Example code-gen for left anti sort merge join

gistfile1.txt

val df1 = spark.range(10).select($"id".as("k1"))
val df2 = spark.range(4).select($"id".as("k2"))
df1.join(df2.hint("SHUFFLE_MERGE"), $"k1" === $"k2", "left_anti")

== Subtree 5 / 5 (maxMethodCodeSize:296; maxConstantPoolSize:156(0.24% used); numInnerClasses:0) ==
*(5) Project [id#0L AS k1#2L]
+- *(5) SortMergeJoin [id#0L], [k2#6L], LeftAnti
   :- *(2) Sort [id#0L ASC NULLS FIRST], false, 0
   :  +- Exchange hashpartitioning(id#0L, 5), ENSURE_REQUIREMENTS, [id=#27]
   :     +- *(1) Range (0, 10, step=1, splits=2)
   +- *(4) Sort [k2#6L ASC NULLS FIRST], false, 0
      +- Exchange hashpartitioning(k2#6L, 5), ENSURE_REQUIREMENTS, [id=#33]
         +- *(3) Project [id#4L AS k2#6L]
            +- *(3) Range (0, 4, step=1, splits=2)

Generated code:
/* 001 */ public Object generate(Object[] references) {
/* 002 */   return new GeneratedIteratorForCodegenStage5(references);
/* 003 */ }
/* 004 */
/* 005 */ // codegenStageId=5
/* 006 */ final class GeneratedIteratorForCodegenStage5 extends org.apache.spark.sql.execution.BufferedRowIterator {
/* 007 */   private Object[] references;
/* 008 */   private scala.collection.Iterator[] inputs;
/* 009 */   private scala.collection.Iterator smj_streamedInput_0;
/* 010 */   private scala.collection.Iterator smj_bufferedInput_0;
/* 011 */   private InternalRow smj_streamedRow_0;
/* 012 */   private InternalRow smj_bufferedRow_0;
/* 013 */   private long smj_value_2;
/* 014 */   private org.apache.spark.sql.execution.ExternalAppendOnlyUnsafeRowArray smj_matches_0;
/* 015 */   private long smj_value_3;
/* 016 */   private org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter[] smj_mutableStateArray_0 = new org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter[2];
/* 017 */
/* 018 */   public GeneratedIteratorForCodegenStage5(Object[] references) {
/* 019 */     this.references = references;
/* 020 */   }
/* 021 */
/* 022 */   public void init(int index, scala.collection.Iterator[] inputs) {
/* 023 */     partitionIndex = index;
/* 024 */     this.inputs = inputs;
/* 025 */     smj_streamedInput_0 = inputs[0];
/* 026 */     smj_bufferedInput_0 = inputs[1];
/* 027 */
/* 028 */     smj_matches_0 = new org.apache.spark.sql.execution.ExternalAppendOnlyUnsafeRowArray(1, 2147483647);
/* 029 */     smj_mutableStateArray_0[0] = new org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter(1, 0);
/* 030 */     smj_mutableStateArray_0[1] = new org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter(1, 0);
/* 031 */
/* 032 */   }
/* 033 */
/* 034 */   private boolean findNextJoinRows(
/* 035 */     scala.collection.Iterator streamedIter,
/* 036 */     scala.collection.Iterator bufferedIter) {
/* 037 */     smj_streamedRow_0 = null;
/* 038 */     int comp = 0;
/* 039 */     while (smj_streamedRow_0 == null) {
/* 040 */       if (!streamedIter.hasNext()) return false;
/* 041 */       smj_streamedRow_0 = (InternalRow) streamedIter.next();
/* 042 */       long smj_value_0 = smj_streamedRow_0.getLong(0);
/* 043 */       if (false) {
/* 044 */         if (!smj_matches_0.isEmpty()) {
/* 045 */           smj_matches_0.clear();
/* 046 */         }
/* 047 */         return false;
/* 048 */
/* 049 */       }
/* 050 */       if (!smj_matches_0.isEmpty()) {
/* 051 */         comp = 0;
/* 052 */         if (comp == 0) {
