Add Dispatch Tracking

[steve-the-edwards]

Add the runtime's CoroutineContext to the WorkflowSession info and then also forward the CoroutineDispatcher through the ConfigSnapshot that is used by the WorkflowRuntimeTracer. This can help us get definitive logging about the dispatcher being used in the runtime.

[tcmulcahy]

This is a breaking change for anyone implementing WorkflowInterceptor. I don't know if that's a concern....

[steve-the-edwards]

New method is fine, no?

[tcmulcahy]

This won't always work. e.g. see the documentation from https://github.com/Kotlin/kotlinx.coroutines/blob/5d4954b17ac18c572e22a9a6e7bb4e4368ec568c/kotlinx-coroutines-core/common/src/MainCoroutineDispatcher.kt#L45 :

    /**
     * Returns a name of this main dispatcher for debugging purposes. This implementation returns
     * `Dispatchers.Main` or `Dispatchers.Main.immediate` if it is the same as the corresponding
     * reference in [Dispatchers] or a short class-name representation with address otherwise.
     */
    override fun toString(): String = toStringInternalImpl() ?: "$classSimpleName@$hexAddress"

The IO dispatcher - https://github.com/Kotlin/kotlinx.coroutines/blob/5d4954b17ac18c572e22a9a6e7bb4e4368ec568c/kotlinx-coroutines-core/native/src/Dispatchers.kt#L44 - is similar

Maybe you should drop the Dispatchers. from the beginning of the string if it exists?

[steve-the-edwards]

good idea.

[steve-the-edwards]

Changed it to

append("Dispatch: ${runtimeDispatch?.toString()?.substringAfter("Dispatchers.")?.take(8)}")

substringAfter returns original string by default if does not contain the substring.