storedcollection.java

嵌入式数据库Berkeley DB-4.5.20源代码

        try {
            i = storedOrExternalIterator(coll);
            boolean changed = false;
            while (i.hasNext()) {
                if (add(i.next())) {
                    changed = true;
                }
            }
            StoredIterator.close(i);
            commitAutoCommit(doAutoCommit);
            return changed;
        } catch (Exception e) {
            StoredIterator.close(i);
            throw handleException(e, doAutoCommit);
        }
    }

    /**
     * Removes all this collection's elements that are also contained in the
     * specified collection (optional operation).
     * This method conforms to the {@link Collection#removeAll} interface.
     *
     * @throws UnsupportedOperationException if the collection is read-only.
     *
     * @throws RuntimeExceptionWrapper if a {@link DatabaseException} is
     * thrown.
     */
    public boolean removeAll(Collection coll) {

        return removeAll(coll, true);
    }

    /**
     * Retains only the elements in this collection that are contained in the
     * specified collection (optional operation).
     * This method conforms to the {@link Collection#removeAll} interface.
     *
     * @throws UnsupportedOperationException if the collection is read-only.
     *
     * @throws RuntimeExceptionWrapper if a {@link DatabaseException} is
     * thrown.
     */
    public boolean retainAll(Collection coll) {

        return removeAll(coll, false);
    }

    private boolean removeAll(Collection coll, boolean ifExistsInColl) {
	StoredIterator i = null;
        boolean doAutoCommit = beginAutoCommit();
        try {
            boolean changed = false;
            i = storedIterator();
            while (i.hasNext()) {
                if (ifExistsInColl == coll.contains(i.next())) {
                    i.remove();
                    changed = true;
                }
            }
            i.close();
            commitAutoCommit(doAutoCommit);
            return changed;
        } catch (Exception e) {
            if (i != null) {
                i.close();
            }
            throw handleException(e, doAutoCommit);
        }
    }

    /**
     * Compares the specified object with this collection for equality.
     * A value comparison is performed by this method and the stored values
     * are compared rather than calling the equals() method of each element.
     * This method conforms to the {@link Collection#equals} interface.
     *
     * @throws RuntimeExceptionWrapper if a {@link DatabaseException} is
     * thrown.
     */
    public boolean equals(Object other) {

        if (other instanceof Collection) {
            Collection otherColl = StoredCollection.copyCollection(other);
            StoredIterator i = storedIterator();
            try {
                while (i.hasNext()) {
                    if (!otherColl.remove(i.next())) {
                        return false;
                    }
                }
                return otherColl.isEmpty();
            } finally {
                i.close();
            }
        } else {
            return false;
        }
    }

    /*
     * Add this in to keep FindBugs from whining at us about implementing
     * equals(), but not hashCode().
     */
    public int hashCode() {
	return super.hashCode();
    }

    /**
     * Returns a copy of this collection as an ArrayList.  This is the same as
     * {@link #toArray()} but returns a collection instead of an array.
     *
     * @return an {@link ArrayList} containing a copy of all elements in this
     * collection.
     *
     * @throws RuntimeExceptionWrapper if a {@link DatabaseException} is
     * thrown.
     */
    public List toList() {

        ArrayList list = new ArrayList();
        StoredIterator i = storedIterator();
        try {
            while (i.hasNext()) list.add(i.next());
            return list;
        } finally {
            i.close();
        }
    }

    /**
     * Converts the collection to a string representation for debugging.
     * WARNING: The returned string may be very large.
     *
     * @return the string representation.
     *
     * @throws RuntimeExceptionWrapper if a {@link DatabaseException} is
     * thrown.
     */
    public String toString() {
	StringBuffer buf = new StringBuffer();
	buf.append("[");
	StoredIterator i = storedIterator();
        try {
            while (i.hasNext()) {
                if (buf.length() > 1) buf.append(',');
                buf.append(i.next().toString());
            }
            buf.append(']');
            return buf.toString();
        } finally {
            i.close();
        }
    }

