magicstore.java

Java的面向对象数据库系统的源代码

                        } else {
                            return container;
                        }
                    }
                }
            }
        }

        // search global table ONLY if ta doesn't contain the container
        if (cid == null) {
            cid = (ClusterID) idTable.elementForKey(id);
        }


        if (cid == null) {
            return null;
        } else {
            // System.out.println ("-");
            Cluster cluster = clusterStore.loadCluster(cid, magicTa);

            if (cluster == null) {
                throw new ObjectNotFoundException("No object registered for ID: " + id);
            }

            if (transaction != null) {
                transaction.lrucid = cid;
            }

            try {
                container = cluster.containerForID(id);

                if (container.isDeleted()) {
                    return null;
                } else {
                    return container;
                }
            } catch (NullPointerException e) {
                env.logWriter.newEntry(this, "NullPointerException during " + cluster + ".containerForID(" + id + "). We were able to load a cluster for that ID but the cluster did not contain the container. This is an inconsistent view.", e, LogWriter.ERROR);
                throw e;
            }

        }
    }

    public DxSet objectNames(Transaction ta) {
        env.logWriter.newEntry(this, "Returning objectnames", LogWriter.DEBUG);

        return nameTable.keySet();
    }

    public synchronized ObjectContainer containerForName(Transaction ta, String name) throws Exception {
        if (name == null) {
            return null;
        }

        MagicTransaction wizardTa = (MagicTransaction) ta;

        if (ta == null || wizardTa.nameTable == null) {
            ObjectID oid = (ObjectID) nameTable.elementForKey(name);
            return oid != null ? containerForID(ta, oid) : null;
        }

        if (ta != null) {
            ObjectID oid = (ObjectID) wizardTa.nameTable.elementForKey(name);
            return oid != null ? containerForID(ta, oid) : null;
        }
        return null;
    }


    public synchronized void nameContainer(Transaction ta, ObjectContainer container, String name)
            throws PermissionDeniedException {

        if (env.logWriter.hasTarget(LogWriter.DEBUG3)) {
            env.logWriter.newEntry(this, "nameContainer(), nameTable=" + nameTable + ".", LogWriter.DEBUG3);
        }

        MagicTransaction transaction = (MagicTransaction) ta;
        if (transaction.nameTable == null) {
            Object o = null;
            try {
                java.lang.reflect.Method method = nameTable.getClass().getDeclaredMethod("clone", null);
                if (env.logWriter.hasTarget(LogWriter.DEBUG)) {
                    env.logWriter.newEntry(this, "nameContainer(), nameTable=" + nameTable + ", nameTable.getClass().getDeclaredMethod(\"clone\",null)=" + method + ".", LogWriter.DEBUG);
                }
                o = method.invoke(nameTable, null);
            } catch (Exception e) {
                env.logWriter.newEntry(this, "nameContainer(): caught: ", e, LogWriter.INFO);
            }

            if (o == null) {
                o = nameTable.clone();
            }


            transaction.nameTable = (DxMap) o;
        }

        String oldName = container.name();
        if (oldName != null) {
            transaction.nameTable.removeForKey(oldName);
            transaction.nameTableChanges_push(new NameTableChange(container.id(), oldName,
                                                             NameTableChange.STATE_REMOVED));
        }

        container.nameTarget(name);

        if (name != null) {
            if (oldName == null) {
                garbageCollector.notifyNewObjectName(container);
            }
            transaction.nameTable.addForKey(container.id(), name);
            transaction.nameTableChanges_push(new NameTableChange(container.id(), name, NameTableChange.STATE_ADDED));
        }
    }


    public synchronized DxBag clusterOfID(ObjectID id) throws Exception {
        throw new RuntimeException("this method is implementation specific and should be removed from StoreManager");
    }


    public synchronized void prepareCommitTransaction(Transaction ta) throws IOException, ClassNotFoundException {
        if (env.logWriter.hasTarget(LogWriter.DEBUG3)) {
            env.logWriter.newEntry(this, "prepareCommitTransaction()", LogWriter.DEBUG3);
        }

        MagicTransaction transaction = (MagicTransaction) ta;

        // initialize transaction data fields
        transaction.commitClusterIDs = new DxHashSet(64);

        DxIterator it = transaction.idTable.iterator();
//      env.logWriter.newEntry( this, "idTable count: " + taData.idTable.count(), LogWriter.DEBUG2 );
        ClusterID cid;

        while ((cid = (ClusterID) it.next()) != null) {
            if (env.logWriter.hasTarget(LogWriter.DEBUG3)) {
                env.logWriter.newEntry(this, "checking cluster: " + cid + " ...", LogWriter.DEBUG3);
            }

            if (!transaction.commitClusterIDs.contains(cid)) {
//              env.logWriter.newEntry( this, "prepare commit cluster: " + cid, LogWriter.DEBUG2 );
                transaction.commitClusterIDs.add(cid);

