Class: SSHKit::Backend::ConnectionPool

Inherits:
Object
  • Object
show all
Defined in:
lib/sshkit/backends/connection_pool.rb

Overview

The ConnectionPool caches connections and allows them to be reused, so long as the reuse happens within the ‘idle_timeout` period. Timed out connections are eventually closed, forcing a new connection to be used in that case.

Additionally, a background thread is started to check for abandoned connections that have timed out without any attempt at being reused. These are eventually closed as well and removed from the cache.

If ‘idle_timeout` set to `false`, `0`, or `nil`, no caching is performed, and a new connection is created and then immediately closed each time. The default timeout is 30 (seconds).

There is a single public method: ‘with`. Example usage:

pool = SSHKit::Backend::ConnectionPool.new
pool.with(Net::SSH.method(:start), "host", "username") do |connection|
  # do stuff with connection
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(idle_timeout = 30) ⇒ ConnectionPool

Returns a new instance of ConnectionPool.



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# File 'lib/sshkit/backends/connection_pool.rb', line 44

def initialize(idle_timeout=30)
  @idle_timeout = idle_timeout
  @caches = {}
  @caches.extend(MonitorMixin)
  @timed_out_connections = Queue.new

  # Spin up eviction loop only if caching is enabled
  if cache_enabled?
    Thread.new { run_eviction_loop }
  end
end

Instance Attribute Details

#idle_timeout ⇒ Object

Returns the value of attribute idle_timeout.



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# File 'lib/sshkit/backends/connection_pool.rb', line 42

def idle_timeout
  @idle_timeout
end

Instance Method Details

#close_connections ⇒ Object

Immediately close all cached connections and empty the pool.



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# File 'lib/sshkit/backends/connection_pool.rb', line 80

def close_connections
  caches.synchronize do
    caches.values.each(&:clear)
    caches.clear
    process_deferred_close
  end
end

#flush_connections ⇒ Object

Immediately remove all cached connections, without closing them. This only exists for unit test purposes.



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# File 'lib/sshkit/backends/connection_pool.rb', line 75

def flush_connections
  caches.synchronize { caches.clear }
end

#with(connection_factory, *args) ⇒ Object

Creates a new connection or reuses a cached connection (if possible) and yields the connection to the given block. Connections are created by invoking the ‘connection_factory` proc with the given `args`. The arguments are used to construct a key used for caching.



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# File 'lib/sshkit/backends/connection_pool.rb', line 60

def with(connection_factory, *args)
  cache = find_cache(args)
  conn = cache.pop || begin
    connection_factory.call(*args)
  end
  yield(conn)
ensure
  cache.push(conn) unless conn.nil?
  # Sometimes the args mutate as a result of opening a connection. In this
  # case we need to update the cache key to match the new args.
  update_key_if_args_changed(cache, args)
end