// mmap.cpp

/**
*    Copyright (C) 2008 10gen Inc.
*
*    This program is free software: you can redistribute it and/or  modify
*    it under the terms of the GNU Affero General Public License, version 3,
*    as published by the Free Software Foundation.
*
*    This program is distributed in the hope that it will be useful,
*    but WITHOUT ANY WARRANTY; without even the implied warranty of
*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*    GNU Affero General Public License for more details.
*
*    You should have received a copy of the GNU Affero General Public License
*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "stdafx.h"
#include "mmap.h"

namespace mongo {

    set<MemoryMappedFile*> mmfiles;

    MemoryMappedFile::~MemoryMappedFile() {
        close();
        mmfiles.erase(this);
    }

    /*static*/
    int closingAllFiles = 0;
    void MemoryMappedFile::closeAllFiles() {
        if ( closingAllFiles ) {
            out() << "warning closingAllFiles=" << closingAllFiles << endl;
            return;
        }
        ++closingAllFiles;
        for ( set<MemoryMappedFile*>::iterator i = mmfiles.begin(); i != mmfiles.end(); i++ )
            (*i)->close();
        log() << "  closeAllFiles() finished" << endl;
        --closingAllFiles;
    }

    void MemoryMappedFile::updateLength( const char *filename, int &length ) const {
        if ( !boost::filesystem::exists( filename ) )
            return;
        // make sure we map full length if preexisting file.
        length = boost::filesystem::file_size( filename );
    }

#if defined(_WIN32)

} // namespace mongo

#include "windows.h"

namespace mongo {

    MemoryMappedFile::MemoryMappedFile() {
        fd = 0;
        maphandle = 0;
        view = 0;
        mmfiles.insert(this);
    }

    void MemoryMappedFile::close() {
        if ( view )
            UnmapViewOfFile(view);
        view = 0;
        if ( maphandle )
            CloseHandle(maphandle);
        maphandle = 0;
        if ( fd )
            CloseHandle(fd);
        fd = 0;
    }

    std::wstring toWideString(const char *s) {
        std::basic_ostringstream<TCHAR> buf;
        buf << s;
        return buf.str();
    }

    unsigned mapped = 0;

    void* MemoryMappedFile::map(const char *filename, int length) {
        updateLength( filename, length );
        std::wstring filenamew = toWideString(filename);

        fd = CreateFile(
                 filenamew.c_str(), GENERIC_WRITE | GENERIC_READ, FILE_SHARE_READ,
                 NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
        if ( fd == INVALID_HANDLE_VALUE ) {
            out() << "CreateFile failed " << filename << endl;
            return 0;
        }

#if defined(_WIN32)
        if ( mapped > 500000000 ) {
            out() << "WARNING: too much mem mapped for win32" << endl;
//		if( length > 50000000 )
//			length = 50000000;
        }
        mapped += length;
#endif

        maphandle = CreateFileMapping(fd, NULL, PAGE_READWRITE, 0, length, NULL);
        if ( maphandle == NULL ) {
            out() << "CreateFileMapping failed " << filename << endl;
            return 0;
        }

        view = MapViewOfFile(maphandle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
        if ( view == 0 ) {
            out() << "MapViewOfFile failed " << filename << " errno:";
            out() << GetLastError();
            out() << endl;
        }

        return view;
    }

    void MemoryMappedFile::flush(bool) {
    }

#else

} // namespace mongo

#include <errno.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

namespace mongo {

    MemoryMappedFile::MemoryMappedFile() {
        fd = 0;
        maphandle = 0;
        view = 0;
        len = 0;
        mmfiles.insert(this);
    }

    void MemoryMappedFile::close() {
        if ( view )
            munmap(view, len);
        view = 0;

        if ( fd )
            ::close(fd);
        fd = 0;
    }

#ifndef O_NOATIME
#warning NO O_NOATIME
#define O_NOATIME 0
#endif

    void* MemoryMappedFile::map(const char *filename, int length) {
        updateLength( filename, length );
        len = length;

        fd = open(filename, O_CREAT | O_RDWR | O_NOATIME, S_IRUSR | S_IWUSR);
        if ( !fd ) {
            out() << "couldn't open " << filename << ' ' << errno << endl;
            return 0;
        }

        /* make sure the file is the full desired length */
        off_t filelen = lseek(fd, 0, SEEK_END);
        if ( filelen < length ) {
//        log() << "map: file length=" << (unsigned) filelen << " want:"
//        << length
//        << endl;
            if ( filelen != 0 ) {
                problem() << "failure mapping new file " << filename << " length:" << length << endl;
                return 0;
            }
            // Check for end of disk.
            lseek(fd, length - 1, SEEK_SET);
            write(fd, "", 1);
            Logstream &l = log();
            l << "new datafile " << filename << " filling with zeroes...";
            l.flush();
            Timer t;
            int z = 8192;
            char buf[z];
            memset(buf, 0, z);
            int left = length;
            while ( 1 ) {
                if ( left <= z ) {
                    write(fd, buf, left);
                    break;
                }
                write(fd, buf, z);
                left -= z;
            }
            l << "done " << ((double)t.millis())/1000.0 << " secs" << endl;
        }

        view = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
        if ( view == MAP_FAILED ) {
            out() << "  mmap() failed for " << filename << " len:" << length << " errno:" << errno << endl;
            return 0;
        }
        return view;
    }

    void MemoryMappedFile::flush(bool sync) {
        if ( msync(view, len, sync ? MS_SYNC : MS_ASYNC) )
            problem() << "msync error " << errno << endl;
    }

#endif

    void* MemoryMappedFile::map(const char *filename) {
        return map( filename , file_size( filename ) ); // file_size is from boost
    }

} // namespace mongo