QHash uses an array representing the difference between 2^i and
the next prime; when growing, it calculates 2^x + array[x] (with
`x' representing the "hash table size in bits").
For some reason lost in history the differences are actually wrong
and the calculation above leads to using composite numbers.
Hence: use the right sequence and always produce primes. The right
sequence is actually A092131 from OEIS: http://oeis.org/A092131
Note that the sequence starts at A(1), but we need A(0) too.
Also we truncate the sequence to when growing too much, just like
the old code did, and use powers of two in that case instead.
Task-number: QTBUG-36866
Change-Id: Id2e3fc9cb567c0fdca305dee38f480e17639ca04
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
This implementation is based on GCC's implementation of std::hash<FP>, but only
to the extent of checking for zero before hashing the bits. The bit hasher is
the Qt one; I didn't even look what GCC uses.
The check against 0.0 is mandated by the requirement to have
\forall x,y: x == y => qHash(x) == qHash(y)
which would be violated for x = 0.0 and y = -0.0 if we only hashed the bits.
Implemented out-of-line to avoid potential FP-comparison warnings, as well
as to be able to use the file-static hash() functions, which gets inlined
unlike qHashBits(), which cannot be.
[ChangeLog][QtCore][QHash/QSet] Allowed to use float, double and long double
as QHash/QSet keys.
Change-Id: I38cec4afb860f17e9f8be7b67544e58b330f8fff
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
According to my profiling of Qt Creator, qHash and the SHA-1 calculation
are the hottest spots remaining in QtCore. The current qHash function is
not really vectorizable. We could come up with a different algorithm
that is more SIMD-friendly, but since we have the CRC32 instruction that
can read 32- and 64-bit entities, we're set.
This commit also updates the benchmark for QHash and benchmarks both
the hashing function itself and the QHash class. The updated
benchmarks for the CRC32 on my machine shows that the hashing function
is *always* improved, but the hashing isn't always. In particular, the
current algorithm is better for the "numbers" case, for which the data
sample differs in very few bits. The new code is 33% slower for that
particular case.
On average, the improvement (including the "numbers" case) is:
compared to qHash only QHash
Qt 5.0 function 2.54x 1.06x
Qt 4.x function 4.34x 1.34x
Java function 2.71x 1.11x
Test machine: Sandybridge Core i7-2620M @ 2.66 GHz with turbo disabled
for the benchmarks
Change-Id: Ia80b98c0e20d785816f7a7f6ddf40b4b302c7297
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Default values should have mark-up to denote that they are code.
This commit changes:
-"property is true" to "property is \c true".
-"Returns true" to "Returns \c true".
-"property is false" to "property is \c false".
-"returns true" to "returns \c true".
-"returns false" to "returns \c false".
src/3rdparty and non-documentation instances were ignored.
Task-number: QTBUG-33360
Change-Id: Ie87eaa57af947caa1230602b61c5c46292a4cf4e
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
These members were introduced in 4.8, but left undocumented. Because we
consider undocumented API to be internal, the members are \since 5.2.
Change-Id: I52e2840a8cfaa7f59f410b3e2a06c0942ea06539
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Remove all trailing whitespace from the following list of files:
*.cpp *.h *.conf *.qdoc *.pro *.pri *.mm *.rc *.pl *.qps *.xpm *.txt *README
excluding 3rdparty, test-data and auto generated code.
Note A): the only non 3rdparty c++-files that still
have trailing whitespace after this change are:
* src/corelib/codecs/cp949codetbl_p.h
* src/corelib/codecs/qjpunicode.cpp
* src/corelib/codecs/qbig5codec.cpp
* src/corelib/xml/qxmlstream_p.h
* src/tools/qdoc/qmlparser/qqmljsgrammar.cpp
* src/tools/uic/ui4.cpp
* tests/auto/other/qtokenautomaton/tokenizers/*
* tests/benchmarks/corelib/tools/qstring/data.cpp
* util/lexgen/tokenizer.cpp
Note B): in about 30 files some overlapping 'leading tab' and
'TAB character in non-leading whitespace' issues have been fixed
to make the sanity bot happy. Plus some general ws-fixes here
and there as asked for during review.
Change-Id: Ia713113c34d82442d6ce4d93d8b1cf545075d11d
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Change copyrights and license headers from Nokia to Digia
Change-Id: If1cc974286d29fd01ec6c19dd4719a67f4c3f00e
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
The hashing functions for QDateTime and QHostAddress did not get the
noexcept keyword because they might allocate memory. QDateTime doesn't
do it now, but it could in the future. QHostAddress does allocate
memory today.
