* doc/apt.conf.5.xml:

  - add and document APT::Cache-{Start,Grow,Limit} options for mmap control

apt-pkg/contrib/mmap.cc

@@ -398,6 +398,8 @@ bool DynamicMMap::Grow() {
 	if (Limit != 0 && WorkSpace >= Limit)
 		return _error->Error(_("Unable to increase the size of the MMap as the "
 		                       "limit of %lu bytes is already reached."), Limit);
+	if (GrowFactor <= 0)
+		return _error->Error(_("Unable to increase size of the MMap as automatic growing is disabled by user."));
 
 	unsigned long const newSize = WorkSpace + GrowFactor;
 

apt-pkg/pkgcachegen.cc

@@ -1094,6 +1094,18 @@ static bool BuildCache(pkgCacheGenerator &Gen,
    return true;
 }
 									/*}}}*/
+DynamicMMap* pkgCacheGenerator::CreateDynamicMMap(FileFd *CacheF, unsigned long Flags) {
+   unsigned long const MapStart = _config->FindI("APT::Cache-Start", 24*1024*1024);
+   unsigned long const MapGrow = _config->FindI("APT::Cache-Grow", 1*1024*1024);
+   unsigned long const MapLimit = _config->FindI("APT::Cache-Limit", 0);
+   Flags |= MMap::Moveable;
+   if (_config->FindB("APT::Cache-Fallback", false) == true)
+      Flags |= MMap::Fallback;
+   if (CacheF != NULL)
+      return new DynamicMMap(*CacheF, Flags, MapStart, MapGrow, MapLimit);
+   else
+      return new DynamicMMap(Flags, MapStart, MapGrow, MapLimit);
+}
 // CacheGenerator::MakeStatusCache - Construct the status cache		/*{{{*/
 // ---------------------------------------------------------------------
 /* This makes sure that the status cache (the cache that has all 
@@ -1109,7 +1121,6 @@ bool pkgCacheGenerator::MakeStatusCache(pkgSourceList &List,OpProgress *Progress
 			MMap **OutMap,bool AllowMem)
 {
    bool const Debug = _config->FindB("Debug::pkgCacheGen", false);
-   unsigned long const MapSize = _config->FindI("APT::Cache-Limit",24*1024*1024);
    
    vector<pkgIndexFile *> Files;
    for (vector<metaIndex *>::const_iterator i = List.begin();
@@ -1181,7 +1192,7 @@ bool pkgCacheGenerator::MakeStatusCache(pkgSourceList &List,OpProgress *Progress
       unlink(CacheFile.c_str());
       CacheF = new FileFd(CacheFile,FileFd::WriteEmpty);
       fchmod(CacheF->Fd(),0644);
-      Map = new DynamicMMap(*CacheF,MMap::Public | MMap::Moveable, MapSize);
+      Map = CreateDynamicMMap(CacheF, MMap::Public);
       if (_error->PendingError() == true)
 	 return false;
       if (Debug == true)
@@ -1190,7 +1201,7 @@ bool pkgCacheGenerator::MakeStatusCache(pkgSourceList &List,OpProgress *Progress
    else
    {
       // Just build it in memory..
-      Map = new DynamicMMap(MMap::Moveable, MapSize);
+      Map = CreateDynamicMMap(NULL);
       if (Debug == true)
 	 std::clog << "Open memory Map (not filebased)" << std::endl;
    }
@@ -1297,13 +1308,12 @@ __deprecated bool pkgMakeOnlyStatusCache(OpProgress &Progress,DynamicMMap **OutM
    { return pkgCacheGenerator::MakeOnlyStatusCache(&Progress, OutMap); }
 bool pkgCacheGenerator::MakeOnlyStatusCache(OpProgress *Progress,DynamicMMap **OutMap)
 {
-   unsigned long MapSize = _config->FindI("APT::Cache-Limit",20*1024*1024);
    vector<pkgIndexFile *> Files;
    unsigned long EndOfSource = Files.size();
    if (_system->AddStatusFiles(Files) == false)
       return false;
-   
-   SPtr<DynamicMMap> Map = new DynamicMMap(MMap::Moveable, MapSize);
+
+   SPtr<DynamicMMap> Map = CreateDynamicMMap(NULL);
    unsigned long CurrentSize = 0;
    unsigned long TotalSize = 0;
    

