ó ú2ec@sÆdZddlZddljjZddddgZdefd„ƒYZdefd „ƒYZd efd „ƒYZ defd „ƒYZ defd „ƒYZ e ƒZ d„Z e je _dS(s Registry for handling request-local module globals sanely Dealing with module globals in a thread-safe way is good if your application is the sole responder in a thread, however that approach fails to properly account for various scenarios that occur with WSGI applications and middleware. What is actually needed in the case where a module global is desired that is always set properly depending on the current request, is a stacked thread-local object. Such an object is popped or pushed during the request cycle so that it properly represents the object that should be active for the current request. To make it easy to deal with such variables, this module provides a special StackedObjectProxy class which you can instantiate and attach to your module where you'd like others to access it. The object you'd like this to actually "be" during the request is then registered with the RegistryManager middleware, which ensures that for the scope of the current WSGI application everything will work properly. Example: .. code-block:: python #yourpackage/__init__.py from paste.registry import RegistryManager, StackedObjectProxy myglobal = StackedObjectProxy() #wsgi app stack app = RegistryManager(yourapp) #inside your wsgi app class yourapp(object): def __call__(self, environ, start_response): obj = someobject # The request-local object you want to access # via yourpackage.myglobal if environ.has_key('paste.registry'): environ['paste.registry'].register(myglobal, obj) You will then be able to import yourpackage anywhere in your WSGI app or in the calling stack below it and be assured that it is using the object you registered with Registry. RegistryManager can be in the WSGI stack multiple times, each time it appears it registers a new request context. Performance =========== The overhead of the proxy object is very minimal, however if you are using proxy objects extensively (Thousands of accesses per request or more), there are some ways to avoid them. A proxy object runs approximately 3-20x slower than direct access to the object, this is rarely your performance bottleneck when developing web applications. Should you be developing a system which may be accessing the proxy object thousands of times per request, the performance of the proxy will start to become more noticeable. In that circumstance, the problem can be avoided by getting at the actual object via the proxy with the ``_current_obj`` function: .. code-block:: python #sessions.py Session = StackedObjectProxy() # ... initialization code, etc. # somemodule.py import sessions def somefunc(): session = sessions.Session._current_obj() # ... tons of session access This way the proxy is used only once to retrieve the object for the current context and the overhead is minimized while still making it easy to access the underlying object. The ``_current_obj`` function is preceded by an underscore to more likely avoid clashing with the contained object's attributes. **NOTE:** This is *highly* unlikely to be an issue in the vast majority of cases, and requires incredibly large amounts of proxy object access before one should consider the proxy object to be causing slow-downs. This section is provided solely in the extremely rare case that it is an issue so that a quick way to work around it is documented. iÿÿÿÿNtStackedObjectProxytRegistryManagertStackedObjectRestorertrestorert NoDefaultcBseZRS((t__name__t __module__(((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyRbscBseZdZedd„Zd„Zd„Zd„Zd„Zd„Z d„Z d „Z d „Z d „Z d „Zd „Zd„Zd„Zd„Zd„Zd„Zdd„Zd„Zd„Zdeje_d„Zdeje_dd„Zdeje_RS(s»Track an object instance internally using a stack The StackedObjectProxy proxies access to an object internally using a stacked thread-local. This makes it safe for complex WSGI environments where access to the object may be desired in multiple places without having to pass the actual object around. New objects are added to the top of the stack with _push_object while objects can be removed with _pop_object. tDefaultcCs@||jd(treprRRtAttributeErrorRRRtid(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt__repr__s   cCst|jƒƒS(N(titerR(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt__iter__¥scCst|jƒƒS(N(tboolR(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt__bool__¨scCst|jƒƒS(N(tlenR(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt__len__«scCs||jƒkS(N(R(RR$((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt __contains__®scCst|jƒƒS(N(R1R(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt __nonzero__±scCsty|jj}Wntk r)d}nX|r8|dS|jjdtƒ}|tk r]|Std|jƒ‚dS(sÉReturns