From bd3ed0b04f826b20cce83f9b77fc13c0eefd3902 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Wed, 18 Aug 2010 23:59:21 -0700
Subject: add Rainbows::ThreadTimeout middleware

This allows for per-dispatch timeouts similar to (but not exactly)
the way Mongrel (1.1.x) implemented them with threads.
---
 lib/rainbows/thread_timeout.rb | 94 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 lib/rainbows/thread_timeout.rb

(limited to 'lib/rainbows/thread_timeout.rb')

diff --git a/lib/rainbows/thread_timeout.rb b/lib/rainbows/thread_timeout.rb
new file mode 100644
index 0000000..53c675b
--- /dev/null
+++ b/lib/rainbows/thread_timeout.rb
@@ -0,0 +1,94 @@
+# -*- encoding: binary -*-
+require 'thread'
+
+# Soft timeout middleware for thread-based concurrency models in \Rainbows!
+# This timeout only includes application dispatch, and will not take into
+# account the (rare) response bodies that are dynamically generated while
+# they are being written out to the client.
+#
+# In your rackup config file (config.ru), the following line will
+# cause execution to timeout in 1.5 seconds.
+#
+#    use Rainbows::ThreadTimeout, :timeout => 1.5
+#    run MyApplication.new
+#
+# You may also specify a threshold, so the timeout does not take
+# effect until there are enough active clients.  It does not make
+# sense to set a +:threshold+ higher or equal to the
+# +worker_connections+ \Rainbows! configuration parameter.
+# You may specify a negative threshold to be an absolute
+# value relative to the +worker_connections+ parameter, thus
+# if you specify a threshold of -1, and have 100 worker_connections,
+# ThreadTimeout will only activate when there are 99 active requests.
+#
+#    use Rainbows::ThreadTimeout, :timeout => 1.5, :threshold => -1
+#    run MyApplication.new
+#
+# This middleware only affects elements below it in the stack, so
+# it can be configured to ignore certain endpoints or middlewares.
+#
+# Timed-out requests will cause this middleware to return with a
+# "408 Request Timeout" response.
+
+class Rainbows::ThreadTimeout < Struct.new(:app, :timeout,
+                                           :threshold, :watchdog,
+                                           :active, :lock)
+
+  # :stopdoc:
+  class ExecutionExpired < ::Exception
+  end
+
+  def initialize(app, opts)
+    timeout = opts[:timeout]
+    Numeric === timeout or
+      raise TypeError, "timeout=#{timeout.inspect} is not numeric"
+
+    if threshold = opts[:threshold]
+      Integer === threshold or
+        raise TypeError, "threshold=#{threshold.inspect} is not an integer"
+      threshold == 0 and
+        raise ArgumentError, "threshold=0 does not make sense"
+      threshold < 0 and
+        threshold += Rainbows::G.server.worker_connections
+    end
+    super(app, timeout, threshold, nil, {}, Mutex.new)
+  end
+
+  def call(env)
+    lock.synchronize do
+      start_watchdog unless watchdog
+      active[Thread.current] = Time.now + timeout
+    end
+    begin
+      app.call(env)
+    ensure
+      lock.synchronize { active.delete(Thread.current) }
+    end
+    rescue ExecutionExpired
+      [ 408, { 'Content-Type' => 'text/plain', 'Content-Length' => '0' }, [] ]
+  end
+
+  def start_watchdog
+    self.watchdog = Thread.new do
+      begin
+        if next_wake = lock.synchronize { active.values }.min
+          next_wake -= Time.now
+          sleep(next_wake) if next_wake > 0
+        else
+          sleep(timeout)
+        end
+
+        # "active.size" is atomic in MRI 1.8 and 1.9
+        next if threshold && active.size < threshold
+
+        now = Time.now
+        lock.synchronize do
+          active.delete_if do |thread, time|
+            time >= now and thread.raise(ExecutionExpired).nil?
+          end
+        end
+      end while true
+    end
+  end
+  # :startdoc:
+end
-- 
cgit v1.2.3-24-ge0c7