Error handling

This page describes how configuration providers deal with errors arising from sources and binders.

It can be summarized in two simple rules:

• If an error occurs and no correct settings instance has been observed for the requested type thus far, the error is propagated to the calling code, resulting in exceptions from Get method. A subsequent settings update with correct data automatically "heals" future Get calls.

• If an error occurs and a correct settings instance has already been observed for the requested type at least once, the error is reported in background and does not cause Get method to fail: last seen correct instance is returned from cache instead.

// the source contains incorrect data

provider.Get<MySettings>(); // throws an exception

// the source updates with correct data

provider.Get<MySettings>(); // returns settings

// the source updates with incorrect data once again

provider.Get<MySettings>(); // returns settings from cache

The second guarantee can be violated by cache overflow events. Read the caching section to find out how to avoid them.

Observe method never produces OnError or OnCompleted notifications. It only reports successful settings updates. The errors are handled in background and can be logged.

Related pages

Configuration providerLog errorsObtain settings from providerObtain settings from provider