genericpeergroup.java

jxta平台的开发包

        }
        if (resolverClassID.equals(name)) {
            resolver = (ResolverService) service;
            return;
        }
        if (discoveryClassID.equals(name)) {
            discovery = (DiscoveryService) service;
            return;
        }
        if (pipeClassID.equals(name)) {
            pipe = (PipeService) service;
            return;
        }
        if (membershipClassID.equals(name)) {
            membership = (MembershipService) service;
            return;
        }
        if (peerinfoClassID.equals(name)) {
            peerinfo = (PeerInfoService) service;
            return;
        }
        if (rendezvousClassID.equals(name)) {
            rendezvous = (RendezVousService) service;
            return;
        }
        if (accessClassID.equals(name)) {
            access = (AccessService) service;
            return;
        }
    }
    
    private void clearShortCut(ModuleClassID name) {
        if (endpointClassID.equals(name)) {
            endpoint = null;
            return;
        }
        if (resolverClassID.equals(name)) {
            resolver = null;
            return;
        }
        if (discoveryClassID.equals(name)) {
            discovery = null;
            return;
        }
        if (pipeClassID.equals(name)) {
            pipe = null;
            return;
        }
        if (membershipClassID.equals(name)) {
            membership = null;
            return;
        }
        if (peerinfoClassID.equals(name)) {
            peerinfo = null;
            return;
        }
        if (rendezvousClassID.equals(name)) {
            rendezvous = null;
            return;
        }
        if (accessClassID.equals(name)) {
            access = null;
            return;
        }
    }
    
    /**
     * Adds a service to the set.
     * Returns any pre-existing one.
     **/
    private synchronized Service addServiceSync(ModuleClassID name, Service service) {
        if (stopping) {
            return null;
        }
        
        Service p = (Service) services.remove(name);
        
        services.put(name, service);
        return p;
    }
    
    /**
     * Adds a service to the set.
     *
     * <p/>Removes any pre-existing one with the same name.
     **/
    protected void addService(ModuleClassID name, Service service) {
        Service oldp = addServiceSync(name, service);
        
        setShortCut(name, service);
        
        if ((oldp != null) && (oldp != service)) {
            LOG.warn("Service replaced for " + name);
            // oldp.stopApp(); maybe ?
        }
    }
    
    /**
     * Call a service by name.
     *
     * @param name the service name
     * @return Service, the Service registered by that name
     **/
    synchronized public Service lookupService(ID name) throws ServiceNotFoundException {
        // Null services are never registered, so we do not need to test that
        // case.
        Service p = (Service) services.get(name);
        
        if (p == null) {
            throw new ServiceNotFoundException(name.toString());
        }
        return p.getInterface();
    }
    
    /**
     * {@inheritDoc}
     * Group implementations do not have to support mapping.
     * it would be nice to separate better Interfaces, so that
     * Interface Objects can do things that the real service does
     * not have to implement.
     */
    public Service lookupService(ID name, int roleIndex)
    throws ServiceNotFoundException {
        
        // If the role number is != 0, it can't be honored: we
        // do not have an explicit map.
        
        if (roleIndex != 0) {
            throw (new ServiceNotFoundException(
            "" + name + "[" + roleIndex + "]"));
            
        }
        return lookupService(name);
    }
    
    /**
     * {@inheritDoc}
     **/
    public Iterator getRoleMap(ID name) {
        // No translation; use the given name in a singleton.
        return Collections.singletonList(name).iterator();
    }
    
    /**
     * check that all required services are registered
     **/
    protected void checkServices() throws ServiceNotFoundException {
        Service ignored;
        
        ignored = lookupService(endpointClassID);
        ignored = lookupService(resolverClassID);
        ignored = lookupService(membershipClassID);
        ignored = lookupService(accessClassID);
        
        /**
         * ignored = lookupService(discoveryClassID);
         * ignored = lookupService(pipeClassID);
         * ignored = lookupService(rendezvousClassID);
         * ignored = lookupService(peerinfoClassID);
         **/
    }
    
    /**
     * We're stopping. Remove all services and stop them.
     **/
    private synchronized void removeAllServicesSync() {
        
        stopping = true;
        
