Add configuration option to control maximum number of persisted events/sessions

[fractalwrench]

Goal

The bugsnag-android SDK persists events & sessions to disk if it is unable to deliver them to the API due to network failure. This provides a configuration option to control how many payloads should be stored on disk for both events and sessions.

Changeset

• Added maxPersistedEvents and maxPersistedSessions to Configuration with a default value of 32
• Added MAX_PERSISTED_EVENTS and MAX_PERSISTED_SESSIONS for reading configuration options from the manifest
• Updated EventStore and SessionStore so that they respect the configuration options
• Fixed a bug in discardOldestFileIfNeeded(), where in the unlikely scenario that >32 payloads were persisted on disk, the function would delete all the payloads if another payload needed persisting

Testing

Added integration tests which verify the event/session store classes only persist up to the configured limit, and that this limit can be changed. Unit tests verify that the max persisted events/sessions configuration options are validated as necessary.

[bugsnagbot]

Android notifier sizes

Format	Size impact of Bugsnag (kB)	Size impact of Bugsnag when Minified (kB)
APK	1441.64	1361.29
arm64_v8a	369.25	287.33
armeabi	348.77	266.85
armeabi_v7a	332.39	250.47
x86	410.2	328.28
x86_64	389.73	307.81

Generated by 🚫 Danger

[tomlongridge]

Do we definitely want to allow the value 0 for this configuration? Does that not effectively break the functionality as nothing would be delivered?

[fractalwrench]

Do we definitely want to allow the value 0 for this configuration? Does that not effectively break the functionality as nothing would be delivered?

I felt this was a reasonable, if a bit of an unusual, use-case. It would still allow users to send handled errors and sessions if they didn't want to persist them on disk if delivery was not possible. This is effectively what we do for Internal Error reporting already.