CodeGenerator¶

CodeGenerator is a base class for generators of JVM bytecode for expression evaluation.

[[internal-properties]] .CodeGenerator's Internal Properties [cols="1,2",options="header",width="100%"] |=== | Name | Description

| [[cache]] cache | Guava's https://google.github.io/guava/releases/19.0/api/docs/com/google/common/cache/LoadingCache.html[LoadingCache] with at most 100 pairs of CodeAndComment and GeneratedClass.

[[logging]] [TIP] ==== Enable INFO or DEBUG logging level for org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator logger to see what happens inside.

Add the following line to conf/log4j.properties:

log4j.logger.org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator=DEBUG

Refer to spark-logging.md[Logging].¶

=== [[contract]] CodeGenerator Contract

[source, scala]¶

package org.apache.spark.sql.catalyst.expressions.codegen

abstract class CodeGenerator[InType, OutType] { def create(in: InType): OutType def canonicalize(in: InType): InType def bind(in: InType, inputSchema: Seq[Attribute]): InType def generate(expressions: InType, inputSchema: Seq[Attribute]): OutType def generate(expressions: InType): OutType }

.CodeGenerator Contract [cols="1,2",options="header",width="100%"] |=== | Method | Description

| [[generate]] generate a| Generates an evaluator for expression(s) that may (optionally) have expression(s) bound to a schema (i.e. a collection of spark-sql-Expression-Attribute.md[Attribute]).

Used in:

• ExpressionEncoder for UnsafeProjection (for serialization)

|===

=== [[doCompile]] Compiling Java Source Code using Janino -- doCompile Internal Method

CAUTION: FIXME

=== [[compile]] Finding or Compiling Java Source Code -- compile Method

CAUTION: FIXME

=== [[create]] create Method

[source, scala]¶

create(references: Seq[Expression]): UnsafeProjection¶

CAUTION: FIXME

[NOTE]¶

create is used when:

• CodeGenerator <>

• GenerateOrdering creates a code gen ordering for SortOrder expressions¶

Creating CodegenContext¶

newCodeGenContext(): CodegenContext

newCodeGenContext simply creates a new CodegenContext.

newCodeGenContext is used when:

• GenerateMutableProjection is requested to create a MutableProjection

• GenerateOrdering is requested to create a BaseOrdering

• GeneratePredicate is requested to create a Predicate

• GenerateSafeProjection is requested to create a Projection

• GenerateUnsafeProjection is requested to create a UnsafeProjection

• GenerateColumnAccessor is requested to create a ColumnarIterator