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QHostInfo: optimize container usage

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Replace Java-style iterators with STL-style iterators.
Java-style iterators have overhead.

Use std::stable_partition with erase() instead of using remove()
in a loop, with quadratic complexity.

Introduce local template homebrew any_of (analog of std::any_of from C++11)
to simplify current code. Also it's needed for following changes
in this class.

Change-Id: I2b11889ccc7630597c72aa20cdb266ae6ca2471a
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
This commit is contained in:
Anton Kudryavtsev 2016-03-09 12:21:55 +03:00
parent a3def2869d
commit 447a508d00
1 changed files with 38 additions and 24 deletions
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62
src/network/kernel/qhostinfo.cpp
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@ -49,6 +49,8 @@
#include <qurl.h>
#include <private/qnetworksession_p.h>
#include <algorithm>
#ifdef Q_OS_UNIX
# include <unistd.h>
#endif
@ -59,6 +61,26 @@ QT_BEGIN_NAMESPACE
Q_GLOBAL_STATIC(QHostInfoLookupManager, theHostInfoLookupManager)
namespace {
struct ToBeLookedUpEquals {
typedef bool result_type;
explicit ToBeLookedUpEquals(const QString &toBeLookedUp) Q_DECL_NOTHROW : m_toBeLookedUp(toBeLookedUp) {}
result_type operator()(QHostInfoRunnable* lookup) const Q_DECL_NOTHROW
{
return m_toBeLookedUp == lookup->toBeLookedUp;
}
private:
QString m_toBeLookedUp;
};
// ### C++11: remove once we can use std::any_of()
template<class InputIt, class UnaryPredicate>
bool any_of(InputIt first, InputIt last, UnaryPredicate p)
{
return std::find_if(first, last, p) != last;
}
}
/*!
\class QHostInfo
\brief The QHostInfo class provides static functions for host name lookups.
@ -496,17 +518,17 @@ void QHostInfoRunnable::run()
// now also iterate through the postponed ones
{
QMutexLocker locker(&manager->mutex);
QMutableListIterator<QHostInfoRunnable*> iterator(manager->postponedLookups);
while (iterator.hasNext()) {
QHostInfoRunnable* postponed = iterator.next();
if (toBeLookedUp == postponed->toBeLookedUp) {
// we can now emit
iterator.remove();
hostInfo.setLookupId(postponed->id);
postponed->resultEmitter.emitResultsReady(hostInfo);
delete postponed;
}
const auto partitionBegin = std::stable_partition(manager->postponedLookups.rbegin(), manager->postponedLookups.rend(),
ToBeLookedUpEquals(toBeLookedUp)).base();
const auto partitionEnd = manager->postponedLookups.end();
for (auto it = partitionBegin; it != partitionEnd; ++it) {
QHostInfoRunnable* postponed = *it;
// we can now emit
hostInfo.setLookupId(postponed->id);
postponed->resultEmitter.emitResultsReady(hostInfo);
delete postponed;
}
manager->postponedLookups.erase(partitionBegin, partitionEnd);
}
manager->lookupFinished(this);
@ -573,13 +595,7 @@ void QHostInfoLookupManager::work()
QHostInfoRunnable* postponed = iterator.next();
// check if none of the postponed hostnames is currently running
bool alreadyRunning = false;
for (int i = 0; i < currentLookups.length(); i++) {
if (currentLookups.at(i)->toBeLookedUp == postponed->toBeLookedUp) {
alreadyRunning = true;
break;
}
}
const bool alreadyRunning = any_of(currentLookups.cbegin(), currentLookups.cend(), ToBeLookedUpEquals(postponed->toBeLookedUp));
if (!alreadyRunning) {
iterator.remove();
scheduledLookups.prepend(postponed); // prepend! we want to finish it ASAP
@ -594,13 +610,11 @@ void QHostInfoLookupManager::work()
QHostInfoRunnable *scheduled = iterator.next();
// check if a lookup for this host is already running, then postpone
for (int i = 0; i < currentLookups.size(); i++) {
if (currentLookups.at(i)->toBeLookedUp == scheduled->toBeLookedUp) {
iterator.remove();
postponedLookups.append(scheduled);
scheduled = 0;
break;
}
const bool alreadyRunning = any_of(currentLookups.cbegin(), currentLookups.cend(), ToBeLookedUpEquals(scheduled->toBeLookedUp));
if (alreadyRunning) {
iterator.remove();
postponedLookups.append(scheduled);
scheduled = 0;
}
if (scheduled && currentLookups.size() < threadPool.maxThreadCount()) {