Support for memory-only caching

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

diff --git a/apt-pkg/contrib/mmap.cc b/apt-pkg/contrib/mmap.cc
index 9febc5cdde70019bc11c2b79808d632388610445..098c61ca6efe2bde9880537841673f1669171e95 100644 (file)
--- a/apt-pkg/contrib/mmap.cc
+++ b/apt-pkg/contrib/mmap.cc
@@ -1,6 +1,6 @@
 // -*- mode: cpp; mode: fold -*-
 // Description                                                         /*{{{*/
-// $Id: mmap.cc,v 1.2 1998/07/04 05:57:42 jgg Exp $
+// $Id: mmap.cc,v 1.15 1999/04/18 06:36:36 jgg Exp $
 /* ######################################################################
    
    MMap Class - Provides 'real' mmap or a faked mmap using read().
@@ -21,13 +21,16 @@
    ##################################################################### */
                                                                        /*}}}*/
 // Include Files                                                       /*{{{*/
+#ifdef __GNUG__
+#pragma implementation "apt-pkg/mmap.h"
+#endif 
+
 #define _BSD_SOURCE
-#include <pkglib/mmap.h>
-#include <pkglib/error.h>
+#include <apt-pkg/mmap.h>
+#include <apt-pkg/error.h>
 
 #include <sys/mman.h>
 #include <sys/stat.h>
-#include <sys/user.h>
 #include <unistd.h>
 #include <fcntl.h>
                                                                        /*}}}*/
@@ -35,11 +38,19 @@
 // MMap::MMap - Constructor                                            /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-MMap::MMap(File &F,unsigned long Flags) : Fd(F), Flags(Flags), iSize(0),
+MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0),
                      Base(0)
 {
    if ((Flags & NoImmMap) != NoImmMap)
-      Map();
+      Map(F);
+}
+                                                                       /*}}}*/
+// MMap::MMap - Constructor                                            /*{{{*/
+// ---------------------------------------------------------------------
+/* */
+MMap::MMap(unsigned long Flags) : Flags(Flags), iSize(0),
+                     Base(0)
+{
 }
                                                                        /*}}}*/
 // MMap::~MMap - Destructor                                            /*{{{*/
@@ -47,13 +58,13 @@ MMap::MMap(File &F,unsigned long Flags) : Fd(F), Flags(Flags), iSize(0),
 /* */
 MMap::~MMap()
 {
-   Close(true);
+   Close();
 }
                                                                        /*}}}*/
 // MMap::Map - Perform the mapping                                     /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-bool MMap::Map()
+bool MMap::Map(FileFd &Fd)
 {
    iSize = Fd.Size();
    
@@ -65,6 +76,9 @@ bool MMap::Map()
    if ((Flags & Public) != Public)
       Map = MAP_PRIVATE;
    
+   if (iSize == 0)
+      return _error->Error("Can't mmap an empty file");
+   
    // Map it.
    Base = mmap(0,iSize,Prot,Map,Fd.Fd(),0);
    if (Base == (void *)-1)
@@ -76,30 +90,35 @@ bool MMap::Map()
 // MMap::Close - Close the map                                         /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-bool MMap::Close(bool DoClose)
+bool MMap::Close(bool DoSync)
 {
-   if (Fd.IsOpen() == false)
+   if ((Flags & UnMapped) == UnMapped || Base == 0 || iSize == 0)
       return true;
-
-   Sync();
+   
+   if (DoSync == true)
+      Sync();
    
    if (munmap((char *)Base,iSize) != 0)
       _error->Warning("Unable to munmap");
    
