mirror of
https://github.com/rfyiamcool/cronlib.git
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add cron parser
This commit is contained in:
rfyiamcool
571
cron_parser.go
Normal file
571
cron_parser.go
Normal file
@@ -0,0 +1,571 @@
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package cronlib
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//
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// crontab parser import from https://github.com/robfig/cron/blob/master/parser.go
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//
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import (
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"fmt"
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"math"
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"strconv"
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"strings"
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"time"
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)
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// ConstantDelaySchedule represents a simple recurring duty cycle, e.g. "Every 5 minutes".
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// It does not support jobs more frequent than once a second.
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type ConstantDelaySchedule struct {
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Delay time.Duration
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}
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// Every returns a crontab Schedule that activates once every duration.
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// Delays of less than a second are not supported (will round up to 1 second).
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// Any fields less than a Second are truncated.
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func Every(duration time.Duration) ConstantDelaySchedule {
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if duration < time.Second {
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duration = time.Second
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}
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return ConstantDelaySchedule{
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Delay: duration - time.Duration(duration.Nanoseconds())%time.Second,
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}
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}
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// Next returns the next time this should be run.
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// This rounds so that the next activation time will be on the second.
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func (schedule ConstantDelaySchedule) Next(t time.Time) time.Time {
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return t.Add(schedule.Delay - time.Duration(t.Nanosecond())*time.Nanosecond)
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}
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// The Schedule describes a job's duty cycle.
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type TimeRunner interface {
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// Return the next activation time, later than the given time.
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// Next is invoked initially, and then each time the job is run.
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Next(time.Time) time.Time
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}
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// SpecSchedule specifies a duty cycle (to the second granularity), based on a
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// traditional crontab specification. It is computed initially and stored as bit sets.
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type SpecSchedule struct {
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Second, Minute, Hour, Dom, Month, Dow uint64
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}
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// bounds provides a range of acceptable values (plus a map of name to value).
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type bounds struct {
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min, max uint
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names map[string]uint
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}
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// The bounds for each field.
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var (
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seconds = bounds{0, 59, nil}
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minutes = bounds{0, 59, nil}
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hours = bounds{0, 23, nil}
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dom = bounds{1, 31, nil}
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months = bounds{1, 12, map[string]uint{
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"jan": 1,
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"feb": 2,
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"mar": 3,
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"apr": 4,
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"may": 5,
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"jun": 6,
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"jul": 7,
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"aug": 8,
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"sep": 9,
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"oct": 10,
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"nov": 11,
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"dec": 12,
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}}
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dow = bounds{0, 6, map[string]uint{
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"sun": 0,
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"mon": 1,
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"tue": 2,
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"wed": 3,
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"thu": 4,
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"fri": 5,
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"sat": 6,
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}}
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)
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const (
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// Set the top bit if a star was included in the expression.
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starBit = 1 << 63
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)
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// Next returns the next time this schedule is activated, greater than the given
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// time. If no time can be found to satisfy the schedule, return the zero time.
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func (s *SpecSchedule) Next(t time.Time) time.Time {
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// General approach:
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// For Month, Day, Hour, Minute, Second:
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// Check if the time value matches. If yes, continue to the next field.
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// If the field doesn't match the schedule, then increment the field until it matches.
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// While incrementing the field, a wrap-around brings it back to the beginning
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// of the field list (since it is necessary to re-verify previous field
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// values)
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// Start at the earliest possible time (the upcoming second).
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t = t.Add(1*time.Second - time.Duration(t.Nanosecond())*time.Nanosecond)
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// This flag indicates whether a field has been incremented.
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added := false
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// If no time is found within five years, return zero.
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yearLimit := t.Year() + 5
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WRAP:
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if t.Year() > yearLimit {
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return time.Time{}
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}
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// Find the first applicable month.
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// If it's this month, then do nothing.
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for 1<<uint(t.Month())&s.Month == 0 {
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// If we have to add a month, reset the other parts to 0.
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if !added {
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added = true
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// Otherwise, set the date at the beginning (since the current time is irrelevant).
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t = time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, t.Location())
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}
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t = t.AddDate(0, 1, 0)
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// Wrapped around.
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if t.Month() == time.January {
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goto WRAP
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}
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}
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// Now get a day in that month.