the current active object being proxied to In the event that no object was pushed, the default object if provided will be used. Otherwise, a TypeError will be raised. iÿÿÿÿR s8No object (name: %s) has been registered for this threadN( R tobjectsR,tNoneR tgetRRR(RR7tobj((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyR´s   cCsNy|jjj|ƒWn0tk rIg|j_|jjj|ƒnXdS(spMake ``obj`` the active object for this thread-local. This should be used like: .. code-block:: python obj = yourobject() module.glob = StackedObjectProxy() module.glob._push_object(obj) try: ... do stuff ... finally: module.glob._pop_object(conf) N(R R7tappendR,(RR:((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt _push_objectÊs   cCseyA|jjjƒ}|r@||k r@td||fƒ‚nWntk r`tdƒ‚nXdS(s¢Remove a thread-local object. If ``obj`` is given, it is checked against the popped object and an error is emitted if they don't match. sBThe object popped (%s) is not the same as the object expected (%s)s-No object has been registered for this threadN(R R7tpoptAssertionErrorR,(RR:tpopped((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt _pop_objectàs cCsGy.y|jj}Wntk r'gSX|SWntk rBgSXdS(sjReturns all of the objects stacked in this container (Might return [] if there are none) N(R R7R,R>(Rtobjs((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt _object_stackðs   cCs,tjƒ}|r"tj||ƒS|jƒS(N(Rtin_restorationtget_saved_proxied_objt_current_obj_orig(Rt request_id((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt_current_obj_restorations s.%s (StackedObjectRestorer restoration enabled)cCs tjƒs|j|ƒndS(N(RRCt_push_object_orig(RR:((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt_push_object_restoration s cCs tjƒs|j|ƒndS(N(RRCt_pop_object_orig(RR:((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt_pop_object_restorations N(RRt__doc__RRRRR!R#R%R&R'R*R.R0R2R4R5R6RR<R8R@RBRGRIRK(((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyRds:                       tRegistrycBsAeZdZd„Zd„Zd„Zd„ZeZd„ZRS(swTrack objects and stacked object proxies for removal The Registry object is instantiated a single time for the request no matter how many times the RegistryManager is used in a WSGI stack. Each RegistryManager must call ``prepare`` before continuing the call to start a new context for object registering. Each context is tracked with a dict inside a list. The last list element is the currently executing context. Each context dict is keyed by the id of the StackedObjectProxy instance being proxied, the value is a tuple of the StackedObjectProxy instance and the object being tracked. cCs g|_dS(s•Create a new Registry object ``prepare`` must still be called before this Registry object can be used to register objects. N(treglist(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyR(scCs|jjiƒdS(såUsed to create a new registry context Anytime a new RegistryManager is called, ``prepare`` needs to be called on the existing Registry object. This sets up a new context for registering objects. N(RNR;(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pytprepare1scCse|jd}t|ƒ}||krD|j||dƒ||=n|j|ƒ||f||t|jƒ s>|j|ƒ|jkrBdS||jf|j|j|ƒ|jD]3}x*tj|ƒD]\}}|j|ƒq‚WqlWdS(s§Save the state of this request's Registry (if it hasn't already been saved) to the saved_registry_states dict, keyed by the request's unique identifierspaste.registryN(R9R3RNtget_request_idRkRVRWtenable_restoration(RRctregistryRNRPR:((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyRbæs cCs€|j|d}t|ƒd}t|ƒ}xDtrs|dkrL|jƒS||}||krfPn|d8}q0W||dS(svRetrieve the saved object proxied by the specified StackedObjectProxy for the request identified by request_idii(RkR3R-RaRE(RRPRFRNt stack_levelRRtcontext((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyRDûs      cCshd|jkrdSxNdD]F}t||ƒ}t||dƒ}||j|d<||j|||jkr.|j|\}}||_n||j_dS(sWEnable a restoration context in the current thread for the specified request_idN(RkRNRlRF(RRFRoRN((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pytrestoration_begin+s cCs%y |j`Wntk r nXdS(s9Register a restoration context as finished, if one existsN(RlRFR,(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pytrestoration_end5s  cCst|jdtƒS(sŠDetermine if a restoration context is active for the current thread. Returns the request_id it's active for if so, otherwise FalseRF(RRlR_(R((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyRC<s( RRRLRRbRDRnRmRyRzRC(((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyR¸s(      cCs t|ƒS(N(R(tappt global_conf((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pytmake_registry_managerEs(RLRVtpaste.util.threadinglocaltutilR t__all__tobjectRRRMRRRR}(((s8/usr/local/lib/python2.7/dist-packages/paste/registry.pyt[s   µJU‰