file.cpp

用于嵌入式环境的数据库

        char* cFileName = new char[strlen(fileName) + 5];
        strcat(strcpy(cFileName, fileName), ".cnt");
        
#ifdef DISKLESS_CONFIGURATION
        cfh = INVALID_HANDLE_VALUE;
#else
        cfh = CreateFile(cFileName, GENERIC_READ|GENERIC_WRITE, 
                         0, NULL, OPEN_ALWAYS,
                         FILE_FLAG_RANDOM_ACCESS|FILE_FLAG_WRITE_THROUGH,
                         NULL);
        delete[] cFileName;
        if (cfh == INVALID_HANDLE_VALUE) {
            status = errno;
            return status;
        }
#endif
        cmh = CreateFileMapping(cfh, NULL, PAGE_READWRITE, 0, 
                                nPages*sizeof(int), NULL);
        status = GetLastError();
        if (cmh == NULL) { 
            CloseHandle(cfh);
            return status;
        }
        diskUpdateCount = (int*)MapViewOfFile(cmh, FILE_MAP_ALL_ACCESS, 
                                              0, 0, 0);
        if (diskUpdateCount == NULL) { 
            status = GetLastError();
            CloseHandle(cmh);
            CloseHandle(cfh);
            return status;
        } 
        rootPage = dbMalloc(pageSize);
        int maxCount = 0;
        for (int i = 0; i < nPages; i++) {      
            int count = diskUpdateCount[i];
            currUpdateCount[i] = count;
            if (count > maxCount) { 
                maxCount = count;
            }
        }
        updateCounter = maxCount;
        nRecovered = 0;
        recoveredEvent.open(true);
        syncEvent.open();
        startSync();
    }
#endif
    return ok; 
}

#if defined(REPLICATION_SUPPORT)
void dbFile::syncToDisk()
{
    syncThread.setPriority(dbThread::THR_PRI_LOW);
    dbCriticalSection cs(syncCS);
    while (doSync) { 
        int i, j, k; 
        int maxUpdated = 0;
        for (i = 0; i < int(mmapSize >> dbModMapBlockBits);) { 
            int updateCounters[dbMaxSyncSegmentSize];
            for (j=i; j < int(mmapSize >> dbModMapBlockBits) && j-i < dbMaxSyncSegmentSize 
                     && currUpdateCount[j] > diskUpdateCount[j]; j++)
            {
                updateCounters[j-i] = currUpdateCount[j];
            }
            if (i != j) { 
                size_t pos = (i << dbModMapBlockBits) & ~(pageSize-1);
                size_t size = (((j-i) << dbModMapBlockBits) + pageSize - 1) & ~(pageSize-1);
#ifdef NO_MMAP
                DWORD written;
                if (SetFilePointer(fh, pos, NULL, FILE_BEGIN) != pos ||
                    !WriteFile(fh, mmapAddr + pos, size, &written, NULL) 
                    || written != (DWORD)size) 
                { 
                    dbTrace("Failed to save page to the disk, position=%ld, size=%ld, error=%d\n",
                            (long)pos, (long)size, GetLastError());
                }
#else
                FlushViewOfFile(mmapAddr + pos, size);
#endif
                for (k = 0; i < j; k++, i++) {  
                    diskUpdateCount[i] = updateCounters[k];
                }
                maxUpdated = i;
            } else { 
                i += 1;
            }
            if (!doSync) { 
                return;
            }
        }
        if (maxUpdated != 0) { 
            FlushViewOfFile(diskUpdateCount, maxUpdated*sizeof(int));
        }
        if (closing && maxUpdated == 0) { 
            return;
        } else { 
            syncEvent.wait(syncCS, dbSyncTimeout);
        }
    }
}
#endif

int dbFile::create(const char* name, bool noBuffering)
{
    fh = CreateFile(name, GENERIC_READ|GENERIC_WRITE, 0, FASTDB_SECURITY_ATTRIBUTES, CREATE_ALWAYS, 
                    (noBuffering ? FILE_FLAG_NO_BUFFERING : 0)|FILE_FLAG_SEQUENTIAL_SCAN, NULL); 
    if (fh == INVALID_HANDLE_VALUE) {
        return GetLastError();
    }
    mh = NULL;
    mmapAddr = NULL;
    sharedName = NULL;
    return ok;
}

int dbFile::read(void* buf, size_t& readBytes, size_t size)
{  
    DWORD count;
    if (ReadFile(fh, buf, size, &count, NULL)) { 
        readBytes = count;
        return ok;
    } else { 
        readBytes = 0;
        return GetLastError();
    }
}

