From 89357c7b0fc5e76091510af504058c036fa1b2f9 Mon Sep 17 00:00:00 2001

From: Milian Wolff <mail@milianw.de>

Date: Wed, 10 Dec 2014 21:04:24 +0100

Subject: [PATCH 29/30] Reduce the amount of allocations by preallocating a

 buffer.

Sadly, QByteArray cannot be cleared without destroying the buffer.

But we can guesstimate the target size of the buffer and thus

reduce the amount of allocations.

This also adds a benchmark for ImapParser::parseString.

---

 libs/imapparser.cpp                |  1 +

 libs/tests/imapparserbenchmark.cpp | 19 +++++++++++++++++++

 2 files changed, 20 insertions(+)

diff --git a/libs/imapparser.cpp b/libs/imapparser.cpp

index 6f9f592..f3301e7 100644

--- a/libs/imapparser.cpp

+++ b/libs/imapparser.cpp

@@ -186,6 +186,7 @@ int ImapParser::parseQuotedString( const QByteArray &data, QByteArray &result, i

   // quoted string

   if ( data[begin] == '"' ) {

     ++begin;

+    result.reserve(qMin(32, data.size() - begin));

     for ( int i = begin; i < data.length(); ++i ) {

       const char ch = data.at( i );

       if ( foundSlash ) {

diff --git a/libs/tests/imapparserbenchmark.cpp b/libs/tests/imapparserbenchmark.cpp

index fd4335c..ee861a0 100644

--- a/libs/tests/imapparserbenchmark.cpp

+++ b/libs/tests/imapparserbenchmark.cpp

@@ -95,6 +95,25 @@ class ImapParserBenchmark : public QObject

       }

     }

+    void parseString_data()

+    {

+      QTest::addColumn<QByteArray>( "data" );

+      QTest::newRow("plain") << QByteArray("fooobarasdf something more lalala");

+      QTest::newRow("quoted") << QByteArray("\"fooobarasdf\" something more lalala");

+    }

+

+    void parseString()

+    {

+      QFETCH(QByteArray, data);

+      QByteArray result;

+      qint64 sum = 0;

+      QBENCHMARK {

+        sum += ImapParser::parseString( data, result );

+      }

+      QVERIFY(!result.isEmpty());

+      QVERIFY(sum > 0);

+    }

+

     void parseNumber()

     {

       QByteArray data( "123456" );

-- 

2.1.0