Class: Mongo::Dequeue

Inherits:
Object
  • Object
show all
Defined in:
lib/mongo-dequeue.rb

Overview

heavily inspired by github.com/skiz/mongo_queue

Constant Summary collapse

DEFAULT_CONFIG = 
{
	:timeout    => 300,
	:default_priority => 3
}.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(collection, opts = {}) ⇒ Dequeue

Create a new instance of MongoDequeue with the provided mongodb connection and optional configuration. See DEFAULT_CONFIG for default configuration and possible configuration options.

Example:

db = Mongo::Connection.new('localhost')
config = {:timeout => 90, :attempts => 2}
queue = Mongo::Queue.new(db, config)



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# File 'lib/mongo-dequeue.rb', line 23

def initialize(collection, opts={})
	@collection = collection
	@config = DEFAULT_CONFIG.merge(opts)
	@batch = []
end

Instance Attribute Details

#batch ⇒ Object (readonly)

Returns the value of attribute batch.



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# File 'lib/mongo-dequeue.rb', line 8

def batch
  @batch
end

#collection ⇒ Object (readonly)

Returns the value of attribute collection.



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# File 'lib/mongo-dequeue.rb', line 8

def collection
  @collection
end

#config ⇒ Object (readonly)

Returns the value of attribute config.



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# File 'lib/mongo-dequeue.rb', line 8

def config
  @config
end

Class Method Details

.generate_duplicate_key(body) ⇒ Object 



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# File 'lib/mongo-dequeue.rb', line 232

def self.generate_duplicate_key(body)
	return Digest::MD5.hexdigest(body) if body.class == "String"
	return Digest::MD5.hexdigest(body) if body.class == "Fixnum"
	#else
	return Digest::MD5.hexdigest(body.to_json) #won't ever match a duplicate. Need a better way to handle hashes and arrays.
end

Instance Method Details

#batchprocess ⇒ Object 



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# File 'lib/mongo-dequeue.rb', line 72

def batchprocess()
	js = %Q|
   		function(batch) {
   			var nowutc = new Date();
   			var ret = [];
   			for(i in batch){
   				e = batch[i];
   				//ret.push(e);
   				var query = {
   					'duplicate_key': e.duplicate_key,
   					'complete': false,
   					'locked_at': null
   				};
   				var object = {
   					'$set': {
						'body': e.body,
						'inserted_at': nowutc,
						'complete': false,
						'locked_till': null,
						'completed_at': null,
						'priority': e.priority,
						'duplicate_key': e.duplicate_key,
						'completecount': 0
					},
					'$inc': {'count': 1}
   				};
   		
   				db.#{collection.name}.update(query, object, true);
   			}
   			return ret;
   		}
       |
       cmd = BSON::OrderedHash.new
       cmd['$eval'] = js
       cmd['args'] = [@batch]
       cmd['nolock'] = true
	result = collection.db.command(cmd)
	@batch.clear
	#pp result
end

#batchpush(body, item_opts = {}) ⇒ Object

add a new item into the delayed batch



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# File 'lib/mongo-dequeue.rb', line 64

def batchpush(body, item_opts = {})
	@batch << {
		:body => body,
		:duplicate_key => item_opts[:duplicate_key] || Mongo::Dequeue.generate_duplicate_key(body),
		:priority => item_opts[:priority] || @config[:default_priority]
	}
end

#cleanup ⇒ Object

Removes completed job history



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# File 'lib/mongo-dequeue.rb', line 157

def cleanup()
	collection.remove({:complete=>true});
end

#complete(id) ⇒ Object

Remove the document from the queue. This should be called when the work is done and the document is no longer needed. You must provide the process identifier that the document was locked with to complete it.



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# File 'lib/mongo-dequeue.rb', line 142

def complete(id)
	begin
		cmd = BSON::OrderedHash.new
		cmd['findandmodify'] = collection.name
		cmd['query']         = {:_id => BSON::ObjectId.from_string(id)}
		cmd['update']        = {'$set' => {:completed_at => Time.now.utc, :complete => true}, '$inc' => {:completecount => 1} }
		cmd['limit']         = 1
		collection.db.command(cmd)
	rescue Mongo::OperationFailure => of
	#opfailure happens when item has been already completed
	return nil
	end
end

#flush! ⇒ Object

Remove all items from the queue. Use with caution!