int dbFile::write(void const* buf, size_t& writtenBytes, size_t size)
{  
    DWORD count;
    if (WriteFile(fh, buf, size, &count, NULL)) { 
        writtenBytes = count;
        return ok;
    } else { 
        writtenBytes = 0;
        return GetLastError();
    }
}


int dbFile::flush(bool physical)
{
#if defined(REPLICATION_SUPPORT)
    dbCriticalSection cs(replCS);
    if (db == NULL) { 
        physical = true;
    }
    if (!physical) {
        updateCounter += 1; 
    }
#endif
#if defined(REPLICATION_SUPPORT) || (defined(NO_MMAP) && !defined(DISKLESS_CONFIGURATION))
    int* map = pageMap;
    for (int i = 0, n = pageMapSize; i < n; i++) { 
        if (map[i] != 0) { 
            size_t pos = (size_t)i << (dbModMapBlockBits + 5);
            unsigned mask = map[i];
            int count = 0;
            do { 
                int size = 0;
                while ((mask & 1) == 0) { 
                    pos += dbModMapBlockSize;
                    mask >>= 1;
                    count += 1;
                }  
                while (true) {  
                    do { 
#ifdef REPLICATION_SUPPORT
                        if (!physical) {
                            currUpdateCount[(pos + size) >> dbModMapBlockBits] = updateCounter;
                        }
#endif
                        size += dbModMapBlockSize;
                        mask >>= 1;
                        count += 1;
                    } while ((mask & 1) != 0);
                    if (i+1 < n && count == 32 && size < dbMaxSyncSegmentSize*dbModMapBlockSize 
                        && (map[i+1] & 1) != 0) 
                    { 
                        map[i] = 0;
                        mask = map[++i];
                        count = 0;
                    } else { 
                        break;
                    }
                }
#if defined(REPLICATION_SUPPORT)
                if (db != NULL) { 
                    if (!physical) { 
                        for (int j = db->nServers; --j >= 0;) { 
                            if (db->con[j].status == dbReplicatedDatabase::ST_STANDBY) { 
                                ReplicationRequest rr;
                                rr.op = ReplicationRequest::RR_UPDATE_PAGE;
                                rr.nodeId = db->id;
                                rr.page.updateCount = updateCounter;
                                rr.page.offs = pos;
                                rr.size = size;
                                db->writeReq(j, rr, mmapAddr + pos, size);
                            }
                        }
                    }
                    pos += size;
                    continue;
                } 
#endif
#ifndef DISKLESS_CONFIGURATION
                DWORD written;
                if (SetFilePointer(fh, pos, NULL, FILE_BEGIN) != pos ||
                    !WriteFile(fh, mmapAddr + pos, size, &written, NULL) 
                    || written != (DWORD)size) 
                { 
                    return GetLastError();
                }
#endif
                pos += size;
            } while (mask != 0);
            map[i] = 0;
        }
    }
#endif
#if !defined(NO_MMAP) && !defined(DISKLESS_CONFIGURATION) && !defined(REPLICATION_SUPPORT)
    if (!FlushViewOfFile(mmapAddr, mmapSize)) { 
        return GetLastError();
    }
#endif
    return ok;
}

int dbFile::setSize(size_t size, char const* sharedName, bool initialize)
{
#if defined(REPLICATION_SUPPORT)
    dbCriticalSection cs1(syncCS);
    dbCriticalSection cs2(replCS);
#endif
#ifdef DISKLESS_CONFIGURATION
    assert(false);
#else
#ifdef NO_MMAP
    char* newBuf = (char*)VirtualAlloc(NULL, size, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
    if (newBuf == NULL) { 
        return GetLastError();
    }
    if (SetFilePointer(fh, size, NULL, FILE_BEGIN) != size || !SetEndOfFile(fh)) {
        return GetLastError();
    }

