【Spark105】Spark SQL动态代码生成一

 

2015-09-02 14:46:27,681-[TS] DEBUG Executor task launch worker-0 org.apache.spark.sql.catalyst.expressions.codegen.GenerateUnsafeProjection - code for input[0, StringType],input[1, StringType],input[2, StringType],input[3, StringType],input[4, StringType]:

 

日志中的如下信息是如何产生的，这是列及其类型么？

input[0, StringType],input[1, StringType],input[2, StringType],input[3, StringType],input[4, StringType]

 

 

代码：

 

 

/**
 * A projection that returns UnsafeRow.
 */
abstract class UnsafeProjection extends Projection {
  //将IntervalRow转换为UnsafeRow
  override def apply(row: InternalRow): UnsafeRow
}

 

 

2. UnsafeRow的pointTo方法

  /**
   * Update this UnsafeRow to point to different backing data.
   *
   * @param baseObject the base object
   * @param baseOffset the offset within the base object
   * @param numFields the number of fields in this row
   * @param sizeInBytes the size of this row's backing data, in bytes
   */
  public void pointTo(Object baseObject, long baseOffset, int numFields, int sizeInBytes) {
    assert numFields >= 0 : "numFields (" + numFields + ") should >= 0";
    this.bitSetWidthInBytes = calculateBitSetWidthInBytes(numFields);
    this.baseObject = baseObject;
    this.baseOffset = baseOffset;
    this.numFields = numFields;
    this.sizeInBytes = sizeInBytes;
  }

 

 

 

 

package org.apache.spark.sql.test;

import org.apache.spark.sql.catalyst.InternalRow;
import org.apache.spark.sql.catalyst.expressions.UnsafeRow;
import org.apache.spark.unsafe.Platform;
import org.apache.spark.unsafe.types.UTF8String;

///在Spark的代码中中没有UnsafeProjection的子类，UnsafeProjection的子类是动态生成的
//UnsafeProjection是一个抽象类，子类需要实现apply方法
class SpecificUnsafeProjection extends org.apache.spark.sql.catalyst.expressions.UnsafeProjection {
  
  ///涉及的expressions
  private org.apache.spark.sql.catalyst.expressions.Expression[] expressions;
  
  //apply方法返回的结果
  private UnsafeRow convertedStruct10;
  private byte[] buffer11;
  private int cursor12;
  
  
  public SpecificUnsafeProjection(org.apache.spark.sql.catalyst.expressions.Expression[] expressions) {
    this.expressions = expressions;
    this.convertedStruct10 = new UnsafeRow();
    //buffer11是字节数组，长度为48
    this.buffer11 = new byte[48];
    this.cursor12 = 0;
  }
  
  // Scala.Function1 need this
//  public Object apply(Object row) {
//    return apply((InternalRow) row);
//  }
  
  public UnsafeRow apply(InternalRow i) {
    
    //cursor12首先复制为48，这个更buffer11的长度一样
    cursor12 = 48;

    //这步操作是对convertedStruct10(UnsafeRow)的一些属性更新更新
    //第二个参数是baseOffset，值是
    //第三个参数(值5)是Row中的列数
    //第四个参数cursor12表示这个Row的sizeInBytes(the size of this row's backing data, in bytes)
    convertedStruct10.pointTo(buffer11, Platform.BYTE_ARRAY_OFFSET, 5, cursor12);
    
    /* input[0, StringType] */
      
   //第一列是否为null
    boolean isNull0 = i.isNullAt(0); 

    //不为null，则通过调用getUTF8String获取其UTF8String数据
    UTF8String primitive1 = isNull0 ? null : (i.getUTF8String(0));
    
    //获取第一列的字节数(如果是null，则为0)，加到cursor12上。
    int numBytes14 = cursor12 + (isNull0 ? 0 : org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.getSize(primitive1));
    //如果第一列不为null 
   if (buffer11.length < numBytes14) {
      // This will not happen frequently, because the buffer is re-used.
      //扩容
      byte[] tmpBuffer13 = new byte[numBytes14 * 2];
      //将buffer11的数据复制到tmpBuffer13，然后将tmpBuffer13复制给buffer11，此时buffer11完成了扩容的工作
      Platform.copyMemory(buffer11, Platform.BYTE_ARRAY_OFFSET,
        tmpBuffer13, Platform.BYTE_ARRAY_OFFSET, buffer11.length);
      buffer11 = tmpBuffer13;
    }
    //更新值
    convertedStruct10.pointTo(buffer11, Platform.BYTE_ARRAY_OFFSET, 5, numBytes14);
    
    
    if (isNull0) {
      convertedStruct10.setNullAt(0);
    } else {
      cursor12 += org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.write(convertedStruct10, 0, cursor12, primitive1);
    }
    
