[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/cron.go

@@ -0,0 +1,355 @@
+package cron
+
+import (
+	"context"
+	"sort"
+	"sync"
+	"time"
+)
+
+// Cron keeps track of any number of entries, invoking the associated func as
+// specified by the schedule. It may be started, stopped, and the entries may
+// be inspected while running.
+type Cron struct {
+	entries   []*Entry
+	chain     Chain
+	stop      chan struct{}
+	add       chan *Entry
+	remove    chan EntryID
+	snapshot  chan chan []Entry
+	running   bool
+	logger    Logger
+	runningMu sync.Mutex
+	location  *time.Location
+	parser    ScheduleParser
+	nextID    EntryID
+	jobWaiter sync.WaitGroup
+}
+
+// ScheduleParser is an interface for schedule spec parsers that return a Schedule
+type ScheduleParser interface {
+	Parse(spec string) (Schedule, error)
+}
+
+// Job is an interface for submitted cron jobs.
+type Job interface {
+	Run()
+}
+
+// Schedule describes a job's duty cycle.
+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
+}
+
+// EntryID identifies an entry within a Cron instance
+type EntryID int
+
+// Entry consists of a schedule and the func to execute on that schedule.
+type Entry struct {
+	// ID is the cron-assigned ID of this entry, which may be used to look up a
+	// snapshot or remove it.
+	ID EntryID
+
+	// Schedule on which this job should be run.
+	Schedule Schedule
+
+	// Next time the job will run, or the zero time if Cron has not been
+	// started or this entry's schedule is unsatisfiable
+	Next time.Time
+
+	// Prev is the last time this job was run, or the zero time if never.
+	Prev time.Time
+
+	// WrappedJob is the thing to run when the Schedule is activated.
+	WrappedJob Job
+
+	// Job is the thing that was submitted to cron.
+	// It is kept around so that user code that needs to get at the job later,
+	// e.g. via Entries() can do so.
+	Job Job
+}
+
+// Valid returns true if this is not the zero entry.
+func (e Entry) Valid() bool { return e.ID != 0 }
+
+// byTime is a wrapper for sorting the entry array by time
+// (with zero time at the end).
+type byTime []*Entry
+
+func (s byTime) Len() int      { return len(s) }
+func (s byTime) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+func (s byTime) Less(i, j int) bool {
+	// Two zero times should return false.
+	// Otherwise, zero is "greater" than any other time.
+	// (To sort it at the end of the list.)
+	if s[i].Next.IsZero() {
+		return false
+	}
+	if s[j].Next.IsZero() {
+		return true
+	}
+	return s[i].Next.Before(s[j].Next)
+}
+
+// New returns a new Cron job runner, modified by the given options.
+//
+// Available Settings
+//
+//   Time Zone
+//     Description: The time zone in which schedules are interpreted
+//     Default:     time.Local
+//
+//   Parser
+//     Description: Parser converts cron spec strings into cron.Schedules.
+//     Default:     Accepts this spec: https://en.wikipedia.org/wiki/Cron
+//
+//   Chain
+//     Description: Wrap submitted jobs to customize behavior.
+//     Default:     A chain that recovers panics and logs them to stderr.
+//
+// See "cron.With*" to modify the default behavior.
+func New(opts ...Option) *Cron {
+	c := &Cron{
+		entries:   nil,
+		chain:     NewChain(),
+		add:       make(chan *Entry),
+		stop:      make(chan struct{}),
+		snapshot:  make(chan chan []Entry),
+		remove:    make(chan EntryID),
+		running:   false,
+		runningMu: sync.Mutex{},
+		logger:    DefaultLogger,
+		location:  time.Local,
+		parser:    standardParser,
+	}
+	for _, opt := range opts {
+		opt(c)
+	}
+	return c
+}
+
+// FuncJob is a wrapper that turns a func() into a cron.Job
+type FuncJob func()
+
+func (f FuncJob) Run() { f() }
+
+// AddFunc adds a func to the Cron to be run on the given schedule.
+// The spec is parsed using the time zone of this Cron instance as the default.
+// An opaque ID is returned that can be used to later remove it.
+func (c *Cron) AddFunc(spec string, cmd func()) (EntryID, error) {
+	return c.AddJob(spec, FuncJob(cmd))
+}
+
+// AddJob adds a Job to the Cron to be run on the given schedule.
+// The spec is parsed using the time zone of this Cron instance as the default.
+// An opaque ID is returned that can be used to later remove it.
+func (c *Cron) AddJob(spec string, cmd Job) (EntryID, error) {
+	schedule, err := c.parser.Parse(spec)
+	if err != nil {
+		return 0, err
+	}
+	return c.Schedule(schedule, cmd), nil
+}
+
+// Schedule adds a Job to the Cron to be run on the given schedule.
+// The job is wrapped with the configured Chain.
