database.cpp

用于嵌入式环境的数据库

    commitDelay = 0;
    commitTimeout = 0;
    commitTimerStarted = 0;
    backupFileName = NULL;
    backupPeriod = 0;
    opened = false;
    stopDelayedCommitThread = false;
    databaseNameLen = strlen(dbName);
    char* name = new char[databaseNameLen+16];
    sprintf(name, "%s.in", dbName);
    databaseName = name;
    if (fiName == NULL) { 
        fileName = new char[databaseNameLen + 5];
        sprintf(fileName, "%s.fdb", dbName);
    } else { 
        fileName = new char[strlen(fiName)+1];
        strcpy(fileName, fiName);
    }

    dbInitializationMutex::initializationStatus status;
    status = initMutex.initialize(name);
    if (status == dbInitializationMutex::InitializationError) { 
        handleError(DatabaseOpenError, 
                    "Failed to start database initialization");
        return false;
    }
    sprintf(name, "%s.dm", dbName);
    if (!shm.open(name)) { 
        handleError(DatabaseOpenError, "Failed to open database monitor");
        return false;
    }
    monitor = shm.get();
    sprintf(name, "%s.ws", dbName);
    if (!writeSem.open(name)) { 
        handleError(DatabaseOpenError, 
                    "Failed to initialize database writers semaphore");
        return false;
    }
    sprintf(name, "%s.rs", dbName);
    if (!readSem.open(name)) { 
        handleError(DatabaseOpenError, 
                    "Failed to initialize database readers semaphore");
        return false;
    }
    sprintf(name, "%s.us", dbName);
    if (!upgradeSem.open(name)) { 
        handleError(DatabaseOpenError, 
                    "Failed to initialize database upgrade semaphore");
        return false;
    }
    sprintf(name, "%s.bce", dbName);
    if (!backupCompletedEvent.open(name)) { 
        handleError(DatabaseOpenError, 
                    "Failed to initialize database backup completed event");
        return false;
    }    
    if (commitDelaySec != 0) { 
        sprintf(name, "%s.dce", dbName);
        if (!delayedCommitStopTimerEvent.open(name)) { 
            handleError(DatabaseOpenError, 
                        "Failed to initialize delayed commit event");
            return false;
        }    
        delayedCommitStartTimerEvent.open();
        commitThreadSyncEvent.open();
    }
    backupInitEvent.open();
    backupFileName = NULL;

    allocatedSize = 0;
    size_t indexSize = initIndexSize < dbFirstUserId 
        ? size_t(dbFirstUserId) : initIndexSize;
    indexSize = DOALIGN(indexSize, dbHandlesPerPage);
            
    size_t fileSize = initSize ? initSize : dbDefaultInitDatabaseSize;

    if (fileSize < indexSize*sizeof(offs_t)*4) {
        fileSize = indexSize*sizeof(offs_t)*4;
    }
    fileSize = DOALIGN(fileSize, dbBitmapSegmentSize);
#ifdef DISKLESS_CONFIGURATION
    mmapSize = fileSize;
#else
    mmapSize = 0;
#endif

    for (int i = dbBitmapId + dbBitmapPages; --i >= 0;) { 
        bitmapPageAvailableSpace[i] = INT_MAX;
    }
    currRBitmapPage = currPBitmapPage = dbBitmapId;
    currRBitmapOffs = currPBitmapOffs = 0;
    reservedChain = NULL;
    tables = NULL;
    modified = false;
    selfId = 0;
    maxClientId = 0;
    threadContextList.reset();
    attach();

    if (status == dbInitializationMutex::NotYetInitialized) { 
        sprintf(name, "%s.cs", dbName);
        if (!cs.create(name, &monitor->sem)) { 
            handleError(DatabaseOpenError,
                        "Failed to initialize database monitor");
            return false;
        }
        if (accessType == dbConcurrentUpdate) { 
            sprintf(name, "%s.mcs", dbName);
            if (!mutatorCS.create(name, &monitor->mutatorSem)) { 
                handleError(DatabaseOpenError,
                            "Failed to initialize database monitor");
                return false;
            }
        }
        readSem.reset();
        writeSem.reset();
        upgradeSem.reset();
        monitor->nReaders = 0;
        monitor->nWriters = 0;
        monitor->nWaitReaders = 0;
        monitor->nWaitWriters = 0;
        monitor->waitForUpgrade = false;
        monitor->version = version = 1;
        monitor->users = 0;
        monitor->backupInProgress = 0;
        monitor->forceCommitCount = 0;
        monitor->lastDeadlockRecoveryTime = 0;
        monitor->delayedCommitContext = NULL;
        monitor->concurrentTransId = 1;
        monitor->commitInProgress = false;
        monitor->uncommittedChanges = false;
        monitor->clientId = 0;
        monitor->exclusiveLockOwner = 0;
        memset(monitor->dirtyPagesMap, 0, dbDirtyPageBitmapSize);
        memset(monitor->sharedLockOwner, 0, sizeof(monitor->sharedLockOwner));
    
