name: Restart Preempted Libc++ Workflow

# The libc++ builders run on preemptable VMs, which can be shutdown at any time.
# This workflow identifies when a workflow run was canceled due to the VM being preempted,
# and restarts the workflow run.

# We identify a canceled workflow run by checking the annotations of the check runs in the check suite,
# which should contain the message "The runner has received a shutdown signal."

# Note: If a job is both preempted and also contains a non-preemption failure, we do not restart the workflow.

on:
  workflow_run:
    workflows: [Build and Test libc\+\+]
    types:
      - completed

permissions:
  contents: read

jobs:
  restart:
    if: github.repository_owner == 'llvm' && (github.event.workflow_run.conclusion == 'failure' || github.event.workflow_run.conclusion == 'cancelled')
    name: "Restart Job"
    permissions:
      statuses: read
      checks: write
      actions: write
    runs-on: ubuntu-24.04
    steps:
      - name: "Restart Job"
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea #v7.0.1
        with:
          script: |
            const failure_regex = /Process completed with exit code 1./
            const preemption_regex = /(The runner has received a shutdown signal)|(The operation was canceled)/

            const wf_run = context.payload.workflow_run
            core.notice(`Running on "${wf_run.display_title}" by @${wf_run.actor.login} (event: ${wf_run.event})\nWorkflow run URL: ${wf_run.html_url}`)


            async function create_check_run(conclusion, message) {
                // Create a check run on the given workflow run to indicate if
                // we are restarting the workflow or not.
                if (conclusion != 'success' && conclusion != 'skipped' && conclusion != 'neutral') {
                  core.setFailed('Invalid conclusion: ' + conclusion)
                }
                await github.rest.checks.create({
                    owner: context.repo.owner,
                    repo: context.repo.repo,
                    name: 'Restart Preempted Job',
                    head_sha: wf_run.head_sha,
                    status: 'completed',
                    conclusion: conclusion,
                    output: {
                      title: 'Restarted Preempted Job',
                      summary: message
                    }
                })
            }

            console.log('Listing check runs for suite')
            const check_suites = await github.rest.checks.listForSuite({
              owner: context.repo.owner,
              repo: context.repo.repo,
              check_suite_id: context.payload.workflow_run.check_suite_id,
              per_page: 100 // FIXME: We don't have 100 check runs yet, but we should handle this better.
            })

            check_run_ids = [];
            for (check_run of check_suites.data.check_runs) {
              console.log('Checking check run: ' + check_run.id);
              if (check_run.status != 'completed') {
                console.log('Check run was not completed. Skipping.');
                continue;
              }
              if (check_run.conclusion != 'failure' && check_run.conclusion != 'cancelled') {
                console.log('Check run had conclusion: ' + check_run.conclusion + '. Skipping.');
                continue;
              }
              check_run_ids.push(check_run.id);
            }

            has_preempted_job = false;

            for (check_run_id of check_run_ids) {
              console.log('Listing annotations for check run: ' + check_run_id);

              annotations = await github.rest.checks.listAnnotations({
                owner: context.repo.owner,
                repo: context.repo.repo,
                check_run_id: check_run_id
              })

              // For temporary debugging purposes to see the structure of the annotations.
              console.log(annotations);

              has_failed_job = false;
              saved_failure_message = null;

              for (annotation of annotations.data) {
                if (annotation.annotation_level != 'failure') {
                  continue;
                }

                const preemption_match = annotation.message.match(preemption_regex);

                if (preemption_match != null) {
                  console.log('Found preemption message: ' + annotation.message);
                  has_preempted_job = true;
                }

