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 2025-03-14 UTC."],[[["The webpage provides a version history for the `PullResponse` structure in the Google Cloud Pub/Sub C++ library, ranging from version 2.11.0 up to the latest release candidate, 2.37.0-rc."],["The content details how message handling works, highlighting that messages will be redelivered if `handler.nack()` is called or the handler goes out of scope."],["For exactly-once delivery subscriptions, messages are no longer redelivered after a successful `handler.ack()` call, but with best-efforts subscriptions, redelivery is still possible even after a successful acknowledgement."],["If `handler` is not an rvalue, the use of `std::move(handler).ack()` or `std::move(handler).nack()` is necessary for proper message handling."],["The document refers users to the Google Cloud Pub/Sub documentation on exactly-once delivery for additional information."]]],[]]
