Current File : //usr/lib64/python2.7/site-packages/tornado/stack_context.pyo
�
��L]c @� s� d Z d d l m Z m Z m Z m Z d d l Z d d l Z d d l m Z d e
f d � � YZ d e j f d � � YZ
e
� Z d e f d
� � YZ d e f d � � YZ d
e f d � � YZ d � Z d � Z d � Z d � Z d S( s `StackContext` allows applications to maintain threadlocal-like state
that follows execution as it moves to other execution contexts.
The motivating examples are to eliminate the need for explicit
``async_callback`` wrappers (as in `tornado.web.RequestHandler`), and to
allow some additional context to be kept for logging.
This is slightly magic, but it's an extension of the idea that an
exception handler is a kind of stack-local state and when that stack
is suspended and resumed in a new context that state needs to be
preserved. `StackContext` shifts the burden of restoring that state
from each call site (e.g. wrapping each `.AsyncHTTPClient` callback
in ``async_callback``) to the mechanisms that transfer control from
one context to another (e.g. `.AsyncHTTPClient` itself, `.IOLoop`,
thread pools, etc).
Example usage::
@contextlib.contextmanager
def die_on_error():
try:
yield
except Exception:
logging.error("exception in asynchronous operation",exc_info=True)
sys.exit(1)
with StackContext(die_on_error):
# Any exception thrown here *or in callback and its descendants*
# will cause the process to exit instead of spinning endlessly
# in the ioloop.
http_client.fetch(url, callback)
ioloop.start()
Most applications shouldn't have to work with `StackContext` directly.
Here are a few rules of thumb for when it's necessary:
* If you're writing an asynchronous library that doesn't rely on a
stack_context-aware library like `tornado.ioloop` or `tornado.iostream`
(for example, if you're writing a thread pool), use
`.stack_context.wrap()` before any asynchronous operations to capture the
stack context from where the operation was started.
* If you're writing an asynchronous library that has some shared
resources (such as a connection pool), create those shared resources
within a ``with stack_context.NullContext():`` block. This will prevent
``StackContexts`` from leaking from one request to another.
* If you want to write something like an exception handler that will
persist across asynchronous calls, create a new `StackContext` (or
`ExceptionStackContext`), and make your asynchronous calls in a ``with``
block that references your `StackContext`.
i ( t absolute_importt divisiont print_functiont with_statementN( t raise_exc_infot StackContextInconsistentErrorc B� s e Z RS( ( t __name__t
__module__( ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR M s t _Statec B� s e Z d � Z RS( c C� s t � d f | _ d S( N( t tuplet Nonet contexts( t self( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt __init__R s ( R R R
( ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR Q s t StackContextc B� sD e Z d Z d � Z d � Z d � Z d � Z d � Z d � Z RS( s Establishes the given context as a StackContext that will be transferred.
Note that the parameter is a callable that returns a context
manager, not the context itself. That is, where for a
non-transferable context manager you would say::
with my_context():
StackContext takes the function itself rather than its result::
with StackContext(my_context):
The result of ``with StackContext() as cb:`` is a deactivation
callback. Run this callback when the StackContext is no longer
needed to ensure that it is not propagated any further (note that
deactivating a context does not affect any instances of that
context that are currently pending). This is an advanced feature
and not necessary in most applications.
c C� s | | _ g | _ t | _ d S( N( t context_factoryR t Truet active( R R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR
k s c C� s
t | _ d S( N( t FalseR ( R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt _deactivatep s c C� s* | j � } | j j | � | j � d S( N( R R t appendt __enter__( R t context( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt entert s c C� s& | j j � } | j | | | � d S( N( R t popt __exit__( R t typet valuet tracebackR ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt exity s c C� sc t j | _ | j d | f | f | _ | j t _ y | j � Wn | j t _ � n X| j S( Ni ( t _stateR t old_contextst new_contextsR R ( R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s c C� s[ z | j | | | � Wd t j } | j t _ | | j k rM t d � � n d | _ Xd S( NsW stack_context inconsistency (may be caused by yield within a "with StackContext" block)( R R R R R R R
( R R R R t final_contexts( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s ( R R t __doc__R
R R R R R ( ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR W s
t ExceptionStackContextc B� s; e Z d Z d � Z d � Z d � Z d � Z d � Z RS( sA Specialization of StackContext for exception handling.
