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/xml/dom/qdom.cpp | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'src/xml/dom/qdom.cpp') diff --git a/src/xml/dom/qdom.cpp b/src/xml/dom/qdom.cpp index bbc877eead..26c1a2122b 100644 --- a/src/xml/dom/qdom.cpp +++ b/src/xml/dom/qdom.cpp @@ -60,6 +60,9 @@ #include #include #include +#include + + #include QT_BEGIN_NAMESPACE @@ -4081,10 +4084,10 @@ void QDomElementPrivate::save(QTextStream& s, int depth, int indent) const } s << '<' << qName << nsDecl; - QSet outputtedPrefixes; /* Write out attributes. */ if (!m_attr->map.isEmpty()) { + QDuplicateTracker outputtedPrefixes; QHash::const_iterator it = m_attr->map.constBegin(); for (; it != m_attr->map.constEnd(); ++it) { s << ' '; @@ -4105,9 +4108,8 @@ void QDomElementPrivate::save(QTextStream& s, int depth, int indent) const * arrive in those situations. */ if((!it.value()->ownerNode || it.value()->ownerNode->prefix != it.value()->prefix) && - !outputtedPrefixes.contains(it.value()->prefix)) { + !outputtedPrefixes.hasSeen(it.value()->prefix)) { s << " xmlns:" << it.value()->prefix << "=\"" << encodeText(it.value()->namespaceURI, s, true, true) << '\"'; - outputtedPrefixes.insert(it.value()->prefix); } } } -- cgit v1.2.3