bazel packages: delete NativeProvider, dematerialize StructImpl.provider
This change merges NativeProvider into BuiltinProvider. The two
classes were almost identical.
Also, it removes the StructImpl.provider
field to save one word of space in each instance of NativeInfo.
This requires each subclass to define getProvider,
which is straightforward but leads to a tiresome diff.
(Sadly this doesn't yield tangible space savings; I'm not sure why.)
All the interesting changes are in lib.packages. The rest is repetitive.
This is a small step towards withering StructImpl and StructApi
out of existence.
NO_IFTTT=spurious warning
PiperOrigin-RevId: 341102857
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BuiltinProvider.java b/src/main/java/com/google/devtools/build/lib/packages/BuiltinProvider.java
index 0ff81ee..13aae66 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/BuiltinProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/BuiltinProvider.java
@@ -14,18 +14,21 @@
package com.google.devtools.build.lib.packages;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.NativeProvider.NativeKey;
+import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
import javax.annotation.Nullable;
-import net.starlark.java.eval.EvalException;
import net.starlark.java.eval.Printer;
-import net.starlark.java.eval.Starlark;
import net.starlark.java.syntax.Location;
/**
- * Base class for declared providers {@see Provider} defined in native code.
+ * Base class for declared providers {@see Provider} built into Blaze.
*
- * <p>Every subclass of {@link BuiltinProvider} corresponds to a single declared provider. This is
- * enforced by final {@link #equals(Object)} and {@link #hashCode()}.
+ * <p>Every subclass of {@link BuiltinProvider} should have exactly one instance. If multiple
+ * instances of the same subclass are instantiated, they are considered equivalent. This design is
+ * motivated by the need for serialization. Starlark providers are readily identified by the pair
+ * (.bzl file name, sequence number during execution). BuiltinProviders need an analogous
+ * serializable identifier, yet JVM classes (notoriously) don't have a predictable initialization
+ * order, so we can't use a sequence number. A distinct subclass for each built-in provider acts as
+ * that identifier.
*
* <p>Implementations of native declared providers should subclass this class, and define a method
* in the subclass definition to create instances of its corresponding Info object. The method
@@ -34,33 +37,29 @@
*/
@Immutable
public abstract class BuiltinProvider<T extends Info> implements Provider {
- private final NativeKey key;
+ private final Key key;
private final String name;
private final Class<T> valueClass;
+ public BuiltinProvider(String name, Class<T> valueClass) {
+ this.key = new Key(name, getClass());
+ this.name = name;
+ this.valueClass = valueClass;
+ }
+
public Class<T> getValueClass() {
return valueClass;
}
- public BuiltinProvider(String name, Class<T> valueClass) {
- @SuppressWarnings("unchecked")
- Class<? extends BuiltinProvider<?>> clazz = (Class<? extends BuiltinProvider<?>>) getClass();
- key = new NativeKey(name, clazz);
- this.name = name;
- this.valueClass = valueClass;
- }
-
/**
- * equals() implements singleton class semantics.
+ * Defines the equivalence relation: all BuiltinProviders of the same Java class are equal,
+ * regardless of {@code name} or {@code valueClass}.
*/
@Override
public final boolean equals(@Nullable Object other) {
return other != null && this.getClass().equals(other.getClass());
}
- /**
- * hashCode() implements singleton class semantics.
- */
@Override
public final int hashCode() {
return getClass().hashCode();
@@ -72,7 +71,7 @@
}
@Override
- public NativeKey getKey() {
+ public Key getKey() {
return key;
}
@@ -88,19 +87,60 @@
@Override
public void repr(Printer printer) {
+ // TODO(adonovan): change to '<provider name>'.
printer.append("<function " + getPrintableName() + ">");
}
- /**
- * Convenience method for subclasses of this class to throw a consistent error when a provider is
- * unable to be constructed from Starlark.
- */
- protected final T throwUnsupportedConstructorException() throws EvalException {
- throw Starlark.errorf("'%s' cannot be constructed from Starlark", getPrintableName());
- }
-
/** Returns the identifier of this provider. */
public StarlarkProviderIdentifier id() {
return StarlarkProviderIdentifier.forKey(getKey());
}
+
+ /**
+ * Implement this to mark that a built-in provider should be exported with certain name to
+ * Starlark. Broken: only works for rules, not for aspects. DO NOT USE FOR NEW CODE!
+ *
+ * @deprecated Use declared providers mechanism exclusively to expose providers to both native and
+ * Starlark code.
+ */
+ @Deprecated
+ public interface WithLegacyStarlarkName {
+ String getStarlarkName();
+ }
+
+ /** A serializable reference to a {@link BuiltinProvider}. */
+ @AutoCodec
+ @Immutable
+ public static final class Key extends Provider.Key {
+ private final String name;
+ private final Class<? extends Provider> providerClass;
+
+ public Key(String name, Class<? extends Provider> providerClass) {
+ this.name = name;
+ this.providerClass = providerClass;
+ }
+
+ public String getName() {
+ return name;
+ }
+
+ public Class<? extends Provider> getProviderClass() {
+ return providerClass;
+ }
+
+ @Override
+ public int hashCode() {
+ return providerClass.hashCode();
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ return obj instanceof Key && providerClass.equals(((Key) obj).providerClass);
+ }
+
+ @Override
+ public String toString() {
+ return name;
+ }
+ }
}