Change-Id: Ia5f80942944bfc2b8c405306c467bfd88ef0e48c
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Add the seed to QPair, QUuid, QPersistentModelIndex's qHash(), and fix
qHash documentation for them and for many other datatypes.
Change-Id: I1386f3ed42ee1a832371a242ee5c82895ba92c2b
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
The new randomization of QHash is enabled by default. There may be cases
where you need deterministic behavior, e.g. for debugging or regression
testing. This patch disables randomization if QT_HASH_SEED is defined.
Change-Id: Idfad55ea7aba830add0a36334f0f763c62fdce13
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
The files in this change were still in qtbase/doc/src or required for
it. qtbase/doc/src should now only contain example documentation and
images for the example documentation.
Change-Id: Ia7ca8e7fd2b316e77c706a08df71303bc8294213
Reviewed-by: Marius Storm-Olsen <marius.storm-olsen@nokia.com>
This should help to silence coverity which was complaining
hundreds of times about Qt not initializing h and next in
QHashNode.
Change-Id: Ib7977693e9786d4b310799e4f428115c65bb3fee
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This change fixes most qdoc errors in QtCore. There are about 900 left.
The main thing this change does is moving documentation from qtcore from
/doc/src to /src/corelib/doc.
Other issues resolved are mis-use of qdoc commands.
Change-Id: I002d01edfb13575e8bf27ce91596a577a92562d1
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@nokia.com>
Port of Robin's work from I0a53aa4581e25b351b9cb5033415b5163d05fe71
on top of the new qHash patches (the original commit just introduced
lots of conflicts, so I redid it from scratch).
This is based on the work done in the QHash benchmark over the past
few months experimenting with the performance of the string hashing
algorithm used by Java.
The Java algorithm, in turn, appears to have been based off a
variant of djb's work at http://cr.yp.to/cdb/cdb.txt.
This commit provides a performance boost of ~12-33% on the
QHash benchmark.
Unfortunately, the rcc test depends on QHash ordering.
Randomizing QHash or changing qHash will cause the test to fail
(see QTBUG-25078), so for now the testdata is changed as well.
Done-with: Robin Burchell
Change-Id: Ie05d8e21588d1b2d4bd555ef254e1eb101864b75
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
The implementation of the various qHash overloads offered by
Qt can change at any time for any reason
(speed, quality, security, ...).
Therefore, relying on the fact that qHash will always give
an identical result across Qt versions (... across different
processes, etc.), given identical input, is wrong.
Note that this also implies that one cannot rely on QHash
having a stable ordering (even without the random qHash seed).
For such use cases, one must use f.i. a private hash function
that will never change outside his own control.
This patch adds a private hash function for QStrings,
which is identical to the Qt(4) qHash(QString) implementation.
A couple of spots in Qt where the results of a qHash call were
actually saved on disk are ported to use the new function,
and a bit of documentation is added to QHash docs.
Change-Id: Ia3731ea26ac68649b535b95e9f36fbec3df693c8
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
It was never introduced in Qt 4, probably because of the implicit
conversion to QString (that is, adding the qHash overload for
QLatin1String in Qt 4 would have been a BIC).
Change-Id: I2ebc8e73a85be497866820e0ca416dd11167bb53
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Algorithmic complexity attacks against hash tables have been known
since 2003 (cf. [1, 2]), and they have been left unpatched for years
until the 2011 attacks [3] against many libraries /
(reference) implementations of programming languages.
This patch adds a qHash overload taking two arguments: the value to
be hashed, and a uint to be used as a seed for the hash function
itself (support the global QHash seed was added in a previous patch).
The seed itself is not used just yet; instead, 0 is passed.
Compatibility with the one-argument qHash(T) implementation is kept
through a catch-all template.
[1] http://www.cs.rice.edu/~scrosby/hash/CrosbyWallach_UsenixSec2003.pdf
[2] http://perldoc.perl.org/perlsec.html#Algorithmic-Complexity-Attacks
[3] http://www.ocert.org/advisories/ocert-2011-003.html
Task-number: QTBUG-23529
Change-Id: I1d0a84899476d134db455418c8043a349a7e5317
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>
Algorithmic complexity attacks against hash tables have been known
since 2003 (cf. [1, 2]), and they have been left unpatched for years
until the 2011 attacks [3] against many libraries /
(reference) implementations of programming languages.