    
    /* input[1, StringType] */
    
    boolean isNull2 = i.isNullAt(1);
    UTF8String primitive3 = isNull2 ? null : (i.getUTF8String(1));
    
    
    int numBytes15 = cursor12 + (isNull2 ? 0 : org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.getSize(primitive3));
    if (buffer11.length < numBytes15) {
      // This will not happen frequently, because the buffer is re-used.
      byte[] tmpBuffer13 = new byte[numBytes15 * 2];
      Platform.copyMemory(buffer11, Platform.BYTE_ARRAY_OFFSET,
        tmpBuffer13, Platform.BYTE_ARRAY_OFFSET, buffer11.length);
      buffer11 = tmpBuffer13;
    }
    convertedStruct10.pointTo(buffer11, Platform.BYTE_ARRAY_OFFSET, 5, numBytes15);
    
    
    if (isNull2) {
      convertedStruct10.setNullAt(1);
    } else {
      cursor12 += org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.write(convertedStruct10, 1, cursor12, primitive3);
    }
    
    
    /* input[2, StringType] */
    
    boolean isNull4 = i.isNullAt(2);
    UTF8String primitive5 = isNull4 ? null : (i.getUTF8String(2));
    
    
    int numBytes16 = cursor12 + (isNull4 ? 0 : org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.getSize(primitive5));
    if (buffer11.length < numBytes16) {
      // This will not happen frequently, because the buffer is re-used.
      byte[] tmpBuffer13 = new byte[numBytes16 * 2];
      Platform.copyMemory(buffer11, Platform.BYTE_ARRAY_OFFSET,
        tmpBuffer13, Platform.BYTE_ARRAY_OFFSET, buffer11.length);
      buffer11 = tmpBuffer13;
    }
    convertedStruct10.pointTo(buffer11, Platform.BYTE_ARRAY_OFFSET, 5, numBytes16);
    
    
    if (isNull4) {
      convertedStruct10.setNullAt(2);
    } else {
      cursor12 += org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.write(convertedStruct10, 2, cursor12, primitive5);
    }
    
    
    /* input[3, StringType] */
    
    boolean isNull6 = i.isNullAt(3);
    UTF8String primitive7 = isNull6 ? null : (i.getUTF8String(3));
    
    
    int numBytes17 = cursor12 + (isNull6 ? 0 : org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.getSize(primitive7));
    if (buffer11.length < numBytes17) {
      // This will not happen frequently, because the buffer is re-used.
      byte[] tmpBuffer13 = new byte[numBytes17 * 2];
      Platform.copyMemory(buffer11, Platform.BYTE_ARRAY_OFFSET,
        tmpBuffer13, Platform.BYTE_ARRAY_OFFSET, buffer11.length);
      buffer11 = tmpBuffer13;
    }
    convertedStruct10.pointTo(buffer11, Platform.BYTE_ARRAY_OFFSET, 5, numBytes17);
    
    
    if (isNull6) {
      convertedStruct10.setNullAt(3);
    } else {
      cursor12 += org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.write(convertedStruct10, 3, cursor12, primitive7);
    }
    
    
    /* input[4, StringType] */
    
    boolean isNull8 = i.isNullAt(4);
    UTF8String primitive9 = isNull8 ? null : (i.getUTF8String(4));
    
    
    int numBytes18 = cursor12 + (isNull8 ? 0 : org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.getSize(primitive9));
    if (buffer11.length < numBytes18) {
      // This will not happen frequently, because the buffer is re-used.
      byte[] tmpBuffer13 = new byte[numBytes18 * 2];
      Platform.copyMemory(buffer11, Platform.BYTE_ARRAY_OFFSET,
        tmpBuffer13, Platform.BYTE_ARRAY_OFFSET, buffer11.length);
      buffer11 = tmpBuffer13;
    }
    convertedStruct10.pointTo(buffer11, Platform.BYTE_ARRAY_OFFSET, 5, numBytes18);
    
    
    if (isNull8) {
      convertedStruct10.setNullAt(4);
    } else {
      cursor12 += org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters.UTF8StringWriter.write(convertedStruct10, 4, cursor12, primitive9);
    }
    
    
    
    return convertedStruct10;
  }
}