    // Inherit javadoc
    public int size() {

        int count = 0;
        boolean countDups = iterateDuplicates();
        CursorConfig cursorConfig = view.currentTxn.isLockingMode() ?
            CursorConfig.READ_UNCOMMITTED : null;
        DataCursor cursor = null;
        try {
            cursor = new DataCursor(view, false, cursorConfig);
            OperationStatus status = cursor.getFirst(false);
            while (status == OperationStatus.SUCCESS) {
                if (countDups) {
                    count += cursor.count();
                } else {
                    count += 1;
                }
                status = cursor.getNextNoDup(false);
            }
        } catch (Exception e) {
            throw StoredContainer.convertException(e);
        } finally {
            closeCursor(cursor);
        }
        return count;
    }

    /**
     * Returns an iterator representing an equality join of the indices and
     * index key values specified.
     * This method does not exist in the standard {@link Collection} interface.
     *
     * <p><strong>Warning:</strong> The iterator returned must be explicitly
     * closed using {@link StoredIterator#close()} or {@link
     * StoredIterator#close(java.util.Iterator)} to release the underlying
     * database cursor resources.</p>
     *
     * <p>The returned iterator supports only the two methods: hasNext() and
     * next().  All other methods will throw UnsupportedOperationException.</p>
     *
     * @param indices is an array of indices with elements corresponding to
     * those in the indexKeys array.
     *
     * @param indexKeys is an array of index key values identifying the
     * elements to be selected.
     *
     * @param joinConfig is the join configuration, or null to use the
     * default configuration.
     *
     * @return an iterator over the elements in this collection that match
     * all specified index key values.
     *
     * @throws IllegalArgumentException if this collection is indexed or if a
     * given index does not have the same store as this collection.
     *
     * @throws RuntimeExceptionWrapper if a {@link DatabaseException} is
     * thrown.
     */
    public StoredIterator join(StoredContainer[] indices, Object[] indexKeys,
                               JoinConfig joinConfig) {

        try {
            DataView[] indexViews = new DataView[indices.length];
            for (int i = 0; i < indices.length; i += 1) {
                indexViews[i] = indices[i].view;
            }
            DataCursor cursor = view.join(indexViews, indexKeys, joinConfig);
            return new StoredIterator(this, false, cursor);
        } catch (Exception e) {
            throw StoredContainer.convertException(e);
        }
    }

    final Object getFirstOrLast(boolean doGetFirst) {

        DataCursor cursor = null;
        try {
            cursor = new DataCursor(view, false);
            OperationStatus status;
            if (doGetFirst) {
                status = cursor.getFirst(false);
            } else {
                status = cursor.getLast(false);
            }
            return (status == OperationStatus.SUCCESS) ?
                    makeIteratorData(null, cursor) : null;
        } catch (Exception e) {
            throw StoredContainer.convertException(e);
        } finally {
            closeCursor(cursor);
        }
    }

    Object makeIteratorData(BaseIterator iterator, DataCursor cursor) {

        return makeIteratorData(iterator,
                                cursor.getKeyThang(),
                                cursor.getPrimaryKeyThang(),
                                cursor.getValueThang());
    }

    abstract Object makeIteratorData(BaseIterator iterator,
                                     DatabaseEntry keyEntry,
                                     DatabaseEntry priKeyEntry,
                                     DatabaseEntry valueEntry);

    abstract boolean hasValues();

    boolean iterateDuplicates() {

        return true;
    }

    void checkIterAddAllowed()
        throws UnsupportedOperationException {

        if (!areDuplicatesAllowed()) {
            throw new UnsupportedOperationException("duplicates required");
        }
    }

    int getIndexOffset() {

        return 0;
    }

    private static Collection copyCollection(Object other) {

        if (other instanceof StoredCollection) {
            return ((StoredCollection) other).toList();
        } else {
            return new ArrayList((Collection) other);
        }
    }
}