Github user rxin commented on a diff in the pull request:

    https://github.com/apache/spark/pull/7236#discussion_r33977873
  
    --- Diff: 
unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java ---
    @@ -207,6 +207,78 @@ public boolean equals(final Object other) {
         }
       }
     
    +  private char charAt(int bytePos) {
    +    int num = numBytes(bytes[bytePos]);
    +    if (num == 1) return (char) bytes[bytePos];
    +    int l = bytes[bytePos] & 0x000F;
    +    l = l << 8 + num + 1 >> 8 + num + 1;
    +    for (int i = 1; i < num; i++) {
    +      l = l << 6;
    +      l = l | (0x003F & bytes[bytePos + i]);
    +    }
    +    return (char) l;
    +  }
    +
    +  public int levenshteinDistance(UTF8String other) {
    +    // Implementation adopted from 
org.apache.common.lang3.StringUtils.getLevenshteinDistance
    +
    +    int n = length();
    +    int m = other.length();
    +
    +    if (n == 0) {
    +      return m;
    +    } else if (m == 0) {
    +      return n;
    +    }
    +
    +    UTF8String s;
    +    UTF8String t;
    +
    +    if (n <= m) {
    +      s = this;
    +      t = other;
    +    } else {
    +      s = other;
    +      t = this;
    +      n = s.length();
    +      m = t.length();
    +    }
    +
    +    int p[] = new int[n + 1];
    --- End diff --
    
    actually this one is probably ok -- I think JIT with the proper escape 
analysis can do on-stack allocation for this.


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