createStep(): Cache finished derivations

Dependencies

• [2] HUUZFPPK Fix race between the queue monitor and the builder threads
• [3] 24BMQDZA Start of single-process hydra-queue-runner
• [4] 2IQRXLWE Support cancelling builds
• [5] 22LDPAIP Check non-runnable steps for unsupported system type
• [6] NJJ7H64S Very basic multi-threaded queue runner
• [7] HLSHCK3C Support requiredSystemFeatures
• [8] ENXUSMSV Make concurrency more robust
• [9] GKZN4UV7 Make the queue monitor more robust, and better debug output
• [10] JAUB2FT5 getQueuedBuilds(): Handle dependent builds first

Change contents

• replacement in src/hydra-queue-runner/hydra-queue-runner.cc at line 307
  [3.1249]→[2.263:323](∅→∅)
  − Build::ptr referringBuild, Step::ptr referringStep,
  [3.1249]

  [3.0]
  + Build::ptr referringBuild, Step::ptr referringStep, std::set<Path> & finishedDrvs,
• replacement in src/hydra-queue-runner/hydra-queue-runner.cc at line 568
  [3.354]→[2.367:460](∅→∅)
  − Step::ptr step = createStep(store, build->drvPath, build, 0, newSteps, newRunnable);
  [3.354]

  [3.355]
  + std::set<Path> finishedDrvs; // FIXME: re-use?

  + Step::ptr step = createStep(store, build->drvPath, build, 0, finishedDrvs, newSteps, newRunnable);
• replacement in src/hydra-queue-runner/hydra-queue-runner.cc at line 718
  [3.4065]→[2.550:606](∅→∅)
  − Build::ptr referringBuild, Step::ptr referringStep,
  [3.4065]

  [3.443]
  + Build::ptr referringBuild, Step::ptr referringStep, std::set<Path> & finishedDrvs,
• edit in src/hydra-queue-runner/hydra-queue-runner.cc at line 721
  [3.11566]

  [2.607]
  + if (finishedDrvs.find(drvPath) != finishedDrvs.end()) return 0;

  +
• replacement in src/hydra-queue-runner/hydra-queue-runner.cc at line 789
  [3.12108]→[3.12108:12133](∅→∅)
  − if (valid) return 0;
  [3.12108]

  [3.12133]
  + if (valid) {

  + finishedDrvs.insert(drvPath);

  + return 0;

  + }
• replacement in src/hydra-queue-runner/hydra-queue-runner.cc at line 800
  [3.12329]→[2.1993:2072](∅→∅)
  − auto dep = createStep(store, i.first, 0, step, newSteps, newRunnable);
  [3.12329]

  [3.12374]
  + auto dep = createStep(store, i.first, 0, step, finishedDrvs, newSteps, newRunnable);