From f21a6d409ea0504c64cd72861fc16b6f3e080086 Mon Sep 17 00:00:00 2001 From: Marc Mutz Date: Wed, 18 Dec 2019 15:43:24 +0100 Subject: QStringList: use local storage in removeDuplicates() If available, use a C++17 std::pmr::unordered_set with a monotonic buffer resource and a 256-byte stack buffer to avoid the per-element allocations of QSet. Results on my machine: RESULT : tst_QStringList::removeDuplicates():"empty": - 0.00014 msecs per iteration (total: 74, iterations: 524288) + 0.000031 msecs per iteration (total: 66, iterations: 2097152) RESULT : tst_QStringList::removeDuplicates():"short-dup-0.00": - 0.00043 msecs per iteration (total: 57, iterations: 131072) + 0.00013 msecs per iteration (total: 69, iterations: 524288) RESULT : tst_QStringList::removeDuplicates():"short-dup-0.50": - 0.00049 msecs per iteration (total: 65, iterations: 131072) + 0.00032 msecs per iteration (total: 85, iterations: 262144) RESULT : tst_QStringList::removeDuplicates():"short-dup-0.66": - 0.00057 msecs per iteration (total: 75, iterations: 131072) + 0.00039 msecs per iteration (total: 52, iterations: 131072) RESULT : tst_QStringList::removeDuplicates():"short-dup-0.75": - 0.00064 msecs per iteration (total: 85, iterations: 131072) + 0.00048 msecs per iteration (total: 63, iterations: 131072) RESULT : tst_QStringList::removeDuplicates():"long-dup-0.00": - 0.083 msecs per iteration (total: 85, iterations: 1024) + 0.039 msecs per iteration (total: 80, iterations: 2048) RESULT : tst_QStringList::removeDuplicates():"long-dup-0.50": - 0.11 msecs per iteration (total: 58, iterations: 512) + 0.078 msecs per iteration (total: 80, iterations: 1024) RESULT : tst_QStringList::removeDuplicates():"long-dup-0.66": - 0.13 msecs per iteration (total: 70, iterations: 512) + 0.10 msecs per iteration (total: 53, iterations: 512) RESULT : tst_QStringList::removeDuplicates():"long-dup-0.75": - 0.16 msecs per iteration (total: 86, iterations: 512) + 0.13 msecs per iteration (total: 69, iterations: 512) When interpreting the data, take into account that each iteration contains _also_ a deep copy of the QStringList d/t the detach from 'input'. The pattern is used elsewhere in Qt, so I've put the class that implements the seen set into a private header file and used in some other places I found. Change-Id: I1f71a82008a16d5a3818f91f290ade21d837805e Reviewed-by: Giuseppe D'Angelo --- src/corelib/tools/tools.pri | 1 + 1 file changed, 1 insertion(+) (limited to 'src/corelib/tools/tools.pri') diff --git a/src/corelib/tools/tools.pri b/src/corelib/tools/tools.pri index 40c84157cd..e078ab4409 100644 --- a/src/corelib/tools/tools.pri +++ b/src/corelib/tools/tools.pri @@ -12,6 +12,7 @@ HEADERS += \ tools/qcontainerfwd.h \ tools/qcontainertools_impl.h \ tools/qcryptographichash.h \ + tools/qduplicatetracker_p.h \ tools/qfreelist_p.h \ tools/qhash.h \ tools/qhashfunctions.h \ -- cgit v1.2.3