    iSize = 0;
-   if (DoClose == true)
-      Fd.Close();
    return true;
 }
                                                                        /*}}}*/
 // MMap::Sync - Syncronize the map with the disk                       /*{{{*/
 // ---------------------------------------------------------------------
-/* */
+/* This is done in syncronous mode - the docs indicate that this will 
+   not return till all IO is complete */
 bool MMap::Sync()
 {   
-   if ((Flags & ReadOnly) == ReadOnly)
+   if ((Flags & UnMapped) == UnMapped)
+      return true;
+   
+#ifdef _POSIX_SYNCHRONIZED_IO   
+   if ((Flags & ReadOnly) != ReadOnly)
       if (msync((char *)Base,iSize,MS_SYNC) != 0)
         return _error->Error("msync","Unable to write mmap");
+#endif   
    return true;
 }
                                                                        /*}}}*/
@@ -108,9 +127,15 @@ bool MMap::Sync()
 /* */
 bool MMap::Sync(unsigned long Start,unsigned long Stop)
 {
-   if ((Flags & ReadOnly) == ReadOnly)
-      if (msync((char *)Base+(int)(Start/PAGE_SIZE)*PAGE_SIZE,Stop - Start,MS_SYNC) != 0)
+   if ((Flags & UnMapped) == UnMapped)
+      return true;
+   
+#ifdef _POSIX_SYNCHRONIZED_IO
+   unsigned long PSize = sysconf(_SC_PAGESIZE);
+   if ((Flags & ReadOnly) != ReadOnly)
+      if (msync((char *)Base+(int)(Start/PSize)*PSize,Stop - Start,MS_SYNC) != 0)
         return _error->Error("msync","Unable to write mmap");
+#endif   
    return true;
 }
                                                                        /*}}}*/
@@ -118,26 +143,50 @@ bool MMap::Sync(unsigned long Start,unsigned long Stop)
 // DynamicMMap::DynamicMMap - Constructor                              /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-DynamicMMap::DynamicMMap(File &F,unsigned long Flags,unsigned long WorkSpace) : 
-             MMap(F,Flags | NoImmMap), WorkSpace(WorkSpace)
+DynamicMMap::DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace) : 
+             MMap(F,Flags | NoImmMap), Fd(&F), WorkSpace(WorkSpace)
 {
-   unsigned long EndOfFile = Fd.Size();
-   Fd.Seek(WorkSpace);
+   if (_error->PendingError() == true)
+      return;
+   
+   unsigned long EndOfFile = Fd->Size();
+   Fd->Seek(WorkSpace);
    char C = 0;
-   Fd.Write(&C,sizeof(C));
-   Map();
+   Fd->Write(&C,sizeof(C));
+   Map(F);
    iSize = EndOfFile;
 }
                                                                        /*}}}*/
+// DynamicMMap::DynamicMMap - Constructor for a non-file backed map    /*{{{*/
+// ---------------------------------------------------------------------
+/* This is just a fancy malloc really.. */
+DynamicMMap::DynamicMMap(unsigned long Flags,unsigned long WorkSpace) :
+             MMap(Flags | NoImmMap | UnMapped), Fd(0), WorkSpace(WorkSpace)
+{
+   if (_error->PendingError() == true)
+      return;
+   
+   Base = new unsigned char[WorkSpace];
+   iSize = 0;
+}
+                                                                       /*}}}*/
 // DynamicMMap::~DynamicMMap - Destructor                              /*{{{*/
 // ---------------------------------------------------------------------
 /* We truncate the file to the size of the memory data set */
 DynamicMMap::~DynamicMMap()
 {
+   if (Fd == 0)
+   {
+      delete [] (unsigned char *)Base;
+      return;
+   }
+   
    unsigned long EndOfFile = iSize;
+   Sync();
+   iSize = WorkSpace;
    Close(false);
-   ftruncate(Fd.Fd(),EndOfFile);
-   Fd.Close();
+   ftruncate(Fd->Fd(),EndOfFile);
+   Fd->Close();
 }  
                                                                        /*}}}*/
 // DynamicMMap::RawAllocate - Allocate a raw chunk of unaligned space  /*{{{*/
@@ -152,7 +201,7 @@ unsigned long DynamicMMap::RawAllocate(unsigned long Size,unsigned long Aln)
    iSize = Result + Size;
    
    // Just in case error check
-   if (Result > WorkSpace)
+   if (Result + Size > WorkSpace)
    {
       _error->Error("Dynamic MMap ran out of room");
       return 0;