Supporting Procs as timeouts

README.md

@@ -92,6 +92,19 @@ parameters take precedence:
 use Rack::Timeout, service_timeout: 15, wait_timeout: 30
 ```
 
+```ruby
+# config/initializers/rack_timeout.rb
+
+# pass the conditional variables as a proc object
+Rails.application.config.middleware.insert_before(
+  Rack::Runtime,
+  Rack::Timeout,
+  service_timeout: ->(ENV) {
+    ENV['DEV'] || ENV['ADMIN']] || ENV.fetch('DEV_TIMEOUT', 15).to_i
+  }
+)
+```
+
 For more on these settings, please see [doc/settings](doc/settings.md).
 
 Further Documentation

lib/rack/timeout/core.rb

@@ -53,12 +53,27 @@ def read_timeout_property value, default
       when nil   ; read_timeout_property default, default
       when false ; false
       when 0     ; false
+      when Proc
+        value
+      when String
+        read_timeout_property value.to_i, default
       else
         value.is_a?(Numeric) && value > 0 or raise ArgumentError, "value #{value.inspect} should be false, zero, or a positive number."
         value
       end
     end
 
+    # New helper: if +value+ is a Proc, then it will be called with +*args+ and
+    # the result returned.  Otherwise, the +value+ is returned as is.
+    def proc_or_value(value, *args)
+      case value
+      when Proc
+        value.call(*args)
+      else
+        value
+      end
+    end
+
     attr_reader \
       :service_timeout,   # How long the application can take to complete handling the request once it's passed down to it.
       :wait_timeout,      # How long the request is allowed to have waited before reaching rack. If exceeded, the request is 'expired', i.e. dropped entirely without being passed down to the application.
@@ -86,6 +101,11 @@ def initialize(app, service_timeout:nil, wait_timeout:nil, wait_overtime:nil, se
       @app = app
     end
 
+    # Overriding attribute readers to evaluate Procs
+    def service_timeout; proc_or_value(@service_timeout, @env); end
+    def wait_timeout; proc_or_value(@wait_timeout, @env); end
+    def wait_overtime; proc_or_value(@wait_overtime, @env); end
+    def service_past_wait; proc_or_value(@service_past_wait, @env); end
 
     RT = self # shorthand reference
     def call(env)

test/basic_test.rb

@@ -14,6 +14,13 @@ def test_timeout
     end
   end
 
+  def test_timeout_with_proc
+    self.settings = { service_timeout: proc { 5 } }
+    assert_raises(Rack::Timeout::RequestTimeoutError) do
+      get "/sleep"
+    end
+  end
+
   def test_wait_timeout
     self.settings = { service_timeout: 1, wait_timeout: 15 }
     assert_raises(Rack::Timeout::RequestExpiryError) do