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# File 'lib/mongo-dequeue.rb', line 30

def flush!
	collection.drop
end

#peek ⇒ Object 



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# File 'lib/mongo-dequeue.rb', line 239

def peek
	firstfew = collection.find({
		:complete => false,
		'$or'=>[{:locked_till=> nil},{:locked_till=>{'$lt'=>Time.now.utc}}]
	},
	:sort => [[:priority, :descending],[:inserted_at, :ascending]],
	:limit => 10)
	return firstfew
end

#pop(opts = {}) ⇒ Object

:id=>“4e039c372b70275e345206e4”



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# File 'lib/mongo-dequeue.rb', line 120

def pop(opts = {})
	begin
		timeout = opts[:timeout] || @config[:timeout]
		cmd = BSON::OrderedHash.new
		cmd['findandmodify'] = collection.name
		cmd['update']        = {'$set' => {:locked_till => Time.now.utc+timeout}}
		cmd['query']         = {:complete => false, '$or'=>[{:locked_till=> nil},{:locked_till=>{'$lt'=>Time.now.utc}}] }
		cmd['sort']          = {:priority=>-1,:inserted_at=>1}
		cmd['limit']         = 1
		cmd['new']           = true
		result = collection.db.command(cmd)
	rescue Mongo::OperationFailure => of
	return nil
	end
	return {
		:body => result['value']['body'],
		:id => result['value']['_id'].to_s
	}
end

#push(body, item_opts = {}) ⇒ Object

Insert a new item into the queue.

Example:

queue.insert(:name => 'Billy', :email => '[email protected]', :message => 'Here is the thing you asked for')



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# File 'lib/mongo-dequeue.rb', line 38

def push(body, item_opts = {})
	dup_key = item_opts[:duplicate_key] || Mongo::Dequeue.generate_duplicate_key(body)

	selector = {
		:duplicate_key => dup_key,
		:complete => false,
		:locked_at => nil
	}
	item = {
		'$set' => {
			:body => body,
			:inserted_at => Time.now.utc,
			:complete => false,
			:locked_till => nil,
			:completed_at => nil,
			:priority => item_opts[:priority] || @config[:default_priority],
			:duplicate_key => dup_key,
			:completecount => 0
		},
		'$inc' => {:count => 1 }
	}

	id = collection.update(selector, item, :upsert => true)
end

#stats ⇒ Object

Provides some information about what is in the queue. We are using an eval to ensure that a lock is obtained during the execution of this query so that the results are not skewed. please be aware that it will lock the database during the execution, so avoid using it too often, even though it it very tiny and should be relatively fast.



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# File 'lib/mongo-dequeue.rb', line 165

def stats
	js = "function queue_stat(){
		      return db.eval(
		      function(){
		      	var nowutc = new Date();
		      	var a = db.#{collection.name}.count({'complete': false, '$or':[{'locked_till':null},{'locked_till':{'$lt':nowutc}}] });
		        var c = db.#{collection.name}.count({'complete': true});
		        var t = db.#{collection.name}.count();
		        var l = db.#{collection.name}.count({'complete': false, 'locked_till': {'$gte':nowutc} });
		        var rc = db.#{collection.name}.group({
		        	'key': {},
		        	'cond': {'complete':true},
		        	'$reduce': function(obj, prev){prev.count += (obj.completecount - 1);},
		        	'initial': {count: 0}
		        });
		        var p = db.#{collection.name}.group({
					'key': {'priority':1},
					'cond': {},
					'$reduce': function(obj, prev){if(obj.complete){prev.complete += 1;}else{prev.waiting += 1;}},
					'initial': {complete: 0, waiting:0}
				});
				var tasks = db.#{collection.name}.group({
					'key': {'body.task':1},
					'cond': {},
					'$reduce': function(obj, prev){if(obj.complete){prev.complete += 1;}else{prev.waiting += 1;}},
					'initial': {complete: 0, waiting:0}
				});

		        return [a, c, t, l, rc[0] ? rc[0].count : 0, p, tasks];
		      }
		    );
		  }"

	#possible additions

	#db.job_queue.group({
	#'key': {'priority':1},
	#'cond': {},
	#'$reduce': function(obj, prev){if(obj.complete){prev.complete += 1;}else{prev.waiting += 1;}},
	#'initial': {complete: 0, waiting:0}
	#});

	#db.job_queue.group({
	#'key': {'body.task':1},
	#'cond': {},
	#'$reduce': function(obj, prev){if(obj.complete){prev.complete += 1;}else{prev.waiting += 1;}},
	#'initial': {complete: 0, waiting:0}
	#});

	cmd = BSON::OrderedHash.new
       cmd['$eval'] = js
       cmd['nolock'] = true

	available, complete, total, locked, redundant_completes, priority, tasks =  collection.db.command(cmd)['retval']

	#available, complete, total, locked, redundant_completes, priority, tasks = collection.db.eval(js)
	
	{ :locked    => locked.to_i,
		:complete => complete.to_i,
		:available => available.to_i,
		:total     => total.to_i,
		:redundantcompletes => redundant_completes,
		:priority => priority,
		:tasks => tasks
	}
end