wizardstore.java

用Java写的面相对象的数据库管理系统

            } 
            
            if (ta != null) {
                ((TransactionData)ta.data).lrucid = cid;
            } 
            
            container = cluster.containerForID( id );
            return container.isDeleted() ? null : container;
        } 
    } 
    
    
    public synchronized ObjectContainer containerForName( Transaction ta, String name ) throws Exception {
        if (name == null) {
            return null;
        } 
        
        TransactionData taData = (TransactionData)ta.data;
        
        if (ta == null || taData.nameTable == null) {
            ObjectID oid = (ObjectID)nameTable.elementForKey( name );
            return oid != null ? containerForID( ta, oid ) : null;
        } 
        
        if (ta != null) {
            ObjectID oid = (ObjectID)taData.nameTable.elementForKey( name );
            return oid != null ? containerForID( ta, oid ) : null;
        } 
        return null;
    } 
    
    
    public synchronized void nameContainer( Transaction ta, ObjectContainer container, String name ) 
            throws PermissionDeniedExc {
        
        if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
            env.logWriter.newEntry( this, "nameContainer()", LogWriter.DEBUG3 );
        } 
        
        TransactionData taData = (TransactionData)ta.data;
        if (taData.nameTable == null) {
            taData.nameTable = (DxMap)nameTable.clone();
        } 
        
        String oldName = container.name();
        if (oldName != null) {
            taData.nameTable.removeForKey( oldName );
            taData.nameTableChanges_push( new NameTableChange( container.id(), oldName,
                    NameTableChange.STATE_REMOVED ) );
        } 
        
        container.nameTarget( name );
        
        if (name != null) {
            taData.nameTable.addForKey( container.id(), name );
            taData.nameTableChanges_push( new NameTableChange( container.id(), name, NameTableChange.STATE_ADDED ) );
        } 
    } 
    
    
    public synchronized DxBag clusterOfID( ObjectID id ) throws Exception {
        if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
            env.logWriter.newEntry( this, "clusterOfID()", LogWriter.DEBUG3 );
        } 
        
        ClusterID cid = (ClusterID)idTable.elementForKey( id );
        if (cid == null) {
            throw new ObjectNotFoundExc( "" );
        } 
        
        Cluster cluster = clusterStore.loadCluster( cid );
        
        DxBag result = new DxArrayBag();
        DxIterator it = cluster.containers.iterator();
        while (it.next() != null) {
            ObjectContainer container = (ObjectContainer)it.object();
            result.add( container.id() );
        } 
        return result;
    } 
    
    
    public synchronized void prepareCommitTransaction( Transaction ta ) throws Exception {
        if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
            env.logWriter.newEntry( this, "prepareCommitTransaction()", LogWriter.DEBUG3 );
        } 
        
        TransactionData taData = (TransactionData)ta.data;
        
        // initialize transaction data fields
        taData.commitClusterIDs = new DxHashSet( 64 );
        
        DxIterator it = taData.idTable.iterator();
        env.logWriter.newEntry( this, "idTable count: " + taData.idTable.count(), LogWriter.DEBUG );
        ClusterID cid;
        
        while ((cid = (ClusterID)it.next()) != null) {
            if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
                env.logWriter.newEntry( this, "checking cluster: " + cid + " ...", LogWriter.DEBUG3 );
            } 
            
            if (!taData.commitClusterIDs.contains( cid )) {
                env.logWriter.newEntry( this, "prepare commit cluster: " + cid, LogWriter.DEBUG );
                taData.commitClusterIDs.add( cid );
                
                Cluster cluster = clusterStore.loadCluster( cid );
                
                // we don't need to do all the stuff if there is no WRITE
                // lock
                if (cluster.lock.level( ta ) >= Lock.LEVEL_WRITE) {
                    
                    // delete containers from cluster and
                    // prepare newID and deletedID tables
                    DxIterator it2 = cluster.containers.iterator();
                    WizardObjectContainer container;
                    while ((container = (WizardObjectContainer)it2.next()) != null) {
                        
                        if (container.isDeleted()) {
                            clusterStore.invalidateContainer( container );
                            taData.idTableChanges_push( new IDTableChange( container.id(), cid,
                                    NameTableChange.STATE_REMOVED ) );
                            
                            if (container.name() != null) {
                                taData.nameTableChanges_push( new NameTableChange( container.id(), container.name(),
                                        NameTableChange.STATE_REMOVED ) );
                            } 
                        } 
                        container.clearState();
                    } 
                } 
                clusterStore.prepareCommitCluster( ta, cid );
            } 
        } 
    } 
    
    
    protected void beginCommit( Transaction ta ) throws Exception {
        env.logWriter.newEntry( this, "beginCommit...", LogWriter.DEBUG );
        
        // do nothing if this was just a read transaction
        if (ta.maxLockLevel() < Lock.LEVEL_WRITE) {
            return;
        }
        
        int commitCount = 0;

        // read the current commitCount from file
        File f = new File( env.dir + COMMIT_FLAG_NAME );
        if (f.exists()) {
            DataInputStream in = null;
            try {
                in = new DataInputStream( new FileInputStream( f ) );
                commitCount = in.readInt();
            }
            finally {
                if (in != null) {
                    in.close();
                }
            }
        }
        commitCount ++;
        
