From 4a93285b166ceceaea2e10c8fc6a254d2f7093b9 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Wed, 11 Jul 2018 10:00:43 -0700
Subject: [PATCH] QtCore: use C++11 thread_local instead of QThreadStorage

It's more efficient than our QThreadStorage and definitely much better
than the Q_GLOBAL_STATIC+QThreadStorage solution. We can do this because
the last compiler not to have thread_local support was MSVC 2013, which
is no longer supported since Qt 5.11.

QThreadStorage also managed the lifetimes of pointers for us, so the
equivalent thread_local requires std::unique_ptr.

Change-Id: Id59bdd8f1a804b809e22fffd15405f1b394c48d8
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
---
 src/corelib/animation/qabstractanimation.cpp | 21 ++++-------
 src/corelib/global/qrandom.cpp               |  1 -
 src/corelib/text/qregularexpression.cpp      | 39 +++++---------------
 3 files changed, 18 insertions(+), 43 deletions(-)

diff --git a/src/corelib/animation/qabstractanimation.cpp b/src/corelib/animation/qabstractanimation.cpp
index ce9cb70565a..181ba437718 100644
--- a/src/corelib/animation/qabstractanimation.cpp
+++ b/src/corelib/animation/qabstractanimation.cpp
@@ -149,7 +149,6 @@
 #include "qabstractanimation_p.h"
 
 #include <QtCore/qmath.h>
-#include <QtCore/qthreadstorage.h>
 #include <QtCore/qcoreevent.h>
 #include <QtCore/qpointer.h>
 #include <QtCore/qscopedvaluerollback.h>
@@ -214,8 +213,6 @@ typedef QList<QAbstractAnimation*>::ConstIterator AnimationListConstIt;
     QUnifiedTimer drives animations indirectly, via QAbstractAnimationTimer.
 */
 
-Q_GLOBAL_STATIC(QThreadStorage<QUnifiedTimer *>, unifiedTimer)
-
 QUnifiedTimer::QUnifiedTimer() :
     QObject(), defaultDriver(this), lastTick(0), timingInterval(DEFAULT_TIMER_INTERVAL),
     currentAnimationIdx(0), insideTick(false), insideRestart(false), consistentTiming(false), slowMode(false),
@@ -233,11 +230,12 @@ QUnifiedTimer::~QUnifiedTimer()
 QUnifiedTimer *QUnifiedTimer::instance(bool create)
 {
     QUnifiedTimer *inst;
-    if (create && !unifiedTimer()->hasLocalData()) {
+    static thread_local std::unique_ptr<QUnifiedTimer> unifiedTimer;
+    if (create && !unifiedTimer) {
         inst = new QUnifiedTimer;
-        unifiedTimer()->setLocalData(inst);
+        unifiedTimer.reset(inst);
     } else {
-        inst = unifiedTimer() ? unifiedTimer()->localData() : nullptr;
+        inst = unifiedTimer.get();
     }
     return inst;
 }
@@ -550,10 +548,6 @@ bool QUnifiedTimer::canUninstallAnimationDriver(QAnimationDriver *d)
     return d == driver && driver != &defaultDriver;
 }
 
-#if QT_CONFIG(thread)
-Q_GLOBAL_STATIC(QThreadStorage<QAnimationTimer *>, animationTimer)
-#endif
-
 QAnimationTimer::QAnimationTimer() :
     QAbstractAnimationTimer(), lastTick(0),
     currentAnimationIdx(0), insideTick(false),
@@ -569,11 +563,12 @@ QAnimationTimer *QAnimationTimer::instance(bool create)
 {
     QAnimationTimer *inst;
 #if QT_CONFIG(thread)
-    if (create && !animationTimer()->hasLocalData()) {
+    static thread_local std::unique_ptr<QAnimationTimer> animationTimer;
+    if (create && !animationTimer) {
         inst = new QAnimationTimer;
-        animationTimer()->setLocalData(inst);
+        animationTimer.reset(inst);
     } else {
-        inst = animationTimer() ? animationTimer()->localData() : nullptr;
+        inst = animationTimer.get();
     }
 #else
     Q_UNUSED(create);
diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp
index 34df85133bf..eb7eca63882 100644
--- a/src/corelib/global/qrandom.cpp
+++ b/src/corelib/global/qrandom.cpp
@@ -46,7 +46,6 @@
 #include <qendian.h>
 #include <qmutex.h>
 #include <qobjectdefs.h>
-#include <qthreadstorage.h>
 
 #include <errno.h>
 
diff --git a/src/corelib/text/qregularexpression.cpp b/src/corelib/text/qregularexpression.cpp
index 1db27fc4e48..0c8215cebb3 100644
--- a/src/corelib/text/qregularexpression.cpp
+++ b/src/corelib/text/qregularexpression.cpp
@@ -47,7 +47,6 @@
 #include <QtCore/qmutex.h>
 #include <QtCore/qstringlist.h>
 #include <QtCore/qdebug.h>
-#include <QtCore/qthreadstorage.h>
 #include <QtCore/qglobal.h>
 #include <QtCore/qatomic.h>
 #include <QtCore/qdatastream.h>
@@ -962,43 +961,24 @@ void QRegularExpressionPrivate::getPatternInfo()
     Simple "smartpointer" wrapper around a pcre2_jit_stack_16, to be used with
     QThreadStorage.
 */
-class QPcreJitStackPointer
+namespace {
+struct PcreJitStackFree
 {
-    Q_DISABLE_COPY(QPcreJitStackPointer)
-
-public:
-    /*!
-        \internal
-    */
-    QPcreJitStackPointer()
-    {
-        // The default JIT stack size in PCRE is 32K,
-        // we allocate from 32K up to 512K.
-        stack = pcre2_jit_stack_create_16(32 * 1024, 512 * 1024, nullptr);
-    }
-    /*!
-        \internal
-    */
-    ~QPcreJitStackPointer()
+    void operator()(pcre2_jit_stack_16 *stack)
     {
         if (stack)
             pcre2_jit_stack_free_16(stack);
     }
-
-    pcre2_jit_stack_16 *stack;
 };
-
-Q_GLOBAL_STATIC(QThreadStorage<QPcreJitStackPointer *>, jitStacks)
+static thread_local std::unique_ptr<pcre2_jit_stack_16, PcreJitStackFree> jitStacks;
+}
 
 /*!
     \internal
 */
 static pcre2_jit_stack_16 *qtPcreCallback(void *)
 {
-    if (jitStacks()->hasLocalData())
-        return jitStacks()->localData()->stack;
-
-    return nullptr;
+    return jitStacks.get();
 }
 
 /*!
@@ -1094,9 +1074,10 @@ static int safe_pcre2_match_16(const pcre2_code_16 *code,
     int result = pcre2_match_16(code, subject, length,
                                 startOffset, options, matchData, matchContext);
 
-    if (result == PCRE2_ERROR_JIT_STACKLIMIT && !jitStacks()->hasLocalData()) {
-        QPcreJitStackPointer *p = new QPcreJitStackPointer;
-        jitStacks()->setLocalData(p);
+    if (result == PCRE2_ERROR_JIT_STACKLIMIT && !jitStacks) {
+        // The default JIT stack size in PCRE is 32K,
+        // we allocate from 32K up to 512K.
+        jitStacks.reset(pcre2_jit_stack_create_16(32 * 1024, 512 * 1024, NULL));
 
         result = pcre2_match_16(code, subject, length,
                                 startOffset, options, matchData, matchContext);