doc: Speed up XSLT builds

The upstream XSLT stylesheets use some very general XPath expressions in
some places that end up being very slow.  We can optimize them with
knowledge about the DocBook document structure and our particular use
thereof.  For example, when counting preceding chapters to get a number
for the current chapter, we only need to count preceding sibling
nodes (more or less) instead of searching through the entire node tree
for chapter elements.

This change attacks the slowest pieces as identified by xsltproc
--profile.  This makes the HTML build roughly 10 times faster, resulting
in the new total build time being about the same as the old DSSSL-based
build.  Some of the non-HTML build targets (especially FO) will also
benefit a bit, but they have not been specifically analyzed.

With this, also remove the pg.fast parameter, which was previously a
hack to get the build to a manageable speed.

Alexander Lakhin <a.lakhin@postgrespro.ru>, with some additional
tweaking by me

doc/src/sgml/stylesheet-common.xsl

@@ -7,11 +7,10 @@
   all output formats (HTML, HTML Help, XSL-FO, etc.).
   -->
 
+<xsl:include href="stylesheet-speedup-common.xsl" />
 
 <!-- Parameters -->
 
-<xsl:param name="pg.fast" select="'0'"/>
-
 <!--
 <xsl:param name="draft.mode">
   <xsl:choose>
@@ -31,9 +30,8 @@
 <xsl:param name="callout.graphics" select="'0'"></xsl:param>
 <xsl:param name="toc.section.depth">2</xsl:param>
 <xsl:param name="linenumbering.extension" select="'0'"></xsl:param>
-<xsl:param name="generate.index" select="1 - $pg.fast"></xsl:param>
-<xsl:param name="section.autolabel" select="1 - $pg.fast"></xsl:param>
-<xsl:param name="section.label.includes.component.label" select="1 - $pg.fast"></xsl:param>
+<xsl:param name="section.autolabel" select="1"></xsl:param>
+<xsl:param name="section.label.includes.component.label" select="1"></xsl:param>
 <xsl:param name="refentry.xref.manvolnum" select="0"/>
 <xsl:param name="formal.procedures" select="0"></xsl:param>
 <xsl:param name="punct.honorific" select="''"></xsl:param>