This patch adds a global integer, to be used as a seed for the hash
function itself. The seed is randomly initialized the first time a
QHash detaches from shared_null.
Right now the seed is not used at all -- another patch will modify
qHash to make use of it.
[1] http://www.cs.rice.edu/~scrosby/hash/CrosbyWallach_UsenixSec2003.pdf
[2] http://perldoc.perl.org/perlsec.html#Algorithmic-Complexity-Attacks
[3] http://www.ocert.org/advisories/ocert-2011-003.html
Task-number: QTBUG-23529
Change-Id: I7519e4c02b9c2794d1c14079b01330eb356e9c65
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
C++11 adds cbegin()/cend() functions for the same reason Qt has
constBegin()/constEnd(). This patch adds these functions to the
Qt containers with the same implementation as constBegin()/constEnd().
It also fixes the return types in the documentation of existing
constFind() functions (documentation only).
C++11 only adds cbegin()/cend() (and crbegin()/crend(), which Qt doesn't have).
In particular, it doesn't add cfind(), so I didn't supply these, even though
Qt comes with constFind().
This is a forward-port of https://qt.gitorious.org/qt/qt/merge_requests/1365.
Change-Id: Ida086b64246b24e25254eafbcb06c8e33388502b
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
QDoc now has support for Doxygen style commands for italics, bold
and list items. This change applies that change in QDoc to the
actual documentation.
Task-number: QTBUG-24578
Change-Id: I519bf9c29b14092e3ab6067612f42bf749eeedf5
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
I'm sure 'line' can't contain anything resembling a format string,
but better safe than sorry.
Change-Id: I0aa0f4a5a03d97b18d6a866c27fa721fcbe0f77b
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>
As in the past, to avoid rewriting various autotests that contain
line-number information, an extra blank line has been inserted at the
end of the license text to ensure that this commit does not change the
total number of lines in the license header.
Change-Id: I311e001373776812699d6efc045b5f742890c689
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
We're trying to deprecate these, so don't use them anymore.
The inline uses of these have been left intact, for the moment. Inline code will
need to create their own non-inline allocation methods (for future-proofing to
allow alterations in how e.g. individual containers allocate)
Change-Id: I1071a487c25e95b7bb81a3327b20c5481fb5ed22
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
This was only being used to initialize static read-only RefCount
instances, where the value is hard-wired to -1. Instead of allowing
initialization with arbitrary values (which for a reference count can be
error prone) the intent of the macro is made explicit with its
replacement Q_REFCOUNT_INITIALIZE_STATIC.
Change-Id: I5b0f3f1eb58c3d010e49e9259ff4d06cbab2fd35
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
, and make it strictly a POD struct.
Since this operator was only being used to set the initial (owned) value
of the reference count, the name of the function introduced here to
replace it makes that use case explicit.
Change-Id: I2feadd2ac35dcb75ca211471baf5044a5f57cd62
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Dealt with all necessary changes that are marked in the code: removing
methods left only for binary compatibility with earlier Qt 4 versions
and other methods marked for removal.
Change-Id: I47109ccd9ed40addc345416be9e172570723955e
Reviewed-on: http://codereview.qt-project.org/4534
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
Similar to QLinkedList QList, QMap, QVector, QByteArray and QString,
keep the shared_null in shareable memory and never modify it.
Change-Id: Ia8b72ef0288575bed658153d9d54434580988bda
Reviewed-on: http://codereview.qt-project.org/4533
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
This is the beginning of revision history for this module. If you
want to look at revision history older than this, please refer to the
Qt Git wiki for how to use Git history grafting. At the time of
writing, this wiki is located here:
http://qt.gitorious.org/qt/pages/GitIntroductionWithQt
If you have already performed the grafting and you don't see any
history beyond this commit, try running "git log" with the "--follow"
argument.
Branched from the monolithic repo, Qt master branch, at commit
896db169ea224deb96c59ce8af800d019de63f12
Giuseppe D'Angelo
Marc Mutz
Thiago Macieira
Thorbjørn Martsum
Jerome Pasion
Geir Vattekar
Mitch Curtis
Axel Waggershauser
Roman Pasechnik
Sergio Ahumada
David Schulz
Iikka Eklund
Konstantin Ritt
aavit
Casper van Donderen
Lars Knoll
Giuseppe D'Angelo
Marcel Krems
Kent Hansen
João Abecasis
Jason McDonald
Robin Burchell
Bradley T. Hughes
Jyri Tahtela
Qt by Nokia