version 0.1.1

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.1.1
+
+- Handle multiple ats (at: ["mon 8:00, tues 9:30"]).
+- Job callbacks (:before_tick, :after_tick, etc).
+
 ## 0.1.0
 
 - First release.

README.md

@@ -1,6 +1,8 @@
 # Zhong
 
-Useful, reliable distributed cron.
+Useful, reliable distributed cron. Tired of your cron-like scheduler running key jobs twice? Would you like to be able to run your cron server on multiple machines and have it "just work"? Have we got the gem for you.
+
+Zhong uses Redis to acquire exclusive locks on jobs, as well as recording when they last ran. This means that you can rest easy at night, knowing that your customers are getting their monthly Goat Fancy magazine subscriptions and you are rolling around in your piles of money without a care in the world.
 
 # Installation
 
@@ -18,13 +20,25 @@ r = Redis.new
 Zhong.schedule(redis: r) do |s|
   s.category "stuff" do
     s.every(5.seconds, "foo") { puts "foo" }
-    s.every(1.week, "baz", at: "mon 22:45") { puts "baz" }
+    s.every(1.week, "baz", at: ["mon 22:45", "wed 23:13"]) { puts "baz" }
   end
 
   s.category "clutter" do
-    s.every(1.second, "compute", if: -> (t) { rand < 0.5 }) { puts "something happened" }
+    s.every(1.second, "compute", if: -> (t) { t.wday == 3 && rand < 0.5 }) { puts "something happened on wednesday" }
+  end
+
+  # note: callbacks that return nil or false will cause event to not run
+  s.on(:before_tick) do
+    puts "ding"
+    true
+  end
+
+  s.on(:after_tick) do
+    puts "dong"
+    true
   end
 end
+
 ```
 
 ## TODO

lib/zhong/at.rb

@@ -43,6 +43,11 @@ def next_at(time = Time.now)
     def self.parse(at, grace: 0)
       return unless at
 
+      # TODO: refactor this mess
+      if at.respond_to?(:each)
+        return MultiAt.new(at.map { |a| parse(a, grace: grace) })
+      end
+
       case at
       when /\A([[:alpha:]]+)\s+(.*)\z/
         wday = WDAYS[$1]
@@ -67,4 +72,16 @@ def self.parse(at, grace: 0)
       throw FailedToParse, at
     end
   end
+
+  class MultiAt
+    attr_accessor :ats
+
+    def initialize(ats = [])
+      @ats = ats
+    end
+
+    def next_at(time = Time.now)
+      ats.map { |at| at.next_at(time) }.min
+    end
+  end
 end

lib/zhong/job.rb

@@ -95,7 +95,7 @@ def to_s
 
     def next_at
       every_time = @every.next_at(@last_ran) if @last_ran && @every
-      at_time = @at.next_at(time) if @at
+      at_time = @at.next_at(Time.now) if @at
       [every_time, at_time, Time.now].compact.max || "now"
     end
 

lib/zhong/scheduler.rb

@@ -12,6 +12,7 @@ class Scheduler
 
     def initialize(config = {})
       @jobs = {}
+      @callbacks = {}
       @config = DEFAULT_CONFIG.merge(config)
       @logger = @config[:logger] ||= Util.default_logger
       @redis = @config[:redis] ||= Redis.new(ENV["REDIS_URL"])
@@ -28,7 +29,18 @@ def category(name)
     end
 
     def every(period, name, opts = {}, &block)
-      add(Job.new(name, opts.merge(@config).merge(every: period, category: @category), &block))
+      job = Job.new(name, opts.merge(@config).merge(every: period, category: @category), &block)
+      add(job)
+    end
+
+    def error_handler(&block)
+      @error_handler = block if block_given?
+      @error_handler
+    end
+
+    def on(event, &block)
+      fail "Unsupported callback #{event}" unless [:before_tick, :after_tick, :before_run, :after_run].include?(event.to_sym)
+      (@callbacks[event.to_sym] ||= []) << block
     end
 
     def start
@@ -39,11 +51,20 @@ def start
       @logger.info "starting at #{redis_time}"
 
       loop do
-        now = redis_time
+        if fire_callbacks(:before_tick)
+          now = redis_time
 
-        jobs.each { |_, job| job.run(now) }
+          jobs.each do |_, job|
+            if fire_callbacks(:before_run, job, now)
+              job.run(now)
+              fire_callbacks(:after_run, job, now)
+            end
+          end
 
-        sleep(interval)
+          fire_callbacks(:after_tick)
+
+          sleep(interval)
+        end
 
         break if @stop
       end
@@ -56,6 +77,10 @@ def stop
       Thread.new { @logger.info "stopped" }
     end
 
+    def fire_callbacks(event, *args)
+      @callbacks[event].to_a.all? { |h| h.call(*args) }
+    end
+
     private
 
     def add(job)

lib/zhong/version.rb

@@ -1,3 +1,3 @@
 module Zhong
-  VERSION = "0.1.0"
+  VERSION = "0.1.1"
 end