doc/src/sgml/stylesheet-speedup-common.xsl

+<?xml version="1.0" encoding="utf-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+                version='1.0'>
+
+<!-- Performance-optimized versions of some upstream templates from common/
+     directory -->
+
+<!-- from common/labels.xsl -->
+
+<xsl:template match="chapter" mode="label.markup">
+  <xsl:choose>
+    <xsl:when test="@label">
+      <xsl:value-of select="@label"/>
+    </xsl:when>
+    <xsl:when test="string($chapter.autolabel) != 0">
+      <xsl:if test="$component.label.includes.part.label != 0 and
+                      ancestor::part">
+        <xsl:variable name="part.label">
+          <xsl:apply-templates select="ancestor::part"
+                               mode="label.markup"/>
+        </xsl:variable>
+        <xsl:if test="$part.label != ''">
+          <xsl:value-of select="$part.label"/>
+          <xsl:apply-templates select="ancestor::part"
+                               mode="intralabel.punctuation">
+            <xsl:with-param name="object" select="."/>
+          </xsl:apply-templates>
+        </xsl:if>
+      </xsl:if>
+      <xsl:variable name="format">
+        <xsl:call-template name="autolabel.format">
+          <xsl:with-param name="format" select="$chapter.autolabel"/>
+        </xsl:call-template>
+      </xsl:variable>
+      <xsl:choose>
+        <xsl:when test="$label.from.part != 0 and ancestor::part">
+          <xsl:number from="part" count="chapter" format="{$format}" level="any"/>
+        </xsl:when>
+        <xsl:otherwise>
+          <!-- Optimization for pgsql-docs: When counting to get label for
+               this chapter, preceding chapters can only be our siblings or
+               children of a preceding part, so only count those instead of
+               scanning the entire node tree. -->
+          <!-- <xsl:number from="book" count="chapter" format="{$format}" level="any"/> -->
+          <xsl:number value="count(../preceding-sibling::part/chapter) + count(preceding-sibling::chapter) + 1" format="{$format}"/>
+        </xsl:otherwise>
+      </xsl:choose>
+    </xsl:when>
+  </xsl:choose>
+</xsl:template>
+
+<xsl:template match="appendix" mode="label.markup">
+  <xsl:choose>
+    <xsl:when test="@label">
+      <xsl:value-of select="@label"/>
+    </xsl:when>
+    <xsl:when test="string($appendix.autolabel) != 0">
+      <xsl:if test="$component.label.includes.part.label != 0 and
+                      ancestor::part">
+        <xsl:variable name="part.label">
+          <xsl:apply-templates select="ancestor::part"
+                               mode="label.markup"/>
+        </xsl:variable>
+        <xsl:if test="$part.label != ''">
+          <xsl:value-of select="$part.label"/>
+          <xsl:apply-templates select="ancestor::part"
+                               mode="intralabel.punctuation">
+            <xsl:with-param name="object" select="."/>
+          </xsl:apply-templates>
+        </xsl:if>
+      </xsl:if>
+      <xsl:variable name="format">
+        <xsl:call-template name="autolabel.format">
+          <xsl:with-param name="format" select="$appendix.autolabel"/>
+        </xsl:call-template>
+      </xsl:variable>
+      <xsl:choose>
+        <xsl:when test="$label.from.part != 0 and ancestor::part">
+          <xsl:number from="part" count="appendix" format="{$format}" level="any"/>
+        </xsl:when>
+        <xsl:otherwise>
+          <!-- Optimization for pgsql-docs: When counting to get label for
+               this appendix, preceding appendixes can only be our siblings or
+               children of a preceding part, so only count those instead of
+               scanning the entire node tree. -->
+          <!-- <xsl:number from="book|article" count="appendix" format="{$format}" level="any"/> -->
+          <xsl:number value="count(../preceding-sibling::part/appendix) + count(preceding-sibling::appendix) + 1" format="{$format}"/>
+        </xsl:otherwise>
+      </xsl:choose>
+    </xsl:when>
+  </xsl:choose>
+</xsl:template>
+
+</xsl:stylesheet>

