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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documentation for various versions of the Google Cloud Pub/Sub C++ client library, detailing the \u003ccode\u003ePullResponse\u003c/code\u003e structure.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent version is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, while the oldest documented version listed is \u003ccode\u003e2.11.0\u003c/code\u003e, with numerous versions in between.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003ePullResponse\u003c/code\u003e documentation explains the behavior of message handling, including acknowledging (\u003ccode\u003eack\u003c/code\u003e) and negatively acknowledging (\u003ccode\u003enack\u003c/code\u003e) messages.\u003c/p\u003e\n"],["\u003cp\u003eThe content outlines the difference in message redelivery behavior between exactly-once delivery subscriptions and best-efforts subscriptions.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation mentions the use of \u003ccode\u003estd::move(handler)\u003c/code\u003e for invoking \u003ccode\u003eack()\u003c/code\u003e or \u003ccode\u003enack()\u003c/code\u003e when the \u003ccode\u003ehandler\u003c/code\u003e is not an rvalue.\u003c/p\u003e\n"]]],[],null,[]]
