// 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 ) {
        cout << "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 ) {
        cout << "CreateFile failed " << filename << endl;
        return 0;
    }

#if defined(_WIN32)
    if ( mapped > 500000000 ) {
        cout << "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 ) {
        cout << "CreateFileMapping failed " << filename << endl;
        return 0;
    }

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