From 349c0de0912884388f2490d4bfd6905424ccf194 Mon Sep 17 00:00:00 2001
From: Lars Knoll <lars.knoll@nokia.com>
Date: Tue, 20 Mar 2012 20:45:27 +0100
Subject: Significantly speed up insertion into QJsonObject/Array

The code was only allocating memory for the next insertion
leading to a reallocation of the whole data for every
single insertion.

The code now reserves some space and uses a decent growth
strategy to avoid repeated reallocs.

Change-Id: I48b0feab71ba8ca73e7037f8460080f198b2f009
Reviewed-by: Jamey Hicks <jamey.hicks@nokia.com>
---
 src/corelib/json/qjson.cpp |  8 --------
 src/corelib/json/qjson_p.h | 21 +++++++++++++++++++--
 2 files changed, 19 insertions(+), 10 deletions(-)

(limited to 'src')

diff --git a/src/corelib/json/qjson.cpp b/src/corelib/json/qjson.cpp
index 4f7372a6c0..26f26b211e 100644
--- a/src/corelib/json/qjson.cpp
+++ b/src/corelib/json/qjson.cpp
@@ -241,14 +241,6 @@ bool Entry::operator ==(const QString &key) const
         return (shallowKey() == key);
 }
 
-bool Entry::operator >=(const QString &key) const
-{
-    if (value.latinKey)
-        return (shallowLatin1Key() >= key);
-    else
-        return (shallowKey() >= key);
-}
-
 bool Entry::operator ==(const Entry &other) const
 {
     if (value.latinKey) {
diff --git a/src/corelib/json/qjson_p.h b/src/corelib/json/qjson_p.h
index 0742ced39b..f8f41c2e25 100644
--- a/src/corelib/json/qjson_p.h
+++ b/src/corelib/json/qjson_p.h
@@ -620,15 +620,24 @@ public:
 
     bool operator ==(const QString &key) const;
     inline bool operator !=(const QString &key) const { return !operator ==(key); }
-    bool operator >=(const QString &key) const;
+    inline bool operator >=(const QString &key) const;
 
     bool operator ==(const Entry &other) const;
     bool operator >=(const Entry &other) const;
 };
 
+inline bool Entry::operator >=(const QString &key) const
+{
+    if (value.latinKey)
+        return (shallowLatin1Key() >= key);
+    else
+        return (shallowKey() >= key);
+}
+
 inline bool operator <(const QString &key, const Entry &e)
 { return e >= key; }
 
+
 class Header {
 public:
     qle_uint tag; // 'qbjs'
@@ -735,7 +744,15 @@ public:
 
     Data *clone(Base *b, int reserve = 0)
     {
-        int size = sizeof(Header) + b->size + reserve;
+        int size = sizeof(Header) + b->size;
+        if (ref.load() == 1 && alloc >= size + reserve)
+            return this;
+
+        if (reserve) {
+            if (reserve < 128)
+                reserve = 128;
+            size = qMax(size + reserve, size *2);
+        }
         char *raw = (char *)malloc(size);
         Q_CHECK_PTR(raw);
         memcpy(raw + sizeof(Header), b, b->size);
-- 
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