Rails delay_job的确切工作执行顺序

问题描述

|| 我正在使用Collectoridea的delay_job版本：https://github.com/collectiveidea/delayed_job 谁能指出我当工人去选择下一份工作时所使用的实际标准？我假设它就像\“ SELECT ID FROM delay_jobs where run_at> Now（）ORDER BY priority ASC，run_at ASC LIMIT 1 \”（优先选择优先，run_at时间第二），但是我还没有\'无法准确找到要考虑的内容。我已经在GitHub上的代码中做了一些探索，但是还没有找到下一份工作的实际查询。对几件事感到好奇，包括是否将\'created_at \'，\'attempts \'或\'Failed_at \'纳入优先级。 （而且我意识到我不太可能找到实际的sql，这只是表示我假设查询所做的一种简单方法）。 其次，该宝石的实际文档有什么好的来源？对于在Rails中如此普遍使用的东西，我所见过的文档相当稀疏。     

解决方法

有点挖掘源代码可以在backend / active_record.rb中看到：

    scope :ready_to_run,lambda {|worker_name,max_run_time|
      where([\'(run_at <= ? AND (locked_at IS NULL OR locked_at < ?) OR locked_by = ?) AND failed_at IS NULL\',db_time_now,db_time_now - max_run_time,worker_name])
    }
    scope :by_priority,order(\'priority ASC,run_at ASC\')

    # Find a few candidate jobs to run (in case some immediately get locked by others).
    def self.find_available(worker_name,limit = 5,max_run_time = Worker.max_run_time)
      scope = self.ready_to_run(worker_name,max_run_time)
      scope = scope.scoped(:conditions => [\'priority >= ?\',Worker.min_priority]) if Worker.min_priority
      scope = scope.scoped(:conditions => [\'priority <= ?\',Worker.max_priority]) if Worker.max_priority

      ::ActiveRecord::Base.silence do
        scope.by_priority.all(:limit => limit)
      end
    end

同样，backend / base.rb中的这一位很有趣：

    def reserve(worker,max_run_time = Worker.max_run_time)
      # We get up to 5 jobs from the db. In case we cannot get exclusive access to a job we try the next.
      # this leads to a more even distribution of jobs across the worker processes
      find_available(worker.name,5,max_run_time).detect do |job|
        job.lock_exclusively!(max_run_time,worker.name)
      end
    end

工人叫

reserve

以选择下一份工作。     ,

delayed_job/lib/delayed/backend/active_record.rb

self.find_available

通话

ready_to_run

然后根据当前工作人员的最小/最大优先级对其进行范围划分 然后按ѭ6订购

scope :ready_to_run

电话

where([\'(run_at <= ? AND (locked_at IS NULL OR locked_at < ?) OR locked_by = ?) AND failed_at IS NULL\',worker_name])

所以它产生类似

SELECT * FROM jobs where run at <= ? AND locked_at IS NULL OR locked_at < ?) OR locked_by = ?) AND failed_at IS NULL AND priority >= ? AND priority <= ? ORDER BY priority ASC,run_at ASC