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List:       kmail-devel
Subject:    Re: Displaying large message takes loooong
From:       Don Sanders <sanders () kde ! org>
Date:       2002-10-16 17:36:54
[Download RAW message or body]

On Tuesday 15 October 2002 19:07, Marc Mutz wrote:
> On Tuesday 15 October 2002 08:53, Don Sanders wrote:
> <snip>
>
> > Martin sent me the mail and I can reproduce the problem. There's
> > something very wrong going on here, so maybe I can get this
> > optimization into 3.1 as a bug fix.
>
> <snip>
>
> This would be cool!

The problem is replace does a while( (index = find( before, index ) ) != -1 ) 
and find calls length and length does a strlen on data().

So for Martin's attachment strlen gets called on an 800k string 7k times.

I'm thinking of a fix something like this.

Don.

["qcstring.diff" (text/x-diff)]

Index: tools/qcstring.h
===================================================================
RCS file: /home/kde/qt-copy/src/tools/qcstring.h,v
retrieving revision 1.45
diff -d -u -b -p -r1.45 qcstring.h
--- tools/qcstring.h	2002/09/06 12:32:03	1.45
+++ tools/qcstring.h	2002/10/16 17:14:48
@@ -232,6 +232,8 @@ public:
 		operator const char *() const;
     QCString    &operator+=( const char *str );
     QCString    &operator+=( char c );
+private:
+    int	find( const char *str, int index, bool cs, uint l ) const;
 };
 
 
Index: tools/qcstring.cpp
===================================================================
RCS file: /home/kde/qt-copy/src/tools/qcstring.cpp,v
retrieving revision 1.45
diff -d -u -b -p -r1.45 qcstring.cpp
--- tools/qcstring.cpp	2002/09/06 12:32:03	1.45
+++ tools/qcstring.cpp	2002/10/16 17:14:51
@@ -931,13 +931,17 @@ int QCString::find( char c, int index, b
 
 int QCString::find( const char *str, int index, bool cs ) const
 {
+    find( str, index, cs, length() );
+}
+    
+int QCString::find( const char *str, int index, bool cs, uint l ) const
+{
     if ( (uint)index >= size() )
 	return -1;
     if ( !str )
 	return -1;
     if ( !*str )
 	return index;
-    const uint l = length();
     const uint sl = qstrlen( str );
     if ( sl + index > l )
 	return -1;
@@ -1168,7 +1172,6 @@ int QCString::contains( const char *str,
 
     \sa right(), mid()
 */
-
 QCString QCString::left( uint len ) const
 {
     if ( isEmpty() ) {
@@ -1626,6 +1629,7 @@ QCString &QCString::replace( char c, con
     // s == "English is English"
     \endcode
 */
+
 QCString &QCString::replace( const char *before, const char *after )
 {
     if ( before == after || isNull() )
@@ -1641,7 +1645,7 @@ QCString &QCString::replace( const char 
 
     if ( bl == al ) {
 	if ( bl ) {
-	    while( (index = find( before, index ) ) != -1 ) {
+	    while( (index = find( before, index, TRUE, len ) ) != -1 ) {
 		memcpy( d+index, after, al );
 		index += bl;
 	    }
@@ -1650,7 +1654,7 @@ QCString &QCString::replace( const char 
 	uint to = 0;
 	uint movestart = 0;
 	uint num = 0;
-	while( (index = find( before, index ) ) != -1 ) {
+	while( (index = find( before, index, TRUE, len ) ) != -1 ) {
 	    if ( num ) {
 		int msize = index - movestart;
 		if ( msize > 0 ) {
@@ -1681,7 +1685,7 @@ QCString &QCString::replace( const char 
 	    uint indices[4096];
 	    uint pos = 0;
 	    while( pos < 4095 ) {
-		index = find(before, index);
+		index = find(before, index, TRUE, len);
 		if ( index == -1 )
 		    break;
 		indices[pos++] = index;

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