side for a maximum of
maxAwaitTimeMS
(specified on theChangeStreamOptions
passed to the method that created this change stream) before making another request.A thread from the pool will be occupied by this method until it returns, so performance degradation is possible if the number of polling change streams is too close to the total number of threads in the thread pool. To configure the total number of threads in the pool, set the
MongoClientOptions.threadPoolSize
option on client creation.If the result contains an error, it is likely one of the following: -
MongoError.CommandError
if an error occurs while fetching more results from the server. -MongoError.LogicError
if this function is called after the change stream has died. -MongoError.LogicError
if this function is called and the session associated with this change stream is inactive. -DecodingError
if an error occurs decoding the server’s response.Declaration
Swift
public func next() -> Result<T, Error>?
Return Value
A
Result<T, Error>?
containing the nextT
in this change stream or an error if one occurred, ornil
if the change stream is exhausted. This method will block until one of those conditions is met, potentially after multiple requests to the server. -
Attempt to get the next
T
from this change stream, returningnil
if there are no results.The change stream will wait server-side for a maximum of
maxAwaitTimeMS
(specified on theChangeStreamOptions
passed to the method that created this change stream) before returningnil
.This method may be called repeatedly while
isAlive
is true to retrieve new data.Declaration
Swift
public func tryNext() -> Result<T, Error>?
Return Value
A
Result<T, Error>?
containing the nextT
in this change stream, an error if one occurred, ornil
if there was no data.If the result is an error, it is likely one of the following:
MongoError.CommandError
if an error occurs while fetching more results from the server.MongoError.LogicError
if this function is called after the change stream has died.MongoError.LogicError
if this function is called and the session associated with this change stream is inactive.
DecodingError
if an error occurs decoding the server’s response.
-
Kill this change stream.
This method may be called from another thread safely even if this change stream is blocked retrieving results. This is mainly useful for freeing a thread that the change stream is blocking with a long running operation.
This method is automatically called in the
deinit
ofChangeStream
, so it is not necessary to call it manually.This method will have no effect if the change stream is already dead.
Declaration
Swift
public func kill()