dataview.java

linux 下的源代码分析阅读器 red hat公司新版

         * Requires: if value param, value or entity binding
         * Requires: if retPrimaryKey, primary key binding (no index).
         * Requires: if retValue, value or entity binding
         */
        DatabaseEntry keyThang = new DatabaseEntry();
        DatabaseEntry valueThang = new DatabaseEntry();
        useValue(value, valueThang, null);
        OperationStatus status;
        if (keyAssigner != null) {
            keyAssigner.assignKey(keyThang);
            if (!range.check(keyThang)) {
                throw new IllegalArgumentException(
                    "assigned key out of range");
            }
            DataCursor cursor = new DataCursor(this, true);
            try {
                status = cursor.getCursor().putNoOverwrite(keyThang,
                                                           valueThang);
            } finally {
                cursor.close();
            }
        } else {
            /* Assume QUEUE/RECNO access method. */
            if (currentTxn.isCDBCursorOpen(db)) {
                throw new IllegalStateException(
                  "cannot open CDB write cursor when read cursor is open");
            }
            status = DbCompat.append(db, useTransaction(),
                                     keyThang, valueThang);
            if (status == OperationStatus.SUCCESS && !range.check(keyThang)) {
                db.delete(useTransaction(), keyThang);
                throw new IllegalArgumentException(
                    "appended record number out of range");
            }
        }
        if (status == OperationStatus.SUCCESS) {
            returnPrimaryKeyAndValue(keyThang, valueThang,
                                     retPrimaryKey, retValue);
        }
        return status;
    }

    /**
     * Returns the current transaction if the database is transaction, or null
     * if the database is not transactional or there is no current transaction.
     */
    Transaction useTransaction() {
        return transactional ?  currentTxn.getTransaction() : null;
    }

    /**
     * Deletes all records in the current range.
     */
    void clear()
        throws DatabaseException {

        DataCursor cursor = new DataCursor(this, true);
        try {
            OperationStatus status = OperationStatus.SUCCESS;
            while (status == OperationStatus.SUCCESS) {
                if (keysRenumbered) {
                    status = cursor.getFirst(true);
                } else {
                    status = cursor.getNext(true);
                }
                if (status == OperationStatus.SUCCESS) {
                    cursor.delete();
                }
            }
        } finally {
            cursor.close();
        }
    }

    /**
     * Returns a cursor for this view that reads only records having the
     * specified index key values.
     */
    DataCursor join(DataView[] indexViews, Object[] indexKeys,
                    JoinConfig joinConfig)
        throws DatabaseException {

        DataCursor joinCursor = null;
        DataCursor[] indexCursors = new DataCursor[indexViews.length];
        try {
            for (int i = 0; i < indexViews.length; i += 1) {
                indexCursors[i] = new DataCursor(indexViews[i], false);
                indexCursors[i].getSearchKey(indexKeys[i], null, false);
            }
            joinCursor = new DataCursor(this, indexCursors, joinConfig, true);
            return joinCursor;
        } finally {
            if (joinCursor == null) {
                // An exception is being thrown, so close cursors we opened.
                for (int i = 0; i < indexCursors.length; i += 1) {
                    if (indexCursors[i] != null) {
                        try { indexCursors[i].close(); }
                        catch (Exception e) {
			    /* FindBugs, this is ok. */
			}
                    }
                }
            }
        }
    }

    /**
     * Returns a cursor for this view that reads only records having the
     * index key values at the specified cursors.
     */
    DataCursor join(DataCursor[] indexCursors, JoinConfig joinConfig)
        throws DatabaseException {

        return new DataCursor(this, indexCursors, joinConfig, false);
    }

    /**
     * Returns primary key and value if return parameters are non-null.
     */
    private void returnPrimaryKeyAndValue(DatabaseEntry keyThang,
                                          DatabaseEntry valueThang,
                                          Object[] retPrimaryKey,
                                          Object[] retValue)
        throws DatabaseException {

        // Requires: if retPrimaryKey, primary key binding (no index).
        // Requires: if retValue, value or entity binding

        if (retPrimaryKey != null) {
            if (keyBinding == null) {
                throw new IllegalArgumentException(
                    "returning key requires primary key binding");
            } else if (isSecondary()) {
                throw new IllegalArgumentException(
                    "returning key requires unindexed view");
            } else {
                retPrimaryKey[0] = keyBinding.entryToObject(keyThang);
            }
        }
        if (retValue != null) {
            retValue[0] = makeValue(keyThang, valueThang);
        }
    }

