cron

README

cron

To download the specific tagged release, run:

go get gitee.com/go-wena/cron

Import it in your program as:

import "gitee.com/go-wena/cron"

Refer to the documentation here: http://godoc.org/gitee.com/go-wena/cron

Cron spec format

There are two cron spec formats in common usage:

• The "standard" cron format, described on the Cron wikipedia page and used by the cron Linux system utility.

• The cron format used by the Quartz Scheduler, commonly used for scheduled jobs in Java software

The original version of this package included an optional "seconds" field, which made it incompatible with both of these formats. Now, the "standard" format is the default format accepted, and the Quartz format is opt-in.

---

this lib is part of https://github.com/robfig/cron

Documentation

Index

• type ConstantDelaySchedule
  • func Every(duration time.Duration) ConstantDelaySchedule
  • func (schedule ConstantDelaySchedule) Next(t time.Time) time.Time
• type ParseOption
• type Parser
  • func NewParser(options ParseOption) Parser
  • func (p Parser) Parse(spec string) (Schedule, error)
• type Schedule
  • func ParseStandard(standardSpec string) (Schedule, error)
• type ScheduleParser
• type SpecSchedule
  • func (s *SpecSchedule) Next(t time.Time) time.Time

Types

type ConstantDelaySchedule

type ConstantDelaySchedule struct {
	Delay time.Duration
}

ConstantDelaySchedule represents a simple recurring duty cycle, e.g. "Every 5 minutes". It does not support jobs more frequent than once a second.

func Every

func Every(duration time.Duration) ConstantDelaySchedule

Every returns a crontab Schedule that activates once every duration. Delays of less than a second are not supported (will round up to 1 second). Any fields less than a Second are truncated.

func (ConstantDelaySchedule) Next

func (schedule ConstantDelaySchedule) Next(t time.Time) time.Time

Next returns the next time this should be run. This rounds so that the next activation time will be on the second.

type ParseOption

type ParseOption int

Configuration options for creating a parser. Most options specify which fields should be included, while others enable features. If a field is not included the parser will assume a default value. These options do not change the order fields are parse in.

const (
	Second         ParseOption = 1 << iota // Seconds field, default 0
	SecondOptional                         // Optional seconds field, default 0
	Minute                                 // Minutes field, default 0
	Hour                                   // Hours field, default 0
	Dom                                    // Day of month field, default *
	Month                                  // Month field, default *
	Dow                                    // Day of week field, default *
	DowOptional                            // Optional day of week field, default *
	Descriptor                             // Allow descriptors such as @monthly, @weekly, etc.
)

type Parser

type Parser struct {
	// contains filtered or unexported fields
}

Parser A custom Parser that can be configured.

func NewParser

func NewParser(options ParseOption) Parser

NewParser creates a Parser with custom options.

It panics if more than one Optional is given, since it would be impossible to correctly infer which optional is provided or missing in general.

Examples

// Standard parser without descriptors
specParser := NewParser(Minute | Hour | Dom | Month | Dow)
sched, err := specParser.Parse("0 0 15 */3 *")

// Same as above, just excludes time fields
specParser := NewParser(Dom | Month | Dow)
sched, err := specParser.Parse("15 */3 *")

// Same as above, just makes Dow optional
specParser := NewParser(Dom | Month | DowOptional)
sched, err := specParser.Parse("15 */3")

func (Parser) Parse

func (p Parser) Parse(spec string) (Schedule, error)

Parse returns a new crontab schedule representing the given spec. It returns a descriptive error if the spec is not valid. It accepts crontab specs and features configured by NewParser.

type Schedule

type Schedule interface {
	// Next returns the next activation time, later than the given time.
	// Next is invoked initially, and then each time the job is run.
	Next(time.Time) time.Time
}

Schedule describes a job's duty cycle.

func ParseStandard

func ParseStandard(standardSpec string) (Schedule, error)

ParseStandard returns a new crontab schedule representing the given standardSpec (https://en.wikipedia.org/wiki/Cron). It requires 5 entries representing: minute, hour, day of month, month and day of week, in that order. It returns a descriptive error if the spec is not valid.

It accepts

• Standard crontab specs, e.g. "* * * * ?"
• Descriptors, e.g. "@midnight", "@every 1h30m"

type ScheduleParser

type ScheduleParser interface {
	Parse(spec string) (Schedule, error)
}

ScheduleParser is an interface for schedule spec parsers that return a Schedule

type SpecSchedule

type SpecSchedule struct {
	Second, Minute, Hour, Dom, Month, Dow uint64

	// Override location for this schedule.
	Location *time.Location
}

SpecSchedule specifies a duty cycle (to the second granularity), based on a traditional crontab specification. It is computed initially and stored as bit sets.

func (*SpecSchedule) Next

func (s *SpecSchedule) Next(t time.Time) time.Time

Next returns the next time this schedule is activated, greater than the given time. If no time can be found to satisfy the schedule, return the zero time.