documentations: - doc/xml.html doc/xmlmem.html: added a module describing

documentations: - doc/xml.html doc/xmlmem.html: added a module describing memory interfaces and use, updated the main page. Daniel
2025-03-20 18:50:08 +03:00 · 2000-10-13 10:23:06 +00:00 · 2000-10-13 10:23:06 +00:00 · 189446d2fa
commit 189446d2fa
parent 2f971a26da
4 changed files with 213 additions and 18 deletions
--- a/5
+++ b/5
@ -1,3 +1,8 @@
+Fri Oct 13 12:21:48 CEST 2000 Daniel Veillard <Daniel.Veillard@w3.org>
+
+	* doc/xml.html doc/xmlmem.html: added a module describing memory
+	  interfaces and use, updated the main page.
+
 Fri Oct 13 01:23:48 CEST 2000 Daniel Veillard <Daniel.Veillard@w3.org>

 	* nanoftp.c nanohttp.c xmlIO.c: Wayne Davison Win32 patch
--- a/config.h.in
+++ b/config.h.in
@ -14,6 +14,7 @@
 #undef HAVE_ISNAN
 #undef HAVE_LIBHISTORY
 #undef HAVE_LIBREADLINE
+#undef SOCKLEN_T

 /* Define if you have the class function.  */
 #undef HAVE_CLASS
@ -153,5 +154,3 @@
 /* Define if compiler has function prototypes */
 #undef PROTOTYPES

-/* Type of socket length (socklen_t) */
-#undef SOCKLEN_T
--- a/doc/xml.html
+++ b/doc/xml.html
@ -3,7 +3,7 @@
 <html>
 <head>
  <title>The XML C library for Gnome</title>
-  <meta name="GENERATOR" content="amaya V3.2">
+  <meta name="GENERATOR" content="amaya V3.2.1">
  <meta http-equiv="Content-Type" content="text/html">
 </head>

@ -53,6 +53,7 @@ alt="W3C Logo"></a></p>
  libxml2</a></li>
  <li><a href="encoding.html">libxml Internationalization support</a></li>
  <li><a href="xmlio.html">libxml Input/Output interfaces</a></li>
+  <li><a href="xmlmem.html">libxml Memory interfaces</a></li>
 </ul>

 <h2><a name="Introducti">Introduction</a></h2>
@ -65,23 +66,29 @@ structured documents/data.</p>

 <p>Here are some key points about libxml:</p>
 <ul>
+  <li>Libxml exports Push and Pull type parser interfaces for both XML and
+    HTML.</li>
+  <li>Libxml can do Dtd validation at parse time, using a parsed document
+    instance, or with an arbitrary Dtd.</li>
+  <li>Libxml now includes a nearly complete <a
+    href="http://www.w3.org/TR/xpath">XPath</a> and <a
+    href="http://www.w3.org/TR/xptr/">XPointer</a> implementations.</li>
  <li>It is written in plain C, making as few assumptions as possible, and
-    sticking closely to ANSI C for easy embedding.</li>
+    sticking closely to ANSI C/POSIX for easy embedding. Works on
+    Linux/Unix/Windows, ported to a number of other platforms. </li>
+  <li>Basic support for HTTP and FTP client allowing to fetch remote
+  resources</li>
+  <li>The design of modular, most of the extensions can be compiled out.</li>
  <li>The internal document repesentation is as close as possible to the <a
    href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
  <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
    like interface</a>; the interface is designed to be compatible with <a
    href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
-  <li>Libxml now includes a nearly complete <a
-    href="http://www.w3.org/TR/xpath">XPath</a> implementation.</li>
-  <li>Libxml exports Push and Pull type parser interfaces for both XML and
-    HTML.</li>
  <li>This library is released both under the <a
    href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
-    IPR</a> and the GNU LGPL. Use either at your convenience, basically this
-    should make everybody happy, if not, drop me a mail.</li>
-  <li>There is <a href="upgrade.html">a first set of instructions</a>
-    concerning upgrade from libxml-1.x to libxml-2.x</li>
+    IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
+    LGPL</a>. Use either at your convenience, basically this should make
+    everybody happy, if not, drop me a mail.</li>
 </ul>

 <h2><a name="Documentat">Documentation</a></h2>
@ -125,8 +132,9 @@ structured documents/data.</p>
 <p>Well, bugs or missing features are always possible, and I will make a point
 of fixing them in a timely fashion. The best way to report a bug is to use the
 <a href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug tracking
-database</a>. I look at reports there regularly and it's good to have a
-reminder when a bug is still open. Check the <a
+database</a> (make sure to use the "gnome-xml" module name, not libxml or
+libxml2). I look at reports there regularly and it's good to have a reminder
+when a bug is still open. Check the <a
 href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
 and be sure to specify that the bug is for the package gnome-xml.</p>