doc/src/sgml/stylesheet-speedup-xhtml.xsl

+<?xml version="1.0" encoding="utf-8"?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+                xmlns="http://www.w3.org/1999/xhtml"
+                version='1.0'>
+
+<!-- Performance-optimized versions of some upstream templates from xhtml/
+     directory -->
+
+<!-- from xhtml/autoidx.xsl -->
+
+<xsl:template match="indexterm" mode="reference">
+  <xsl:param name="scope" select="."/>
+  <xsl:param name="role" select="''"/>
+  <xsl:param name="type" select="''"/>
+  <xsl:param name="position"/>
+  <xsl:param name="separator" select="''"/>
+
+  <xsl:variable name="term.separator">
+    <xsl:call-template name="index.separator">
+      <xsl:with-param name="key" select="'index.term.separator'"/>
+    </xsl:call-template>
+  </xsl:variable>
+
+  <xsl:variable name="number.separator">
+    <xsl:call-template name="index.separator">
+      <xsl:with-param name="key" select="'index.number.separator'"/>
+    </xsl:call-template>
+  </xsl:variable>
+
+  <xsl:variable name="range.separator">
+    <xsl:call-template name="index.separator">
+      <xsl:with-param name="key" select="'index.range.separator'"/>
+    </xsl:call-template>
+  </xsl:variable>
+
+  <xsl:choose>
+    <xsl:when test="$separator != ''">
+      <xsl:value-of select="$separator"/>
+    </xsl:when>
+    <xsl:when test="$position = 1">
+      <xsl:value-of select="$term.separator"/>
+    </xsl:when>
+    <xsl:otherwise>
+      <xsl:value-of select="$number.separator"/>
+    </xsl:otherwise>
+  </xsl:choose>
+
+  <xsl:choose>
+    <xsl:when test="@zone and string(@zone)">
+      <xsl:call-template name="reference">
+        <xsl:with-param name="zones" select="normalize-space(@zone)"/>
+        <xsl:with-param name="position" select="position()"/>
+        <xsl:with-param name="scope" select="$scope"/>
+        <xsl:with-param name="role" select="$role"/>
+        <xsl:with-param name="type" select="$type"/>
+      </xsl:call-template>
+    </xsl:when>
+    <xsl:otherwise>
+      <a>
+        <xsl:apply-templates select="." mode="class.attribute"/>
+        <xsl:variable name="title">
+          <xsl:choose>
+            <xsl:when test="$index.prefer.titleabbrev != 0">
+              <xsl:apply-templates select="(ancestor-or-self::set|ancestor-or-self::book|ancestor-or-self::part|ancestor-or-self::reference|ancestor-or-self::partintro|ancestor-or-self::chapter|ancestor-or-self::appendix|ancestor-or-self::preface|ancestor-or-self::article|ancestor-or-self::section|ancestor-or-self::sect1|ancestor-or-self::sect2|ancestor-or-self::sect3|ancestor-or-self::sect4|ancestor-or-self::sect5|ancestor-or-self::refentry|ancestor-or-self::refsect1|ancestor-or-self::refsect2|ancestor-or-self::refsect3|ancestor-or-self::simplesect|ancestor-or-self::bibliography|ancestor-or-self::glossary|ancestor-or-self::index|ancestor-or-self::webpage|ancestor-or-self::topic)[last()]" mode="titleabbrev.markup"/>
+            </xsl:when>
+            <xsl:otherwise>
+              <xsl:apply-templates select="(ancestor-or-self::set|ancestor-or-self::book|ancestor-or-self::part|ancestor-or-self::reference|ancestor-or-self::partintro|ancestor-or-self::chapter|ancestor-or-self::appendix|ancestor-or-self::preface|ancestor-or-self::article|ancestor-or-self::section|ancestor-or-self::sect1|ancestor-or-self::sect2|ancestor-or-self::sect3|ancestor-or-self::sect4|ancestor-or-self::sect5|ancestor-or-self::refentry|ancestor-or-self::refsect1|ancestor-or-self::refsect2|ancestor-or-self::refsect3|ancestor-or-self::simplesect|ancestor-or-self::bibliography|ancestor-or-self::glossary|ancestor-or-self::index|ancestor-or-self::webpage|ancestor-or-self::topic)[last()]" mode="title.markup"/>
+            </xsl:otherwise>
+          </xsl:choose>
+        </xsl:variable>
+
+        <xsl:attribute name="href">
+          <xsl:choose>
+            <xsl:when test="$index.links.to.section = 1">
+              <xsl:call-template name="href.target">
