From 3b1b72ac4d8975d24a3176dd1b5a39b5fead71a8 Mon Sep 17 00:00:00 2001 From: Jean Chalard Date: Fri, 11 May 2012 22:56:50 +0900 Subject: [PATCH] More optimizations We don't merge tails anyway, and we can't do it any more because that would break the bigram lookup algorithm. The speedup is about 20%, and possibly double this if there are no bigrams. Bug: 6394357 Change-Id: I9eec11dda9000451706d280f120404a2acbea304 --- .../latin/makedict/BinaryDictInputOutput.java | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java index 3c818cc56..bb1042324 100644 --- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java +++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java @@ -489,10 +489,17 @@ public class BinaryDictInputOutput { // Merging tails can only be done if there are no attributes. Searching for attributes // in LatinIME code depends on a total breadth-first ordering, which merging tails // breaks. If there are no attributes, it should be fine (and reduce the file size) - // to merge tails, and the following step would be necessary. - // If eventually the code runs on Android, searching through the whole array each time - // may be a performance concern. - list.remove(node); + // to merge tails, and removing the node from the list would be necessary. However, + // we don't merge tails because breaking the breadth-first ordering would result in + // extreme overhead at bigram lookup time (it would make the search function O(n) instead + // of the current O(log(n)), where n=number of nodes in the dictionary which is pretty + // high). + // If no nodes are ever merged, we can't have the same node twice in the list, hence + // searching for duplicates in unnecessary. It is also very performance consuming, + // since `list' is an ArrayList so it's an O(n) operation that runs on all nodes, making + // this simple list.remove operation O(n*n) overall. On Android this overhead is very + // high. + // For future reference, the code to remove duplicate is a simple : list.remove(node); list.add(node); final ArrayList branches = node.mData; final int nodeSize = branches.size();