* [BREAK] merged lp:~mvo/apt/history

[apt.git] / apt-pkg / contrib / mmap.cc

diff --git a/apt-pkg/contrib/mmap.cc b/apt-pkg/contrib/mmap.cc
index 4d5fcf71e67c5bdda2ddf504cf9c39c90d0d1ed9..f440f94898f2a03ec77988af3f0794572d21a2dd 100644 (file)
--- a/apt-pkg/contrib/mmap.cc
+++ b/apt-pkg/contrib/mmap.cc
@@ -140,8 +140,10 @@ bool MMap::Sync(unsigned long Start,unsigned long Stop)
 // DynamicMMap::DynamicMMap - Constructor                              /*{{{*/
 // ---------------------------------------------------------------------
 /* */
 // DynamicMMap::DynamicMMap - Constructor                              /*{{{*/
 // ---------------------------------------------------------------------
 /* */

-DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace) :
-             MMap(F,Flags | NoImmMap), Fd(&F), WorkSpace(WorkSpace)
+DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long const &Workspace,
+                        unsigned long const &Grow, unsigned long const &Limit) :
+               MMap(F,Flags | NoImmMap), Fd(&F), WorkSpace(Workspace),
+               GrowFactor(Grow), Limit(Limit)

 {
    if (_error->PendingError() == true)
       return;
 {
    if (_error->PendingError() == true)
       return;


@@ -165,32 +167,48 @@ DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace)
 /* We try here to use mmap to reserve some space - this is much more
    cooler than the fallback solution to simply allocate a char array
    and could come in handy later than we are able to grow such an mmap */
 /* We try here to use mmap to reserve some space - this is much more
    cooler than the fallback solution to simply allocate a char array
    and could come in handy later than we are able to grow such an mmap */

-DynamicMMap::DynamicMMap(unsigned long Flags,unsigned long WorkSpace) :
-             MMap(Flags | NoImmMap | UnMapped), Fd(0), WorkSpace(WorkSpace)
+DynamicMMap::DynamicMMap(unsigned long Flags,unsigned long const &WorkSpace,
+                        unsigned long const &Grow, unsigned long const &Limit) :
+               MMap(Flags | NoImmMap | UnMapped), Fd(0), WorkSpace(WorkSpace),
+               GrowFactor(Grow), Limit(Limit)

 {
 {

-   if (_error->PendingError() == true)
-      return;
+       if (_error->PendingError() == true)
+               return;
+
+       // disable Moveable if we don't grow
+       if (Grow == 0)
+               Flags &= ~Moveable;
+
+#ifndef __linux__
+       // kfreebsd doesn't have mremap, so we use the fallback
+       if ((Flags & Moveable) == Moveable)
+               Flags |= Fallback;
+#endif

 
 #ifdef _POSIX_MAPPED_FILES
 
 #ifdef _POSIX_MAPPED_FILES

-   // Set the permissions.
-   int Prot = PROT_READ;
-   int Map = MAP_PRIVATE | MAP_ANONYMOUS;
-   if ((Flags & ReadOnly) != ReadOnly)
-      Prot |= PROT_WRITE;
-   if ((Flags & Public) == Public)
-      Map = MAP_SHARED | MAP_ANONYMOUS;
+       if ((Flags & Fallback) != Fallback) {
+               // Set the permissions.
+               int Prot = PROT_READ;
+               int Map = MAP_PRIVATE | MAP_ANONYMOUS;
+               if ((Flags & ReadOnly) != ReadOnly)
+                       Prot |= PROT_WRITE;
+               if ((Flags & Public) == Public)
+                       Map = MAP_SHARED | MAP_ANONYMOUS;

 
 

-   // use anonymous mmap() to get the memory
-   Base = (unsigned char*) mmap(0, WorkSpace, Prot, Map, -1, 0);
+               // use anonymous mmap() to get the memory
+               Base = (unsigned char*) mmap(0, WorkSpace, Prot, Map, -1, 0);

 
 

