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Re: Performance improvement for a recursive function?

Subject: Re: Performance improvement for a recursive function?
From: Wolfgang Laun <wolfgang.laun@xxxxxxxxx>
Date: Tue, 13 Dec 2011 08:46:28 +0100
Re:  Performance improvement for a recursive function?
This function permits processing of all contained commands.

I don't have the time to analyze what should be done for each; I saw
that m0,0 was dropped.

It's fast enough now :-)

-W

<xsl:function name="my:compose-path-data" as="xs:string*">
	<xsl:param name="data" as="xs:string*"/>
    <xsl:analyze-string select = "$data"
                        regex = "[ Mlm](\d+),(\d+)|[hv](\d+)|z">
       <xsl:matching-substring>
          <xsl:variable name="cmd" select="substring(regex-group(0),1,1)"/>
          <xsl:choose>
             <xsl:when test="$cmd = (' ', 'M', 'l', 'm')">
               <xsl:value-of
select="concat($cmd,regex-group(1),',',regex-group(2))"/>
             </xsl:when>
             <xsl:when test="$cmd = ('h', 'v')">
               <xsl:value-of select="concat($cmd,regex-group(3))"/>
             </xsl:when>
             <xsl:when test="$cmd = 'z'">
               <xsl:value-of select="$cmd"/>
             </xsl:when>
          </xsl:choose>
       </xsl:matching-substring>
    </xsl:analyze-string>
</xsl:function>


On 13 December 2011 01:07, Manfred Staudinger
<manfred.staudinger@xxxxxxxxx> wrote:
> Hi,
>
> I need some help to improve the performance of a function, as I have
> run out of ideas what to change!
>
> In the process to convert some data to SVG I transform (or even break
> up) @Data attribute of the Path element and then use the function
> my:compose-path-data [1] to put the parts together into a string
> again. The attribute string is a succession of path commands, where
> each path command  (see the global variable below) consists of a one
> byte character followed by zero, one, or two integers. Having about
> 2200 Path elements, most of them have a @Data attribute with between 5
> an 50 path commands.
>
> A few attribute strings are bigger (up to 1MB) and contain up to
> 100000 path commands. As the function is called for each path command
> it is tail recursive, but the performance is still a big problem: to
> process 41337 path commands it takes 861 sec! The first 5000 path
> commands are processed in 14 sec (at 355.87 per sec) the last 5000
> take 671 sec (only at 7.5 per sec).
>
> What Saxon reports [2] is consistent with the above. In case you want
> to try it, I have uploaded the specific test case here:
>   http:///test.rudolphina.org/test01-perform-data.xsl
>   http:///test.rudolphina.org/test01-perform-data-org.xml
>
> Using Saxon-HE 9.3.0.5J and Java version 1.6.0_14 on Windows. XP Home.
> Hardware ASUS Eee PC 1000H with Intel. Atom N270 (1.60 GHz)
>
> Regards,
> Manfred
>
> [1]
> <xsl:function name="my:compose-path-data" as="xs:string*">
>   <xsl:param name="c" as="xs:integer*"/>
>   <xsl:param name="i-c" as="xs:integer"/>
>   <xsl:param name="xy" as="xs:integer*"/>
>   <xsl:param name="i-xy" as="xs:integer"/>
>   <xsl:param name="i-end" as="xs:integer"/>
>   <xsl:param name="result" as="xs:string?"/>
>   <xsl:variable name="cmd" select="key('path', $c[$i-c], $path-cmd)"
> as="element()?"/>
>   <xsl:sequence select="if ($i-c gt $i-end)
>      then $result
>      else my:compose-path-data($c, $i-c + 1,
>         $xy, $i-xy + xs:integer($cmd/n),
>         $i-end,
>         concat($result, $cmd/@char, if ($cmd/n=2)
>            then (: M, m, l, (blank) :) concat($xy[$i-xy], ',',
$xy[$i-xy+1])
>            else  if ($cmd/n=1)
>               then (: h, v :) string($xy[$i-xy])
>               else (: z :) ())
>         )"/>
> </xsl:function>
>
> and on the stylesheet level
> <xsl:variable name="path-cmd">
>   <path>
>      <cmd char=" "><n>2</n><code>32</code></cmd>
>      <cmd char="M"><n>2</n><code>77</code></cmd>
>      <cmd char="l"><n>2</n><code>108</code></cmd>
>      <cmd char="m"><n>2</n><code>109</code></cmd>
>      <cmd char="h"><n>1</n><code>104</code></cmd>
>      <cmd char="v"><n>1</n><code>118</code></cmd>
>      <cmd char="z"><n>0</n><code>122</code></cmd>
>   </path>
> </xsl:variable>
> <xsl:key name="path" match="cmd" use="xs:integer(code)"/><!-- $path-cmd -->
>
> [2]
> Stylesheet compilation time: 4218 milliseconds
> Using parser org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser
> net.sf.saxon.tree.tiny.TinyBuilder
> Tree built in 1375 milliseconds
> Tree size: 4 nodes, 0 characters, 11 attributes
> Execution time: 14m 31.579s (871579ms)
> Memory used: 36559128
> NamePool contents: 33 entries in 33 chains. 8 prefixes, 8 URIs

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