Add support for setting max idle http pool size

config/config.example.yml

@@ -206,7 +206,7 @@ https_only: false
 #disable_proxy: false
 
 ##
-## Size of the HTTP pool used to connect to youtube. Each
+## Max size of the HTTP pool used to connect to youtube. Each
 ## domain ('youtube.com', 'ytimg.com', ...) has its own pool.
 ##
 ## Accepted values: a positive integer
@@ -215,6 +215,19 @@ https_only: false
 #pool_size: 100
 
 
+##
+## Idle size of the HTTP pool used to connect to youtube. Each
+## domain ('youtube.com', 'ytimg.com', ...) has its own pool.
+##
+## When unset this value has the same value as pool_size 
+##
+## Accepted values: a positive integer
+## Default: <none> (internally this means that it has the same value as pool_size)
+##
+#idle pool_size: 100
+
+
+
 ##
 ## Additional cookies to be sent when requesting the youtube API.
 ##

src/invidious.cr

@@ -91,14 +91,19 @@ SOFTWARE = {
   "branch"  => "#{CURRENT_BRANCH}",
 }
 
-YT_POOL = YoutubeConnectionPool.new(YT_URL, capacity: CONFIG.pool_size)
+YT_POOL = YoutubeConnectionPool.new(YT_URL, max_capacity: CONFIG.pool_size, idle_capacity: CONFIG.idle_pool_size)
 
 # Image request pool
 
-GGPHT_POOL = YoutubeConnectionPool.new(URI.parse("https://yt3.ggpht.com"), capacity: CONFIG.pool_size)
+GGPHT_POOL = YoutubeConnectionPool.new(
+  URI.parse("https://yt3.ggpht.com"),
+  max_capacity: CONFIG.pool_size,
+  idle_capacity: CONFIG.idle_pool_size
+)
 
 COMPANION_POOL = CompanionConnectionPool.new(
-  capacity: CONFIG.pool_size
+  max_capacity: CONFIG.pool_size,
+  idle_capacity: CONFIG.idle_pool_size
 )
 
 # CLI

src/invidious/config.cr

@@ -157,8 +157,12 @@ class Config
   property host_binding : String = "0.0.0.0"
   # Path and permissions to make Invidious listen on a UNIX socket instead of a TCP port
   property socket_binding : SocketBindingConfig? = nil
-  # Pool size for HTTP requests to youtube.com and ytimg.com (each domain has a separate pool of `pool_size`)
+
+  # Max pool size for HTTP requests to youtube.com and ytimg.com (each domain has a separate pool)
   property pool_size : Int32 = 100
+  # Idle pool size for HTTP requests to youtube.com and ytimg.com (each domain has a separate pool)
+  property idle_pool_size : Int32? = nil
+
   # HTTP Proxy configuration
   property http_proxy : HTTPProxyConfig? = nil
 

src/invidious/yt_backend/connection_pool.cr

@@ -4,11 +4,24 @@ private YTIMG_POOLS = {} of String => YoutubeConnectionPool
 
 struct YoutubeConnectionPool
   property! url : URI
-  property! capacity : Int32
+  property! max_capacity : Int32
+  property! idle_capacity : Int32
   property! timeout : Float64
   property pool : DB::Pool(HTTP::Client)
 
-  def initialize(url : URI, @capacity = 5, @timeout = 5.0)
+  def initialize(
+    url : URI,
+    *,
+    @max_capacity : Int32 = 5,
+    idle_capacity : Int32? = nil,
+    @timeout : Float64 = 5.0,
+  )
+    if idle_capacity.nil?
+      @idle_capacity = @max_capacity
+    else
+      @idle_capacity = idle_capacity
+    end
+
     @url = url
     @pool = build_pool()
   end
@@ -33,10 +46,12 @@ struct YoutubeConnectionPool
   end
 
   private def build_pool
+    # We call the getter for the instance variables instead of using them directly
+    # because the getters defined by property! ensures that the value is not a nil
     options = DB::Pool::Options.new(
       initial_pool_size: 0,
-      max_pool_size: capacity,
-      max_idle_pool_size: capacity,
+      max_pool_size: max_capacity,
+      max_idle_pool_size: idle_capacity,
       checkout_timeout: timeout
     )
 
@@ -47,13 +62,22 @@ struct YoutubeConnectionPool
 end
 
 struct CompanionConnectionPool
+  property! max_capacity : Int32
+  property! idle_capacity : Int32
+  property! timeout : Float64
   property pool : DB::Pool(HTTP::Client)
 
-  def initialize(capacity = 5, timeout = 5.0)
+  def initialize(*, @max_capacity : Int32 = 5, idle_capacity : Int32? = nil, @timeout : Float64 = 5.0)
+    if idle_capacity.nil?
+      @idle_capacity = @max_capacity
+    else
+      @idle_capacity = idle_capacity
+    end
+
     options = DB::Pool::Options.new(
       initial_pool_size: 0,
-      max_pool_size: capacity,
-      max_idle_pool_size: capacity,
+      max_pool_size: max_capacity,
+      max_idle_pool_size: idle_capacity.not_nil!,
       checkout_timeout: timeout
     )
 
@@ -145,7 +169,11 @@ def get_ytimg_pool(subdomain)
     return pool
   else
     LOGGER.info("ytimg_pool: Creating a new HTTP pool for \"https://#{subdomain}.ytimg.com\"")
-    pool = YoutubeConnectionPool.new(URI.parse("https://#{subdomain}.ytimg.com"), capacity: CONFIG.pool_size)
+    pool = YoutubeConnectionPool.new(
+      URI.parse("https://#{subdomain}.ytimg.com"),
+      max_capacity: CONFIG.pool_size,
+      idle_capacity: CONFIG.idle_pool_size
+    )
     YTIMG_POOLS[subdomain] = pool
 
     return pool