    memcpy(newBuf, mmapAddr, mmapSize);
    VirtualFree(mmapAddr, 0, MEM_RELEASE);
    mmapAddr = newBuf;
    mmapSize = size;
#else
    if (!UnmapViewOfFile(mmapAddr) || !CloseHandle(mh)) { 
        return GetLastError();
    } 
    mh = CreateFileMapping(fh, FASTDB_SECURITY_ATTRIBUTES, PAGE_READWRITE, 0, size, sharedName);
    int status = GetLastError();
    if (mh == NULL) { 
        printf("CreateFileMapping failed: %d\n", status);
        return status;
    }
    mmapAddr = (char*)MapViewOfFile(mh, FILE_MAP_ALL_ACCESS, 0, 0, 0);
    if (mmapAddr == NULL) { 
        return GetLastError();
    }
    if (initialize && status != ERROR_ALREADY_EXISTS)
        //&& osinfo.dwPlatformId != VER_PLATFORM_WIN32_NT) 
    {
        // Windows 95 doesn't initialize pages
        memset(mmapAddr+mmapSize, 0, size - mmapSize);
    } 
    mmapSize = size;
#endif
#if defined(NO_MMAP) || defined(REPLICATION_SUPPORT) 
    int newPageMapSize = (size + dbModMapBlockSize*32 - 1) >> (dbModMapBlockBits + 5);
    int* newPageMap = new int[newPageMapSize];
    memcpy(newPageMap, pageMap, pageMapSize*sizeof(int));
    memset(newPageMap + pageMapSize, 0, 
           (newPageMapSize-pageMapSize)*sizeof(int));
    delete[] pageMap;
    pageMapSize = newPageMapSize;    
    pageMap = newPageMap;    
#endif

#endif
    return ok;
}

int dbFile::close()
{
    delete[] sharedName;
#if defined(REPLICATION_SUPPORT)
    if (db != NULL) { 
        closing = true;
        stopSync();
        { 
            dbCriticalSection cs(replCS);
            if (nRecovered != 0) { 
                recoveredEvent.wait(replCS);
            }
        }
        syncEvent.close();
        recoveredEvent.close();
        UnmapViewOfFile(diskUpdateCount);
        CloseHandle(cmh);
        CloseHandle(cfh);
    }
    delete[] currUpdateCount;
    currUpdateCount = NULL;
    dbFree(rootPage);
    rootPage = NULL;
#endif
    if (mmapAddr != NULL) { 
#if defined(NO_MMAP)
        int rc = flush();
        if (rc != ok) { 
            return rc;
        }
        VirtualFree(mmapAddr, 0, MEM_RELEASE);    
        delete[] pageMap;
#else
        if (!UnmapViewOfFile(mmapAddr)) { 
            return GetLastError();
        }
#if defined(REPLICATION_SUPPORT)
        delete[] pageMap;
#endif
#endif
    }
    if (mh != NULL) { 
        if (!CloseHandle(mh)) {
            return GetLastError();
        }
    }
    return fh == INVALID_HANDLE_VALUE || CloseHandle(fh) ? ok : GetLastError();
}

char* dbFile::errorText(int code, char* buf, size_t bufSize)
{
#ifndef PHAR_LAP    
    int len = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
                            NULL,
                            code,
                            0,
                            buf,
                            bufSize-1,
                            NULL);
    if (len == 0) { 
        char errcode[64];
        sprintf(errcode, "unknown error code %u", code);
        strncpy(buf, errcode, bufSize-1);
    }
#else
    char errcode[64];
    sprintf(errcode, "unknown error code %u", code);
    strncpy(buf, errcode, bufSize-1);
#endif
    buf[bufSize-1] = '\0';
    return buf;
}

#else // Unix

#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#ifndef NO_MMAP
#include <sys/mman.h>
#endif

#ifndef O_SYNC
#define O_SYNC  O_FSYNC
#endif

#ifndef O_DSYNC
#define O_DSYNC O_SYNC
#endif


int dbFile::open(char const* name, char const*, bool readonly, size_t initSize, bool replicationSupport)
{
#if defined(USE_SYSV_SHARED_MEMORY) && defined(DISKLESS_CONFIGURATION)
    if (!shmem.open(name, initSize)) { 
        return errno;
    }
    mmapSize = initSize;           
    mmapAddr = shmem.get_base();
    fd = -1;
#else
#ifndef NO_MMAP
    int mmap_attr = MAP_SHARED;
#endif
    int status;
#ifdef DISKLESS_CONFIGURATION
#ifndef MAP_ANONYMOUS 
    fd = ::open("/dev/zero", O_RDWR, 0);
#else
    fd = -1; 
    mmap_attr |= MAP_ANONYMOUS;
#endif // MAP_ANONYMOUS 
    mmapSize = initSize;
#else // DISKLESS_CONFIGURATION
    fd = ::open(name, readonly ? O_RDONLY : O_RDWR/*|O_DSYNC*/|O_CREAT, 0666);
    if (fd < 0) { 
        return errno;
    }
    mmapSize = lseek(fd, 0, SEEK_END); 
    if (!readonly && mmapSize == 0) {