Transaction specification

This is the engineering specification for the Transaction object.

Features

• Target enumeration
• Optimized
• Target selectors
• Named plans
• Serialization

Overview

A transaction aggregates requests for plans to be assigned to targets. Transactions are meant to be committed to a Runtime. Transactions are ephemeral. Transactions should be as "dumb" as possible; a reasonable implementation is no more than a log of requested operations and their parameters.

MVP

Simple initializer: A transaction is cheap to create.

Example pseudo-code:

transaction = Transaction()

add API: Provide an API for a basic add operation.

This API must accept a plan and a target object.

Example pseudo-code:

# Associate a plan with a target.
transaction.addPlan(plan, to: target)

commit API: Provide an API for committing a transaction to a runtime.

Example pseudo-code:

transaction.commitToRuntime(runtime)

Operation enumeration: Operations recorded to a transaction are enumerable.

Operations are enumerated in the order in which they were recorded.

Copying plans: When a plan is added to a transaction it must be copied. This ensures that subsequent modifications to a plan object do not affect the transaction. For example:

Example pseudo-code:

plan.fromValue = 0
transaction.addPlan(plan, to: target)

plan.fromValue = 5
transaction.addPlan(plan, to: target)

Notice that each entry has a different fromValue in the following log:

[
  {action: 'add', plan: {..., fromValue = 0}}, 
  {action: 'add', plan: {..., fromValue = 5}}
]