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for !dayMatches(s, t) {
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if !added {
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added = true
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t = time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
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}
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t = t.AddDate(0, 0, 1)
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if t.Day() == 1 {
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goto WRAP
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}
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}
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for 1<<uint(t.Hour())&s.Hour == 0 {
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if !added {
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added = true
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t = time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, t.Location())
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}
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t = t.Add(1 * time.Hour)
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if t.Hour() == 0 {
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goto WRAP
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}
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}
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for 1<<uint(t.Minute())&s.Minute == 0 {
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if !added {
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added = true
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t = t.Truncate(time.Minute)
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}
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t = t.Add(1 * time.Minute)
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if t.Minute() == 0 {
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goto WRAP
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}
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}
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for 1<<uint(t.Second())&s.Second == 0 {
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if !added {
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added = true
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t = t.Truncate(time.Second)
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}
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t = t.Add(1 * time.Second)
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if t.Second() == 0 {
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goto WRAP
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}
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}
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return t
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}
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// dayMatches returns true if the schedule's day-of-week and day-of-month
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// restrictions are satisfied by the given time.
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func dayMatches(s *SpecSchedule, t time.Time) bool {
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var (
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domMatch bool = 1<<uint(t.Day())&s.Dom > 0
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dowMatch bool = 1<<uint(t.Weekday())&s.Dow > 0
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)
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if s.Dom&starBit > 0 || s.Dow&starBit > 0 {
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return domMatch && dowMatch
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}
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return domMatch || dowMatch
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}
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// Configuration options for creating a parser. Most options specify which
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// fields should be included, while others enable features. If a field is not
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// included the parser will assume a default value. These options do not change
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// the order fields are parse in.
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type ParseOption int
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const (
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Second ParseOption = 1 << iota // Seconds field, default 0
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Minute // Minutes field, default 0
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Hour // Hours field, default 0
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Dom // Day of month field, default *
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Month // Month field, default *
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Dow // Day of week field, default *
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DowOptional // Optional day of week field, default *
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Descriptor // Allow descriptors such as @monthly, @weekly, etc.
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)
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var places = []ParseOption{
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Second,
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Minute,
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Hour,
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Dom,
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Month,
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Dow,
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}
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var defaults = []string{
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"0",
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"0",
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"0",
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"*",
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"*",
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"*",
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}
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// A custom Parser that can be configured.
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type Parser struct {
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options ParseOption
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optionals int
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}
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// Creates a custom Parser with custom options.
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//
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// // Standard parser without descriptors
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// specParser := NewParser(Minute | Hour | Dom | Month | Dow)
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// sched, err := specParser.Parse("0 0 15 */3 *")
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//
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// // Same as above, just excludes time fields
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// subsParser := NewParser(Dom | Month | Dow)
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// sched, err := specParser.Parse("15 */3 *")
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//
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// // Same as above, just makes Dow optional
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// subsParser := NewParser(Dom | Month | DowOptional)
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// sched, err := specParser.Parse("15 */3")
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//
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func NewParser(options ParseOption) Parser {
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optionals := 0
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if options&DowOptional > 0 {
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options |= Dow
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optionals++
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}
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return Parser{options, optionals}
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}
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// Parse returns a new crontab schedule representing the given spec.
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// It returns a descriptive error if the spec is not valid.
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// It accepts crontab specs and features configured by NewParser.
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func (p Parser) Parse(spec string) (TimeRunner, error) {
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if len(spec) == 0 {
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return nil, fmt.Errorf("Empty spec string")
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}
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if spec[0] == '@' && p.options&Descriptor > 0 {
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return parseDescriptor(spec)
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}
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// Figure out how many fields we need
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max := 0
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for _, place := range places {
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if p.options&place > 0 {
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max++
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}
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}
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min := max - p.optionals
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// Split fields on whitespace
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fields := strings.Fields(spec)
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// Validate number of fields
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if count := len(fields); count < min || count > max {
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if min == max {
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return nil, fmt.Errorf("Expected exactly %d fields, found %d: %s", min, count, spec)
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}
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return nil, fmt.Errorf("Expected %d to %d fields, found %d: %s", min, max, count, spec)
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}
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// Fill in missing fields
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fields = expandFields(fields, p.options)
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var err error
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field := func(field string, r bounds) uint64 {
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if err != nil {
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return 0
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}
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var bits uint64
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bits, err = getField(field, r)
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return bits
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}
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var (
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second = field(fields[0], seconds)
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minute = field(fields[1], minutes)
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hour = field(fields[2], hours)
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dayofmonth = field(fields[3], dom)
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month = field(fields[4], months)
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dayofweek = field(fields[5], dow)
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)
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if err != nil {
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return nil, err
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}
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return &SpecSchedule{
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Second: second,
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Minute: minute,
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Hour: hour,
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Dom: dayofmonth,
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Month: month,
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Dow: dayofweek,
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}, nil
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}
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func expandFields(fields []string, options ParseOption) []string {
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n := 0
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count := len(fields)
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expFields := make([]string, len(places))
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copy(expFields, defaults)
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for i, place := range places {
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if options&place > 0 {
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expFields[i] = fields[n]
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n++
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}
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if n == count {
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break
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}
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}
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return expFields
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}
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var standardParser = NewParser(
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Minute | Hour | Dom | Month | Dow | Descriptor,
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)
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// ParseStandard returns a new crontab schedule representing the given standardSpec
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// (https://en.wikipedia.org/wiki/Cron). It differs from Parse requiring to always
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// pass 5 entries representing: minute, hour, day of month, month and day of week,
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// in that order. It returns a descriptive error if the spec is not valid.
