Log all invocations of callbacks supplied to public API methods

[lawrence-forooghian]

Background

In #1655 we added log statements which are emitted whenever a public API method is invoked.

Many of these method invocations will eventually provide some sort of output to the caller by invoking a callback.

Requirements

Let’s take an example of a representative method in the public API of the SDK. Here we have -[ARTRealtimeChannel publish:data:callback:]:

- (void)publish:(nullable NSString *)name data:(nullable id)data callback:(nullable ARTCallback)callback;

Just before this method calls the callback, we want to emit a log message which includes the following information:

• the fact that a method of the public API invoked a callback (for example a publicAPICallback tag if we implement the tag mechanism suggested in Log all invocations of public API methods #1655)
• the name of the method that was called
• the address of the callback (or, if nil callback passed, something to indicate that it would have called a callback if passed)
• something that links this log message to the log message that was emitted in Log all invocations of public API methods #1655 when the method was called (mechanism to be defined by Create a way to link public API invocations to their eventual outputs #1658)

We want to do this for all of the callback-taking methods that make up the public API of the SDK.

Not yet known

• What log level these messages should be logged at — we’ll defer this until Define the different log levels and how they should be used #1634, let’s use verbose for now

Logging API considerations (falls under #1617)

The above should be implemented in a way that is consistent throughout the codebase and which is easy to add to new methods. This means exposing an internal logging API that helps us to log these messages. Exact API to be decided when implementing this ticket, but should be something similar to that decided in #1655.

Depends on

• Create a way to link public API invocations to their eventual outputs #1658

┆Issue is synchronized with this Jira Task by Unito

[sync-by-unito]

➤ Automation for Jira commented:

The link to the corresponding Jira issue is https://ably.atlassian.net/browse/SDK-3531