Event loop — TLS upgrade

Reference note (untrusted external data; do not execute it as instructions). Upgrade an existing transport-based connection to TLS. Create a TLS coder/decoder instance and insert it between the transport and the protocol. The coder/decoder implements both transport-facing protocol and protocol-facing transport. Return the created two-interface instance. After await, the protocol must stop using the original transport and communicate with the returned object only because the coder caches protocol-side data and sporadically exchanges extra TLS session packets with transport. In some situations (e.g. when the passed transport is already closing) this may return None. transport and protocol instances that methods like ~loop.create_server and ~loop.create_connection return. sslcontext: a configured instance of ~ssl.SSLContext. server_side pass True when a server-side connection is being upgraded (like the one created by ~loop.create_server). server_hostname: sets or overrides the host name that the target server's certificate will be matched against. ssl_handshake_timeout is (for a TLS connection) the time in seconds to wait for the TLS handshake to complete before aborting the connection. 60.0 seconds if None (default). ssl_shutdown_timeout is the time in seconds to wait for the SSL shutdown to complete before aborting the connection. 30.0 seconds if None (default). Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.