snmpsession.java

java1.6众多例子参考

    public void run() {
        myThread = Thread.currentThread();
        myThread.setPriority(Thread.NORM_PRIORITY);

        SnmpInformRequest reqc = null;
        while (myThread != null) {
            try {
                reqc = nextResponse();
                if (reqc != null) {
                    processResponse(reqc);
                }
            } catch (ThreadDeath d) {
                myThread = null;
                if (isDebugOn()) {
                    debug("run", "Session thread unexpectedly shutting down");
                }
                throw d ;
            }
        }
        if (isTraceOn()) {
            trace("run", "Session thread shutting down");
        }
        myThread = null ;
    }
    
    private void processResponse(SnmpInformRequest reqc) {
        
        while (reqc != null && myThread != null) {
            try {
                if (reqc != null) {
                    if (isTraceOn()) {
                        trace("processResponse", "Processing response to req = " + reqc.getRequestId());
                    }
                    reqc.processResponse() ;  // Handles out of memory.
                    reqc = null ;  // finished processing.
                }
				
            } catch (Exception e) {
                if (isDebugOn()) {
                    debug("processResponse", e);
                }
                reqc = null ;
            } catch (OutOfMemoryError ome) {
                if (isDebugOn()) {
                    debug("processResponse", "Out of memory error in session thread");
                    debug("processResponse", ome);
                }
                Thread.currentThread().yield();
                continue ;   // re-process the request.
            }
        }
    }
    
    // HANDLING INFORM REQUESTS LIST AND INFORM RESPONSES LIST
    //--------------------------------------------------------
    
    /**
     * Adds an inform request.
     * @param snmpreq The inform request to add.
     * @exception SnmpStatusException SNMP adaptor is not ONLINE or session is dead.
     */
    synchronized void addInformRequest(SnmpInformRequest snmpreq) throws SnmpStatusException {
        
        // If the adaptor is not ONLINE, stop adding requests.
        //
        if (!isSessionActive()) {
            throw new SnmpStatusException("SNMP adaptor is not ONLINE or session is dead...") ;
        }
        informRequestList.put(snmpreq, snmpreq);
    }
    
    /**
     * Deletes an inform request.
     * @param snmpreq The inform request to delete.
     */
    synchronized void removeInformRequest(SnmpInformRequest snmpreq) {
	// deleteRequest can be called from destroySnmpSession.
	//In such a case remove is done in cancelAllRequest method.
	if(!isBeingCancelled)
	    informRequestList.remove(snmpreq) ;

        if (syncInformReq != null && syncInformReq == snmpreq) {
            resetSyncMode() ;
        }
    }
            
    /**
     * Cancels all pending inform requests in this session.
     */
    private void cancelAllRequests() {
        final SnmpInformRequest[] list;
	
	synchronized(this) {
	    
	    if (informRequestList.isEmpty()) {
		return ;
	    }

	    isBeingCancelled = true;
	    
	    list = new SnmpInformRequest[informRequestList.size()];
	    java.util.Iterator it = informRequestList.values().iterator();
	    int i = 0;
	    while(it.hasNext()) {
		SnmpInformRequest req = (SnmpInformRequest)it.next();
		list[i++] = req;
		it.remove();
	    }
	    informRequestList.clear();
	}
	
	for(int i = 0; i < list.length; i++)
	    list[i].cancelRequest();
    }
    
    /**
     * Adds the inform request object which received a response to an inform request 
     * generated by the session.  This is added to a private store, which
     * will be eventually picked up by the dispatcher for processing.
     * @param reqc The inform request that received the response from the manager.
     */
    void addResponse(SnmpInformRequest reqc) {
        
        SnmpInformRequest snmpreq = (SnmpInformRequest) reqc ;
        if (isSessionActive()) {
            synchronized(this) {
                informRespq.push(reqc) ;
                this.notifyAll() ;
            }
        } else {
            if (isDebugOn()) {
                debug("addResponse", "Adaptor not ONLINE or session thread dead. So inform response is dropped..." + reqc.getRequestId());
            }
        }
        return ;
    }

    private synchronized SnmpInformRequest nextResponse() {
        
        if (informRespq.isEmpty()) {
            try {
                if (isTraceOn()) {
                    trace("nextResponse", "Blocking for response");
                }
                this.wait();
            } catch(InterruptedException e) {
            }
        }
        if (informRespq.isEmpty())
            return null;
        SnmpInformRequest reqc = (SnmpInformRequest) informRespq.firstElement();
        informRespq.removeElementAt(0) ;
        return reqc ;
    }
    
    private synchronized void cancelAllResponses() {
        if (informRespq != null) {
            syncInformReq = null ;
            informRespq.removeAllElements() ;
            this.notifyAll() ;
        }
    }
    
    /**
     * Destroys any pending inform requests and then stops the session.
     * The session will not be usable after this method returns.
     */
    final void destroySession() {
        
        cancelAllRequests() ;
        cancelAllResponses() ;
        synchronized(this) {
            informSocket.close() ;
            informSocket = null ;
        }
        snmpQman.stopQThreads() ;
        snmpQman = null ;
        killSessionThread() ;
    }
    
    /**
     * Make sure you are killing the thread when it is active. Instead
     * prepare for a graceful exit.
     */
    private synchronized void killSessionThread() {
        
        if ((myThread != null) && (myThread.isAlive())) {
            if (isTraceOn()) {
                trace("killSessionThread", "Destroying session");
            }
            if (!thisSessionContext()) {
                myThread = null ;
                this.notifyAll() ;
            } else
                myThread = null ;
        }
    }

    /**
     * Finalizer of the <CODE>SnmpSession</CODE> objects.
     * This method is called by the garbage collector on an object 
     * when garbage collection determines that there are no more references to the object.
     * <P>Removes all the requests for this SNMP session, closes the socket and
     * sets all the references to the <CODE>SnmpSession</CODE> object to <CODE>null</CODE>.
     */
    public void finalize() {
        
        if (informRespq != null)
            informRespq.removeAllElements() ;
        informRespq = null ;
        if (informSocket != null)
            informSocket.close() ;
        informSocket = null ;

        if (isTraceOn()) {
            trace("finalize", "Shutting all servers");
        }
        snmpQman = null ;
    }
    
    // TRACES & DEBUG
    //---------------
    
    boolean isTraceOn() {
        return Trace.isSelected(Trace.LEVEL_TRACE, Trace.INFO_ADAPTOR_SNMP);
    }

    void trace(String clz, String func, String info) {
        Trace.send(Trace.LEVEL_TRACE, Trace.INFO_ADAPTOR_SNMP, clz, func, info);
    }

    void trace(String func, String info) {
        trace(dbgTag, func, info);
    }
    
    boolean isDebugOn() {
        return Trace.isSelected(Trace.LEVEL_DEBUG, Trace.INFO_ADAPTOR_SNMP);
    }

    void debug(String clz, String func, String info) {
        Trace.send(Trace.LEVEL_DEBUG, Trace.INFO_ADAPTOR_SNMP, clz, func, info);
    }

    void debug(String clz, String func, Throwable exception) {
        Trace.send(Trace.LEVEL_DEBUG, Trace.INFO_ADAPTOR_SNMP, clz, func, exception);
    }

    void debug(String func, String info) {
        debug(dbgTag, func, info);
    }
    
    void debug(String func, Throwable exception) {
        debug(dbgTag, func, exception);
    }
}