Class: CouchWatcher::DatabaseListener

Inherits:
Object
  • Object
show all
Defined in:
lib/couchwatcher/database_listener.rb

Instance Method Summary collapse

Constructor Details

#initialize(database_url) ⇒ DatabaseListener

Returns a new instance of DatabaseListener.



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# File 'lib/couchwatcher/database_listener.rb', line 14

def initialize(database_url)
  @database_url = database_url
  @last_sequence = nil
  @thread = nil
  @DatabaseCallback = Struct.new(:callback_proc, :include_document) 
  @database_callbacks = []
  @DocumentCallback = Struct.new(:document_id, :callback_proc, :include_document) 
  @document_callbacks = []
end

Instance Method Details

#add_database_callback(callback_proc, include_document) ⇒ Object 



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# File 'lib/couchwatcher/database_listener.rb', line 24

def add_database_callback(callback_proc, include_document)
  if !@thread.nil?
    say "Error: cannot add callbacks to a running listener", :red
    return nil
  end
  
  database_callback = @DatabaseCallback.new(callback_proc, include_document)
  @database_callbacks << database_callback
  return database_callback
end

#add_document_callback(document_id, callback_proc, include_document) ⇒ Object 



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# File 'lib/couchwatcher/database_listener.rb', line 44

def add_document_callback(document_id, callback_proc, include_document)
  if !@thread.nil?
    say "Error: cannot add callbacks to a running listener", :red
    return nil
  end

  document_callback = @DocumentCallback.new(document_id, callback_proc, include_document)
  @document_callbacks << document_callback
  return document_callback
end

#remove_database_callback(database_callback) ⇒ Object 



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# File 'lib/couchwatcher/database_listener.rb', line 35

def remove_database_callback(database_callback)
  if !@thread.nil?
    say "Error: cannot remove callbacks from a running listener", :red
    return
  end

  @database_callbacks.delete(database_callback)
end

#remove_document_callback(document_callback) ⇒ Object 



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# File 'lib/couchwatcher/database_listener.rb', line 55

def remove_document_callback(document_callback)
  if !@thread.nil?
    say "Error: cannot remove callbacks from a running listener", :red
    return
  end

  @document_callbacks.delete(document_callback)
end

#say(message, color = nil) ⇒ Object

shortcut to say



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# File 'lib/couchwatcher/database_listener.rb', line 9

def say(message, color=nil)
  @shell ||= Thor::Shell::Basic.new
  @shell.say message, color
end

#start_watching(verbose, polling_interval) ⇒ Object 



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# File 'lib/couchwatcher/database_listener.rb', line 64

def start_watching(verbose, polling_interval)
  if !@thread.nil?
    say "Error: listener is already running listener", :red
    return
  end

  say "Database watching started for: #{@database_url}", :green if verbose
  @thread = Thread.new do
    
    # get the sequence
    if @last_sequence.nil?
      data = get_info()
      if data.nil? || data["update_seq"].nil?
        say "Error: the database cannnot be watched: #{@database_url}. Check that the couchdb is running, the database exists, and you have adequate permissions.", :red
        return
      end 

      @last_sequence = data["update_seq"]
    end

    @connection_stopped = false
    while true

      #puts "Checking heartbeat: #{@database_url} sequence: #{@last_sequence} connecte"

      # stopped the connection
      if @connection_stopped
        return 

      # the sequence number has been returned so start polling
      elsif @last_sequence
        results = get_changes()
                
        #puts "Checking heartbeat: #{@database_url} sequence: #{@last_sequence}"

        results.each do |result|

          document_id = result["id"]
          document_rev = result["changes"][0]["rev"]
          document = result["doc"]
        
          # tell a change
          say "Change detected in database: #{@database_url} document: #{document_id}", :green if verbose

          # call the database watchers
          @database_callbacks.each do |callback| 
            if callback.include_document 
              callback.callback_proc.call(@database_url, document_id, document_rev, document)
            else
              callback.callback_proc.call(@database_url, document_id, document_rev)
            end
          end

          # call the document watchers
          @document_callbacks.each do |callback| 
            if (callback.document_id==document_id)
              if callback.include_document 
                callback.callback_proc.call(@database_url, document_id, document_rev, document)
              else
                callback.callback_proc.call(@database_url, document_id, document_rev)
              end
            end
          end
        end
      end
    
      sleep polling_interval 
    end
  end
end

#stop_watching(verbose) ⇒ Object 



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# File 'lib/couchwatcher/database_listener.rb', line 135

def stop_watching(verbose)
  if @thread.nil?
    say "Error: cannot stop because listener is is not running", :red
    return
  end

  # give the thread time to finish
  @connection_stopped = true
  @thread.kill
  @thread = nil
  say "Database watching stopped for: #{@database_url}", :green if verbose
end