1 files changed, 176 insertions, 0 deletions
diff --git a/internal/media/manager.go b/internal/media/manager.go
new file mode 100644
index 000000000..7f626271a
--- /dev/null
+++ b/internal/media/manager.go
@@ -0,0 +1,176 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package media
+
+import (
+	"context"
+	"errors"
+	"runtime"
+
+	"codeberg.org/gruf/go-runners"
+	"codeberg.org/gruf/go-store/kv"
+	"github.com/sirupsen/logrus"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+)
+
+// Manager provides an interface for managing media: parsing, storing, and retrieving media objects like photos, videos, and gifs.
+type Manager interface {
+	// ProcessMedia begins the process of decoding and storing the given data as an attachment.
+	// It will return a pointer to a Media struct upon which further actions can be performed, such as getting
+	// the finished media, thumbnail, attachment, etc.
+	//
+	// data should be a function that the media manager can call to return raw bytes of a piece of media.
+	//
+	// accountID should be the account that the media belongs to.
+	//
+	// ai is optional and can be nil. Any additional information about the attachment provided will be put in the database.
+	ProcessMedia(ctx context.Context, data DataFunc, accountID string, ai *AdditionalMediaInfo) (*ProcessingMedia, error)
+	ProcessEmoji(ctx context.Context, data DataFunc, shortcode string, id string, uri string, ai *AdditionalEmojiInfo) (*ProcessingEmoji, error)
+	// NumWorkers returns the total number of workers available to this manager.
+	NumWorkers() int
+	// QueueSize returns the total capacity of the queue.
+	QueueSize() int
+	// JobsQueued returns the number of jobs currently in the task queue.
+	JobsQueued() int
+	// ActiveWorkers returns the number of workers currently performing jobs.
+	ActiveWorkers() int
+	// Stop stops the underlying worker pool of the manager. It should be called
+	// when closing GoToSocial in order to cleanly finish any in-progress jobs.
+	// It will block until workers are finished processing.
+	Stop() error
+}
+
+type manager struct {
+	db         db.DB
+	storage    *kv.KVStore
+	pool       runners.WorkerPool
+	numWorkers int
+	queueSize  int
+}
+
+// NewManager returns a media manager with the given db and underlying storage.
+//
+// A worker pool will also be initialized for the manager, to ensure that only
+// a limited number of media will be processed in parallel.
+//
+// The number of workers will be the number of CPUs available to the Go runtime,
+// divided by 2 (rounding down, but always at least 1).
+//
+// The length of the queue will be the number of workers multiplied by 10.
+//
+// So for an 8 core machine, the media manager will get 4 workers, and a queue of length 40.
+// For a 4 core machine, this will be 2 workers, and a queue length of 20.
+// For a single or 2-core machine, the media manager will get 1 worker, and a queue of length 10.
+func NewManager(database db.DB, storage *kv.KVStore) (Manager, error) {
+	numWorkers := runtime.NumCPU() / 2
+	// make sure we always have at least 1 worker even on single-core machines
+	if numWorkers == 0 {
+		numWorkers = 1
+	}
+	queueSize := numWorkers * 10
+
+	m := &manager{
+		db:         database,
+		storage:    storage,
+		pool:       runners.NewWorkerPool(numWorkers, queueSize),
+		numWorkers: numWorkers,
+		queueSize:  queueSize,
+	}
+
+	if start := m.pool.Start(); !start {
+		return nil, errors.New("could not start worker pool")
+	}
+	logrus.Debugf("started media manager worker pool with %d workers and queue capacity of %d", numWorkers, queueSize)
+
+	return m, nil
+}
+
+func (m *manager) ProcessMedia(ctx context.Context, data DataFunc, accountID string, ai *AdditionalMediaInfo) (*ProcessingMedia, error) {
+	processingMedia, err := m.preProcessMedia(ctx, data, accountID, ai)
+	if err != nil {
+		return nil, err
+	}
+
+	logrus.Tracef("ProcessMedia: about to enqueue media with attachmentID %s, queue length is %d", processingMedia.AttachmentID(), m.pool.Queue())
+	m.pool.Enqueue(func(innerCtx context.Context) {
+		select {
+		case <-innerCtx.Done():
+			// if the inner context is done that means the worker pool is closing, so we should just return
+			return
+		default:
+			// start loading the media already for the caller's convenience
+			if _, err := processingMedia.LoadAttachment(innerCtx); err != nil {
+				logrus.Errorf("ProcessMedia: error processing media with attachmentID %s: %s", processingMedia.AttachmentID(), err)
+			}
+		}
+	})
+	logrus.Tracef("ProcessMedia: succesfully queued media with attachmentID %s, queue length is %d", processingMedia.AttachmentID(), m.pool.Queue())
+
+	return processingMedia, nil
+}
+
+func (m *manager) ProcessEmoji(ctx context.Context, data DataFunc, shortcode string, id string, uri string, ai *AdditionalEmojiInfo) (*ProcessingEmoji, error) {
+	processingEmoji, err := m.preProcessEmoji(ctx, data, shortcode, id, uri, ai)
+	if err != nil {
+		return nil, err
+	}
+
+	logrus.Tracef("ProcessEmoji: about to enqueue emoji with id %s, queue length is %d", processingEmoji.EmojiID(), m.pool.Queue())
+	m.pool.Enqueue(func(innerCtx context.Context) {
+		select {
+		case <-innerCtx.Done():
+			// if the inner context is done that means the worker pool is closing, so we should just return
+			return
+		default:
+			// start loading the emoji already for the caller's convenience
+			if _, err := processingEmoji.LoadEmoji(innerCtx); err != nil {
+				logrus.Errorf("ProcessEmoji: error processing emoji with id %s: %s", processingEmoji.EmojiID(), err)
+			}
+		}
+	})
+	logrus.Tracef("ProcessEmoji: succesfully queued emoji with id %s, queue length is %d", processingEmoji.EmojiID(), m.pool.Queue())
+
+	return processingEmoji, nil
+}
+
+func (m *manager) NumWorkers() int {
+	return m.numWorkers
+}
+
+func (m *manager) QueueSize() int {
+	return m.queueSize
+}
+
+func (m *manager) JobsQueued() int {
+	return m.pool.Queue()
+}
+
+func (m *manager) ActiveWorkers() int {
+	return m.pool.Workers()
+}
+
+func (m *manager) Stop() error {
+	logrus.Info("stopping media manager worker pool")
+
+	stopped := m.pool.Stop()
+	if !stopped {
+		return errors.New("could not stop media manager worker pool")
+	}
+	return nil
+}