Add a flag to evaluate the top level transitions in Skyframe

This adds a new PrepareAnalysisPhaseFunction, which started out as a copy of
some existing code from SkyframeExecutor, BuildView, AnalysisPhaseRunner,
AnalysisUtils, and ConfigurationResolver, which was then modified to work
inside Skyframe.

Most of our tests already work with the new code, except for some of the tests
related to configuration trimming in combination with dependency cycles. The
reason for this is that we can only recover from dependency cycles at the end
of a Skyframe invocation, but never inside a Skyframe invocation. The new code
therefore cannot return partial results like the old code.

This seems to make null builds a bit faster. In my testing, I saw null build
times for a single test target go from ~50ms to ~40ms. This is probably due to
slightly better caching - it seems that computing the configuration transitions
and top-level targets is non-negligible, even if there's only a single
top-level configuration for a single top-level target.

This might be an even bigger win if there are a lot of top-level targets and
configurations.

PiperOrigin-RevId: 207083192

1 files changed, 19 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/AbstractLabelCycleReporter.java b/src/main/java/com/google/devtools/build/lib/skyframe/AbstractLabelCycleReporter.java
index ec4d791148..cb410f2227 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/AbstractLabelCycleReporter.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/AbstractLabelCycleReporter.java
@@ -48,6 +48,22 @@ abstract class AbstractLabelCycleReporter implements CyclesReporter.SingleCycleR
 
   protected abstract boolean canReportCycle(SkyKey topLevelKey, CycleInfo cycleInfo);
 
+  /**
+   * Can be used to skip individual keys on the path to cycle.
+   *
+   * @param key
+   */
+  protected boolean shouldSkip(SkyKey key) {
+    return false;
+  }
+
+  /**
+   * Can be used to report an additional message about the cycle.
+   *
+   * @param eventHandler
+   * @param topLevelKey
+   * @param cycleInfo
+   */
   protected String getAdditionalMessageAboutCycle(
       ExtendedEventHandler eventHandler, SkyKey topLevelKey, CycleInfo cycleInfo) {
     return "";
@@ -75,6 +91,9 @@ abstract class AbstractLabelCycleReporter implements CyclesReporter.SingleCycleR
       ImmutableList<SkyKey> pathToCycle = cycleInfo.getPathToCycle();
       ImmutableList<SkyKey> cycle = cycleInfo.getCycle();
       for (SkyKey value : pathToCycle) {
+        if (shouldSkip(value)) {
+          continue;
+        }
         cycleMessage.append("\n    ");
         cycleMessage.append(prettyPrint(value));
       }