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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe webpage provides a version history for the \u003ccode\u003ePullResponse\u003c/code\u003e 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.\u003c/p\u003e\n"],["\u003cp\u003eThe content details how message handling works, highlighting that messages will be redelivered if \u003ccode\u003ehandler.nack()\u003c/code\u003e is called or the handler goes out of scope.\u003c/p\u003e\n"],["\u003cp\u003eFor exactly-once delivery subscriptions, messages are no longer redelivered after a successful \u003ccode\u003ehandler.ack()\u003c/code\u003e call, but with best-efforts subscriptions, redelivery is still possible even after a successful acknowledgement.\u003c/p\u003e\n"],["\u003cp\u003eIf \u003ccode\u003ehandler\u003c/code\u003e is not an rvalue, the use of \u003ccode\u003estd::move(handler).ack()\u003c/code\u003e or \u003ccode\u003estd::move(handler).nack()\u003c/code\u003e is necessary for proper message handling.\u003c/p\u003e\n"],["\u003cp\u003eThe document refers users to the Google Cloud Pub/Sub documentation on exactly-once delivery for additional information.\u003c/p\u003e\n"]]],[],null,[]]