+func (c *Cron) Schedule(schedule Schedule, cmd Job) EntryID {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	c.nextID++
+	entry := &Entry{
+		ID:         c.nextID,
+		Schedule:   schedule,
+		WrappedJob: c.chain.Then(cmd),
+		Job:        cmd,
+	}
+	if !c.running {
+		c.entries = append(c.entries, entry)
+	} else {
+		c.add <- entry
+	}
+	return entry.ID
+}
+
+// Entries returns a snapshot of the cron entries.
+func (c *Cron) Entries() []Entry {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		replyChan := make(chan []Entry, 1)
+		c.snapshot <- replyChan
+		return <-replyChan
+	}
+	return c.entrySnapshot()
+}
+
+// Location gets the time zone location
+func (c *Cron) Location() *time.Location {
+	return c.location
+}
+
+// Entry returns a snapshot of the given entry, or nil if it couldn't be found.
+func (c *Cron) Entry(id EntryID) Entry {
+	for _, entry := range c.Entries() {
+		if id == entry.ID {
+			return entry
+		}
+	}
+	return Entry{}
+}
+
+// Remove an entry from being run in the future.
+func (c *Cron) Remove(id EntryID) {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		c.remove <- id
+	} else {
+		c.removeEntry(id)
+	}
+}
+
+// Start the cron scheduler in its own goroutine, or no-op if already started.
+func (c *Cron) Start() {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		return
+	}
+	c.running = true
+	go c.run()
+}
+
+// Run the cron scheduler, or no-op if already running.
+func (c *Cron) Run() {
+	c.runningMu.Lock()
+	if c.running {
+		c.runningMu.Unlock()
+		return
+	}
+	c.running = true
+	c.runningMu.Unlock()
+	c.run()
+}
+
+// run the scheduler.. this is private just due to the need to synchronize
+// access to the 'running' state variable.
+func (c *Cron) run() {
+	c.logger.Info("start")
+
+	// Figure out the next activation times for each entry.
+	now := c.now()
+	for _, entry := range c.entries {
+		entry.Next = entry.Schedule.Next(now)
+		c.logger.Info("schedule", "now", now, "entry", entry.ID, "next", entry.Next)
+	}
+
+	for {
+		// Determine the next entry to run.
+		sort.Sort(byTime(c.entries))
+
+		var timer *time.Timer
+		if len(c.entries) == 0 || c.entries[0].Next.IsZero() {
+			// If there are no entries yet, just sleep - it still handles new entries
+			// and stop requests.
+			timer = time.NewTimer(100000 * time.Hour)
+		} else {
+			timer = time.NewTimer(c.entries[0].Next.Sub(now))
+		}
+
+		for {
+			select {
+			case now = <-timer.C:
+				now = now.In(c.location)
+				c.logger.Info("wake", "now", now)
+
+				// Run every entry whose next time was less than now
+				for _, e := range c.entries {
+					if e.Next.After(now) || e.Next.IsZero() {
+						break
+					}
+					c.startJob(e.WrappedJob)
+					e.Prev = e.Next
+					e.Next = e.Schedule.Next(now)
+					c.logger.Info("run", "now", now, "entry", e.ID, "next", e.Next)
+				}
+
+			case newEntry := <-c.add:
+				timer.Stop()
+				now = c.now()
+				newEntry.Next = newEntry.Schedule.Next(now)
+				c.entries = append(c.entries, newEntry)
+				c.logger.Info("added", "now", now, "entry", newEntry.ID, "next", newEntry.Next)
+
+			case replyChan := <-c.snapshot:
+				replyChan <- c.entrySnapshot()
+				continue
+
+			case <-c.stop:
+				timer.Stop()
+				c.logger.Info("stop")
+				return
+
+			case id := <-c.remove:
+				timer.Stop()
+				now = c.now()
+				c.removeEntry(id)
+				c.logger.Info("removed", "entry", id)
+			}
+
+			break
+		}
+	}
+}
+
+// startJob runs the given job in a new goroutine.
+func (c *Cron) startJob(j Job) {
+	c.jobWaiter.Add(1)
+	go func() {
+		defer c.jobWaiter.Done()
+		j.Run()
+	}()
+}
+
+// now returns current time in c location
+func (c *Cron) now() time.Time {
+	return time.Now().In(c.location)
+}
+
+// Stop stops the cron scheduler if it is running; otherwise it does nothing.
+// A context is returned so the caller can wait for running jobs to complete.
+func (c *Cron) Stop() context.Context {
+	c.runningMu.Lock()
+	defer c.runningMu.Unlock()
+	if c.running {
+		c.stop <- struct{}{}
+		c.running = false
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		c.jobWaiter.Wait()
+		cancel()
+	}()
+	return ctx
+}
+
+// entrySnapshot returns a copy of the current cron entry list.
+func (c *Cron) entrySnapshot() []Entry {
+	var entries = make([]Entry, len(c.entries))
+	for i, e := range c.entries {
+		entries[i] = *e
+	}
+	return entries
+}
+
+func (c *Cron) removeEntry(id EntryID) {
+	var entries []*Entry
+	for _, e := range c.entries {
+		if e.ID != id {
+			entries = append(entries, e)
+		}
+	}
+	c.entries = entries
+}