        DataOutputStream out = null;
        try {
            out = new DataOutputStream( new FileOutputStream( f ) );
            out.writeInt( commitCount );
        }
        finally {
            if (out != null) {
                out.close();
            }
        }
    }
        

    protected void endCommit( Transaction ta ) throws Exception {
        env.logWriter.newEntry( this, "endCommit...", LogWriter.DEBUG );

        // do nothing if this was just a read transaction
        if (ta.maxLockLevel() < Lock.LEVEL_WRITE) {
            return;
        }
        
        int commitCount = 0;

        // read the current commitCount from file
        File f = new File( env.dir + COMMIT_FLAG_NAME );
        if (f.exists()) {
            DataInputStream in = null;
            try {
                in = new DataInputStream( new FileInputStream( f ) );
                commitCount = in.readInt();
            }
            finally {
                if (in != null) {
                    in.close();
                }
            }
        }
        else {
            throw new RuntimeException( "No commit flag file present." );
        }
        commitCount --;
        
        if (commitCount > 0) {
            DataOutputStream out = null;
            try {
                out = new DataOutputStream( new FileOutputStream( f ) );
                out.writeInt( commitCount );
            }
            finally {
                if (out != null) {
                    out.close();
                }
            }
        }
        else {
            if (!(f.delete())) {
                throw new RuntimeException( "Unable to delete commit flag file. " );
            }
        }
    }
        

    public synchronized void commitTransaction( Transaction ta ) throws Exception {
        if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
            env.logWriter.newEntry( this, "commitTransaction()", LogWriter.DEBUG3 );
        } 
        
        beginCommit( ta );
        
        TransactionData taData = (TransactionData)ta.data;
        
        // actually write changed clusters to disk
        DxIterator it = taData.commitClusterIDs.iterator();
        ClusterID cid;
        while ((cid = (ClusterID)it.next()) != null) {
            if (env.logWriter.hasTarget( LogWriter.DEBUG )) {
                env.logWriter.newEntry( this, "commit cluster: " + cid, LogWriter.DEBUG );
            } 
            
            clusterStore.commitCluster( ta, cid );
        } 
        
        // update global idTable
        boolean isIDTableChanged = false;
        IDTableChange idChange = taData.idTableChanges_pop();

        while (idChange != null) {
            isIDTableChanged = true;
            
            switch (idChange.state) {
            case IDTableChange.STATE_ADDED: {
                idTable.addForKey( idChange.cid, idChange.oid );
                break;
                } 
            case IDTableChange.STATE_REMOVED: {
                idTable.removeForKey( idChange.oid );
                break;
                } 
            default: {
                throw new RuntimeException( "ID change table entry has inproper state." );
                } 
            }
            idChange = (IDTableChange)taData.idTableChanges_pop();
        }
        
        // write changes to disk
        if (isIDTableChanged) {
            commitIDTable();
        }
        
        // update global nameTable
        boolean isNameTableChanged = false;
        NameTableChange nameChange = taData.nameTableChanges_pop();

        while (nameChange != null) {
            isNameTableChanged = true;
            
            switch (nameChange.state) {
            case NameTableChange.STATE_ADDED: {
                nameTable.addForKey( nameChange.oid, nameChange.name );
                break;
                } 
            case NameTableChange.STATE_REMOVED: {
                nameTable.removeForKey( nameChange.name );
                break;
                } 
            default: {
                throw new RuntimeException( "Name change table entry has inproper state." );
                } 
            }
            nameChange = taData.nameTableChanges_pop();
        }

        // write changes to disk
        if (isNameTableChanged) {
            commitNameTable();
        }

        endCommit( ta );
        
        if (env.logWriter.hasTarget( LogWriter.DEBUG )) {
            env.logWriter.newEntry( this, "    idTable.count(): " + idTable.count(), LogWriter.DEBUG );
            env.logWriter.newEntry( this, "    nameTable.count(): " + nameTable.count(), LogWriter.DEBUG );
        } 
    } 
    
    
    /**
     * @param ta ID of the comitting transaction.
     * @param created
     * @param modified
     */
    public synchronized void abortTransaction( Transaction ta ) throws Exception {
        if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
            env.logWriter.newEntry( this, "abortTransaction()", LogWriter.DEBUG3 );
        } 
        
        TransactionData taData = (TransactionData)ta.data;
        taData.commitClusterIDs = new DxHashSet( 64 );
        
        DxIterator it = taData.idTable.iterator();
        ClusterID cid;
        while ((cid = (ClusterID)it.next()) != null) {
            if (!taData.commitClusterIDs.contains( cid )) {
                if (env.logWriter.hasTarget( LogWriter.DEBUG )) {
                    env.logWriter.newEntry( this, "abort cluster: " + cid, LogWriter.DEBUG );
                } 
                
                taData.commitClusterIDs.add( cid );
                clusterStore.abortCluster( ta, cid );
            } 
        }
    } 
    
}