moon v1.26 - New experimental pipeline, trace profiles, and more

In this release, we focused primarily on a next-generation actions pipeline.

New experimental pipeline

The action pipeline or just "pipeline", is the system in which we actually run tasks in topological order when moon run, moon check, or moon ci is executed. The pipeline is powered by the action graph (also known as a task graph or dependency graph) and is quite complex, as we need to efficiently run tasks on our thread pool, ensure dependency tasks are ran before running dependent tasks, handle signals (ctrl + c), and much more.

Our current implementation "works" but could be much better, as it still has some problematic edge cases, doesn't always shutdown correctly, and is pretty much tech debt at this point. To remedy this, we spent the last month working on a new action pipeline that aims to solve all of these problems, with a more modern implementation. Some such improvements are:

• Increased performance with better concurrency handling and scheduling. Threads in the pool should now be constantly utilized.
• More accurately monitors signals (ctrl+c) and shutdowns. We now use Rust channels internally to manage this state.
• The CLI will now wait for aborted/cancelled task handles to exit before the entire CLI exits. This should alleviate zombie processes.

With all that said, unlike previous releases that replaced the old feature with a new feature, we chose to gate this new pipeline behind an experimental flag. We want to ensure this works correctly in all cases, before enabling it by default. So please test it and report back any issues! We've successfully been using it on moon's repository without issue.

experiments:
  actionPipelineV2: true

Generate trace profiles

A major goal of moon is to be extremely efficient and to optimize as much as possible. To help accomplish this goal, we're introducing the global CLI --dump flag, which will generate a trace profile that can be loaded and reviewed in chrome://tracing.

This will display a flame graph with labeled operations, their timing information, and any associated data. This is the first step in capturing this kind of information, and it will only get better moving forward.

Additional shell support

Based on the work in proto, we now have built-in support for additional command line shells. To start, we've updated the unixShell and windowsShell task options to support the following new shells:

• Unix: ion, nu (nushell), pwsh (powershell), xonsh.
• Windows: elvish, fish, nu (nushell), xonsh

And furthermore, we've added Nushell completion support to the moon completions command!

Other changes

View the official release for a full list of changes.

• Updated CLI command execution to be more performant, and to reduce our usage of concurrent locks.
• Updated proto to v0.37.1 (from v0.36.2).