From c733429f4fa9696fb027ddc946e54f6bbb68deaf Mon Sep 17 00:00:00 2001

From: Milian Wolff <mail@milianw.de>

Date: Wed, 10 Dec 2014 21:16:45 +0100

Subject: [PATCH 30/30] Preallocate a capacity of 16 for the returned list.

See also 159abaf2f372eaa633db8f69ff6b1edd459998cc in kdepimlibs on

why. I'll quote it here again:

    In my data, most often the final size of fetchResponse is 16.

    By reserving that data upfront, we can get rid of 3/4 of the

    list allocations, according to the growth-strategy outlined here:

    http://qt-project.org/doc/qt-4.8/containers.html#growth-strategies

    I.e. before, we'd allocate 4, 8, 12, 16. Now we directly allocate

    room for 16.

Thing is, doing this outside of akonadi has no effect, as QList::clear

destroys the internal buffer. With the added benchmark, I now verified

that this patch here does have a positive effect.

---

 libs/imapparser.cpp                |  2 ++

 libs/tests/imapparserbenchmark.cpp | 52 ++++++++++++++++++++++++++------------

 2 files changed, 38 insertions(+), 16 deletions(-)

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

index f3301e7..f5a7457 100644

--- a/libs/imapparser.cpp

+++ b/libs/imapparser.cpp

@@ -79,6 +79,8 @@ int parseParenthesizedListHelper( const QByteArray &data, T &result, int start )

     return start;

   }

+  result.reserve(16);

+

   int count = 0;

   int sublistBegin = start;

   bool insideQuote = false;

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

index ee861a0..7545238 100644

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

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

@@ -27,6 +27,25 @@ Q_DECLARE_METATYPE( QList<QByteArray> )

 class ImapParserBenchmark : public QObject

 {

   Q_OBJECT

+  private:

+    void geneateParseParenthesizedListData()

+    {

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

+      QTest::newRow( "empty" ) << QByteArray();

+      QTest::newRow( "unnested" ) << QByteArray("(\"Foo Bar\" NIL \"foobar\" \"test.com\")");

+      QTest::newRow( "nested" ) << QByteArray("((\"Foo Bar\" NIL \"foobar\" \"test.com\"))");

+      QTest::newRow( "nested-long" ) << QByteArray("(UID 86 REV 0 MIMETYPE \"message/rfc822\" COLLECTIONID 13 SIZE 6114 FLAGS (\\SEEN)"

+                                                   " ANCESTORS ((13 \"/INBOX\") (12 \"imap://mail@mail.test.com/\") (0 \"\")) PLD:ENVELOPE[1] {396}"

+                                                   " (\"Fri, 04 Jun 2010 09:07:54 +0200\" \"Re: [ADMIN] foobar available again!\""

+                                                   " ((\"Foo Bar\" NIL \"foobar\" \"test.com\"))"

+                                                   " NIL NIL"

+                                                   " ((\"Asdf Bla Blub\" NIL \"asdf.bla.blub\" \"123test.org\"))"

+                                                   " ((NIL NIL \"muh.kuh\" \"lalala.com\") (\"Konqi KDE\" NIL \"konqi\" \"kde.org\") (NIL NIL \"all\" \"test.com\"))"

+                                                   " NIL \"<201006040905.33367.foo.bar@test.com>\" \"<4C08A64A.9020205@123test.org>\""

+                                                   " \"<201006040142.56540.muh.kuh@lalala.com> <201006040704.39648.konqi@kde.org> <201006040905.33367.foo.bar@test.com>\""

+                                                   "))");

+    }

+

   private Q_SLOTS:

     void quote_data()

     {

@@ -68,25 +87,12 @@ class ImapParserBenchmark : public QObject

       }

     }

-    void parseParenthesizedList_data()

+    void parseParenthesizedQVarLengthArray_data()

     {

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

-      QTest::newRow( "empty" ) << QByteArray();

-      QTest::newRow( "unnested" ) << QByteArray("(\"Foo Bar\" NIL \"foobar\" \"test.com\")");

-      QTest::newRow( "nested" ) << QByteArray("((\"Foo Bar\" NIL \"foobar\" \"test.com\"))");

-      QTest::newRow( "nested-long" ) << QByteArray("(UID 86 REV 0 MIMETYPE \"message/rfc822\" COLLECTIONID 13 SIZE 6114 FLAGS (\\SEEN)"

-                                                   " ANCESTORS ((13 \"/INBOX\") (12 \"imap://mail@mail.test.com/\") (0 \"\")) PLD:ENVELOPE[1] {396}"

-                                                   " (\"Fri, 04 Jun 2010 09:07:54 +0200\" \"Re: [ADMIN] foobar available again!\""

-                                                   " ((\"Foo Bar\" NIL \"foobar\" \"test.com\"))"

-                                                   " NIL NIL"

-                                                   " ((\"Asdf Bla Blub\" NIL \"asdf.bla.blub\" \"123test.org\"))"

-                                                   " ((NIL NIL \"muh.kuh\" \"lalala.com\") (\"Konqi KDE\" NIL \"konqi\" \"kde.org\") (NIL NIL \"all\" \"test.com\"))"

-                                                   " NIL \"<201006040905.33367.foo.bar@test.com>\" \"<4C08A64A.9020205@123test.org>\""

-                                                   " \"<201006040142.56540.muh.kuh@lalala.com> <201006040704.39648.konqi@kde.org> <201006040905.33367.foo.bar@test.com>\""

-                                                   "))");

+      geneateParseParenthesizedListData();

     }

-    void parseParenthesizedList()

+    void parseParenthesizedQVarLengthArray()

     {

       QFETCH( QByteArray, data );

       QVarLengthArray<QByteArray, 16> result;

@@ -95,6 +101,20 @@ class ImapParserBenchmark : public QObject

       }

     }

+    void parseParenthesizedQList_data()

+    {

+      geneateParseParenthesizedListData();

+    }

+

+    void parseParenthesizedQList()

+    {

+      QFETCH( QByteArray, data );

+      QList<QByteArray> result;

+      QBENCHMARK {

+        ImapParser::parseParenthesizedList( data, result, 0 );

+      }

+    }

+

     void parseString_data()

     {

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

-- 

2.1.0