Class: NewRelic::Security::ParseCron::CronParser

Inherits:
Object
  • Object
show all
Defined in:
lib/newrelic_security/parse-cron/cron_parser.rb

Overview

Parses cron expressions and computes the next occurence of the “job”

Defined Under Namespace

Classes: InternalTime

Constant Summary collapse

SYMBOLS = 
{
  "jan" => "1",
  "feb" => "2",
  "mar" => "3",
  "apr" => "4",
  "may" => "5",
  "jun" => "6",
  "jul" => "7",
  "aug" => "8",
  "sep" => "9",
  "oct" => "10",
  "nov" => "11",
  "dec" => "12",

  "sun" => "0",
  "mon" => "1",
  "tue" => "2",
  "wed" => "3",
  "thu" => "4",
  "fri" => "5",
  "sat" => "6"
}
SUBELEMENT_REGEX = 
%r{^(\d+)(-(\d+)(/(\d+))?)?$}

Instance Method Summary collapse

Constructor Details

#initialize(source, time_source = Time) ⇒ CronParser

Returns a new instance of CronParser.



55
56
57
58
59
 
# File 'lib/newrelic_security/parse-cron/cron_parser.rb', line 55

def initialize(source, time_source = Time)
  @source = interpret_vixieisms(source)
  @time_source = time_source
  validate_source
end

Instance Method Details

#interpret_vixieisms(spec) ⇒ Object 



61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
 
# File 'lib/newrelic_security/parse-cron/cron_parser.rb', line 61

def interpret_vixieisms(spec)
  case spec
  when '@reboot'
    raise ArgumentError, "Can't predict last/next run of @reboot"
  when '@yearly', '@annually'
    '0 0 1 1 *'
  when '@monthly'
    '0 0 1 * *'
  when '@weekly'
    '0 0 * * 0'
  when '@daily', '@midnight'
    '0 0 * * *'
  when '@hourly'
    '0 * * * *'
  else
    spec
  end
end

#last(now = @time_source.now, num = 1) ⇒ Object

returns the last occurence before the given date



110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
 
# File 'lib/newrelic_security/parse-cron/cron_parser.rb', line 110

def last(now = @time_source.now, num = 1)
  t = InternalTime.new(now, @time_source)

  unless time_specs[:month][0].include?(t.month)
    nudge_month(t, :last)
    t.day = 32
  end

  if t.day == 32 || !interpolate_weekdays(t.year, t.month)[0].include?(t.day)
    nudge_date(t, :last)
    t.hour = 24
  end

  unless time_specs[:hour][0].include?(t.hour)
    nudge_hour(t, :last)
    t.min = 60
  end

  # always nudge the minute
  nudge_minute(t, :last)
  t = t.to_time
  if num > 1
    recursive_calculate(:last, t, num)
  else
    t
  end
end

#next(now = @time_source.now, num = 1) ⇒ Object

returns the next occurence after the given date



81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
 
# File 'lib/newrelic_security/parse-cron/cron_parser.rb', line 81

def next(now = @time_source.now, num = 1)
  t = InternalTime.new(now, @time_source)

  unless time_specs[:month][0].include?(t.month)
    nudge_month(t)
    t.day = 0
  end

  unless interpolate_weekdays(t.year, t.month)[0].include?(t.day)
    nudge_date(t)
    t.hour = -1
  end

  unless time_specs[:hour][0].include?(t.hour)
    nudge_hour(t)
    t.min = -1
  end

  # always nudge the minute
  nudge_minute(t)
  t = t.to_time
  if num > 1
    recursive_calculate(:next, t, num)
  else
    t
  end
end

#parse_element(elem, allowed_range) ⇒ Object 



139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
 
# File 'lib/newrelic_security/parse-cron/cron_parser.rb', line 139

def parse_element(elem, allowed_range)
  values = elem.split(',').map do |subel|
    if subel =~ /^\*/
      step = subel.length > 1 ? subel[2..-1].to_i : 1
      stepped_range(allowed_range, step)
    else
      raise ArgumentError, "Bad Vixie-style specification #{subel}" unless SUBELEMENT_REGEX === subel
      if ::Regexp.last_match(5) # with range
        stepped_range(::Regexp.last_match(1).to_i..::Regexp.last_match(3).to_i, ::Regexp.last_match(5).to_i)
      elsif ::Regexp.last_match(3) # range without step
        stepped_range(::Regexp.last_match(1).to_i..::Regexp.last_match(3).to_i, 1)
      else # just a numeric
        [::Regexp.last_match(1).to_i]
      end
      
        
      
    end
  end.flatten.sort

  [Set.new(values), values, elem]
end