io.prestosql.orc.protobuf.ExtensionRegistryFactory Maven / Gradle / Ivy
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
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package io.prestosql.orc.protobuf;
import static io.prestosql.orc.protobuf.ExtensionRegistryLite.EMPTY_REGISTRY_LITE;
/**
* A factory object to create instances of {@link ExtensionRegistryLite}.
*
*
* This factory detects (via reflection) if the full (non-Lite) protocol buffer libraries
* are available, and if so, the instances returned are actually {@link ExtensionRegistry}.
*/
final class ExtensionRegistryFactory {
static final String FULL_REGISTRY_CLASS_NAME = "io.prestosql.orc.protobuf.ExtensionRegistry";
/* Visible for Testing
@Nullable */
static final Class EXTENSION_REGISTRY_CLASS = reflectExtensionRegistry();
/* @Nullable */
static Class reflectExtensionRegistry() {
try {
return Class.forName(FULL_REGISTRY_CLASS_NAME);
} catch (ClassNotFoundException e) {
// The exception allocation is potentially expensive on Android (where it can be triggered
// many times at start up). Is there a way to ameliorate this?
return null;
}
}
/** Construct a new, empty instance. */
public static ExtensionRegistryLite create() {
if (EXTENSION_REGISTRY_CLASS != null) {
try {
return invokeSubclassFactory("newInstance");
} catch (Exception e) {
// return a Lite registry.
}
}
return new ExtensionRegistryLite();
}
/** Get the unmodifiable singleton empty instance. */
public static ExtensionRegistryLite createEmpty() {
if (EXTENSION_REGISTRY_CLASS != null) {
try {
return invokeSubclassFactory("getEmptyRegistry");
} catch (Exception e) {
// return a Lite registry.
}
}
return EMPTY_REGISTRY_LITE;
}
static boolean isFullRegistry(ExtensionRegistryLite registry) {
return EXTENSION_REGISTRY_CLASS != null
&& EXTENSION_REGISTRY_CLASS.isAssignableFrom(registry.getClass());
}
private static final ExtensionRegistryLite invokeSubclassFactory(String methodName)
throws Exception {
return (ExtensionRegistryLite) EXTENSION_REGISTRY_CLASS
.getMethod(methodName).invoke(null);
}
}