From d8110b53ed9ee4d69b92e602e812c6311c1b863b Mon Sep 17 00:00:00 2001
From: Ulf Hermann <ulf.hermann@qt.io>
Date: Wed, 20 Mar 2019 17:15:29 +0100
Subject: Trigger the garbage collector when allocating InternalClass objects

As we check the icAllocator's slots on shouldRunGC() we should also
check shouldRunGC() when adding slots. Otherwise we might never run the
GC when only allocating InternalClasses. In addition, account for the
"unmanaged" size of the PropertyAttributes that are part of the
InternalClass objects. Those can be large.

In cases where an excessive number of large InternalClass objects is
created the garbage collector is now invoked frequently, which costs a
significant number of CPU cycles, but prevents the memory usage from
growing indefinitely.

Task-number: QTBUG-58559
Change-Id: Icf102cb6100f6dba212b8bffe1c178897880eda0
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/qml/jsruntime/qv4internalclass_p.h | 57 ++++++++++------------------------
 1 file changed, 17 insertions(+), 40 deletions(-)

(limited to 'src/qml/jsruntime/qv4internalclass_p.h')

diff --git a/src/qml/jsruntime/qv4internalclass_p.h b/src/qml/jsruntime/qv4internalclass_p.h
index 681cbda5f9..c689637721 100644
--- a/src/qml/jsruntime/qv4internalclass_p.h
+++ b/src/qml/jsruntime/qv4internalclass_p.h
@@ -149,55 +149,31 @@ inline PropertyHash::Entry *PropertyHash::lookup(PropertyKey identifier) const
     }
 }
 
-template<typename T>
-struct SharedInternalClassDataPrivate {
-    SharedInternalClassDataPrivate(ExecutionEngine *)
+template<class T>
+struct SharedInternalClassDataPrivate {};
+
+template<>
+struct SharedInternalClassDataPrivate<PropertyAttributes> {
+    SharedInternalClassDataPrivate(ExecutionEngine *engine)
         : refcount(1),
           m_alloc(0),
           m_size(0),
-          data(nullptr)
+          data(nullptr),
+          m_engine(engine)
     { }
-    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate &other)
-        : refcount(1),
-          m_alloc(other.m_alloc),
-          m_size(other.m_size)
-    {
-        if (m_alloc) {
-            data = new T[m_alloc];
-            memcpy(data, other.data, m_size*sizeof(T));
-        }
-    }
-    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate &other, uint pos, T value)
-        : refcount(1),
-          m_alloc(pos + 8),
-          m_size(pos + 1)
-    {
-        data = new T[m_alloc];
-        if (other.data)
-            memcpy(data, other.data, (m_size - 1)*sizeof(T));
-        data[pos] = value;
-    }
-    ~SharedInternalClassDataPrivate() { delete [] data; }
-
+    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate<PropertyAttributes> &other);
+    SharedInternalClassDataPrivate(const SharedInternalClassDataPrivate<PropertyAttributes> &other,
+                                   uint pos, PropertyAttributes value);
+    ~SharedInternalClassDataPrivate();
 
-    void grow() {
-        if (!m_alloc)
-            m_alloc = 4;
-        T *n = new T[m_alloc * 2];
-        if (data) {
-            memcpy(n, data, m_alloc*sizeof(T));
-            delete [] data;
-        }
-        data = n;
-        m_alloc *= 2;
-    }
+    void grow();
 
     uint alloc() const { return m_alloc; }
     uint size() const { return m_size; }
     void setSize(uint s) { m_size = s; }
 
-    T at(uint i) { Q_ASSERT(data && i < m_alloc); return data[i]; }
-    void set(uint i, T t) { Q_ASSERT(data && i < m_alloc); data[i] = t; }
+    PropertyAttributes at(uint i) { Q_ASSERT(data && i < m_alloc); return data[i]; }
+    void set(uint i, PropertyAttributes t) { Q_ASSERT(data && i < m_alloc); data[i] = t; }
 
     void mark(MarkStack *) {}
 
@@ -205,7 +181,8 @@ struct SharedInternalClassDataPrivate {
 private:
     uint m_alloc;
     uint m_size;
-    T *data;
+    PropertyAttributes *data;
+    ExecutionEngine *m_engine;
 };
 
 template<>
-- 
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