                Cluster cluster = clusterStore.loadCluster(cid, transaction);

                // 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();
                    StorageObjectContainer container;
                    while ((container = (StorageObjectContainer) it2.next()) != null) {

                        if (container.isDeleted()) {
                            if (env.logWriter.hasTarget(LogWriter.DEBUG3)) {
                                env.logWriter.newEntry(this, "container deleted: " + container.id(), LogWriter.DEBUG3);
                            }

                            clusterStore.invalidateContainer(container);
                            transaction.idTableChanges_push(new IDTableChange(container.id(), cid, IDTableChange.STATE_REMOVED));

                            if (container.name() != null) {
                                transaction.nameTableChanges_push(new NameTableChange(container.id(), container.name(), NameTableChange.STATE_REMOVED));
                            }
                        }
                        container.clearState();
                    }
                }
                clusterStore.prepareCommitCluster(ta, cid);
            }
        }
    }


    protected boolean isCleanShutdown() {
        return !(new File(COMMIT_FLAG_NAME).exists());
    }


    protected void beginCommit(Transaction ta) throws IOException {
//      env.logWriter.newEntry( this, "beginCommit...", LogWriter.DEBUG2 );

        // 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.getDatabaseDir() + 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 IOException {
//      env.logWriter.newEntry( this, "endCommit...", LogWriter.DEBUG2 );

        // 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.getDatabaseDir() + 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 IOException, ClassNotFoundException {
        if (env.logWriter.hasTarget(LogWriter.DEBUG3)) {
            env.logWriter.newEntry(this, "commitTransaction()", LogWriter.DEBUG3);
        }

        beginCommit(ta);

        MagicTransaction transaction = (MagicTransaction) ta;

        // actually write changed clusters to disk
        DxSet commitClusterIDs = transaction.commitClusterIDs;
        DxIterator it = commitClusterIDs.iterator();

        ClusterID cid;
        while ((cid = (ClusterID) it.next()) != null) {
            if (env.logWriter.hasTarget(LogWriter.DEBUG2)) {
                env.logWriter.newEntry(this, "commit cluster: " + cid, LogWriter.DEBUG2);
            }
            clusterStore.commitCluster(ta, cid);
        }

        // update global idTable
        boolean isIDTableChanged = false;
        IDTableChange idChange = null;

        while ((idChange = transaction.idTableChanges_pop()) != null) {
            isIDTableChanged = true;

            switch (idChange.state) {
                case IDTableChange.STATE_ADDED:
                    {
//              env.logWriter.newEntry( this, "commit added oid: " + idChange.oid, LogWriter.DEBUG2 );
                        if (idTable.addForKey(idChange.cid, idChange.oid) == false) {
                            throw new IllegalStateException("Unable to add OID to global ID table.");
                        }
                        break;
                    }
                case IDTableChange.STATE_REMOVED:
                    {
                        if (false) {
                            env.logWriter.newEntry(this, "commit removed oid: " + idChange.oid, LogWriter.DEBUG2);
                        }

                        if (idTable.removeForKey(idChange.oid) == null) {
                            throw new IllegalStateException("Unable to remove OID from global ID table.");
                        }
                        break;
                    }
                default:
                    {
                        throw new RuntimeException("ID change table entry has inproper state.");
                    }
            }
        }

        // write changes to disk
        if (isIDTableChanged) {
            commitIDTable();
        }

        // update global nameTable
        boolean isNameTableChanged = false;
        NameTableChange nameChange = transaction.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 = transaction.nameTableChanges_pop();
        }

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

        endCommit(ta);

        if (env.logWriter.hasTarget(LogWriter.DEBUG2)) {
            env.logWriter.newEntry(this, "    idTable.count(): " + idTable.count(), LogWriter.DEBUG2);
            env.logWriter.newEntry(this, "    nameTable.count(): " + nameTable.count(), LogWriter.DEBUG2);
        }
    }


    /**
     * @param ta ID of the comitting transaction.
     */
    public synchronized void abortTransaction(Transaction ta) throws IOException, ClassNotFoundException {
        if (env.logWriter.hasTarget(LogWriter.DEBUG3)) {
            env.logWriter.newEntry(this, "abortTransaction()", LogWriter.DEBUG3);
        }

        clusterStore.abortTransaction((MagicTransaction) ta);
    }

    /**
     Tells this StoreManager to report every named object to the garbage collector.
     */
    public void reportNamedObjectsToGarbageCollector() {
        synchronized (this) {
            DxIterator i = nameTable.elementSet().iterator();

            while (i.next() != null) {
                garbageCollector.notifyNamedObject((ObjectID) i.object());
            }
        }
    }

    public Transaction createTransaction(Env env, User user) {
        return new MagicTransaction(env, user);
    }

}