RowToRowCast.java
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.operator.scalar;
import com.facebook.presto.bytecode.BytecodeBlock;
import com.facebook.presto.bytecode.CallSiteBinder;
import com.facebook.presto.bytecode.ClassDefinition;
import com.facebook.presto.bytecode.MethodDefinition;
import com.facebook.presto.bytecode.Parameter;
import com.facebook.presto.bytecode.Scope;
import com.facebook.presto.bytecode.Variable;
import com.facebook.presto.bytecode.control.IfStatement;
import com.facebook.presto.bytecode.expression.BytecodeExpression;
import com.facebook.presto.common.block.Block;
import com.facebook.presto.common.block.BlockBuilder;
import com.facebook.presto.common.block.BlockBuilderStatus;
import com.facebook.presto.common.function.SqlFunctionProperties;
import com.facebook.presto.common.type.Type;
import com.facebook.presto.metadata.BoundVariables;
import com.facebook.presto.metadata.CastType;
import com.facebook.presto.metadata.FunctionAndTypeManager;
import com.facebook.presto.metadata.SqlOperator;
import com.facebook.presto.spi.PrestoException;
import com.facebook.presto.spi.StandardErrorCode;
import com.facebook.presto.spi.function.FunctionHandle;
import com.facebook.presto.spi.function.JavaScalarFunctionImplementation;
import com.facebook.presto.sql.gen.CachedInstanceBinder;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.hash.Hashing;
import com.google.common.io.BaseEncoding;
import java.lang.invoke.MethodHandle;
import java.util.List;
import static com.facebook.presto.bytecode.Access.FINAL;
import static com.facebook.presto.bytecode.Access.PUBLIC;
import static com.facebook.presto.bytecode.Access.STATIC;
import static com.facebook.presto.bytecode.Access.a;
import static com.facebook.presto.bytecode.Parameter.arg;
import static com.facebook.presto.bytecode.ParameterizedType.type;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantBoolean;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantInt;
import static com.facebook.presto.bytecode.expression.BytecodeExpressions.constantNull;
import static com.facebook.presto.common.function.OperatorType.CAST;
import static com.facebook.presto.common.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.common.type.UnknownType.UNKNOWN;
import static com.facebook.presto.operator.scalar.ScalarFunctionImplementationChoice.ArgumentProperty.valueTypeArgumentProperty;
import static com.facebook.presto.operator.scalar.ScalarFunctionImplementationChoice.NullConvention.RETURN_NULL_ON_NULL;
import static com.facebook.presto.spi.function.Signature.withVariadicBound;
import static com.facebook.presto.sql.gen.InvokeFunctionBytecodeExpression.invokeFunction;
import static com.facebook.presto.sql.gen.SqlTypeBytecodeExpression.constantType;
import static com.facebook.presto.util.CompilerUtils.defineClass;
import static com.facebook.presto.util.CompilerUtils.makeClassName;
import static com.facebook.presto.util.Reflection.methodHandle;
import static com.google.common.base.Preconditions.checkArgument;
public class RowToRowCast
extends SqlOperator
{
public static final RowToRowCast ROW_TO_ROW_CAST = new RowToRowCast();
private RowToRowCast()
{
super(CAST, ImmutableList.of(withVariadicBound("F", "row"), withVariadicBound("T", "row")), ImmutableList.of(), parseTypeSignature("T"), ImmutableList.of(parseTypeSignature("F")));
}
@Override
public BuiltInScalarFunctionImplementation specialize(BoundVariables boundVariables, int arity, FunctionAndTypeManager functionAndTypeManager)
{
checkArgument(arity == 1, "Expected arity to be 1");
Type fromType = boundVariables.getTypeVariable("F");
Type toType = boundVariables.getTypeVariable("T");
if (fromType.getTypeParameters().size() != toType.getTypeParameters().size()) {
throw new PrestoException(StandardErrorCode.INVALID_FUNCTION_ARGUMENT, "the size of fromType and toType must match");
}
Class<?> castOperatorClass = generateRowCast(fromType, toType, functionAndTypeManager);
MethodHandle methodHandle = methodHandle(castOperatorClass, "castRow", SqlFunctionProperties.class, Block.class);
return new BuiltInScalarFunctionImplementation(
false,
ImmutableList.of(valueTypeArgumentProperty(RETURN_NULL_ON_NULL)),
methodHandle);
}
private static Class<?> generateRowCast(Type fromType, Type toType, FunctionAndTypeManager functionAndTypeManager)
{
List<Type> toTypes = toType.getTypeParameters();
List<Type> fromTypes = fromType.getTypeParameters();
CallSiteBinder binder = new CallSiteBinder();
// Embed the SHA256 hash code of input and output types into the generated class name instead of the raw type names,
// which could prevent the class name from hitting the length limitation and invalid characters.
