Ilia Denisov
48 lines
1.7 KiB
Go
48 lines
1.7 KiB
Go
// Package cronutil provides a thin wrapper over github.com/robfig/cron/v3
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// for parsing the five-field cron expressions used by Galaxy services to
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// describe periodic schedules such as turn_schedule. It exposes only the
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// parser and a Next computation; no scheduler runtime, no logging, and no
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// concurrency primitives.
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package cronutil
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import (
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"fmt"
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"time"
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"github.com/robfig/cron/v3"
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)
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// fiveFieldParser parses standard five-field cron expressions
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// (minute, hour, day-of-month, month, day-of-week). The grammar matches
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// what Galaxy services accept for turn_schedule and is the only grammar
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// supported by this package; six-field expressions with a seconds field
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// are rejected.
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var fiveFieldParser = cron.NewParser(
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cron.Minute | cron.Hour | cron.Dom | cron.Month | cron.Dow,
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)
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// Schedule holds a parsed five-field cron expression and computes the
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// next firing time after a given moment. The zero value is not usable;
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// callers obtain a Schedule from Parse.
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type Schedule struct {
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inner cron.Schedule
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}
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// Parse parses expr as a five-field cron expression and returns the
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// resulting Schedule. Parse returns an error if expr is empty, contains
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// a seconds field, or is otherwise rejected by the underlying parser.
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func Parse(expr string) (Schedule, error) {
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inner, err := fiveFieldParser.Parse(expr)
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if err != nil {
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return Schedule{}, fmt.Errorf("cronutil: parse %q: %w", expr, err)
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}
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return Schedule{inner: inner}, nil
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}
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// Next returns the next firing time strictly after after. The returned
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// time is always in UTC; callers passing UTC values therefore get UTC
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// values back. Calling Next on a zero-value Schedule panics.
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func (s Schedule) Next(after time.Time) time.Time {
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return s.inner.Next(after.UTC()).UTC()
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}
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