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| -rw-r--r-- | ftparchive/multicompress.cc | 360 |
1 files changed, 360 insertions, 0 deletions
diff --git a/ftparchive/multicompress.cc b/ftparchive/multicompress.cc new file mode 100644 index 0000000..ac85670 --- /dev/null +++ b/ftparchive/multicompress.cc @@ -0,0 +1,360 @@ +// -*- mode: cpp; mode: fold -*- +// Description /*{{{*/ +/* ###################################################################### + + MultiCompressor + + This class is very complicated in order to optimize for the common + case of its use, writing a large set of compressed files that are + different from the old set. It spawns off compressors in parallel + to maximize compression throughput and has a separate task managing + the data going into the compressors. + + ##################################################################### */ + /*}}}*/ +// Include Files /*{{{*/ +#include <config.h> + +#include <apt-pkg/aptconfiguration.h> +#include <apt-pkg/error.h> +#include <apt-pkg/fileutl.h> +#include <apt-pkg/hashes.h> +#include <apt-pkg/strutl.h> + +#include <cctype> +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/types.h> +#include <unistd.h> + +#include <algorithm> +#include <vector> + +#include "multicompress.h" +#include <apti18n.h> + /*}}}*/ + +using namespace std; + +static std::vector<APT::Configuration::Compressor>::const_iterator findMatchingCompressor(std::string::const_iterator &I, + std::string::const_iterator const &End, std::vector<APT::Configuration::Compressor> const &Compressors) +{ + // Grab a word (aka: a compressor name) + for (; I != End && isspace(*I); ++I); + string::const_iterator Start = I; + for (; I != End && !isspace(*I); ++I); + + auto const Comp = std::find_if(Compressors.begin(), Compressors.end(), + [&](APT::Configuration::Compressor const &C) { return stringcmp(Start, I, C.Name.c_str()) == 0; + }); + if (Comp == Compressors.end()) + _error->Warning(_("Unknown compression algorithm '%s'"),string(Start,I).c_str()); + return Comp; +} + +// MultiCompress::MultiCompress - Constructor /*{{{*/ +// --------------------------------------------------------------------- +/* Setup the file outputs, compression modes and fork the writer child */ +MultiCompress::MultiCompress(string const &Output, string const &Compress, + mode_t const &Permissions, bool const &Write) : Outputter{-1}, Permissions(Permissions) +{ + Outputs = 0; + UpdateMTime = 0; + + auto const Compressors = APT::Configuration::getCompressors(); + // Parse the compression string, a space separated lists of compression types + for (auto I = Compress.cbegin(); I != Compress.cend();) + { + auto const Comp = findMatchingCompressor(I, Compress.cend(), Compressors); + if (Comp == Compressors.end()) + continue; + + // Create and link in a new output + Files *NewOut = new Files; + NewOut->Next = Outputs; + Outputs = NewOut; + NewOut->CompressProg = *Comp; + NewOut->Output = Output + Comp->Extension; + + struct stat St; + if (stat(NewOut->Output.c_str(),&St) == 0) + NewOut->OldMTime = St.st_mtime; + else + NewOut->OldMTime = 0; + } + + if (Write == false) + return; + + /* Open all the temp files now so we can report any errors. File is + made unreable to prevent people from touching it during creating. */ + for (Files *I = Outputs; I != 0; I = I->Next) + I->TmpFile.Open(I->Output + ".new", FileFd::WriteOnly | FileFd::Create | FileFd::Empty, FileFd::Extension, 0600); + if (_error->PendingError() == true) + return; + + if (Outputs == 0) + { + _error->Error(_("Compressed output %s needs a compression set"),Output.c_str()); + return; + } + + Start(); +} + /*}}}*/ +// MultiCompress::~MultiCompress - Destructor /*{{{*/ +// --------------------------------------------------------------------- +/* Just erase the file linked list. */ +MultiCompress::~MultiCompress() +{ + Die(); + + for (; Outputs != 0;) + { + Files *Tmp = Outputs->Next; + delete Outputs; + Outputs = Tmp; + } +} + /*}}}*/ +// MultiCompress::GetStat - Get stat information for compressed files /*{{{*/ +// --------------------------------------------------------------------- +/* This checks each compressed file to make sure it exists and returns + stat information for a random file from the collection. False means + one or more of the files is missing. */ +bool MultiCompress::GetStat(string const &Output,string const &Compress,struct stat &St) +{ + auto const Compressors = APT::Configuration::getCompressors(); + + // Parse the compression string, a space separated lists of compression types + bool DidStat = false; + for (auto I = Compress.cbegin(); I != Compress.cend();) + { + auto const Comp = findMatchingCompressor(I, Compress.cend(), Compressors); + if (Comp == Compressors.end()) + continue; + + string Name = Output + Comp->Extension; + if (stat(Name.c_str(),&St) != 0) + return false; + DidStat = true; + } + return DidStat; +} + /*}}}*/ +// MultiCompress::Start - Start up the writer child /*{{{*/ +// --------------------------------------------------------------------- +/* Fork a child and setup the communication pipe. */ +bool MultiCompress::Start() +{ + // Create a data pipe + int Pipe[2] = {-1,-1}; + if (pipe(Pipe) != 