1 files changed, 36 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java b/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
index 6932d9ea18..dab37d82cb 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java
@@ -30,6 +30,7 @@ import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
 import com.google.devtools.build.lib.analysis.ServerDirectories;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
+import com.google.devtools.build.lib.analysis.skylark.SkylarkActionFactory;
 import com.google.devtools.build.lib.analysis.test.CoverageReportActionFactory;
 import com.google.devtools.build.lib.buildeventstream.PathConverter;
 import com.google.devtools.build.lib.buildtool.BuildRequestOptions;
@@ -1073,11 +1074,46 @@ public final class BlazeRuntime {
     runtime.initWorkspace(directories, binTools);
     CustomExitCodePublisher.setAbruptExitStatusFileDir(serverDirectories.getOutputBase());
 
+    // Most static initializers for @SkylarkSignature-containing classes have already run by this
+    // point, but this will pick up the stragglers.
+    initSkylarkBuiltinsRegistry();
+
     AutoProfiler.setClock(runtime.getClock());
     BugReport.setRuntime(runtime);
     return runtime;
   }
 
+  /**
+   * Configures the Skylark builtins registry.
+   *
+   * <p>Any class containing {@link SkylarkSignature}-annotated fields should call
+   * {@link SkylarkSignatureProcessor#configureSkylarkFunctions} on itself. This serves two
+   * purposes: 1) it initializes those fields for use, and 2) it registers them with the Skylark
+   * builtins registry object
+   * ({@link com.google.devtools.build.lib.syntax.Runtime#getBuiltinRegistry}). Unfortunately
+   * there's some technical debt here: The registry object is static and the registration occurs
+   * inside static initializer blocks.
+   *
+   * <p>The registry supports concurrent read/write access, but read access is not actually
+   * efficient (lockless) until write access is disallowed by calling its
+   * {@link com.google.devtools.build.lib.syntax.Runtime.BuiltinRegistry#freeze freeze} method.
+   * We want to freeze before the build begins, but not before all classes have had a chance to run
+   * their static initializers.
+   *
+   * <p>Therefore, this method first ensures that the initializers have run, and then explicitly
+   * freezes the registry. It ensures initialization by calling a no-op static method on the class.
+   * Only classes whose initializers have been observed to cause {@code BuiltinRegistry} to throw an
+   * exception need to be included here, since that indicates that their initialization did not
+   * happen by this point in time.
+   *
+   * <p>Unit tests don't need to worry about registry freeze exceptions, since the registry isn't
+   * frozen at all for them. They just pay the cost of extra synchronization on every access.
+   */
+  private static void initSkylarkBuiltinsRegistry() {
+    SkylarkActionFactory.forceStaticInitialization();
+    com.google.devtools.build.lib.syntax.Runtime.getBuiltinRegistry().freeze();
+  }
+
   private static String maybeGetPidString() {
     Integer pid = maybeForceJNIByGettingPid(null);
     return pid == null ? "" : "pid " + pid + " and ";