        sprintf(databaseName, "%s.%d", dbName, version);
        int rc = file.open(fileName, databaseName, 
                           accessType == dbReadOnly || accessType == dbConcurrentRead, fileSize, false);
        if (rc != dbFile::ok)
        {
            char msgbuf[64];
            file.errorText(rc, msgbuf, sizeof msgbuf);
            TRACE_MSG(("File open error: %s\n", msgbuf));
            handleError(DatabaseOpenError, "Failed to create database file");
            return false;
        }
        baseAddr = (byte*)file.getAddr();
        fileSize = file.getSize();
        header = (dbHeader*)baseAddr;
        updatedRecordId = 0;
        
        if ((unsigned)header->curr > 1) { 
            handleError(DatabaseOpenError, "Database file was corrupted: "
                        "invalid root index");
            return false;
        }
        if (header->initialized != 1) {
            if (accessType == dbReadOnly || accessType == dbConcurrentRead) { 
                handleError(DatabaseOpenError, "Can not open uninitialized "
                            "file in read only mode");
                return false;
            }
            monitor->curr = header->curr = 0;
            header->size = fileSize;
            size_t used = dbPageSize;
            header->root[0].index = used;
            header->root[0].indexSize = indexSize;
            header->root[0].indexUsed = dbFirstUserId;
            header->root[0].freeList = 0;
            used += indexSize*sizeof(offs_t);
            header->root[1].index = used;
            header->root[1].indexSize = indexSize;
            header->root[1].indexUsed = dbFirstUserId;
            header->root[1].freeList = 0;
            used += indexSize*sizeof(offs_t);

            header->root[0].shadowIndex = header->root[1].index;
            header->root[1].shadowIndex = header->root[0].index;
            header->root[0].shadowIndexSize = indexSize;
            header->root[1].shadowIndexSize = indexSize;
            
            header->majorVersion= FASTDB_MAJOR_VERSION;
            header->minorVersion = FASTDB_MINOR_VERSION;

            index[0] = (offs_t*)(baseAddr + header->root[0].index);
            index[1] = (offs_t*)(baseAddr + header->root[1].index);
            index[0][dbInvalidId] = dbFreeHandleMarker;

            size_t bitmapPages = 
                (used + dbPageSize*(dbAllocationQuantum*8-1) - 1)
                / (dbPageSize*(dbAllocationQuantum*8-1));
            memset(baseAddr+used, 0xFF, (used + bitmapPages*dbPageSize)
                                        / (dbAllocationQuantum*8));
            size_t i;
            for (i = 0; i < bitmapPages; i++) { 
                index[0][dbBitmapId + i] = used + dbPageObjectMarker;
                used += dbPageSize;
            }
            while (i < dbBitmapPages) { 
                index[0][dbBitmapId+i] = dbFreeHandleMarker;
                i += 1;
            }
            currIndex = index[0];
            currIndexSize = dbFirstUserId;
            committedIndexSize = 0;
            initializeMetaTable();
            header->dirty = true;
            memcpy(index[1], index[0], currIndexSize*sizeof(offs_t));
            file.markAsDirty(0, used);
            file.flush(true);
            header->initialized = true;
            file.markAsDirty(0, sizeof(dbHeader));
            file.flush(true);
        } else {
            monitor->curr = header->curr;
            if (header->dirty) { 
                TRACE_MSG(("Database was not normally closed: "
                           "start recovery\n"));
                if (accessType == dbReadOnly || accessType == dbConcurrentRead) { 
                    handleError(DatabaseOpenError,
                                "Can not open dirty file in read only moode");
                    return false;
                }
                recovery();
                TRACE_MSG(("Recovery completed\n"));
            } else { 
                if (file.getSize() != header->size) { 
                    handleError(DatabaseOpenError, "Database file was "
                                "corrupted: file size in header differs "
                                "from actual file size");
                    return false;
                }
            }       
        }
    } else { 
        sprintf(name, "%s.cs", dbName);
        if (!cs.open(name, &monitor->sem)) { 
            handleError(DatabaseOpenError, "Failed to open shared semaphore");
            return false;
        }
        if (accessType == dbConcurrentUpdate) { 
            sprintf(name, "%s.mcs", dbName);
            if (!mutatorCS.open(name, &monitor->mutatorSem)) { 
                handleError(DatabaseOpenError, "Failed to open shared semaphore");
                return false;
            }
        }
        version = 0;
    }
    cs.enter();            
    monitor->users += 1;
    selfId = ++monitor->clientId;
    cs.leave();