byte[] sha256Suffix = Hashing.sha256().hashBytes((fromType + "$" + toType).getBytes()).asBytes();
ClassDefinition definition = new ClassDefinition(
a(PUBLIC, FINAL),
makeClassName(Joiner.on("$").join("RowCast", BaseEncoding.base16().encode(sha256Suffix))),
type(Object.class));
Parameter properties = arg("properties", SqlFunctionProperties.class);
Parameter value = arg("value", Block.class);
MethodDefinition method = definition.declareMethod(
a(PUBLIC, STATIC),
"castRow",
type(Block.class),
properties,
value);
Scope scope = method.getScope();
BytecodeBlock body = method.getBody();
Variable wasNull = scope.declareVariable(boolean.class, "wasNull");
Variable blockBuilder = scope.createTempVariable(BlockBuilder.class);
Variable singleRowBlockWriter = scope.createTempVariable(BlockBuilder.class);
body.append(wasNull.set(constantBoolean(false)));
CachedInstanceBinder cachedInstanceBinder = new CachedInstanceBinder(definition, binder);
// create the row block builder
body.append(blockBuilder.set(
constantType(binder, toType).invoke(
"createBlockBuilder",
BlockBuilder.class,
constantNull(BlockBuilderStatus.class),
constantInt(1))));
body.append(singleRowBlockWriter.set(blockBuilder.invoke("beginBlockEntry", BlockBuilder.class)));
// loop through to append member blocks
for (int i = 0; i < toTypes.size(); i++) {
FunctionHandle functionHandle = functionAndTypeManager.lookupCast(CastType.CAST, fromTypes.get(i), toTypes.get(i));
JavaScalarFunctionImplementation function = functionAndTypeManager.getJavaScalarFunctionImplementation(functionHandle);
Type currentFromType = fromTypes.get(i);
if (currentFromType.equals(UNKNOWN)) {
body.append(singleRowBlockWriter.invoke("appendNull", BlockBuilder.class).pop());
continue;
}
BytecodeExpression fromElement = constantType(binder, currentFromType).getValue(value, constantInt(i));
BytecodeExpression toElement = invokeFunction(scope, cachedInstanceBinder, CAST.name(), function, fromElement);
IfStatement ifElementNull = new IfStatement("if the element in the row type is null...");
ifElementNull.condition(value.invoke("isNull", boolean.class, constantInt(i)))
.ifTrue(singleRowBlockWriter.invoke("appendNull", BlockBuilder.class).pop())
.ifFalse(constantType(binder, toTypes.get(i)).writeValue(singleRowBlockWriter, toElement));
body.append(ifElementNull);
}
// call blockBuilder.closeEntry() and return the single row block
body.append(blockBuilder.invoke("closeEntry", BlockBuilder.class).pop());
body.append(constantType(binder, toType)
.invoke("getObject", Object.class, blockBuilder.cast(Block.class), constantInt(0))
.cast(Block.class)
.ret());
// create constructor
MethodDefinition constructorDefinition = definition.declareConstructor(a(PUBLIC));
BytecodeBlock constructorBody = constructorDefinition.getBody();
Variable thisVariable = constructorDefinition.getThis();
constructorBody.comment("super();")
.append(thisVariable)
.invokeConstructor(Object.class);
cachedInstanceBinder.generateInitializations(thisVariable, constructorBody);
constructorBody.ret();
return defineClass(definition, Object.class, binder.getBindings(), RowToRowCast.class.getClassLoader());
}
}