Package org.apache.drill.exec.compile

Class CodeCompiler

java.lang.Object

org.apache.drill.exec.compile.CodeCompiler

public class CodeCompiler
extends Object

Global code compiler mechanism shared by all threads and operators. Holds a single cache of generated code (keyed by code source) to prevent compiling identical code multiple times. Supports both the byte-code merging and plain-old Java methods of code generation and compilation.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CodeCompiler.CodeGenCompiler	Abstracts out the details of compiling code using the two available mechanisms.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	COMPILE_BASE
static final String	DISABLE_CACHE_CONFIG	Disables the code cache.
static final String	ENABLE_SAVE_CODE_FOR_DEBUG_TOPN	Enables saving generated code for debugging
static final String	MAX_LOADING_CACHE_SIZE_CONFIG	Maximum size of the compiled class cache.
static final String	PREFER_POJ_CONFIG	Prefer to generate code as plain Java when the code generator supports that mechanism.

Constructor Summary

Constructors

Constructor	Description
CodeCompiler(DrillConfig config, OptionSet optionManager)

Method Summary

Modifier and Type	Method	Description
void	close()	Upon close, report the effectiveness of the code cache to the log.
<T> T	createInstance(CodeGenerator<?> cg)	Create a single instance of the generated class.
<T> List<T>	createInstances(CodeGenerator<?> cg, int count)	Create multiple instances of the generated class.
void	flushCache()	Flush the compiled classes from the cache.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

COMPILE_BASE

public static final String COMPILE_BASE

See Also:

• Constant Field Values

MAX_LOADING_CACHE_SIZE_CONFIG

public static final String MAX_LOADING_CACHE_SIZE_CONFIG

Maximum size of the compiled class cache.

See Also:

• Constant Field Values

DISABLE_CACHE_CONFIG

public static final String DISABLE_CACHE_CONFIG

Disables the code cache. Primarily for testing.

See Also:

• Constant Field Values

ENABLE_SAVE_CODE_FOR_DEBUG_TOPN

public static final String ENABLE_SAVE_CODE_FOR_DEBUG_TOPN

Enables saving generated code for debugging

See Also:

• Constant Field Values

PREFER_POJ_CONFIG

public static final String PREFER_POJ_CONFIG

Prefer to generate code as plain Java when the code generator supports that mechanism.

See Also:

• Constant Field Values

Constructor Details

CodeCompiler

public CodeCompiler(DrillConfig config,
 OptionSet optionManager)

Method Details

createInstance

public <T> T createInstance(CodeGenerator<?> cg)
                     throws ClassTransformationException

Create a single instance of the generated class.

Parameters:

cg - code generator for the class to be instantiated.

Returns:

an instance of the generated class

Throws:

ClassTransformationException - general "something is wrong" exception for the Drill compilation chain.

createInstances

public <T> List<T> createInstances(CodeGenerator<?> cg,
 int count)
                            throws ClassTransformationException

Create multiple instances of the generated class.

Parameters:

cg - code generator for the class to be instantiated.

count - the number of instances desired.

Returns:

a list of instances of the generated class.

Throws:

ClassTransformationException - general "something is wrong" exception for the Drill compilation chain.

flushCache

public void flushCache()

Flush the compiled classes from the cache.

The cache has DrillbitContext lifetime, so the only way items go out of it now is by being aged out because of the maximum cache size.

The intent of flushCache() is to make it possible to flush the cache for testing purposes, although this could be used by users in case issues arise. If that happens, remove the visible for testing annotation.

close

public void close()

Upon close, report the effectiveness of the code cache to the log.