#ifdef AUTO_DETECT_PROCESS_CRASH
    sprintf(databaseName + databaseNameLen, ".pid.%d", selfId);
    selfWatchDog.create(databaseName);
#endif


    if (status == dbInitializationMutex::NotYetInitialized) { 
        if (!loadScheme(true)) { 
            return false;
        }
        initMutex.done();
    } else { 
        if (!loadScheme(false)) { 
            return false;
        }
    }
    opened = true;

    if (commitDelaySec != 0) { 
        dbCriticalSection cs(delayedCommitStartTimerMutex);
        commitTimeout = commitDelay = commitDelaySec;
        commitThread.create((dbThread::thread_proc_t)delayedCommitProc, this);
        commitThreadSyncEvent.wait(delayedCommitStartTimerMutex);
    }
    return true;
}

void dbDatabase::scheduleBackup(char const* fileName, time_t period)
{
    if (backupFileName == NULL) { 
        backupFileName = new char[strlen(fileName) + 1];
        strcpy(backupFileName, fileName);
        backupPeriod = period;
        backupThread.create((dbThread::thread_proc_t)backupSchedulerProc, this);
    }
}
 
void dbDatabase::backupScheduler() 
{ 
    backupThread.setPriority(dbThread::THR_PRI_LOW);
    dbCriticalSection cs(backupMutex); 
    while (true) { 
        time_t timeout = backupPeriod;
        if (backupFileName[strlen(backupFileName)-1] != '?') {
            struct stat st;
            if (::stat(backupFileName, &st) == 0) { 
                time_t howOld = time(NULL) - st.st_atime;
                if (timeout < howOld) { 
                    timeout = 0;
                } else { 
                    timeout -= howOld;
                }
            }
        }
        
        backupInitEvent.wait(backupMutex, timeout*1000);
        
        if (backupFileName != NULL) { 
            if (backupFileName[strlen(backupFileName)-1] == '?') {
                time_t currTime = time(NULL);
                char* fileName = new char[strlen(backupFileName) + 32];
                struct tm* t = localtime(&currTime);
                sprintf(fileName, "%.*s-%04d.%02d.%02d_%02d.%02d.%02d", 
                        (int)strlen(backupFileName)-1, backupFileName,
                        t->tm_year + 1900, t->tm_mon+1, t->tm_mday, 
                        t->tm_hour, t->tm_min, t->tm_sec);
                backup(fileName, false);
                delete[] fileName;
            } else { 
                char* newFileName = new char[strlen(backupFileName) + 5];
                sprintf(newFileName,"%s.new", backupFileName);
                backup(newFileName, false);
                ::remove(backupFileName);
                ::rename(newFileName, backupFileName);
                delete[] newFileName;
            }
        } else { 
            return;
        }
    }
}    


void dbDatabase::recovery()
{
    int curr = header->curr;
    header->size = file.getSize();
    header->root[1-curr].indexUsed = header->root[curr].indexUsed; 
    header->root[1-curr].freeList = header->root[curr].freeList; 
    header->root[1-curr].index = header->root[curr].shadowIndex;
    header->root[1-curr].indexSize = 
        header->root[curr].shadowIndexSize;
    header->root[1-curr].shadowIndex = header->root[curr].index;
    header->root[1-curr].shadowIndexSize = 
        header->root[curr].indexSize;
    
    offs_t* dst = (offs_t*)(baseAddr+header->root[1-curr].index);
    offs_t* src = (offs_t*)(baseAddr+header->root[curr].index);
    currIndex = dst;
    for (int i = 0, n = header->root[curr].indexUsed; i < n; i++) { 
        if (dst[i] != src[i]) {