        // stop everything
        Iterator allServices = services.entrySet().iterator();
        
        while (allServices.hasNext()) {
            Map.Entry s = null;
            
            try {
                s = (Map.Entry) allServices.next();
                ((Service) s.getValue()).stopApp();
            } catch (Throwable e) {
                if (LOG.isEnabledFor(Level.ERROR)) {
                    LOG.error("Failed stopping service: " + s, e);
                }
            }
        }
        
        // remove everything
        allServices = services.entrySet().iterator();
        
        while (allServices.hasNext()) {
            Map.Entry s = null;
            
            try {
                s = (Map.Entry) allServices.next();
                clearShortCut(((ModuleClassID) s.getKey()));
                allServices.remove();
            } catch (Throwable e) {
                if (LOG.isEnabledFor(Level.ERROR)) {
                    LOG.error("Failed remove service: " + s, e);
                }
            }
        }
    }
    
    /**
     * Ask a group to unregister and unload a service
     *
     * @param service handle to the service to be removed
     **/
    synchronized private void removeServiceSync(ModuleClassID name,
    Service service)
    throws ServiceNotFoundException, ViolationException {
        // Weak check: you need to actually posess a handle to the
        // service object you're removing, not its name, but
        // you can fake by doing getService() first.
        
        Service p = (Service) services.get(name);
        
        if (p == null) {
            throw new ServiceNotFoundException(name.toString());
        }
        
        if (p != service) {
            throw new ViolationException("Service registered for key was did not match provided instance :" + name);
        }
        
        services.remove(name);
    }
    
    /**
     * Ask a group to unregister and unload a service
     *
     * @param service handle to the service to be removed
     **/
    protected void removeService(ModuleClassID name, Service service)
    throws ServiceNotFoundException, ViolationException {
        removeServiceSync(name, service);
        clearShortCut(name);
        // service.finalize(); FIXME. We probably need a terminate()
        // method instead.
        // FIXME: [[e-mail] 20011013] to make sure the service is
        // no-longer referenced, we should always return interfaces, and
        // have a way to cut the reference to the real service in the
        // interfaces. One way of doing that would be to have to levels
        // of indirection: we should keep one and return references to it.
        // when we want to cut the service loose, we should clear the
        // reference from the interface that we own before letting it go.
        // We need to study the consequences of doing that before implementing
        // it.
    }
    
    /**
     * {@inheritDoc}
     **/
    abstract public boolean compatible(Element compat);
    
    /**
     * {@inheritDoc}
     **/
    public Module loadModule(ID assigned, Advertisement impl)
    throws ProtocolNotSupportedException, PeerGroupException {
        return loadModule(assigned, (ModuleImplAdvertisement) impl, false);
    }
    
    /**
     * Load a Module from a ModuleImplAdv.
     *
     * <p/>Compatibility is checked and load is attempted. If compatible and 
     * loaded successfuly, the resulting Module is initialized and returned.
     * In most cases the other loadModule() method should be preferred, since
     * unlike this one, it will seek many compatible implementation
     * advertisements and try them all until one works. The home group of the new
     * module (its' parent group if the new Module is a group) will be this group.
     *
     * @param assigned Id to be assigned to that module (usually its ClassID).
     * @param implAdv An implementation advertisement for that module.
     * @param privileged If {@code true} then the module is provided the true 
     * group obj instead of just an interface to the group object. This is 
     * normally used only for the group's defined services and applications.
     * @return Module the module loaded and initialized.
     * @throws ProtocolNotSupportedException The module is a protocol and
     * is disabled per the peer's configuration.
     * @throws PeerGroupException The module could not be loaded or initialized
     **/
    protected Module loadModule( ID assigned, ModuleImplAdvertisement implAdv, boolean privileged )
    throws ProtocolNotSupportedException, PeerGroupException {
        
        Element compat = implAdv.getCompat();
        
        if (null == compat) {
            throw new IllegalArgumentException("No compatibility statement for : " + assigned);
        }
        
        if (!compatible(compat)) {
            if (LOG.isEnabledFor(Level.WARN)) {
                LOG.warn( "Incompatible Module : " + assigned) ;
            }
            
            throw new ProtocolNotSupportedException( "Incompatible Module : " + assigned );
        }
        
        Module newMod = null;
        
        if( (null != implAdv.getCode()) && (null != implAdv.getUri()) ) {
            try {
                // Good one. Try it.
                