The supplied ``exception_handler`` function will be called in the
event of an uncaught exception in this context. The semantics are
similar to a try/finally clause, and intended use cases are to log
an error, close a socket, or similar cleanup actions. The
``exc_info`` triple ``(type, value, traceback)`` will be passed to the
exception_handler function.
If the exception handler returns true, the exception will be
consumed and will not be propagated to other exception handlers.
c C� s | | _ t | _ d S( N( t exception_handlerR R ( R R$ ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR
� s c C� s
t | _ d S( N( R R ( R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s c C� s# | d k r | j | | | � Sd S( N( R
R$ ( R R R R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s c C� s5 t j | _ | j d | f | _ | j t _ | j S( Ni ( R R R R R ( R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s c C� sg z# | d k r" | j | | | � SWd t j } | j t _ | | j k rY t d � � n d | _ Xd S( NsW stack_context inconsistency (may be caused by yield within a "with StackContext" block)( R
R$ R R R R R ( R R R R R! ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s ( R R R" R
R R R R ( ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR# � s t NullContextc B� s e Z d Z d � Z d � Z RS( s� Resets the `StackContext`.
Useful when creating a shared resource on demand (e.g. an
`.AsyncHTTPClient`) where the stack that caused the creating is
not relevant to future operations.
c C� s" t j | _ t � d f t _ d S( N( R R R R R
( R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s c C� s | j t _ d S( N( R R R ( R R R R ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR � s ( R R R" R R ( ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR% � s c C� s� t g | d D] } | j r | ^ q � } | d } x' | d k r_ | j r_ | j d } q9 W| } x\ | d k r� | j d } x6 | d k r� | j r� Pn | j | _ | j d } q� W| } qi W| | f S( s* Remove deactivated handlers from the chaini i N( R R R
R ( R t ht stack_contextst headt ctxt parent( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt _remove_deactivated� s ,
c � s� � d k s t � d � r � St j g � � d d rh � d d rh � � f d � } t | _ | S� � f d � } t | _ | S( s
Returns a callable object that will restore the current `StackContext`
when executed.
Use this whenever saving a callback to be executed later in a
different execution context (either in a different thread or
asynchronously in the same thread).
t _wrappedi i c � s8 z' t j } � d t _ � | | � SWd | t _ Xd S( Ni ( R R ( t argst kwargst
current_state( t cap_contextst fn( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt null_wrapper s
c � s� d } z�t j } t � d � � d <} | t _ d } d } d } | d } xI | D]A } y | j � | d 7} WqV t j � } | j d } qV XqV W| d k r� y � | | � } Wq� t j � } | d } q� Xn | d k r� t | | � } n� x_ | d k rV| d 8} | | }
y |
j | � Wq� t j � } |
j d } Pq� Xq� Wd } | d k r{t | | � } n | d k r�t
| � n Wd | t _ X| S( Ni i ( NNN( NNN( R
R R R+ R t syst exc_infoR t _handle_exceptionR R ( R- R. t retR/ R t exct topt last_ctxt stackt nt c( R0 R1 ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt wrapped sP
N( R
t hasattrR R R R, ( R1 R2 R= ( ( R0 R1 s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt wrap� s C c C� sV xO | d k rQ y | j | � r* d } n Wn t j � } n X| j d } q W| S( Ni ( NNN( R
R R3 R4 R ( t tailR7 ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyR5 _ s
c C� s | � | � SWd QXd S( s� Run a coroutine ``func`` in the given `StackContext`.
It is not safe to have a ``yield`` statement within a ``with StackContext``
block, so it is difficult to use stack context with `.gen.coroutine`.
This helper function runs the function in the correct context while
keeping the ``yield`` and ``with`` statements syntactically separate.
Example::
@gen.coroutine
def incorrect():
with StackContext(ctx):
# ERROR: this will raise StackContextInconsistentError
yield other_coroutine()
@gen.coroutine
def correct():
yield run_with_stack_context(StackContext(ctx), other_coroutine)
.. versionadded:: 3.1
N( ( R t func( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt run_with_stack_contextl s ( R" t
__future__R R R R R3 t threadingt tornado.utilR t ExceptionR t localR R t objectR R# R% R+ R? R5 RB ( ( ( s; /usr/lib64/python2.7/site-packages/tornado/stack_context.pyt <module>C s " L0 c
Mini Shell