    /**
     * Populates the key entry and returns whether the key is within range.
     */
    boolean useKey(Object key, Object value, DatabaseEntry keyThang,
                   KeyRange checkRange)
        throws DatabaseException {

        if (key != null) {
            if (keyBinding == null) {
                throw new IllegalArgumentException(
                    "non-null key with null key binding");
            }
            keyBinding.objectToEntry(key, keyThang);
        } else {
            if (value == null) {
                throw new IllegalArgumentException(
                    "null key and null value");
            }
            if (entityBinding == null) {
                throw new IllegalStateException(
                    "EntityBinding required to derive key from value");
            }
            if (!dupsView && isSecondary()) {
                DatabaseEntry primaryKeyThang = new DatabaseEntry();
                entityBinding.objectToKey(value, primaryKeyThang);
                DatabaseEntry valueThang = new DatabaseEntry();
                entityBinding.objectToData(value, valueThang);
                secKeyCreator.createSecondaryKey(secDb, primaryKeyThang,
                                                 valueThang, keyThang);
            } else {
                entityBinding.objectToKey(value, keyThang);
            }
        }
        if (recNumAccess && DbCompat.getRecordNumber(keyThang) <= 0) {
            return false;
        }
        if (checkRange != null && !checkRange.check(keyThang)) {
            return false;
        }
        return true;
    }

    /**
     * Returns whether data keys can be derived from the value/entity binding
     * of this view, which determines whether a value/entity object alone is
     * sufficient for operations that require keys.
     */
    final boolean canDeriveKeyFromValue() {

        return (entityBinding != null);
    }

    /**
     * Populates the value entry and throws an exception if the primary key
     * would be changed via an entity binding.
     */
    void useValue(Object value, DatabaseEntry valueThang,
                  DatabaseEntry checkKeyThang)
        throws DatabaseException {

        if (value != null) {
            if (valueBinding != null) {
                valueBinding.objectToEntry(value, valueThang);
            } else if (entityBinding != null) {
                entityBinding.objectToData(value, valueThang);
                if (checkKeyThang != null) {
                    DatabaseEntry thang = new DatabaseEntry();
                    entityBinding.objectToKey(value, thang);
                    if (!KeyRange.equalBytes(thang, checkKeyThang)) {
                        throw new IllegalArgumentException(
                            "cannot change primary key");
                    }
                }
            } else {
                throw new IllegalArgumentException(
                    "non-null value with null value/entity binding");
            }
        } else {
            valueThang.setData(KeyRange.ZERO_LENGTH_BYTE_ARRAY);
            valueThang.setOffset(0);
            valueThang.setSize(0);
        }
    }

    /**
     * Converts a key entry to a key object.
     */
    Object makeKey(DatabaseEntry keyThang, DatabaseEntry priKeyThang) {

        if (keyBinding == null) {
            throw new UnsupportedOperationException();
        } else {
            DatabaseEntry thang = dupsView ? priKeyThang : keyThang;
            if (thang.getSize() == 0) {
                return null;
            } else {
                return keyBinding.entryToObject(thang);
            }
        }
    }

    /**
     * Converts a key-value entry pair to a value object.
     */
    Object makeValue(DatabaseEntry primaryKeyThang, DatabaseEntry valueThang) {

        Object value;
        if (valueBinding != null) {
            value = valueBinding.entryToObject(valueThang);
        } else if (entityBinding != null) {
            value = entityBinding.entryToObject(primaryKeyThang,
                                                    valueThang);
        } else {
            throw new UnsupportedOperationException(
                "requires valueBinding or entityBinding");
        }
        return value;
    }

    /**
     * Intersects the given key and the current range.
     */
    KeyRange subRange(KeyRange useRange, Object singleKey)
        throws DatabaseException, KeyRangeException {

        return useRange.subRange(makeRangeKey(singleKey));
    }

    /**
     * Intersects the given range and the current range.
     */
    KeyRange subRange(KeyRange useRange,
                      Object beginKey, boolean beginInclusive,
                      Object endKey, boolean endInclusive)
        throws DatabaseException, KeyRangeException {

        if (beginKey == endKey && beginInclusive && endInclusive) {
            return subRange(useRange, beginKey);
        }
        if (!ordered) {
            throw new UnsupportedOperationException(
                    "Cannot use key ranges on an unsorted database");
        }
        DatabaseEntry beginThang =
            (beginKey != null) ? makeRangeKey(beginKey) : null;
        DatabaseEntry endThang =
            (endKey != null) ? makeRangeKey(endKey) : null;

        return useRange.subRange(beginThang, beginInclusive,
                                 endThang, endInclusive);
    }

    /**
     * Returns the range to use for sub-ranges.  Returns range if this is not a
     * dupsView, or the dupsRange if this is a dupsView, creating dupsRange if
     * necessary.
     */
    KeyRange useSubRange()
        throws DatabaseException {

        if (dupsView) {
            synchronized (this) {
                if (dupsRange == null) {
                    DatabaseConfig config =
                        secDb.getPrimaryDatabase().getConfig();
                    dupsRange = new KeyRange(config.getBtreeComparator());
                }
            }
            return dupsRange;
        } else {
            return range;
        }
    }

    /**
     * Given a key object, make a key entry that can be used in a range.
     */
    private DatabaseEntry makeRangeKey(Object key)
        throws DatabaseException {

        DatabaseEntry thang = new DatabaseEntry();
        if (keyBinding != null) {
            useKey(key, null, thang, null);
        } else {
            useKey(null, key, thang, null);
        }
        return thang;
    }
}