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39 | |
40 | #ifndef QJSENGINE_P_H |
41 | #define QJSENGINE_P_H |
42 | |
43 | // |
44 | // W A R N I N G |
45 | // ------------- |
46 | // |
47 | // This file is not part of the Qt API. It exists purely as an |
48 | // implementation detail. This header file may change from version to |
49 | // version without notice, or even be removed. |
50 | // |
51 | // We mean it. |
52 | // |
53 | |
54 | #include <QtCore/private/qobject_p.h> |
55 | #include <QtCore/qmutex.h> |
56 | #include "qjsengine.h" |
57 | #include "private/qtqmlglobal_p.h" |
58 | #include <private/qqmlmetatype_p.h> |
59 | |
60 | QT_BEGIN_NAMESPACE |
61 | |
62 | class QQmlPropertyCache; |
63 | |
64 | namespace QV4 { |
65 | struct ExecutionEngine; |
66 | } |
67 | |
68 | class Q_QML_PRIVATE_EXPORT QJSEnginePrivate : public QObjectPrivate |
69 | { |
70 | Q_DECLARE_PUBLIC(QJSEngine) |
71 | |
72 | public: |
73 | static QJSEnginePrivate* get(QJSEngine*e) { return e->d_func(); } |
74 | static const QJSEnginePrivate* get(const QJSEngine*e) { return e->d_func(); } |
75 | static QJSEnginePrivate* get(QV4::ExecutionEngine *e); |
76 | |
77 | QJSEnginePrivate() = default; |
78 | ~QJSEnginePrivate() override; |
79 | |
80 | static void addToDebugServer(QJSEngine *q); |
81 | static void removeFromDebugServer(QJSEngine *q); |
82 | |
83 | // Locker locks the QQmlEnginePrivate data structures for read and write, if necessary. |
84 | // Currently, locking is only necessary if the threaded loader is running concurrently. If it is |
85 | // either idle, or is running with the main thread blocked, no locking is necessary. This way |
86 | // we only pay for locking when we have to. |
87 | // Consequently, this class should only be used to protect simple accesses or modifications of the |
88 | // QQmlEnginePrivate structures or operations that can be guaranteed not to start activity |
89 | // on the loader thread. |
90 | // The Locker API is identical to QMutexLocker. Locker reuses the QQmlEnginePrivate::mutex |
91 | // QMutex instance and multiple Lockers are recursive in the same thread. |
92 | class Locker |
93 | { |
94 | public: |
95 | inline Locker(const QJSEngine *); |
96 | inline Locker(const QJSEnginePrivate *); |
97 | inline ~Locker(); |
98 | |
99 | inline void unlock(); |
100 | inline void relock(); |
101 | |
102 | private: |
103 | const QJSEnginePrivate *m_ep; |
104 | quint32 m_locked:1; |
105 | }; |
106 | |
107 | // Shared by QQmlEngine |
108 | mutable QRecursiveMutex mutex; |
109 | |
110 | QString uiLanguage; |
111 | |
112 | // These methods may be called from the QML loader thread |
113 | inline QQmlPropertyCache *cache(QObject *obj, int minorVersion = -1, bool doRef = false); |
114 | inline QQmlPropertyCache *cache(const QMetaObject *, int minorVersion = -1, bool doRef = false); |
115 | }; |
116 | |
117 | QJSEnginePrivate::Locker::Locker(const QJSEngine *e) |
118 | : m_ep(QJSEnginePrivate::get(e)) |
119 | { |
120 | relock(); |
121 | } |
122 | |
123 | QJSEnginePrivate::Locker::Locker(const QJSEnginePrivate *e) |
124 | : m_ep(e), m_locked(false) |
125 | { |
126 | relock(); |
127 | } |
128 | |
129 | QJSEnginePrivate::Locker::~Locker() |
130 | { |
131 | unlock(); |
132 | } |
133 | |
134 | void QJSEnginePrivate::Locker::unlock() |
135 | { |
136 | if (m_locked) { |
137 | m_ep->mutex.unlock(); |
138 | m_locked = false; |
139 | } |
140 | } |
141 | |
142 | void QJSEnginePrivate::Locker::relock() |
143 | { |
144 | Q_ASSERT(!m_locked); |
145 | m_ep->mutex.lock(); |
146 | m_locked = true; |
147 | } |
148 | |
149 | /*! |
150 | Returns a QQmlPropertyCache for \a obj if one is available. |
151 | |
152 | If \a obj is null, being deleted or contains a dynamic meta object 0 |
153 | is returned. |
154 | |
155 | The returned cache is not referenced, so if it is to be stored, call addref(). |
156 | |
157 | XXX thread There is a potential future race condition in this and all the cache() |
158 | functions. As the QQmlPropertyCache is returned unreferenced, when called |
159 | from the loader thread, it is possible that the cache will have been dereferenced |
160 | and deleted before the loader thread has a chance to use or reference it. This |
161 | can't currently happen as the cache holds a reference to the |
162 | QQmlPropertyCache until the QQmlEngine is destroyed. |
163 | */ |
164 | QQmlPropertyCache *QJSEnginePrivate::cache(QObject *obj, int minorVersion, bool doRef) |
165 | { |
166 | if (!obj || QObjectPrivate::get(o: obj)->metaObject || QObjectPrivate::get(o: obj)->wasDeleted) |
167 | return nullptr; |
168 | |
169 | Locker locker(this); |
170 | const QMetaObject *mo = obj->metaObject(); |
171 | return QQmlMetaType::propertyCache(metaObject: mo, minorVersion, doRef); |
172 | } |
173 | |
174 | /*! |
175 | Returns a QQmlPropertyCache for \a metaObject. |
176 | |
177 | As the cache is persisted for the life of the engine, \a metaObject must be |
178 | a static "compile time" meta-object, or a meta-object that is otherwise known to |
179 | exist for the lifetime of the QQmlEngine. |
180 | |
181 | The returned cache is not referenced, so if it is to be stored, call addref(). |
182 | */ |
183 | QQmlPropertyCache *QJSEnginePrivate::cache(const QMetaObject *metaObject, int minorVersion, bool doRef) |
184 | { |
185 | Q_ASSERT(metaObject); |
186 | |
187 | Locker locker(this); |
188 | return QQmlMetaType::propertyCache(metaObject, minorVersion, doRef); |
189 | } |
190 | |
191 | |
192 | QT_END_NAMESPACE |
193 | |
194 | #endif // QJSENGINE_P_H |
195 | |