+                <xsl:with-param name="object" select="(ancestor-or-self::set|ancestor-or-self::book|ancestor-or-self::part|ancestor-or-self::reference|ancestor-or-self::partintro|ancestor-or-self::chapter|ancestor-or-self::appendix|ancestor-or-self::preface|ancestor-or-self::article|ancestor-or-self::section|ancestor-or-self::sect1|ancestor-or-self::sect2|ancestor-or-self::sect3|ancestor-or-self::sect4|ancestor-or-self::sect5|ancestor-or-self::refentry|ancestor-or-self::refsect1|ancestor-or-self::refsect2|ancestor-or-self::refsect3|ancestor-or-self::simplesect|ancestor-or-self::bibliography|ancestor-or-self::glossary|ancestor-or-self::index|ancestor-or-self::webpage|ancestor-or-self::topic)[last()]"/>
+                <!-- Optimization for pgsql-docs: We only have an index as a
+                     child of book, so look that up directly instead of
+                     scanning the entire node tree.  Also, don't look for
+                     setindex. -->
+                <!-- <xsl:with-param name="context" select="(//index[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))] | //setindex[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))])[1]"/> -->
+                <xsl:with-param name="context" select="(/book/index[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))])[1]"/>
+              </xsl:call-template>
+            </xsl:when>
+            <xsl:otherwise>
+              <xsl:call-template name="href.target">
+                <xsl:with-param name="object" select="."/>
+                <xsl:with-param name="context" select="(//index[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))] | //setindex[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))])[1]"/>
+              </xsl:call-template>
+            </xsl:otherwise>
+          </xsl:choose>
+
+        </xsl:attribute>
+
+        <xsl:value-of select="$title"/> <!-- text only -->
+      </a>
+
+      <xsl:variable name="id" select="(@id|@xml:id)[1]"/>
+      <xsl:if test="key('endofrange', $id)[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))]">
+        <xsl:apply-templates select="key('endofrange', $id)[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))][last()]" mode="reference">
+          <xsl:with-param name="position" select="position()"/>
+          <xsl:with-param name="scope" select="$scope"/>
+          <xsl:with-param name="role" select="$role"/>
+          <xsl:with-param name="type" select="$type"/>
+          <xsl:with-param name="separator" select="$range.separator"/>
+        </xsl:apply-templates>
+      </xsl:if>
+    </xsl:otherwise>
+  </xsl:choose>
+</xsl:template>
+
+<xsl:template name="reference">
+  <xsl:param name="scope" select="."/>
+  <xsl:param name="role" select="''"/>
+  <xsl:param name="type" select="''"/>
+  <xsl:param name="zones"/>
+
+  <xsl:choose>
+    <xsl:when test="contains($zones, ' ')">
+      <xsl:variable name="zone" select="substring-before($zones, ' ')"/>
+      <xsl:variable name="target" select="key('sections', $zone)"/>
+
+      <a>
+        <xsl:apply-templates select="." mode="class.attribute"/>
+        <xsl:call-template name="id.attribute"/>
+        <xsl:attribute name="href">
+          <xsl:call-template name="href.target">
+            <xsl:with-param name="object" select="$target[1]"/>
+            <xsl:with-param name="context" select="//index[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))][1]"/>
+          </xsl:call-template>
+        </xsl:attribute>
+        <xsl:apply-templates select="$target[1]" mode="index-title-content"/>
+      </a>
+      <xsl:text>, </xsl:text>
+      <xsl:call-template name="reference">
+        <xsl:with-param name="zones" select="substring-after($zones, ' ')"/>
+        <xsl:with-param name="position" select="position()"/>
+        <xsl:with-param name="scope" select="$scope"/>
+        <xsl:with-param name="role" select="$role"/>
+        <xsl:with-param name="type" select="$type"/>
+      </xsl:call-template>
+    </xsl:when>
+    <xsl:otherwise>
+      <xsl:variable name="zone" select="$zones"/>
+      <xsl:variable name="target" select="key('sections', $zone)"/>
+
+      <a>
+        <xsl:apply-templates select="." mode="class.attribute"/>
+        <xsl:call-template name="id.attribute"/>
+        <xsl:attribute name="href">
+          <xsl:call-template name="href.target">
+            <xsl:with-param name="object" select="$target[1]"/>
+            <!-- Optimization for pgsql-docs: Only look for index under book
+                 instead of searching the whole node tree. -->
+            <!-- <xsl:with-param name="context" select="//index[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))][1]"/> -->