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//
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// It accepts
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// - Standard crontab specs, e.g. "* * * * ?"
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// - Descriptors, e.g. "@midnight", "@every 1h30m"
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func ParseStandard(standardSpec string) (TimeRunner, error) {
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return standardParser.Parse(standardSpec)
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}
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var defaultParser = NewParser(
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Second | Minute | Hour | Dom | Month | DowOptional | Descriptor,
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)
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// Parse returns a new crontab schedule representing the given spec.
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// It returns a descriptive error if the spec is not valid.
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//
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// It accepts
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// - Full crontab specs, e.g. "* * * * * ?"
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// - Descriptors, e.g. "@midnight", "@every 1h30m"
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func Parse(spec string) (TimeRunner, error) {
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return defaultParser.Parse(spec)
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}
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// getField returns an Int with the bits set representing all of the times that
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// the field represents or error parsing field value. A "field" is a comma-separated
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// list of "ranges".
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func getField(field string, r bounds) (uint64, error) {
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var bits uint64
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ranges := strings.FieldsFunc(field, func(r rune) bool { return r == ',' })
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for _, expr := range ranges {
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bit, err := getRange(expr, r)
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if err != nil {
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return bits, err
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}
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bits |= bit
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}
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return bits, nil
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}
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// getRange returns the bits indicated by the given expression:
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// number | number "-" number [ "/" number ]
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// or error parsing range.
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func getRange(expr string, r bounds) (uint64, error) {
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var (
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start, end, step uint
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rangeAndStep = strings.Split(expr, "/")
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lowAndHigh = strings.Split(rangeAndStep[0], "-")
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singleDigit = len(lowAndHigh) == 1
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err error
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)
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var extra uint64
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if lowAndHigh[0] == "*" || lowAndHigh[0] == "?" {
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start = r.min
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end = r.max
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extra = starBit
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} else {
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start, err = parseIntOrName(lowAndHigh[0], r.names)
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if err != nil {
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return 0, err
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}
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switch len(lowAndHigh) {
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case 1:
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end = start
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case 2:
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end, err = parseIntOrName(lowAndHigh[1], r.names)
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if err != nil {
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return 0, err
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}
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default:
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return 0, fmt.Errorf("Too many hyphens: %s", expr)
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}
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}
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switch len(rangeAndStep) {
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case 1:
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step = 1
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case 2:
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step, err = mustParseInt(rangeAndStep[1])
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if err != nil {
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return 0, err
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}
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// Special handling: "N/step" means "N-max/step".
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if singleDigit {
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end = r.max
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}
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default:
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return 0, fmt.Errorf("Too many slashes: %s", expr)
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}
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||||
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if start < r.min {
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return 0, fmt.Errorf("Beginning of range (%d) below minimum (%d): %s", start, r.min, expr)
|
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}
|
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if end > r.max {
|
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return 0, fmt.Errorf("End of range (%d) above maximum (%d): %s", end, r.max, expr)
|
||||
}
|
||||
if start > end {
|
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return 0, fmt.Errorf("Beginning of range (%d) beyond end of range (%d): %s", start, end, expr)
|
||||
}
|
||||
if step == 0 {
|
||||
return 0, fmt.Errorf("Step of range should be a positive number: %s", expr)
|
||||
}
|
||||
|
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return getBits(start, end, step) | extra, nil
|
||||
}
|
||||
|
||||
// parseIntOrName returns the (possibly-named) integer contained in expr.
|
||||
func parseIntOrName(expr string, names map[string]uint) (uint, error) {
|
||||
if names != nil {
|
||||
if namedInt, ok := names[strings.ToLower(expr)]; ok {
|
||||
return namedInt, nil
|
||||
}
|
||||
}
|
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return mustParseInt(expr)
|
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}
|
||||
|
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// mustParseInt parses the given expression as an int or returns an error.