/* 053 */           comp = (smj_value_0 > smj_value_3 ? 1 : smj_value_0 < smj_value_3 ? -1 : 0);
/* 054 */         }
/* 055 */
/* 056 */         if (comp == 0) {
/* 057 */           return true;
/* 058 */         }
/* 059 */         smj_matches_0.clear();
/* 060 */       }
/* 061 */
/* 062 */       do {
/* 063 */         if (smj_bufferedRow_0 == null) {
/* 064 */           if (!bufferedIter.hasNext()) {
/* 065 */             smj_value_3 = smj_value_0;
/* 066 */             return !smj_matches_0.isEmpty();
/* 067 */           }
/* 068 */           smj_bufferedRow_0 = (InternalRow) bufferedIter.next();
/* 069 */           long smj_value_1 = smj_bufferedRow_0.getLong(0);
/* 070 */           if (false) {
/* 071 */             smj_bufferedRow_0 = null;
/* 072 */             continue;
/* 073 */           }
/* 074 */           smj_value_2 = smj_value_1;
/* 075 */         }
/* 076 */
/* 077 */         comp = 0;
/* 078 */         if (comp == 0) {
/* 079 */           comp = (smj_value_0 > smj_value_2 ? 1 : smj_value_0 < smj_value_2 ? -1 : 0);
/* 080 */         }
/* 081 */
/* 082 */         if (comp > 0) {
/* 083 */           smj_bufferedRow_0 = null;
/* 084 */         } else if (comp < 0) {
/* 085 */           if (!smj_matches_0.isEmpty()) {
/* 086 */             smj_value_3 = smj_value_0;
/* 087 */             return true;
/* 088 */           } else {
/* 089 */             return false;
/* 090 */           }
/* 091 */         } else {
/* 092 */           if (smj_matches_0.isEmpty()) {
/* 093 */             smj_matches_0.add((UnsafeRow) smj_bufferedRow_0);
/* 094 */           }
/* 095 */
/* 096 */           smj_bufferedRow_0 = null;
/* 097 */         }
/* 098 */       } while (smj_streamedRow_0 != null);
/* 099 */     }
/* 100 */     return false; // unreachable
/* 101 */   }
/* 102 */
/* 103 */   protected void processNext() throws java.io.IOException {
/* 104 */     while (smj_streamedInput_0.hasNext()) {
/* 105 */       findNextJoinRows(smj_streamedInput_0, smj_bufferedInput_0);
/* 106 */
/* 107 */       long smj_value_4 = -1L;
/* 108 */       smj_value_4 = smj_streamedRow_0.getLong(0);
/* 109 */       scala.collection.Iterator<UnsafeRow> smj_iterator_0 = smj_matches_0.generateIterator();
/* 110 */
/* 111 */       boolean wholestagecodegen_hasOutputRow_0 = false;
/* 112 */
/* 113 */       while (!wholestagecodegen_hasOutputRow_0 && smj_iterator_0.hasNext()) {
/* 114 */         InternalRow smj_bufferedRow_1 = (InternalRow) smj_iterator_0.next();
/* 115 */
/* 116 */         wholestagecodegen_hasOutputRow_0 = true;
/* 117 */       }
/* 118 */
/* 119 */       if (!wholestagecodegen_hasOutputRow_0) {
/* 120 */         // load all values of streamed row, because the values not in join condition are not
/* 121 */         // loaded yet.
/* 122 */
/* 123 */         ((org.apache.spark.sql.execution.metric.SQLMetric) references[0] /* numOutputRows */).add(1);
/* 124 */
/* 125 */         // common sub-expressions
/* 126 */
/* 127 */         smj_mutableStateArray_0[1].reset();
/* 128 */
/* 129 */         smj_mutableStateArray_0[1].write(0, smj_value_4);
/* 130 */         append((smj_mutableStateArray_0[1].getRow()).copy());
/* 131 */
/* 132 */       }
/* 133 */       if (shouldStop()) return;
/* 134 */     }
/* 135 */     ((org.apache.spark.sql.execution.joins.SortMergeJoinExec) references[1] /* plan */).cleanupResources();
/* 136 */   }
/* 137 */
/* 138 */ }