+            <xsl:with-param name="context" select="/book/index[count(ancestor::node()|$scope) = count(ancestor::node()) and ($role = @role or $type = @type or (string-length($role) = 0 and string-length($type) = 0))][1]"/>
+          </xsl:call-template>
+        </xsl:attribute>
+        <xsl:apply-templates select="$target[1]" mode="index-title-content"/>
+      </a>
+    </xsl:otherwise>
+  </xsl:choose>
+</xsl:template>
+
+
+<!-- from xhtml/chunk-common.xsl -->
+
+<xsl:template name="chunk-all-sections">
+  <xsl:param name="content">
+    <xsl:apply-imports/>
+  </xsl:param>
+
+  <!-- Optimization for pgsql-docs: Since we set a fixed $chunk.section.depth,
+       we can do away with a bunch of complicated XPath searches for the
+       previous and next sections at various levels. -->
+
+  <xsl:if test="$chunk.section.depth != 1">
+    <xsl:message terminate="yes">
+      <xsl:text>Error: If you change $chunk.section.depth, then you must update the performance-optimized chunk-all-sections-template.</xsl:text>
+    </xsl:message>
+  </xsl:if>
+
+  <xsl:variable name="prev"
+    select="(preceding::book[1]
+             |preceding::preface[1]
+             |preceding::chapter[1]
+             |preceding::appendix[1]
+             |preceding::part[1]
+             |preceding::reference[1]
+             |preceding::refentry[1]
+             |preceding::colophon[1]
+             |preceding::article[1]
+             |preceding::topic[1]
+             |preceding::bibliography[parent::article or parent::book or parent::part][1]
+             |preceding::glossary[parent::article or parent::book or parent::part][1]
+             |preceding::index[$generate.index != 0]
+                               [parent::article or parent::book or parent::part][1]
+             |preceding::setindex[$generate.index != 0][1]
+             |ancestor::set
+             |ancestor::book[1]
+             |ancestor::preface[1]
+             |ancestor::chapter[1]
+             |ancestor::appendix[1]
+             |ancestor::part[1]
+             |ancestor::reference[1]
+             |ancestor::article[1]
+             |ancestor::topic[1]
+             |preceding::sect1[1]
+             |ancestor::sect1[1])[last()]"/>
+
+  <xsl:variable name="next"
+    select="(following::book[1]
+             |following::preface[1]
+             |following::chapter[1]
+             |following::appendix[1]
+             |following::part[1]
+             |following::reference[1]
+             |following::refentry[1]
+             |following::colophon[1]
+             |following::bibliography[parent::article or parent::book or parent::part][1]
+             |following::glossary[parent::article or parent::book or parent::part][1]
+             |following::index[$generate.index != 0]
+                               [parent::article or parent::book][1]
+             |following::article[1]
+             |following::topic[1]
+             |following::setindex[$generate.index != 0][1]
+             |descendant::book[1]
+             |descendant::preface[1]
+             |descendant::chapter[1]
+             |descendant::appendix[1]
+             |descendant::article[1]
+             |descendant::topic[1]
+             |descendant::bibliography[parent::article or parent::book][1]
+             |descendant::glossary[parent::article or parent::book or parent::part][1]
+             |descendant::index[$generate.index != 0]
+                                [parent::article or parent::book][1]
+             |descendant::colophon[1]
+             |descendant::setindex[$generate.index != 0][1]
+             |descendant::part[1]
+             |descendant::reference[1]
+             |descendant::refentry[1]
+             |following::sect1[1]
+             |descendant::sect1[1])[1]"/>
+
+  <xsl:call-template name="process-chunk">
+    <xsl:with-param name="prev" select="$prev"/>
+    <xsl:with-param name="next" select="$next"/>
+    <xsl:with-param name="content" select="$content"/>
+  </xsl:call-template>
+</xsl:template>
+
+</xsl:stylesheet>

doc/src/sgml/stylesheet.xsl

@@ -6,6 +6,7 @@
 
 <xsl:import href="http://docbook.sourceforge.net/release/xsl/current/xhtml/chunk.xsl"/>
 <xsl:include href="stylesheet-common.xsl" />
+<xsl:include href="stylesheet-speedup-xhtml.xsl" />
 
 
 <!-- Parameters -->