@ -160,6 +168,9 @@ href="http://bugs.gnome.org/db/pa/lgnome-xml.html">Gnome bug
 database:</a>:</p>
 <ol>
  <li>provide patches when you find problems</li>
+  <li>provide the diffs when you port libxml to a new platform. They may not
+    be integrated in all cases but help pinpointing portability problems and
+  </li>
  <li>provice documentation fixes (either as patches to the code comments or
    as HTML diffs).</li>
  <li>provide new documentations pieces (translations, examples, etc ...)</li>
@ -219,10 +230,30 @@ platform, get in touch with me to upload the package. I will keep them in the

 <h3>CVS only : check the <a
 href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
-for really accurate description</h3>
+for a really accurate description</h3>
 <ul>
-  <li>working on HTML and XML links recognition layers, get in touch with me
-    if you want to test those.</li>
+  <li>XPointer implementation and testsuite</li>
+  <li>Lot of XPath fixes, added variable and functions registration, more
+    tests</li>
+  <li>Portability fixes, lots of enhancements toward an easy Windows build and
+    release</li>
+  <li>Late validation fixes</li>
+  <li>Integrated a lot of contributed patches</li>
+  <li>added memory management docs</li>
+</ul>
+
+<p>Item floating around but not actively worked on, get in touch with me if
+you want to test those</p>
+<ul>
+  <li>working on HTML and XML links recognition layers</li>
+  <li>parsing/import of Docbook SGML docs</li>
+</ul>
+
+<h3>2.2.4: Oct 1 2000:</h3>
+<ul>
+  <li>main XPath problem fixed</li>
+  <li>Integrated portability patches for Windows</li>
+  <li>Serious bug fixes on the URI and HTML code</li>
 </ul>

 <h3>2.2.3: Sep 17 2000</h3>
@ -1308,6 +1339,6 @@ Gnome CVS base under gnome-xml/example</p>

