@@ -25,10 +25,9 @@ module Invidious::ConnectionPool
2525 # Streaming API for {{method.id.upcase}} request.
2626 # The response will have its body as an `IO` accessed via `HTTP::Client::Response#body_io`.
2727 def {{method.id}} (* args , ** kwargs, & )
28- self .checkout do | client |
28+ self .checkout_with_retry do | client |
2929 client.{{method.id}}(* args, ** kwargs) do | response |
30- result = yield response
31- return result
30+ return yield response
3231 ensure
3332 response.body_io?.try & .skip_to_end
3433 end
@@ -38,45 +37,82 @@ module Invidious::ConnectionPool
3837 # Executes a {{method.id.upcase}} request.
3938 # The response will have its body as a `String`, accessed via `HTTP::Client::Response#body`.
4039 def {{method.id}} (* args , ** kwargs)
41- self .checkout do | client |
40+ self .checkout_with_retry do | client |
4241 return client.{{method.id}}(* args, ** kwargs)
4342 end
4443 end
4544 {% end % }
4645
4746 # Checks out a client in the pool
47+ #
48+ # This method will NOT delete a client that has errored from the pool.
49+ # Use `#checkout_with_retry` to ensure that the pool does not get poisoned.
4850 def checkout (& )
49- # If a client has been deleted from the pool
50- # we won't try to release it
51- client_exists_in_pool = true
52-
53- http_client = pool.checkout
54-
55- # When the HTTP::Client connection is closed, the automatic reconnection
56- # feature will create a new IO to connect to the server with
57- #
58- # This new TCP IO will be a direct connection to the server and will not go
59- # through the proxy. As such we'll need to reinitialize the proxy connection
60-
61- http_client.proxy = make_configured_http_proxy_client() if @reinitialize_proxy && CONFIG .http_proxy
62-
63- response = yield http_client
64- rescue ex : DB ::PoolTimeout
65- # Failed to checkout a client
66- raise ConnectionPool ::PoolCheckoutError .new(ex.message)
67- rescue ex
68- # An error occurred with the client itself.
69- # Delete the client from the pool and close the connection
70- if http_client
71- client_exists_in_pool = false
72- @pool .delete(http_client)
73- http_client.close
51+ pool.checkout do |client |
52+ # When the HTTP::Client connection is closed, the automatic reconnection
53+ # feature will create a new IO to connect to the server with
54+ #
55+ # This new TCP IO will be a direct connection to the server and will not go
56+ # through the proxy. As such we'll need to reinitialize the proxy connection
57+ client.proxy = make_configured_http_proxy_client() if @reinitialize_proxy && CONFIG .http_proxy
58+
59+ response = yield client
60+
61+ return response
62+ rescue ex : DB ::PoolTimeout
63+ # Failed to checkout a client
64+ raise ConnectionPool ::PoolCheckoutError .new(ex.message)
7465 end
66+ end
7567
76- # Raise exception for outer methods to handle
77- raise ConnectionPool ::Error .new(ex.message, cause: ex)
78- ensure
79- pool.release(http_client) if http_client && client_exists_in_pool
68+ # Checks out a client from the pool; retries only if a connection is lost or refused
69+ #
70+ # Will cycle through all of the existing connections at no delay, but any new connections
71+ # that is created will be subject to a delay.
72+ #
73+ # The first attempt to make a new connection will not have the delay, but all subsequent
74+ # attempts will.
75+ #
76+ # To `DB::Pool#retry`:
77+ # - `DB::PoolResourceLost` means that the connection has been lost
78+ # and should be deleted from the pool.
79+ #
80+ # - `DB::PoolResourceRefused` means a new connection was intended to be created but failed
81+ # but the client can be safely released back into the pool to try again later with
82+ #
83+ # See the following code of `crystal-db` for more information
84+ #
85+ # https://github.com/crystal-lang/crystal-db/blob/023dc5de90c11927656fc747601c5f08ea3c906f/src/db/pool.cr#L191
86+ # https://github.com/crystal-lang/crystal-db/blob/023dc5de90c11927656fc747601c5f08ea3c906f/src/db/pool_statement.cr#L41
87+ # https://github.com/crystal-lang/crystal-db/blob/023dc5de90c11927656fc747601c5f08ea3c906f/src/db/pool_prepared_statement.cr#L13
88+ #
89+ def checkout_with_retry (& )
90+ @pool .retry do
91+ self .checkout do |client |
92+ begin
93+ return yield client
94+ rescue ex : IO ::TimeoutError
95+ LOGGER .trace(" Client: #{ client } "
96+ raise DB ::PoolResourceRefused .new
97+ rescue ex : InfoException
98+ raise ex
99+ rescue ex : Exception
100+ # Any other errors should cause the client to be deleted from the pool
101+
102+ # This means that the client is closed and needs to be deleted from the pool
103+ # due its inability to reconnect
104+ if ex.message == " This HTTP::Client cannot be reconnected"
105+ LOGGER .trace(" Checked out client is closed and cannot be reconnected. Trying the next retry attempt..."
106+ else
107+ LOGGER .error(" Client: #{ client } #{ ex } #{ ex.message } "
108+ end
109+
110+ raise DB ::PoolResourceLost (HTTP ::Client ).new(client)
111+ end
112+ end
113+ rescue ex : DB ::PoolRetryAttemptsExceeded
114+ raise PoolRetryAttemptsExceeded .new
115+ end
80116 end
81117 end
82118
@@ -87,6 +123,10 @@ module Invidious::ConnectionPool
87123 class PoolCheckoutError < Error
88124 end
89125
126+ # Raised when too many retries
127+ class PoolRetryAttemptsExceeded < Error
128+ end
129+
90130 # Mapping of subdomain => Invidious::ConnectionPool::Pool
91131 # This is needed as we may need to access arbitrary subdomains of ytimg
92132 private YTIMG_POOLS = {} of String => ConnectionPool ::Pool
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