objectpool.java

Sequoia ERP是一个真正的企业级开源ERP解决方案。它提供的模块包括：电子商务应用(e-commerce), POS系统(point of sales),知识管理,存货与仓库管理

     * it will be released from the pool.  If timestamps are enabled, the client
     * may update the last used time.  Otherwise, the last used time is only
     * updated when an object is acquired or released.  The default value is
     * 30 minutes.
     * @see #setIdleTimeoutEnabled
     * @param millis The idle time, in milliseconds.
     * @throws java.lang.IllegalStateException
     *    Occurs when you try to set the idle timeout after the pool
     *    has been initialized.
     */
    public void setIdleTimeout(long millis) {
        if (initialized)
            throw new IllegalStateException(INITIALIZED);
        idleTimeoutMillis = millis;

        if (log.isDebugEnabled())
            log.debug("setIdleTimeout(" + millis + ")");
    }

    /**
     * Gets the minimum idle time to release an unused object from the pool.
     * @see #setIdleTimeout
     */
    public long getIdleTimeout() {
        return idleTimeoutMillis;
    }

    /**
     * Sets the minimum idle time to make an object eligible for garbage
     * collection.  If the object is in use and has not been used for this
     * amount of time, it may be returned to the pool.  If timestamps are
     * enabled, the client may update the last used time (this is generally
     * recommended if garbage collection is enabled).  Otherwise, the last used
     * time is only updated when an object is acquired or released.  The default
     * value is 20 minutes.
     * @see #setGCEnabled
     * @param millis The idle time, in milliseconds.
     * @throws java.lang.IllegalStateException
     *    Occurs when you try to set the garbage collection idle time after the
     *    pool has been initialized.
     */
    public void setGCMinIdleTime(long millis) {
        if (initialized)
            throw new IllegalStateException(INITIALIZED);
        gcMinIdleMillis = millis;

        if (log.isDebugEnabled())
            log.debug("setGCMinIdleTime(" + millis + ")");
    }

    /**
     * Gets the minimum idle time to make an object eligible for garbage
     * collection.
     * @see #setGCMinIdleTime
     */
    public long getGCMinIdleTime() {
        return gcMinIdleMillis;
    }

    /**
     * Sets the length of time between garbage collection and idle timeout runs.
     * This is inexact - if there are many pools with garbage collection and/or
     * the idle timeout enabled, there will not be a thread for each one, and
     * several nearby actions may be combined.  Likewise if the collection
     * process is lengthy for certain types of pooled objects (not recommended),
     * other actions may be delayed.  This is to prevend an unnecessary
     * proliferation of threads.  Note that this parameter controls
     * both garbage collection and the idle timeout - and they will be performed
     * together if both are enabled.  The deafult value is 2 minutes.
     * @throws java.lang.IllegalStateException
     *    Occurs when you try to set the garbage collection interval after the
     *    pool has been initialized.
     */
    public void setGCInterval(long millis) {
        if (initialized)
            throw new IllegalStateException(INITIALIZED);

        gcIntervalMillis = millis;

        if (log.isDebugEnabled())
            log.debug("setGCInterval(" + gcIntervalMillis + ")");
    }

    /**
     * Gets the length of time between garbage collection and idle timeout runs.
     * @see #setGCInterval
     */
    public long getGCInterval() {
        return gcIntervalMillis;
    }

    /**
     * Sets whether a request for an object will block if the pool size is
     * maxed out and no objects are available.  If set to block, the request
     * will not return until an object is available.  Otherwise, the request
     * will return null immediately (and may be retried).  If multiple
     * requests block, there is no guarantee which will return first.  The
     * default is to block.
     * @throws java.lang.IllegalStateException
     *    Occurs when you try to set the blocking parameter after the
     *    pool has been initialized.
     */
    public void setBlocking(boolean blocking) {
        if (initialized)
            throw new IllegalStateException(INITIALIZED);
        this.blocking = blocking;
    }

    /**
     * Gets whether a request for an object will block if the pool size is
     * maxed out and no objects are available.
     * @see #setBlocking
     */
    public boolean isBlocking() {
        return blocking;
    }

    /** sets how long to wait for a free object when blocking, -1 indicating
     *  forever.
     */
    public void setBlockingTimeout(int blockingTimeout) {
        this.blockingTimeout = blockingTimeout;
    }

    /** get how long this pool will wait for a free object while blocking */
    public int getBlockingTimeout() {
        return this.blockingTimeout;
    }

    /**
     * Sets whether object clients can update the last used time.  If not, the
     * last used time will only be updated when the object is given to a client
     * and returned to the pool.  This time is important if the idle timeout or
     * garbage collection is enabled (particularly the latter).  The default
     * is false.
     * @throws java.lang.IllegalStateException
     *    Occurs when you try to set the timestamp parameter after the
     *    pool has been initialized.
     */
    public void setTimestampUsed(boolean timestamp) {
        if (initialized)
            throw new IllegalStateException(INITIALIZED);

        trackLastUsed = timestamp;

        if (log.isDebugEnabled())
            log.debug("setTimestampUsed(" + timestamp + ")");
    }

    /**
     * Gets whether object clients can update the last used time.
     */
    public boolean isTimestampUsed() {
        return trackLastUsed;
    }

