Merge pull request #327 from byroot/pooling-without-idle-timeout

Allow to disable both connection pooling and pruning idependently

Author: mattbrictson

CHANGELOG.md

@@ -4,7 +4,8 @@ This file is written in reverse chronological order, newer releases will
 appear at the top.
 
 ## `master` (Unreleased)
-
+  * `SSHKit::Backend::Netssh.pool.idle_timeout = 0` doesn't disable connection pooling anymore,
+    only connection expiration. To disable connection polling use `SSHKit::Backend::Netssh.pool.enabled = false`
   * Add your entries below here, remember to credit yourself however you want
     to be credited!
   * make sure working directory for commands is properly cleared after `within` blocks

README.md

@@ -500,13 +500,18 @@ seconds. This timeout can be changed as follows:
 SSHKit::Backend::Netssh.pool.idle_timeout = 60 # seconds
 ```
 
-If you suspect the connection pooling is causing problems, you can disable the
-pooling behaviour entirely by setting the idle_timeout to zero:
+If you suspect the connection pruning is causing problems, you can disable the
+expiration behaviour entirely by setting the idle_timeout to zero:
 
 ```ruby
 SSHKit::Backend::Netssh.pool.idle_timeout = 0 # disabled
 ```
 
+Or even disable the pooling entirely, but it will severely reduce performance:
+```
+SSHKit::Backend::Netssh.pool.enabled = false # disabled
+```
+
 ## Tunneling and other related SSH themes
 
 In order to do special gymnasitcs with SSH, tunneling, aliasing, complex options, etc with SSHKit it is possible to use [the underlying Net::SSH API](https://github.com/capistrano/sshkit/blob/master/EXAMPLES.md#setting-global-ssh-options) however in many cases it is preferred to use the system SSH configuration file at [`~/.ssh/config`](http://man.cx/ssh_config). This allows you to have personal configuration tied to your machine that does not have to be committed with the repository. If this is not suitable (everyone on the team needs a proxy command, or some special aliasing) a file in the same format can be placed in the project directory at `~/yourproject/.ssh/config`, this will be merged with the system settings in `~/.ssh/config`, and with any configuration specified in [`SSHKit::Backend::Netssh.config.ssh_options`](https://github.com/capistrano/sshkit/blob/master/lib/sshkit/backends/netssh.rb#L133).

lib/sshkit/backends/connection_pool.rb

@@ -19,28 +19,35 @@ module Backend
 
     class ConnectionPool
 
-      attr_accessor :idle_timeout
+      attr_accessor :idle_timeout, :enabled
 
       def initialize
         self.idle_timeout = 30
+        self.enabled = true
         @mutex = Mutex.new
         @pool = {}
       end
 
+      def prune_expired?
+        idle_timeout && idle_timeout != 0
+      end
+
       def checkout(*new_connection_args, &block)
         entry = nil
         key = new_connection_args.to_s
-        if idle_timeout
-          prune_expired
+        if enabled
+          prune_expired if prune_expired?
           entry = find_live_entry(key)
         end
         entry || create_new_entry(new_connection_args, key, &block)
       end
 
       def checkin(entry)
-        if idle_timeout
-          prune_expired
-          entry.expires_at = Time.now + idle_timeout
+        if enabled
+          if prune_expired?
+            entry.expires_at = Time.now + idle_timeout
+            prune_expired
+          end
           @mutex.synchronize do
             @pool[entry.key] ||= []
             @pool[entry.key] << entry

test/unit/backends/test_connection_pool.rb

@@ -73,9 +73,16 @@ def test_connections_are_reused_across_threads_multiple_times
         assert_equal t2[:conn], t3[:conn]
       end
 
-      def test_zero_idle_timeout_disables_reuse
+      def test_zero_idle_timeout_disables_pruning
         pool.idle_timeout = 0
 
+        conn1 = pool.checkout("conn", &connect)
+        assert_nil conn1.expires_at
+      end
+
+      def test_enabled_false_disables_pooling
+        pool.enabled = false
+
         conn1 = pool.checkout("conn", &connect)
         pool.checkin conn1