tornado.tcpserver — Basic IOStream-based TCP server Coroutines and concurrency tornado.gen — Generator-based coroutines tornado.locks – Synchronization primitives tornado.queues – Queues for coroutines AsyncHTTPClient() my_future = Future() fetch_future = http_client.fetch(url) def on_fetch(f):my_future.set_result(f.result().body) fetch_future.add_done_callback(on_fetch) return my_future Notice yield is a generator. All generators are asynchronous; when called they return a generator object instead of running to completion. The @gen.coroutine decorator communicates with the generator via the yield

AsyncHTTPClient() my_future = Future() fetch_future = http_client.fetch(url) def on_fetch(f): my_future.set_result(f.result().body) fetch_future.add_done_callback(on_fetch) return my_future Notice that the yield is a generator. All generators are asynchronous; when called they return a generator object instead of running to completion. The @gen.coroutine decorator communicates with the generator via the yield decorator receives a Future from the generator, waits (without blocking) for that Future to complete, then “un- wraps” the Future and sends the result back into the generator as the result of the yield expression

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 19.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 690 42.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703 42.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 19.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 690 42.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703 42.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773 43.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 789 43.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773 43.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 789 43.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773 43.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 789 43.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 806 44.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 822 44.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 805 44.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 821 44.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 805 44.7 Set-Like Collections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 821 44.8 Dequeues mathematical use. More precisely, the set of all finite-length strings S together with the string concatenation operator * forms a free monoid (S, *). The identity element of this set is the empty string, "". Whenever