                Class clazz;
                
                try {
                    clazz = loader.findClass( implAdv.getModuleSpecID() );
                } catch ( ClassNotFoundException notLoaded ) {
                    clazz = loader.defineClass( implAdv );
                }
                
                if( null == clazz ) {
                    throw new ClassNotFoundException( "Cannot load class (" + implAdv.getCode() + ") : " + assigned );
                }
                
                newMod = (Module) clazz.newInstance();
                
                newMod.init(privileged ? this : (PeerGroup) getInterface(), assigned, implAdv);
                
                if (LOG.isEnabledFor(Level.INFO)) {
                    LOG.info("Loaded" + (privileged ? " privileged" : "") + " module : " + implAdv.getDescription() + " (" + implAdv.getCode() + ")" );
                }
            } catch (Exception ex) {
                try {
                    newMod.stopApp();
                } catch (Throwable ignored) {
                    // If this does not work, nothing needs to be done.
                    ;
                }
                throw new PeerGroupException("Could not load module for : " + assigned + " ("+ implAdv.getDescription() + ")", ex );
            }
            
        } else {
            throw new PeerGroupException( "Cannot load class for : " + assigned );
        }
        
        // Publish or renew the lease of this adv since we're using it.
        try {
            if (discovery != null) {
                discovery.publish( implAdv, DEFAULT_LIFETIME, DEFAULT_EXPIRATION );
            }
        } catch (Exception ignored) {;}
        
        // If we reached this point we're done.
        return newMod;
    }
    
    /**
     * {@inheritDoc}
     **/
    public Module loadModule(ID assigned, ModuleSpecID specID, int where) {
        return loadModule(assigned, specID, where, false);
    }
    
    /**
     * Load a module from a ModuleSpecID
     *
     * <p/>Advertisement is sought, compatibility is checked on all candidates
     * and load is attempted. The first one that is compatible and loads
     * successfuly is initialized and returned.
     *
     * @param assignedID Id to be assigned to that module (usually its ClassID).
     * @param specID The specID of this module.
     * @param where May be one of: {@code Here}, {@code FromParent}, or {@ Both}, 
     * meaning that the implementation advertisement will be searched in this 
     * group, its parent or both. As a general guideline, the implementation 
     * advertisements of a group should be searched in its propsective parent 
     * (that is Here), the implementation advertisements of a group standard 
     * service should be searched in the same group than where this group's 
     * advertisement was found (that is, FromParent), while applications may be 
     * sought more freely (Both).
     * @param privileged If {@code true} then the module is provided the true 
     * group obj instead of just an interface to the group object. This is 
     * normally used only for the group's defined services and applications.
     * @return Module the new module, or {@code null} if no usuable 
     * implementation was found.
     */
    protected Module loadModule(ID assignedID, ModuleSpecID specID, int where, boolean privileged) {
        
        boolean fromHere = (where == Here || where == Both);
        boolean fromParent = (where == FromParent || where == Both);
        
        List all = new ArrayList();
        
        if( fromHere && (null != discovery) ) {
            Enumeration here = discoverSome(DiscoveryService.ADV, "MSID", specID.toString(), 120, ModuleImplAdvertisement.class);
            all.addAll( Collections.list(here) );
        }
        
        if( fromParent && (null != getParentGroup()) && (null != parentGroup.getDiscoveryService()) ) {
            Enumeration parent = discoverSome(parentGroup.getDiscoveryService(), DiscoveryService.ADV, "MSID", specID.toString(), 120, ModuleImplAdvertisement.class);
            all.addAll( Collections.list(parent) );
        }
        
        Iterator allModuleImpls = all.iterator();
        Throwable recentFailure = null;
        
        while (allModuleImpls.hasNext()) {
            ModuleImplAdvertisement found = null;
            
            try {
                found = (ModuleImplAdvertisement) allModuleImpls.next();