apt-pkg/pkgcachegen.h

@@ -101,6 +101,7 @@ class pkgCacheGenerator							/*{{{*/
    static bool MakeStatusCache(pkgSourceList &List,OpProgress *Progress,
 			MMap **OutMap = 0,bool AllowMem = false);
    static bool MakeOnlyStatusCache(OpProgress *Progress,DynamicMMap **OutMap);
+   static DynamicMMap* CreateDynamicMMap(FileFd *CacheF, unsigned long Flags = 0);
 
    void ReMap(void const * const oldMap, void const * const newMap);
 

debian/changelog

@@ -40,6 +40,8 @@ apt (0.7.26~exp8) UNRELEASED; urgency=low
   * apt-pkg/pkgcachegen.{cc,h}:
     - make the used MMap moveable (and therefore dynamic resizeable) by
       applying (some) mad pointer magic (Closes: #195018)
+  * doc/apt.conf.5.xml:
+    - add and document APT::Cache-{Start,Grow,Limit} options for mmap control
 
   [ Julian Andres Klode ]
   * methods/ftp.h:
@@ -55,7 +57,7 @@ apt (0.7.26~exp8) UNRELEASED; urgency=low
   * debian/control:
     - Set Standards-Version to 3.9.0
 
- -- David Kalnischkies <kalnischkies@gmail.com>  Mon, 05 Jul 2010 12:05:30 +0200
+ -- David Kalnischkies <kalnischkies@gmail.com>  Fri, 09 Jul 2010 16:55:53 +0200
 
 apt (0.7.26~exp7) experimental; urgency=low
 

doc/apt.conf.5.xml

@@ -199,9 +199,20 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      anything that those packages depend on.</para></listitem>
      </varlistentry>
 
-     <varlistentry><term>Cache-Limit</term>
-     <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
-     information. This sets the size of that cache (in bytes).</para></listitem>
+     <varlistentry><term>Cache-Start, Cache-Grow and Cache-Limit</term>
+     <listitem><para>APT uses since version 0.7.26 a resizable memory mapped cache file to store the 'available'
+     information. <literal>Cache-Start</literal> acts as a hint to which size the Cache will grow
+     and is therefore the amount of memory APT will request at startup. The default value is
+     20971520 bytes (~20 MB). Note that these amount of space need to be available for APT
+     otherwise it will likely fail ungracefully, so for memory restricted devices these value should
+     be lowered while on systems with a lot of configured sources this might be increased.
+     <literal>Cache-Grow</literal> defines in byte with the default of 1048576 (~1 MB) how much
+     the Cache size will be increased in the event the space defined by <literal>Cache-Start</literal>
+     is not enough. These value will be applied again and again until either the cache is big
+     enough to store all information or the size of the cache reaches the <literal>Cache-Limit</literal>.
+     The default of <literal>Cache-Limit</literal> is 0 which stands for no limit.
+     If <literal>Cache-Grow</literal> is set to 0 the automatic grow of the cache is disabled.
+     </para></listitem>
      </varlistentry>
 
      <varlistentry><term>Build-Essential</term>

doc/examples/configure-index

@@ -95,7 +95,9 @@ APT
   Clean-Installed "true";
   Immediate-Configure "true";      // DO NOT turn this off, see the man page
   Force-LoopBreak "false";         // DO NOT turn this on, see the man page
-  Cache-Limit "4194304";
+  Cache-Start "20971520";
+  Cache-Grow "1048576";
+  Cache-Limit "0";
   Default-Release "";
 
   // consider Recommends, Suggests as important dependencies that should