0) + return _error->Errno("pipe",_("Failed to create IPC pipe to subprocess")); + for (int I = 0; I != 2; I++) + SetCloseExec(Pipe[I],true); + + // The child.. + Outputter = fork(); + if (Outputter == 0) + { + close(Pipe[1]); + Child(Pipe[0]); + if (_error->PendingError() == true) + { + _error->DumpErrors(); + _exit(100); + } + _exit(0); + }; + + close(Pipe[0]); + if (Input.OpenDescriptor(Pipe[1], FileFd::WriteOnly, true) == false) + return false; + + if (Outputter == -1) + return _error->Errno("fork",_("Failed to fork")); + return true; +} + /*}}}*/ +// MultiCompress::Die - Clean up the writer /*{{{*/ +// --------------------------------------------------------------------- +/* */ +bool MultiCompress::Die() +{ + if (Input.IsOpen() == false) + return true; + + Input.Close(); + bool Res = ExecWait(Outputter,_("Compress child"),false); + Outputter = -1; + return Res; +} + /*}}}*/ +// MultiCompress::Finalize - Finish up writing /*{{{*/ +// --------------------------------------------------------------------- +/* This is only necessary for statistics reporting. */ +bool MultiCompress::Finalize(unsigned long long &OutSize) +{ + OutSize = 0; + if (Input.IsOpen() == false || Die() == false) + return false; + + time_t Now; + time(&Now); + + // Check the mtimes to see if the files were replaced. + bool Changed = false; + for (Files *I = Outputs; I != 0; I = I->Next) + { + struct stat St; + if (stat(I->Output.c_str(),&St) != 0) + return _error->Error(_("Internal error, failed to create %s"), + I->Output.c_str()); + + if (I->OldMTime != St.st_mtime) + Changed = true; + else + { + // Update the mtime if necessary + if (UpdateMTime > 0 && + (Now - St.st_mtime > (signed)UpdateMTime || St.st_mtime > Now)) + { + utimes(I->Output.c_str(), NULL); + Changed = true; + } + } + + // Force the file permissions + if (St.st_mode != Permissions) + chmod(I->Output.c_str(),Permissions); + + OutSize += St.st_size; + } + + if (Changed == false) + OutSize = 0; + + return true; +} + /*}}}*/ +// MultiCompress::OpenOld - Open an old file /*{{{*/ +// --------------------------------------------------------------------- +/* This opens one of the original output files, possibly decompressing it. */ +bool MultiCompress::OpenOld(FileFd &Fd) +{ + Files *Best = Outputs; + for (Files *I = Outputs; I != 0; I = I->Next) + if (Best->CompressProg.Cost > I->CompressProg.Cost) + Best = I; + + // Open the file + return Fd.Open(Best->Output, FileFd::ReadOnly, FileFd::Extension); +} + /*}}}*/ +// MultiCompress::Child - The writer child /*{{{*/ +// --------------------------------------------------------------------- +/* The child process forks a bunch of compression children and takes + input on FD and passes it to all the compressor child. On the way it + computes the MD5 of the raw data. After this the raw data in the + original files is compared to see if this data is new. If the data + is new then the temp files are renamed, otherwise they are erased. */ +bool MultiCompress::Child(int const &FD) +{ + /* Okay, now we just feed data from FD to all the other FDs. Also + stash a hash of the data to use later. */ + SetNonBlock(FD,false); + unsigned char Buffer[32*1024]; + unsigned long long FileSize = 0; + Hashes MD5(Hashes::MD5SUM); + while (1) + { + WaitFd(FD,false); + int Res = read(FD,Buffer,sizeof(Buffer)); + if (Res == 0) + break; + if (Res < 0) + continue; + + MD5.Add(Buffer,Res); + FileSize += Res; + for (Files *I = Outputs; I != 0; I = I->Next) + { + if (I->TmpFile.Write(Buffer, Res) == false) + { + _error->Errno("write",_("IO to subprocess/file failed")); + break; + } + } + } + + if (_error->PendingError() == true) + return false; + + /* Now we have to copy the files over, or erase them if they + have not changed. First find the cheapest decompressor */ + bool Missing = false; + for (Files *I = Outputs; I != 0; I = I->Next) + { + if (I->OldMTime == 0) + { + Missing = true; + break; + } + } + + // Check the MD5 of the lowest cost entity. + while (Missing == false) + { + FileFd CompFd; + if (OpenOld(CompFd) == false) + { + _error->Discard(); + break; + } + + // Compute the hash + Hashes OldMD5(Hashes::MD5SUM); + unsigned long long NewFileSize = 0; + while (1) + { + unsigned long long Res = 0; + if (CompFd.Read(Buffer,sizeof(Buffer), &Res) == false) + return _error->Errno("read",_("Failed to read while computing MD5")); + if (Res == 0) + break; + NewFileSize += Res; + OldMD5.Add(Buffer,Res); + } + CompFd.Close(); + + // Check the hash + if (OldMD5.GetHashString(Hashes::MD5SUM) == MD5.GetHashString(Hashes::MD5SUM) && + FileSize == NewFileSize) + { + for (Files *I = Outputs; I != 0; I = I->Next) + { + I->TmpFile.Close(); + RemoveFile("MultiCompress::Child", I->TmpFile.Name()); + } + return !_error->PendingError(); + } + break; + } + + // Finalize + for (Files *I = Outputs; I != 0; I = I->Next) + { + // Set the correct file modes + chmod(I->TmpFile.Name().c_str(),Permissions); + + if (rename(I->TmpFile.Name().c_str(),I->Output.c_str()) != 0) + _error->Errno("rename",_("Failed to rename %s to %s"), + I->TmpFile.Name().c_str(),I->Output.c_str()); + I->TmpFile.Close(); + } + + return !_error->PendingError(); +} + /*}}}*/ + |