This uses the run_on_projects attribute introduced earlier for most branches,
adjusts the `ash` method to handle that branch as the legacy implementation
did, and updates try syntax to match builds as well as tests.
In the process, this enables optimizing target tasks, meaning that tasks
specifically requested in the try syntax might be optimized. While this is
probably not ideal, it matches the existing behavior of try (where `-j all` is
the default but all jobs are set to run only when certain files have been
modified). This change can be reverted later, in a more advanced version of
try.
MozReview-Commit-ID: 5FYeUTAsafr
* Implement & document optimization (although legacy kind doesn't do much of it)
* Introduce `optimize_target_tasks` parameter to control whether tasks in the
target set can be optimized (no for try, yes for most other branches)
* Refactor to include resolved taskIds in the optimized task graph
* Include a `label-to-taskid.json` artifact.
* Introduce {'task-reference': '... <dependency-name> ...'} for referring to
parent tasks' taskId.
MozReview-Commit-ID: LWvlWNz49U5
The `taskgraph` package generates TaskCluster task graphs based on collections
of task "kinds". Initially, there is only one kind, the "legacy" kind, which
reads the YAML files from `testing/taskcluster/tasks` to generate the task
graph.
Try syntax is implemented by filtering the tasks in the taskgraph after it has
been created, then extending the result to include any prerequisite tasks.
A collection of `mach taskgraph` subcommands are provided for developers to
extend or debug the task-graph generation process.
MozReview-Commit-ID: 1TJCns4XxZ8
