From 9fc7c145b3b8353d692ac4e6773c98c9f1960546 Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Mon, 11 Aug 2014 15:13:37 +1000
Subject: [PATCH] FEATURE: added method for draining idle connections

---
 lib/freedom_patches/pool_drainer.rb           | 33 +++++++++++++
 .../freedom_patches/pool_drainer_spec.rb      | 47 +++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 lib/freedom_patches/pool_drainer.rb
 create mode 100644 spec/components/freedom_patches/pool_drainer_spec.rb

diff --git a/lib/freedom_patches/pool_drainer.rb b/lib/freedom_patches/pool_drainer.rb
new file mode 100644
index 000000000..f953b32a4
--- /dev/null
+++ b/lib/freedom_patches/pool_drainer.rb
@@ -0,0 +1,33 @@
+
+class ActiveRecord::ConnectionAdapters::ConnectionPool
+
+  # drain all idle connections
+  # if idle_time is specified only connections idle for N seconds will be drained
+  def drain(idle_time=nil)
+    synchronize do
+      @available.clear
+      @connections.delete_if do |conn|
+        try_drain?(conn, idle_time)
+      end
+
+      @connections.each do |conn|
+        @available.add conn if !conn.in_use?
+      end
+    end
+
+  end
+
+  private
+
+  def try_drain?(conn, idle_time)
+    if !conn.in_use?
+      if !idle_time || conn.last_use < idle_time.seconds.ago
+        conn.disconnect!
+        return true
+      end
+    end
+
+    false
+  end
+
+end
diff --git a/spec/components/freedom_patches/pool_drainer_spec.rb b/spec/components/freedom_patches/pool_drainer_spec.rb
new file mode 100644
index 000000000..9ebfd0e69
--- /dev/null
+++ b/spec/components/freedom_patches/pool_drainer_spec.rb
@@ -0,0 +1,47 @@
+require 'spec_helper'
+
+describe 'pool drainer' do
+  let(:pool) do
+    ActiveRecord::Base.connection_pool
+  end
+
+  it 'can correctly drain the connection pool' do
+    pool.drain
+    old = pool.connections.length
+    old.should == 1
+
+    Thread.new do
+      conn = pool.checkout
+      pool.checkin conn
+    end.join
+
+    pool.connections.length.should == (old+1)
+    pool.drain
+    pool.connections.length.should == old
+  end
+
+  it 'can drain with idle time setting' do
+    pool.drain
+    old = pool.connections.length
+    old.should == 1
+
+
+    Thread.new do
+      conn = pool.checkout
+      pool.checkin conn
+    end.join
+
+    pool.connections.length.should == (old+1)
+    pool.drain(1.minute)
+    pool.connections.length.should == (old+1)
+
+    # make sure we don't corrupt internal state
+    20.times do
+      conn = pool.checkout
+      pool.checkin conn
+      pool.drain
+    end
+
+  end
+
+end