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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 list of available versions for \u003ccode\u003ePullResponse\u003c/code\u003e 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\u003eEach listed version number links to the corresponding documentation for \u003ccode\u003estructgoogle_1_1cloud_1_1pubsub_1_1PullResponse\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003ePullResponse\u003c/code\u003e documentation covers the response behavior for blocking pulls, including how messages are redelivered based on whether the handler invokes \u003ccode\u003eack()\u003c/code\u003e or \u003ccode\u003enack()\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe content explains that exactly-once delivery subscriptions stop message redelivery after a successful \u003ccode\u003ehandler.ack()\u003c/code\u003e call, whereas best-effort subscriptions may still redeliver messages in certain circumstances.\u003c/p\u003e\n"],["\u003cp\u003eIt also contains a note that if the handler isn't an rvalue then the user may need to utilize \u003ccode\u003estd::move(handler).ack()\u003c/code\u003e or \u003ccode\u003estd::move(handler).nack()\u003c/code\u003e.\u003c/p\u003e\n"]]],[],null,[]]
