Control the Cloud C++ client library behavior with respect to polling on long running operations.
Some operations in Cloud services return a google.longrunning.Operation object. As their name implies, these objects represent requests that may take a long time to complete, in some cases operations may take tens of seconds or even 30 minutes to complete.
The Cloud C++ client libraries models these long running operations as a google::cloud::future<StatusOr<T>>, where T represents the final result of the operation. In the background, the library polls the service until the operation completes (or fails) and then satisfies the future.
This class defines the interface for policies that control the behavior of this polling loop.
This function is called at the beginning of the polling loop. Policies that are based on relative time should restart their timers when this function is called.
Returns
Type
Description
std::unique_ptr< PollingPolicy >
OnFailure(Status const &)
A callback to indicate that a polling attempt failed.
This is called when a polling request fails. Note that this callback is not invoked when the polling request succeeds with "operation not done".
Parameter
Name
Description
status
Status const &
Returns
Type
Description
bool
true if the failure should be treated as transient and the polling loop should continue.
WaitPeriod()
How long should the polling loop wait before trying again.
[[["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 2025-03-05 UTC."],[[["This page details the `PollingPolicy` class in the Cloud C++ client library, which manages the behavior of polling loops for long-running operations."],["The latest version of the `PollingPolicy` class documentation is for version 2.37.0-rc, and a historical list of available versions are available ranging back to 2.10.1."],["The library uses `google::cloud::future` to model long-running operations and polls the service until the operation completes or fails."],["The `PollingPolicy` class includes functions such as `clone()`, `OnFailure()`, and `WaitPeriod()` to control the polling loop's behavior, including cloning the current policy, handling polling failures, and setting wait times between attempts."],["The `OnFailure()` function, a callback, determines if a polling failure is transient and whether to continue the polling loop, and `WaitPeriod()` determines how long the polling loop should wait between attempts."]]],[]]
