dbwatchmanager.java

来自「Jive是基于JSP/JAVA技术构架的一个大型BBS论坛系统,这是Jive论坛」· Java 代码 · 共 484 行 · 第 1/2 页

        if (isWatched && (isExpirable != expirable)) {
            Connection con = null;
            PreparedStatement pstmt = null;
            try {
                con = ConnectionManager.getConnection();
                pstmt = con.prepareStatement(UPDATE_WATCH_EXPIRATION);
                pstmt.setInt(1, expirable?1:0);
                pstmt.setLong(2, user.getID());
                pstmt.setLong(3, thread.getID());
                pstmt.setInt(4, watchType);
                pstmt.executeUpdate();
            }
            catch( SQLException sqle ) {
                sqle.printStackTrace();
            }
            finally {
                try {  pstmt.close();   }
                catch (Exception e) { e.printStackTrace(); }
                try {  con.close();   }
                catch (Exception e) { e.printStackTrace(); }
            }
            // Remove user's watch list from cache.
            StringBuffer key = new StringBuffer(Long.toString(user.getID()));
            key.append("-").append(watchType);
            factory.cacheManager.watchCache.remove(key.toString());
        }
    }

    public Iterator getWatchedForumThreads(Forum forum, User user, int watchType)
    {
        return getWatchList(user, watchType).watchedThreads(forum);
    }

    public Iterator getWatchedForumThreads(User user, int watchType) {
        return getWatchList(user, watchType).watchedThreads();
    }

    public int getWatchCount(Forum forum, User user, int watchType) {
        return getWatchList(user, watchType).getWatchCount(forum);
    }

    public int getWatchCount(User user, int watchType) {
        return getWatchList(user, watchType).getWatchCount();
    }

    public boolean isWatchedThread(User user, ForumThread thread, int watchType) {
        return getWatchList(user, watchType).isWatchedThread(thread.getID());
    }

    /**
     * Notifies watches that a thread has been updated. If there are email
     * watches, email notifications are sent out.
     *
     * @param thread the thread that was updated.
     * @param message the new message in the thread that triggered the update.
     */
    protected void notifyWatches(ForumThread thread, ForumMessage message) {
        // If watches are turned on.
        if (!emailNotifyEnabled) {
            return;
        }
        // Create a new email watch update task that will send out emails to
        // any users that have watches on the updated thread.
        EmailWatchUpdateTask task = new EmailWatchUpdateTask(this, thread, message);
        TaskEngine.addTask(TaskEngine.LOW_PRIORITY, task);
    }

    /**
     * Deletes all watches on a thread. Typically, this method is called when
     * deleting a thread from the system. A Connection is passed in so that
     * this method can participate in a transaction.
     *
     * @param thread the ForumThread to remove all watches from.
     * @param con a database connection to perform work with.
     */
    protected void deleteThreadWatches(ForumThread thread, Connection con)
            throws SQLException
    {
        int numRows;
        PreparedStatement pstmt = null;
        try {
            pstmt = con.prepareStatement(DELETE_THREAD_WATCHES);
            pstmt.setLong(1,thread.getID());
            numRows = pstmt.executeUpdate();
        }
        finally {
            try {  pstmt.close(); }
            catch (Exception e) { e.printStackTrace(); }
        }
        // If any watches were deleted, expire the watch cache. This is
        // potentially a "bad" thing if there is a huge number of active users
        // looking at their watches, but is a good trade-off for now compared to
        // trying to expire individual cache entries.
        if (numRows > 0) {
            factory.cacheManager.watchCache.clear();
        }
    }

    private WatchList getWatchList(User user, int watchType) {
        // Remove user's watch list from cache.
        StringBuffer key = new StringBuffer(Long.toString(user.getID()));
        key.append("-").append(watchType);

        WatchList watchList =
                (WatchList)factory.cacheManager.watchCache.get(key.toString());
        if (watchList != null) {
            return watchList;
        }

        LongList threadsByDate = new LongList();
        BooleanList expirableByDate = new BooleanList();
        LongList threadsByForum = new LongList();
        LongList forumsByForum = new LongList();

