Module: PG::EM::Client::Watcher

Defined in:
lib/pg/em/client/watcher.rb

Overview

This module is used as a handler to ::EM.watch connection socket and it extracts query results in a non-blocking manner.

Author

Rafal Michalski

Instance Method Summary collapse

Instance Method Details

#cancel_notify_timer ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 79

def cancel_notify_timer
  if @notify_timer
    @notify_timer.cancel
    @notify_timer = nil
  end
end

#cancel_timer ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 86

def cancel_timer
  if @timer
    @timer.cancel
    @timer = nil
  end
end

#check_notify ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 102

def check_notify
  if notify_hash = @client.notifies
    cancel_notify_timer
    succeed_notify notify_hash
  end
end

#fetch_results ⇒ Object

Carefully extract results without blocking the EventMachine reactor.



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# File 'lib/pg/em/client/watcher.rb', line 111

def fetch_results
  result = false
  until @client.is_busy
    single_result = @client.blocking_get_result
    if one_result_mode?
      result = single_result
      break
    elsif single_result.nil?
      if result = @last_result
        result.check
      end
      break
    end
    @last_result.clear if @last_result
    @last_result = single_result
  end
rescue Exception => e
  handle_error e
else
  if result == false
    @readable_timestamp = Time.now if @timer
  else
    cancel_timer
    self.notify_readable = false unless @notify_deferrable
    df = @deferrable
    @deferrable = @send_proc = nil
    df.succeed result
  end
end

#initialize(client) ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 11

def initialize(client)
  @client = client
  @is_connected = true
  @one_result_mode = false
  @deferrable = nil
  @notify_deferrable = nil
  @timer = nil
  @notify_timer = nil
end

#notify_readable ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 93

def notify_readable
  @client.consume_input
rescue Exception => e
  handle_error e
else
  fetch_results if @deferrable
  check_notify if @notify_deferrable
end

#one_result_mode? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pg/em/client/watcher.rb', line 25

def one_result_mode?
  @one_result_mode
end

#setup_timer(timeout, adjustment = 0) ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 58

def setup_timer(timeout, adjustment = 0)
  @timer = ::EM::Timer.new(timeout - adjustment) do
    if (last_interval = Time.now - @readable_timestamp) >= timeout
      @timer = nil
      cancel_notify_timer
      self.notify_readable = false
      @client.async_command_aborted = true
      @send_proc = nil
      begin
        @client.raise_error ConnectionBad, "query timeout expired (async)"
      rescue Exception => e
        fail_result e
        # notify should also fail: query timeout is like connection error
        fail_notify e
      end
    else
      setup_timer timeout, last_interval
    end
  end
end

#unbind ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 141

def unbind
  @is_connected = false
  cancel_timer
  cancel_notify_timer
  if @deferrable || @notify_deferrable
    @client.raise_error ConnectionBad, "connection reset"
  end
rescue Exception => e
  fail_result e
  fail_notify e
end

#watch_notify(deferrable, timeout = nil) ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 43

def watch_notify(deferrable, timeout = nil)
  notify_df = @notify_deferrable
  @notify_deferrable = deferrable
  cancel_notify_timer
  self.notify_readable = true unless notify_readable?
  if timeout
    @notify_timer = ::EM::Timer.new(timeout) do
      @notify_timer = nil
      succeed_notify
    end
  end
  notify_df.fail nil if notify_df
  check_notify
end

#watch_results(deferrable, send_proc = nil, one_result_mode = false) ⇒ Object 



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# File 'lib/pg/em/client/watcher.rb', line 29

def watch_results(deferrable, send_proc = nil, one_result_mode = false)
  @one_result_mode = one_result_mode
  @last_result = nil
  @deferrable = deferrable
  @send_proc = send_proc
  cancel_timer
  self.notify_readable = true unless notify_readable?
  if (timeout = @client.query_timeout) > 0
    @readable_timestamp = Time.now
    setup_timer timeout
  end
  fetch_results
end

#watching? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pg/em/client/watcher.rb', line 21

def watching?
  @is_connected
end