From d6c4a9764d052c9755ab934c97c7a84c48ebd618 Mon Sep 17 00:00:00 2001 From: David Kalnischkies Date: Mon, 9 Nov 2009 10:17:19 +0100 Subject: extent the mmap to be able to handle currently not implemented (but planed) growable mmaps --- apt-pkg/contrib/mmap.cc | 127 ++++++++++++++++++++++++++++++++---------------- apt-pkg/contrib/mmap.h | 10 ++-- 2 files changed, 92 insertions(+), 45 deletions(-) (limited to 'apt-pkg/contrib') diff --git a/apt-pkg/contrib/mmap.cc b/apt-pkg/contrib/mmap.cc index 4d5fcf71e..f440f9489 100644 --- 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(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; @@ -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 */ -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 - // 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 - iSize = 0; + // fallback to a static allocated space + Base = new unsigned char[WorkSpace]; + memset(Base,0,WorkSpace); + iSize = 0; } /*}}}*/ // DynamicMMap::~DynamicMMap - Destructor /*{{{*/ @@ -311,30 +329,55 @@ unsigned long DynamicMMap::WriteString(const char *String, /*}}}*/ // 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 - return false; + return false; #endif + } else { + if ((Flags & Moveable) != Moveable) + return false; + + Base = realloc(Base, newSize); + if (Base == NULL) + return false; + } + + WorkSpace = newSize; + return true; } /*}}}*/ diff --git a/apt-pkg/contrib/mmap.h b/apt-pkg/contrib/mmap.h index bde62217d..cd2b15ba2 100644 --- a/apt-pkg/contrib/mmap.h +++ b/apt-pkg/contrib/mmap.h @@ -50,7 +50,7 @@ class MMap public: enum OpenFlags {NoImmMap = (1<<0),Public = (1<<1),ReadOnly = (1<<2), - UnMapped = (1<<3)}; + UnMapped = (1<<3), Moveable = (1<<4), Fallback = (1 << 5)}; // Simple accessors inline operator void *() {return Base;}; @@ -82,6 +82,8 @@ class DynamicMMap : public MMap FileFd *Fd; unsigned long WorkSpace; + unsigned long const GrowFactor; + unsigned long const Limit; Pool *Pools; unsigned int PoolCount; @@ -96,8 +98,10 @@ class DynamicMMap : public MMap inline unsigned long WriteString(const string &S) {return WriteString(S.c_str(),S.length());}; void UsePools(Pool &P,unsigned int Count) {Pools = &P; PoolCount = Count;}; - DynamicMMap(FileFd &F,unsigned long Flags,unsigned long WorkSpace = 2*1024*1024); - DynamicMMap(unsigned long Flags,unsigned long WorkSpace = 2*1024*1024); + DynamicMMap(FileFd &F,unsigned long Flags,unsigned long const &WorkSpace = 2*1024*1024, + unsigned long const &Grow = 1024*1024, unsigned long const &Limit = 0); + DynamicMMap(unsigned long Flags,unsigned long const &WorkSpace = 2*1024*1024, + unsigned long const &Grow = 1024*1024, unsigned long const &Limit = 0); virtual ~DynamicMMap(); }; -- cgit v1.2.3