-   if(Base == MAP_FAILED)
-      _error->Errno("DynamicMMap",_("Couldn't make mmap of %lu bytes"),WorkSpace);
-#else
-   // fallback to a static allocated space
-   Base = new unsigned char[WorkSpace];
-   memset(Base,0,WorkSpace);
+               if(Base == MAP_FAILED)
+                       _error->Errno("DynamicMMap",_("Couldn't make mmap of %lu bytes"),WorkSpace);
+
+               iSize = 0;
+               return;
+       }

 #endif
 #endif

-   iSize = 0;
+       // fallback to a static allocated space
+       Base = new unsigned char[WorkSpace];
+       memset(Base,0,WorkSpace);
+       iSize = 0;

 }
                                                                        /*}}}*/
 // DynamicMMap::~DynamicMMap - Destructor                              /*{{{*/
 }
                                                                        /*}}}*/
 // DynamicMMap::~DynamicMMap - Destructor                              /*{{{*/


@@ -311,30 +329,55 @@ unsigned long DynamicMMap::WriteString(const char *String,
                                                                        /*}}}*/
 // DynamicMMap::Grow - Grow the mmap                                   /*{{{*/
 // ---------------------------------------------------------------------
                                                                        /*}}}*/
 // DynamicMMap::Grow - Grow the mmap                                   /*{{{*/
 // ---------------------------------------------------------------------

-/* This method will try to grow the mmap we currently use. This doesn't
-   work most of the time because we can't move the mmap around in the
-   memory for now as this would require to adjust quite a lot of pointers
-   but why we should not at least try to grow it before we give up? */
-bool DynamicMMap::Grow()
-{
-#if defined(_POSIX_MAPPED_FILES) && defined(__linux__)
-   unsigned long newSize = WorkSpace + 1024*1024;
+/* This method is a wrapper around different methods to (try to) grow
+   a mmap (or our char[]-fallback). Encounterable environments:
+   1. Moveable + !Fallback + linux -> mremap with MREMAP_MAYMOVE
+   2. Moveable + !Fallback + !linux -> not possible (forbidden by constructor)
+   3. Moveable + Fallback -> realloc
+   4. !Moveable + !Fallback + linux -> mremap alone - which will fail in 99,9%
+   5. !Moveable + !Fallback + !linux -> not possible (forbidden by constructor)
+   6. !Moveable + Fallback -> not possible
+   [ While Moveable and Fallback stands for the equally named flags and
+     "linux" indicates a linux kernel instead of a freebsd kernel. ]
+   So what you can see here is, that a MMAP which want to be growable need
+   to be moveable to have a real chance but that this method will at least try
+   the nearly impossible 4 to grow it before it finally give up: Never say never. */
+bool DynamicMMap::Grow() {
+       if (Limit != 0 && WorkSpace >= Limit)
+               return _error->Error(_("The size of a MMap has already reached the defined limit of %lu bytes,"
+                                      "abort the try to grow the MMap."), Limit);

 
 

-   if(Fd != 0)
-   {
-      Fd->Seek(newSize - 1);
-      char C = 0;
-      Fd->Write(&C,sizeof(C));
-   }
+       unsigned long const newSize = WorkSpace + 1024*1024;

 
 

-   Base = mremap(Base, WorkSpace, newSize, 0);
-   if(Base == MAP_FAILED)
-      return false;
+       if(Fd != 0) {
+               Fd->Seek(newSize - 1);
+               char C = 0;
+               Fd->Write(&C,sizeof(C));
+       }
+       if ((Flags & Fallback) != Fallback) {
+#if defined(_POSIX_MAPPED_FILES) && defined(__linux__)
+   #ifdef MREMAP_MAYMOVE
+               if ((Flags & Moveable) == Moveable)
+                       Base = mremap(Base, WorkSpace, newSize, MREMAP_MAYMOVE);
+               else
+   #endif
+                       Base = mremap(Base, WorkSpace, newSize, 0);

 
 

-   WorkSpace = newSize;
-   return true;
+               if(Base == MAP_FAILED)
+                       return false;

 #else
 #else

-   return false;
+               return false;

 #endif
 #endif

+       } else {
+               if ((Flags & Moveable) != Moveable)
+                       return false;
+
+               Base = realloc(Base, newSize);
+               if (Base == NULL)
+                       return false;
+       }
+
+       WorkSpace = newSize;
+       return true;

 }
                                                                        /*}}}*/
 }
                                                                        /*}}}*/