        Connection con = null;
        PreparedStatement pstmt = null;
        try {
            con = ConnectionManager.getConnection();
            pstmt = con.prepareStatement(ALL_WATCHES);
            pstmt.setLong(1, user.getID());
            pstmt.setInt(2, watchType);
            ResultSet rs = pstmt.executeQuery();
            while (rs.next()) {
                threadsByDate.add(rs.getLong(1));
                expirableByDate.add(rs.getInt(2)==1?true:false);
            }

            pstmt.close();
            pstmt = con.prepareStatement(ALL_WATCHES_BY_FORUM);
            pstmt.setLong(1, user.getID());
            pstmt.setInt(2, watchType);
            rs = pstmt.executeQuery();
            while (rs.next()) {
                threadsByForum.add(rs.getLong(1));
                forumsByForum.add(rs.getLong(2));
            }
        }
        catch( SQLException sqle ) {
            sqle.printStackTrace();
        }
        finally {
            try {  pstmt.close();   }
            catch (Exception e) { e.printStackTrace(); }
            try {  con.close();   }
            catch (Exception e) { e.printStackTrace(); }
        }

        watchList = new WatchList(
                threadsByDate.toArray(),
                expirableByDate.toArray(),
                threadsByForum.toArray(),
                forumsByForum.toArray()
            );
        // Add watch list to cache for next time, then return it.
        factory.cacheManager.watchCache.put(key.toString(), watchList);
        return watchList;
    }

    /**
     * A task the deletes all watches that are "delatable" and that are attached
     * to threads older than a certain value.
     *
     * The class does not deal with watch cache expiration since that would
     * require deletion of the entire cache. Instead, we just let the watch
     * objects expire naturally.
     */
    class DeleteWatchesTask implements Runnable {

        public void run() {
            long now = System.currentTimeMillis();
            long deleteDays = JiveGlobals.DAY * getDeleteDays();
            // Get the oldest date as a correctly padded String.
            String oldestDate = StringUtils.dateToMillis(new Date(now - deleteDays));

            Connection con = null;
            PreparedStatement pstmt = null;
            boolean abortTransaction = false;
            try {
                con = ConnectionManager.getTransactionConnection();
                // Simple case: database supports sub-selects. This query can be
                // slow if many records are affected, but will at least work.
                if (ConnectionManager.supportsSubqueries) {
                    pstmt = con.prepareStatement(EXPIRE_OLD_WATCHES);
                    pstmt.setString(1, oldestDate);
                    pstmt.execute();
                }
                // Complicated case: db doesn't support sub-selects. So, build
                // up the "IN" clause ourselves. We'll submit them 100 records
                // at a time.
                else {
                    pstmt = con.prepareStatement(GET_EXPIRED_WATCHES);
                    pstmt.setString(1, oldestDate);
                    ResultSet rs = pstmt.executeQuery();
                    LongList expiredThreads = new LongList();
                    while (rs.next()) {
                        expiredThreads.add(rs.getLong(1));
                    }
                    pstmt.close();

                    int length = expiredThreads.size();
                    // Do nothing if there are no records to delete.
                    if (length == 0) {
                        return;
                    }

                    int numBlocks = length / 100;
                    for (int i=0; i <= numBlocks; i++) {
                        int blockNum = i*100;
                        // Build up "IN" SQL statement list.
                        StringBuffer buf = new StringBuffer();
                        buf.append(expiredThreads.get(blockNum));
                        int j=1;
                        while (j < 100 && blockNum+j < length) {
                            buf.append(",").append(expiredThreads.get(blockNum+j));
                            j++;
                        }
                        // Do db delete.
                        String sql = "DELETE FROM jiveWatch WHERE threadID IN (" +
                                buf.toString() + ")";
                        Statement stmt = con.createStatement();
                        stmt.execute(sql);
                        stmt.close();
                     }
                }
            }
            catch( SQLException sqle ) {
                abortTransaction = true;
                sqle.printStackTrace();
            }
            finally {
                try {
                    if (ConnectionManager.supportsSubqueries) { pstmt.close(); }
                }
                catch (Exception e) { e.printStackTrace(); }
                try {
                    ConnectionManager.closeTransactionConnection(con, abortTransaction);
                }
                catch (Exception e) { e.printStackTrace(); }
            }
        }
    }
}