[feature] Clean up/uncache remote media (#407)

* Add whereNotEmptyAndNotNull

* Add GetRemoteOlderThanDays

* Add GetRemoteOlderThanDays

* Add PruneRemote to Manager interface

* Start implementing PruneRemote

* add new attachment + status to tests

* fix up and test GetRemoteOlderThan

* fix bad import

* PruneRemote: return number pruned

* add Cached column to mediaattachment

* update + test pruneRemote

* update mediaTest

* use Cached column

* upstep bun to latest version

* embed structs in mediaAttachment

* migrate mediaAttachment to new format

* don't default cached to true

* select only remote media

* update db dependencies

* step bun back to last working version

* update pruneRemote to use Cached field

* fix storage path of test attachments

* add recache logic to manager

* fix trimmed aspect ratio

* test prune and recache

* return errwithcode

* tidy up different paths for emoji vs attachment

* fix incorrect thumbnail type being stored

* expose TransportController to media processor

* implement tee-ing recached content

* add thoughts of dog to test fedi attachments

* test get remote files

* add comment on PruneRemote

* add postData cleanup to recache

* test thumbnail fetching

* add incredible diagram

* go mod tidy

* buffer pipes for recache streaming

* test for client stops reading after 1kb

* add media-remote-cache-days to config

* add cron package

* wrap logrus so it's available to cron

* start and stop cron jobs gracefully

vendor/github.com/robfig/cron/v3/spec.go

@@ -0,0 +1,188 @@
+package cron
+
+import "time"
+
+// SpecSchedule specifies a duty cycle (to the second granularity), based on a
+// traditional crontab specification. It is computed initially and stored as bit sets.
+type SpecSchedule struct {
+	Second, Minute, Hour, Dom, Month, Dow uint64
+
+	// Override location for this schedule.
+	Location *time.Location
+}
+
+// bounds provides a range of acceptable values (plus a map of name to value).
+type bounds struct {
+	min, max uint
+	names    map[string]uint
+}
+
+// The bounds for each field.
+var (
+	seconds = bounds{0, 59, nil}
+	minutes = bounds{0, 59, nil}
+	hours   = bounds{0, 23, nil}
+	dom     = bounds{1, 31, nil}
+	months  = bounds{1, 12, map[string]uint{
+		"jan": 1,
+		"feb": 2,
+		"mar": 3,
+		"apr": 4,
+		"may": 5,
+		"jun": 6,
+		"jul": 7,
+		"aug": 8,
+		"sep": 9,
+		"oct": 10,
+		"nov": 11,
+		"dec": 12,
+	}}
+	dow = bounds{0, 6, map[string]uint{
+		"sun": 0,
+		"mon": 1,
+		"tue": 2,
+		"wed": 3,
+		"thu": 4,
+		"fri": 5,
+		"sat": 6,
+	}}
+)
+
+const (
+	// Set the top bit if a star was included in the expression.
+	starBit = 1 << 63
+)
+
+// 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.
+func (s *SpecSchedule) Next(t time.Time) time.Time {
+	// General approach
+	//
+	// For Month, Day, Hour, Minute, Second:
+	// Check if the time value matches.  If yes, continue to the next field.
+	// If the field doesn't match the schedule, then increment the field until it matches.
+	// While incrementing the field, a wrap-around brings it back to the beginning
+	// of the field list (since it is necessary to re-verify previous field
+	// values)
+
+	// Convert the given time into the schedule's timezone, if one is specified.
+	// Save the original timezone so we can convert back after we find a time.
+	// Note that schedules without a time zone specified (time.Local) are treated
+	// as local to the time provided.
+	origLocation := t.Location()
+	loc := s.Location
+	if loc == time.Local {
+		loc = t.Location()
+	}
+	if s.Location != time.Local {
+		t = t.In(s.Location)
+	}
+
+	// Start at the earliest possible time (the upcoming second).
+	t = t.Add(1*time.Second - time.Duration(t.Nanosecond())*time.Nanosecond)
+
+	// This flag indicates whether a field has been incremented.
+	added := false
+
+	// If no time is found within five years, return zero.
+	yearLimit := t.Year() + 5
+
+WRAP:
+	if t.Year() > yearLimit {
+		return time.Time{}
+	}
+
+	// Find the first applicable month.
+	// If it's this month, then do nothing.
+	for 1<<uint(t.Month())&s.Month == 0 {
+		// If we have to add a month, reset the other parts to 0.
+		if !added {
+			added = true
+			// Otherwise, set the date at the beginning (since the current time is irrelevant).
+			t = time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, loc)
+		}
+		t = t.AddDate(0, 1, 0)
+
+		// Wrapped around.
+		if t.Month() == time.January {
+			goto WRAP
+		}
+	}
+
+	// Now get a day in that month.
+	//
+	// NOTE: This causes issues for daylight savings regimes where midnight does
+	// not exist.  For example: Sao Paulo has DST that transforms midnight on
+	// 11/3 into 1am. Handle that by noticing when the Hour ends up != 0.
+	for !dayMatches(s, t) {
+		if !added {
+			added = true
+			t = time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, loc)
+		}
+		t = t.AddDate(0, 0, 1)
+		// Notice if the hour is no longer midnight due to DST.
+		// Add an hour if it's 23, subtract an hour if it's 1.
+		if t.Hour() != 0 {
+			if t.Hour() > 12 {
+				t = t.Add(time.Duration(24-t.Hour()) * time.Hour)
+			} else {
+				t = t.Add(time.Duration(-t.Hour()) * time.Hour)
+			}
+		}
+
+		if t.Day() == 1 {
+			goto WRAP
+		}
+	}
+
+	for 1<<uint(t.Hour())&s.Hour == 0 {
+		if !added {
+			added = true
+			t = time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, loc)
+		}
+		t = t.Add(1 * time.Hour)
+
+		if t.Hour() == 0 {
+			goto WRAP
+		}
+	}
+
+	for 1<<uint(t.Minute())&s.Minute == 0 {
+		if !added {
+			added = true
+			t = t.Truncate(time.Minute)
+		}
+		t = t.Add(1 * time.Minute)
+
+		if t.Minute() == 0 {
+			goto WRAP
+		}
+	}
+
+	for 1<<uint(t.Second())&s.Second == 0 {
+		if !added {
+			added = true
+			t = t.Truncate(time.Second)
+		}
+		t = t.Add(1 * time.Second)
+
+		if t.Second() == 0 {
+			goto WRAP
+		}
+	}
+
+	return t.In(origLocation)
+}
+
+// dayMatches returns true if the schedule's day-of-week and day-of-month
+// restrictions are satisfied by the given time.
+func dayMatches(s *SpecSchedule, t time.Time) bool {
+	var (
+		domMatch bool = 1<<uint(t.Day())&s.Dom > 0
+		dowMatch bool = 1<<uint(t.Weekday())&s.Dow > 0
+	)
+	if s.Dom&starBit > 0 || s.Dow&starBit > 0 {
+		return domMatch && dowMatch
+	}
+	return domMatch || dowMatch
+}