 <p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>

-<p>$Id: xml.html,v 1.52 2000/09/17 16:38:14 veillard Exp $</p>
+<p>$Id: xml.html,v 1.53 2000/09/29 02:42:04 veillard Exp $</p>
 </body>
 </html>
--- a/doc/xmlmem.html
+++ b/doc/xmlmem.html
@ -0,0 +1,160 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
+                      "http://www.w3.org/TR/REC-html40/loose.dtd">
+<html>
+<head>
+  <title>Libxml memory management</title>
+  <meta name="GENERATOR" content="amaya V3.2">
+  <meta http-equiv="Content-Type" content="text/html">
+</head>
+
+<body bgcolor="#ffffff">
+<h1 align="center">Libxml memory management</h1>
+
+<p>Location: <a
+href="http://xmlsoft.org/xmlmem.html">http://xmlsoft.org/xmlmem.html</a></p>
+
+<p>Libxml home page: <a href="http://xmlsoft.org/">http://xmlsoft.org/</a></p>
+
+<p>Mailing-list archive:  <a
+href="http://xmlsoft.org/messages/">http://xmlsoft.org/messages/</a></p>
+
+<p>Version: $Revision$</p>
+
+<p>Table of Content:</p>
+<ol>
+  <li><a href="#General">General overview</a></li>
+  <li><a href="#setting">Setting libxml set of memory routines</a></li>
+  <li><a href="#cleanup">Cleaning up after parsing</a></li>
+  <li><a href="#Debugging">Debugging routines</a></li>
+  <li><a href="#General">General memory requirements</a></li>
+</ol>
+
+<h2><a name="General">General overview</a></h2>
+
+<p>The module <code><a
+href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlmemory.h</a></code>
+provides the interfaces to the libxml memory system:</p>
+<ul>
+  <li>libxml does not use the libc memory allocator directly but xmlFree(),
+    xmlMalloc() and xmlRealloc()</li>
+  <li>those routines can be reallocated to a specific set of routine, by
+    default the libc ones i.e. free(), malloc() and realloc()</li>
+  <li>the xmlmemory.c module includes a set of debugging routine</li>
+</ul>
+
+<h2><a name="setting">Setting libxml set of memory routines</a></h2>
+
+<p>It is sometimes useful to not use the default memory allocator, either for
+debugging, analysis or to implement a specific behaviour on memory management
+(like on embedded systems). Two function calls are available to do so:</p>
+<ul>
+  <li><a href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlMemGet
+    ()</a> which return the current set of functions in use by the parser</li>
+  <li><a
+    href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlMemSetup()</a>
+    which allow to set up a new set of memory allocation functions</li>
+</ul>
+
+<p>Of course a call to xmlMemSetup() should probably be done before calling
+any other libxml routines (unless you are sure your allocations routines are
+compatibles).</p>
+
+<h2><a name="cleanup">Cleaning up after parsing</a></h2>
+
+<p>Libxml is not stateless, there is a few set of memory structures needing
+allocation before the parser is fully functionnal (some encoding structures
+for example). This also mean that once parsing is finished there is a tiny
+amount of memory (a few hundred bytes) which can be recollected if you don't
+reuse the parser immediately:</p>
+<ul>
+  <li><a href="http://xmlsoft.org/html/gnome-xml-parser.html">xmlCleanupParser
+    ()</a> is a centralized routine to free the parsing states. Note that it
+    won't deallocate any produced tree if any (use the xmlFreeDoc() and
+    related routines for this).</li>
+  <li><a href="http://xmlsoft.org/html/gnome-xml-parser.html">xmlInitParser
+    ()</a> is the dual routine allowing to preallocate the parsing state which
+    can be useful for example to avoid initialization reentrancy problems when
+    using libxml in multithreaded applications</li>
+</ul>
+
+<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
+at the next invocation of parser routines, but be careful of the consequences
+in multithreaded applications.</p>
+
+<h2><a name="Debugging">Debugging routines</a></h2>
+
+<p>When configured using --with-mem-debug flag (off by default), libxml uses a
+set of memory allocation debugging routineskeeping track of all allocated
+blocks and the location in the code where the routine was called. A couple of
+other debugging routines allow to dump the memory allocated infos to a file or
+call a specific routine when a given block number is allocated:</p>
+<ul>
+  <li><a
+    href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlMallocLoc()</a>
+    <a
+    href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlReallocLoc()</a>
+    and <a
+    href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlMemStrdupLoc()</a>
+    are the memory debugging replacement allocation routines</li>
+  <li><a href="http://xmlsoft.org/html/gnome-xml-xmlmemory.html">xmlMemoryDump
+    ()</a> dumps all the informations about the allocated memory block lefts
+    in the <code>.memdump</code> file</li>
+</ul>
+
+<p> When developping libxml memory debug is enabled, the tests programs call
+xmlMemoryDump () and the "make test" regression tests will check for any
+memory leak during the full regression test sequence, this helps a lot
+ensuring that libxml  does not leak memory and bullet proof memory allocations
+use (some libc implementations are known to be far too permissive resulting in
+major portability problems!). </p>
+
+<p>If the .memdump reports a leak, it displays the allocation function and
+also tries to give some informations about the content and structure of the
+allocated blocks left. This is sufficient in most cases to find the culprit,
+but not always. Assuming the allocation problem is reproductible, it is
+possible to find more easilly:</p>
+<ol>
+  <li>write down the block number xxxx not allocated</li>
+  <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
+  <li>run the program under a debugger and set a breakpoint on
+    xmlMallocBreakpoint() a specific function called when this precise block
+    is allocated</li>
+  <li>when the breakpoint is reached you can then do a fine analysis of the
+    allocation an step  to see the condition resulting in the missing
+    deallocation.</li>
+</ol>
+
+<p> I used to use a commercial tool to debug libxml memory problems but after
+noticing that it was not detecting memory leaks that simple mechanism was used
+and proved extremely efficient until now.</p>
+
+<h2><a name="General">General memory requirements</a></h2>
+
+<p>How much libxml memory require ? It's hard to tell in average it depends of
+a number of things:</p>
+<ul>
+  <li>the parser itself should work  in a fixed amout of memory, except for
+    information maintained about the stacks of names and  entities locations.
+    The I/O and encoding handlers will probably account for a few KBytes. This
+    is true for both the XML and HTML parser (though the HTML parser need more
+    state).</li>
+  <li>If you are generating the DOM tree then memory requirements will grow
+    nearly lineary with the size of the data. In general for a balanced
+    textual document the internal memory requirement is about 4 times the size
+    of the UTF8 serialization of this document (exmple the XML-1.0
+    recommendation is a bit more of 150KBytes and takes 650KBytes of main
+    memory when parsed). Validation will add a amount of memory required for
+    maintaining the external Dtd state which should be linear with the
+    complexity of the content model defined by the Dtd </li>
+  <li>If you don't care about the advanced features of libxml like validation,
+    DOM, XPath or XPointer, but really need to work fixed memory requirements,
+    then the SAX interface should be used.</li>
+</ul>
+
+<p></p>
+
+<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
+
+<p>$Id$</p>
+</body>
+</html>