                const failure_match = annotation.message.match(failure_regex);
                if (failure_match != null) {
                  has_failed_job = true;
                  saved_failure_message = annotation.message;
                }
              }
              if (has_failed_job && (! has_preempted_job)) {
                // We only want to restart the workflow if all of the failures were due to preemption.
                // We don't want to restart the workflow if there were other failures.
                //
                // However, libcxx runners running inside docker containers produce both a preemption message and failure message.
                //
                // The desired approach is to ignore failure messages which appear on the same job as a preemption message
                // (An job is a single run with a specific configuration, ex generic-gcc, gcc-14).
                //
                // However, it's unclear that this code achieves the desired approach, and it may ignore all failures
                // if a preemption message is found at all on any run.
                //
                // For now, it's more important to restart preempted workflows than to avoid restarting workflows with
                // non-preemption failures.
                //
                // TODO Figure this out.
                core.notice('Choosing not to rerun workflow because we found a non-preemption failure' +
                  'Failure message: "' + saved_failure_message + '"');
                await create_check_run('skipped', 'Choosing not to rerun workflow because we found a non-preemption failure\n'
                    + 'Failure message: ' + saved_failure_message)
                return;
              }
            }

            if (!has_preempted_job) {
              core.notice('No preempted jobs found. Not restarting workflow.');
              await create_check_run('neutral', 'No preempted jobs found. Not restarting workflow.')
              return;
            }

            core.notice("Restarted workflow: " + context.payload.workflow_run.id);
            await github.rest.actions.reRunWorkflowFailedJobs({
                owner: context.repo.owner,
                repo: context.repo.repo,
                run_id: context.payload.workflow_run.id
              })
            await create_check_run('success', 'Restarted workflow run due to preempted job')

  restart-test:
    if: github.repository_owner == 'llvm' && (github.event.workflow_run.conclusion == 'failure' || github.event.workflow_run.conclusion == 'cancelled') && github.event.actor.login == 'ldionne' # TESTING ONLY
    name: "Restart Job (test)"
    permissions:
      statuses: read
      checks: write
      actions: write
    runs-on: ubuntu-24.04
    steps:
      - name: "Restart Job (test)"
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea #v7.0.1
        with:
          script: |
            const FAILURE_REGEX = /Process completed with exit code 1./
            const PREEMPTION_REGEX = /(The runner has received a shutdown signal)|(The operation was canceled)/

            function log(msg) {
              core.notice(msg)
            }

            const wf_run = context.payload.workflow_run
            log(`Running on "${wf_run.display_title}" by @${wf_run.actor.login} (event: ${wf_run.event})\nWorkflow run URL: ${wf_run.html_url}`)

            log('Listing check runs for suite')
            const check_suites = await github.rest.checks.listForSuite({
              owner: context.repo.owner,
              repo: context.repo.repo,
              check_suite_id: context.payload.workflow_run.check_suite_id,
              per_page: 100 // FIXME: We don't have 100 check runs yet, but we should handle this better.
            })

            preemptions = [];
            legitimate_failures = [];
            for (check_run of check_suites.data.check_runs) {
              log(`Checking check run: ${check_run.id}`);
              if (check_run.status != 'completed') {
                log('Check run was not completed. Skipping.');
                continue;
              }

              if (check_run.conclusion != 'failure' && check_run.conclusion != 'cancelled') {
                log(`Check run had conclusion: ${check_run.conclusion}. Skipping.`);
                continue;
              }

              annotations = await github.rest.checks.listAnnotations({
                owner: context.repo.owner,
                repo: context.repo.repo,
                check_run_id: check_run.id
              })

              preemption_annotation = annotations.data.find(function(annotation) {
                return annotation.annotation_level == 'failure' &&
                       annotation.message.match(PREEMPTION_REGEX) != null;
              });
              if (preemption_annotation != null) {
                log(`Found preemption message: ${preemption_annotation.message}`);
                preemptions.push(check_run);
                break;
              }

              failure_annotation = annotations.data.find(function(annotation) {
                return annotation.annotation_level == 'failure' &&
                       annotation.message.match(FAILURE_REGEX) != null;
              });
              if (failure_annotation != null) {
                log(`Found legitimate failure annotation: ${failure_annotation.message}`);
                legitimate_failures.push(check_run);
                break;
              }
            }

            if (preemptions) {
              log('Found some preempted jobs');
              if (legitimate_failures) {
                log('Also found some legitimate failures, so not restarting the workflow.');
              } else {
                log('Did not find any legitimate failures. Restarting workflow.');
                await github.rest.actions.reRunWorkflowFailedJobs({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  run_id: context.payload.workflow_run.id
                })
              }
            } else {
              log('Did not find any preempted jobs. Not restarting the workflow.');
            }