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"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis webpage provides a list of versioned documentation for the \u003ccode\u003ePullResponse\u003c/code\u003e struct in the Google Cloud Pub/Sub C++ library, starting from version 2.11.0 up to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003ePullResponse\u003c/code\u003e struct is related to blocking pulls in the Pub/Sub service, and messages are redelivered if \u003ccode\u003ehandler.nack()\u003c/code\u003e is called or if the handler goes out of scope.\u003c/p\u003e\n"],["\u003cp\u003eThe service's redelivery behavior varies depending on whether the subscription uses exactly-once delivery or best-efforts delivery, with the former ceasing redelivery after a successful \u003ccode\u003ehandler.ack()\u003c/code\u003e and the latter possibly redelivering even after successful acknowledgment.\u003c/p\u003e\n"],["\u003cp\u003eWhen using a non-rvalue handler, you might need to use \u003ccode\u003estd::move(handler).ack()\u003c/code\u003e or \u003ccode\u003estd::move(handler).nack()\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe exactly-once delivery functionality is explained in the provided link : https://cloud.google.com/pubsub/docs/exactly-once-delivery.\u003c/p\u003e\n"]]],[],null,[]]