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func mustParseInt(expr string) (uint, error) {
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num, err := strconv.Atoi(expr)
|
||||
if err != nil {
|
||||
return 0, fmt.Errorf("Failed to parse int from %s: %s", expr, err)
|
||||
}
|
||||
if num < 0 {
|
||||
return 0, fmt.Errorf("Negative number (%d) not allowed: %s", num, expr)
|
||||
}
|
||||
|
||||
return uint(num), nil
|
||||
}
|
||||
|
||||
// getBits sets all bits in the range [min, max], modulo the given step size.
|
||||
func getBits(min, max, step uint) uint64 {
|
||||
var bits uint64
|
||||
|
||||
// If step is 1, use shifts.
|
||||
if step == 1 {
|
||||
return ^(math.MaxUint64 << (max + 1)) & (math.MaxUint64 << min)
|
||||
}
|
||||
|
||||
// Else, use a simple loop.
|
||||
for i := min; i <= max; i += step {
|
||||
bits |= 1 << i
|
||||
}
|
||||
return bits
|
||||
}
|
||||
|
||||
// all returns all bits within the given bounds. (plus the star bit)
|
||||
func all(r bounds) uint64 {
|
||||
return getBits(r.min, r.max, 1) | starBit
|
||||
}
|
||||
|
||||
// parseDescriptor returns a predefined schedule for the expression, or error if none matches.
|
||||
func parseDescriptor(descriptor string) (TimeRunner, error) {
|
||||
switch descriptor {
|
||||
case "@yearly", "@annually":
|
||||
return &SpecSchedule{
|
||||
Second: 1 << seconds.min,
|
||||
Minute: 1 << minutes.min,
|
||||
Hour: 1 << hours.min,
|
||||
Dom: 1 << dom.min,
|
||||
Month: 1 << months.min,
|
||||
Dow: all(dow),
|
||||
}, nil
|
||||
|
||||
case "@monthly":
|
||||
return &SpecSchedule{
|
||||
Second: 1 << seconds.min,
|
||||
Minute: 1 << minutes.min,
|
||||
Hour: 1 << hours.min,
|
||||
Dom: 1 << dom.min,
|
||||
Month: all(months),
|
||||
Dow: all(dow),
|
||||
}, nil
|
||||
|
||||
case "@weekly":
|
||||
return &SpecSchedule{
|
||||
Second: 1 << seconds.min,
|
||||
Minute: 1 << minutes.min,
|
||||
Hour: 1 << hours.min,
|
||||
Dom: all(dom),
|
||||
Month: all(months),
|
||||
Dow: 1 << dow.min,
|
||||
}, nil
|
||||
|
||||
case "@daily", "@midnight":
|
||||
return &SpecSchedule{
|
||||
Second: 1 << seconds.min,
|
||||
Minute: 1 << minutes.min,
|
||||
Hour: 1 << hours.min,
|
||||
Dom: all(dom),
|
||||
Month: all(months),
|
||||
Dow: all(dow),
|
||||
}, nil
|
||||
|
||||
case "@hourly":
|
||||
return &SpecSchedule{
|
||||
Second: 1 << seconds.min,
|
||||
Minute: 1 << minutes.min,
|
||||
Hour: all(hours),
|
||||
Dom: all(dom),
|
||||
Month: all(months),
|
||||
Dow: all(dow),
|
||||
}, nil
|
||||
}
|
||||
|
||||
const every = "@every "
|
||||
if strings.HasPrefix(descriptor, every) {
|
||||
duration, err := time.ParseDuration(descriptor[len(every):])
|
||||
if err != nil {
|
||||
return nil, fmt.Errorf("Failed to parse duration %s: %s", descriptor, err)
|
||||
}
|
||||
return Every(duration), nil
|
||||
}
|
||||
|
||||
return nil, fmt.Errorf("Unrecognized descriptor: %s", descriptor)
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user