    /**
     * Sets the response for object errors.  If this flag is set and an error
     * event occurs, the object is removed from the pool entirely.  Otherwise,
     * the object is returned to the pool of available objects.  For example, a
     * SQL error may not indicate a bad database connection (flag not set),
     * while a TCP/IP error probably indicates a bad network connection (flag
     * set).  If this flag is not set, you can still manually invalidate
     * objects using markObjectAsInvalid.
     * @see #markObjectAsInvalid
     * @see #objectError
     */
    public void setInvalidateOnError(boolean invalidate) {
        if (initialized)
            throw new IllegalStateException(INITIALIZED);
        invalidateOnError = invalidate;
    }

    /**
     * Gets whether objects are removed from the pool in case of errors.
     */
    public boolean isInvalidateOnError() {
        return invalidateOnError;
    }

    /**
     * Prepares the pool for use.  This must be called exactly once before
     * getObject is even called.  The pool name and object factory must be set
     * before this call will succeed.
     * @throws java.lang.IllegalStateException
     *    Occurs when you try to initialize the pool without setting the object
     *    factory or name, or you initialize the pool more than once.
     */
    public void initialize() {
        if (factory == null || poolName == null)
            throw new IllegalStateException("Factory and Name must be set before pool initialization!");
        if (initialized)
            throw new IllegalStateException("Cannot initialize more than once!");
        initialized = true;
        permits = new FIFOSemaphore(maxSize);
        factory.poolStarted(this);
        lastGC = System.currentTimeMillis();
        //fill pool to min size
        fillToMin();
        /*
        int max = maxSize <= 0 ? minSize : Math.min(minSize, maxSize);
        Collection cs = new LinkedList();
        for(int i=0; i<max; i++)
        {
           cs.add(getObject(null));
        }
        while (Iterator i = cs.iterator(); i.hasNext();)
        {
           releaseObject(i.next());
        } // end of while ()
        */
        collector.addPool(this);
    }

    /**
     * Shuts down the pool.  All outstanding objects are closed and all objects
     * are released from the pool.  No getObject or releaseObject calls will
     * succeed after this method is called - and they will probably fail during
     * this method call.
     */
    public void shutDown() {
        collector.removePool(this);
        factory.poolClosing(this);

        // close all objects
        synchronized (objects) {
            for (Iterator it = objects.values().iterator(); it.hasNext();) {
                ObjectRecord rec = (ObjectRecord) it.next();
                if (null != rec) {
                    if (rec.isInUse())
                        factory.returnObject(rec.getClientObject());
                    factory.deleteObject(rec.getObject());
                    rec.close();
                }
            }
            objects.clear();
            deadObjects.clear();
        }//end of synch

        factory = null;
        poolName = null;
        initialized = false;
    }

    /**
     * Gets an object from the pool.  If all the objects in the pool are in use,
     * creates a new object, adds it to the pool, and returns it.  If all
     * objects are in use and the pool is at maximum size, will block or
     * return null.
     * @see #setBlocking
     */
    public Object getObject() {
        return getObject(null);
    }

    /**
     * Gets an object that fits the specified parameters from the pool.
     * If all the objects in the pool are in use or don't fit, creates
     * a new object, adds it to the pool, and returns it.  If all
     * objects are in use or don't fit and the pool is at maximum size,
     * will block or return null.
     * @see #setBlocking
     */
    public Object getObject(Object parameters) {
        if (objects == null)
            throw new IllegalStateException("Tried to use pool before it was Initialized or after it was ShutDown!");

        Object result = factory.isUniqueRequest();
        if (result != null) // If this is identical to a previous request,
            return result;  // return the same result.  This is the 2.4 total hack to
                            // share local connections within a managed tx.

        try {
            if (permits.attempt(blockingTimeout)) {
                ObjectRecord rec = null;
                synchronized (objects) {
                    for (Iterator it = objects.values().iterator(); it.hasNext();) {
                        rec = (ObjectRecord) it.next();
                        if (null != rec && !rec.isInUse() && factory.checkValidObject(rec.getObject(), parameters)) {
                            log.info("Handing out from pool object: " + rec.getObject());
                            try {
                                rec.setInUse(true);
                            } catch (ConcurrentModificationException e) {
                                log.info("Conflict trying to set rec. in use flag:" + rec.getObject());
                                // That's OK, just go on and try another object
                                continue;//shouldn't happen now.
                            }
                            break;
                        }
                        rec = null;//not found
                    }
                }//synch on objects

                if (rec == null) {
                    try {
                        rec = createNewObject(parameters);
                    } catch (Exception e) {
                        log.error("Exception in creating new object for pool", e);
                        permits.release();
                        throw e;
                    }
                } // end of if ()
                if (rec == null) {
                    permits.release();
                    String message = "Pool is broken, did not find or create an object";
                    log.error(message);
                    throw new RuntimeException(message);
                } // end of if ()
                Object ob = rec.getObject();

                result = factory.prepareObject(ob);
                if (result != ob) rec.setClientObject(result);
                if (result instanceof PooledObject)
                    ((PooledObject) result).addPoolEventListener(this);

                log.debug("Pool " + this + " gave out object: " + result);
                return result;
            }//end of permits
            else {
                //we timed out
                throw new RuntimeException("No ManagedConnections Available!");
            } // end of else
        }//try
        catch (RuntimeException e) {
            throw e;
        } // end of catch
        catch (InterruptedException ie) {
            log.info("Interrupted while requesting permit!", new Exception("stacktrace"));
            throw new RuntimeException("Interrupted while requesting permit!");
        } // end of try-catch
        catch (Exception e) {
            log.info("problem getting connection from pool", e);
            throw new RuntimeException("problem getting connection from pool " + e.getMessage());
        } // end of catch