If the application invokes handler.nack() or allows handler to go out of scope, then the service will redeliver the message.
With exactly-once delivery subscriptions, the service will stop redelivering the message once the application invokes handler.ack() and the invocation succeeds. With best-efforts subscriptions, the service may redeliver the message, even after a successful handler.ack() invocation.
If handler is not an rvalue, you may need to use std::move(handler).ack() or std::move(handler).nack().
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-04-17 UTC."],[[["This webpage provides access to the documentation for various versions of the Google Cloud Pub/Sub C++ library, starting from version 2.11.0 up to the latest release candidate, 2.37.0-rc."],["The content specifically pertains to the `PullResponse` structure within the `google::cloud::pubsub` namespace, detailing how messages are pulled and managed."],["The documentation explains the behavior of message redelivery in both exactly-once delivery and best-effort subscriptions, emphasizing the role of `handler.ack()` and `handler.nack()`."],["It highlights the importance of using `std::move(handler).ack()` or `std::move(handler).nack()` when the handler is not an rvalue."],["The page also includes a link to the Google Cloud Pub/Sub exactly-once delivery documentation."]]],[]]
