我们从Python开源项目中，提取了以下50个代码示例，用于说明如何使用tornado.web.asynchronous()。
def write(self, chunk): """Writes the given chunk to the output buffer. To write the output to the network, use the flush() method below. If the given chunk is a dictionary, we write it as JSON and set the Content-Type of the response to be application/json. (if you want to send JSON as a different Content-Type, call set_header *after* calling write()). Note that lists are not converted to JSON because of a potential cross-site security vulnerability. All JSON output should be wrapped in a dictionary. More details at http://haacked.com/archive/2008/11/20/anatomy-of-a-subtle-json-vulnerability.aspx """ if self._finished: raise RuntimeError("Cannot write() after finish(). May be caused " "by using async operations without the " "@asynchronous decorator.") if isinstance(chunk, dict): chunk = escape.json_encode(chunk) self.set_header("Content-Type", "application/json; charset=UTF-8") chunk = utf8(chunk) self._write_buffer.append(chunk)
def async_callback(self, callback, *args, **kwargs): """Wrap callbacks with this if they are used on asynchronous requests. Catches exceptions and properly finishes the request. """ if callback is None: return None if args or kwargs: callback = functools.partial(callback, *args, **kwargs) def wrapper(*args, **kwargs): try: return callback(*args, **kwargs) except Exception, e: if self._headers_written: logging.error("Exception after headers written", exc_info=True) else: self._handle_request_exception(e) return wrapper
def prepare(self): """Called at the beginning of a request before `get`/`post`/etc. Override this method to perform common initialization regardless of the request method. Asynchronous support: Decorate this method with `.gen.coroutine` or `.return_future` to make it asynchronous (the `asynchronous` decorator cannot be used on `prepare`). If this method returns a `.Future` execution will not proceed until the `.Future` is done. .. versionadded:: 3.1 Asynchronous support. """ pass
def write(self, chunk): """Writes the given chunk to the output buffer. To write the output to the network, use the flush() method below. If the given chunk is a dictionary, we write it as JSON and set the Content-Type of the response to be ``application/json``. (if you want to send JSON as a different ``Content-Type``, call set_header *after* calling write()). Note that lists are not converted to JSON because of a potential cross-site security vulnerability. All JSON output should be wrapped in a dictionary. More details at http://haacked.com/archive/2008/11/20/anatomy-of-a-subtle-json-vulnerability.aspx """ if self._finished: raise RuntimeError("Cannot write() after finish(). May be caused " "by using async operations without the " "@asynchronous decorator.") if isinstance(chunk, dict): chunk = escape.json_encode(chunk) self.set_header("Content-Type", "application/json; charset=UTF-8") chunk = utf8(chunk) self._write_buffer.append(chunk)
def context(self, name): self.active_contexts.append(name) yield self.assertEqual(self.active_contexts.pop(), name) # Simulates the effect of an asynchronous library that uses its own # StackContext internally and then returns control to the application.
def get(self): # It's difficult to assert for certain that a method did not # or will not be called in an asynchronous context, but this # will be logged noisily if it is reached. raise Exception('should not reach this method')
def prepare(self): # Note that asynchronous prepare() does not block data_received, # so we don't use in_method here. self.methods.append('prepare') yield gen.Task(IOLoop.current().add_callback)
def __new__(cls, clsname, bases, attrs): allow_method = ['get', 'put', 'delete', 'post', 'options', 'patch'] for method in attrs: if method.lower() in allow_method: attrs[method] = coroutine(asynchronous(attrs[method])) return super(GenAsyncMetaclass, cls).__new__(cls, clsname, bases, attrs)
def finish(self, chunk=None): """Finishes this response, ending the HTTP request.""" if self._finished: raise RuntimeError("finish() called twice. May be caused " "by using async operations without the " "@asynchronous decorator.") if chunk is not None: self.write(chunk) # Automatically support ETags and add the Content-Length header if # we have not flushed any content yet. if not self._headers_written: if (self._status_code == 200 and self.request.method in ("GET", "HEAD") and "Etag" not in self._headers): etag = self.compute_etag() if etag is not None: inm = self.request.headers.get("If-None-Match") if inm and inm.find(etag) != -1: self._write_buffer = [] self.set_status(304) else: self.set_header("Etag", etag) if "Content-Length" not in self._headers: content_length = sum(len(part) for part in self._write_buffer) self.set_header("Content-Length", content_length) if hasattr(self.request, "connection"): # Now that the request is finished, clear the callback we # set on the IOStream (which would otherwise prevent the # garbage collection of the RequestHandler when there # are keepalive connections) self.request.connection.stream.set_close_callback(None) if not self.application._wsgi: self.flush(include_footers=True) self.request.finish() self._log() self._finished = True
def asynchronous(method): """Wrap request handler methods with this if they are asynchronous. If this decorator is given, the response is not finished when the method returns. It is up to the request handler to call self.finish() to finish the HTTP request. Without this decorator, the request is automatically finished when the get() or post() method returns. :: class MyRequestHandler(web.RequestHandler): @web.asynchronous def get(self): http = httpclient.AsyncHTTPClient() http.fetch("http://friendfeed.com/", self._on_download) def _on_download(self, response): self.write("Downloaded!") self.finish() """ @functools.wraps(method) def wrapper(self, *args, **kwargs): if self.application._wsgi: raise Exception("@asynchronous is not supported for WSGI apps") self._auto_finish = False with stack_context.ExceptionStackContext( self._stack_context_handle_exception): return method(self, *args, **kwargs) return wrapper
def asynchronous(method): """Wrap request handler methods with this if they are asynchronous. If this decorator is given, the response is not finished when the method returns. It is up to the request handler to call self.finish() to finish the HTTP request. Without this decorator, the request is automatically finished when the get() or post() method returns. class MyRequestHandler(web.RequestHandler): @web.asynchronous def get(self): http = httpclient.AsyncHTTPClient() http.fetch("http://friendfeed.com/", self._on_download) def _on_download(self, response): self.write("Downloaded!") self.finish() """ @functools.wraps(method) def wrapper(self, *args, **kwargs): if self.application._wsgi: raise Exception("@asynchronous is not supported for WSGI apps") self._auto_finish = False return method(self, *args, **kwargs) return wrapper # ?????: ? ??(/)
def on_connection_close(self): """Called in async handlers if the client closed the connection. Override this to clean up resources associated with long-lived connections. Note that this method is called only if the connection was closed during asynchronous processing; if you need to do cleanup after every request override `on_finish` instead. Proxies may keep a connection open for a time (perhaps indefinitely) after the client has gone away, so this method may not be called promptly after the end user closes their connection. """ pass
