[query] Fix performance of parse_locus_interval #11216
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Improve the parse trie to use iteration instead of parser recursion.
| class ParseTrieNode(val prev: Char, var hasEnd: Boolean, var children: ArrayBuffer[ParseTrieNode]) { | ||
| def search(next: Char): ParseTrieNode = { | ||
| var i = 0 | ||
| while (i < children.size) { | ||
| val child = children(i) | ||
| if (child.prev == next) | ||
| return child | ||
| i += 1 | ||
| } | ||
| null | ||
| } |
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If this has good enough performance for now, I'm happy to approve as is, but when I suggested linear search would probably be faster than binary search or hash lookup, I was assuming linear search through contiguous memory.
That would be easy to achieve here: just remove the prev field, and add a childLabels: Array[Char]. Then you search through childLabels, and descend to the corresponding element of children on a match.
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that'll work, nice.
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| object ParseTrieNode { | ||
| def generate(data: Array[String]): ParseTrieNode = { | ||
| val root = new ParseTrieNode(null.asInstanceOf[Char], false, new ArrayBuffer[ParseTrieNode]) |
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I'm confused by the null here. Char is a primitive type, I wouldn't have thought this was allowed.
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it probably produces null char. null.asInstanceOf[Int] == 0. Did this to be clear that the char here is a placeholder / unused, but using your array[char] makes this unnecessary!
| else | ||
| Some((s.charAt(0), s.substring(1))) | ||
| }.groupBy(_._1).mapValues { v => oneOfLiteral(v.map(_._2)) } | ||
| val sb: StringBuilder = new StringBuilder() |
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Another potential optimization: to avoid allocating in the parser (and to effectively intern the literal strings), the hasEnd flag on the trie nodes could be replaced by a possibly null value: String, which is a reference to the element of a that led to that node. Then the parser can just return value, or failure if null.
Improve the parse trie to use iteration instead of parser recursion.