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Commit e2fc7dde authored by zhenxingwang's avatar zhenxingwang
Browse files

Use another Vector as a swap to reduce computing complexity 

When doing cache memory thinning, Vector's removeAt requires momory backward movement.
Its computing complexity is O((N-M)*M) where N is ogg page size, M=512.
For big ogg files, N >> M, it is about O(N*M), which is too high that cause ANR sometimes.

Using another Vector as a swap avoids the movement and reduces
computing complexity from O(N*M) to O(M).

Bug:267463829
Test: atest CtsMediaExtractorTestCases
Test: atest CtsMediaV2TestCases
Change-Id: I00ba80e4c59cc1cf9fa993444e1f9548fb7dd469
parent 21c58e94

media/module/extractors/ogg/OggExtractor.cpp

+8 −3
Original line number Diff line number Diff line
@@ -993,16 +993,21 @@ void MyOggExtractor::buildTableOfContents() { 
    size_t numerator = mTableOfContents.size();



    if (numerator > kMaxNumTOCEntries) {

        size_t denom = numerator - kMaxNumTOCEntries;

        Vector<TOCEntry> maxTOC;

        maxTOC.setCapacity(kMaxNumTOCEntries);



        size_t denom = numerator - kMaxNumTOCEntries;

        size_t accum = 0;

        for (ssize_t i = mTableOfContents.size(); i > 0; --i) {

        for (ssize_t i = 0; i < mTableOfContents.size(); i++) {

            accum += denom;

            if (accum >= numerator) {

                mTableOfContents.removeAt(i);

                accum -= numerator;

            } else {

                maxTOC.push(mTableOfContents.itemAt(i));

            }

        }



        mTableOfContents = maxTOC;

    }

}