uploads: fix temp files not being cleaned up quickly enough.

Fix temp files generated during the upload process not being cleaned up quickly enough. This included
downloaded files, generated preview images, and Ugoira video conversions.

Before we relied on `Tempfile` cleaning up files automatically. But this only happened when the
Tempfile object was garbage collected, which could take a long time. In the meantime we could have
hundreds of megabytes of temp files hanging around.

The fix is to explicitly close temp files when we're done with them. But the standard `Tempfile`
class doesn't immediately delete the file when it's closed. So we also have to introduce a
Danbooru::Tempfile wrapper that deletes the tempfile as soon as it's closed.

app/logical/bigquery_export_service.rb

@@ -55,20 +55,21 @@ class BigqueryExportService
 
     file = dump_records!
     upload_to_bigquery!(file)
+  ensure
+    file&.close
   end
 
   # Dump the table's records to a gzipped, newline-delimited JSON tempfile.
-  def dump_records!
-    file = Tempfile.new("danbooru-export-dump-", binmode: true)
-    file = Zlib::GzipWriter.new(file)
+  def dump_records!(file = Danbooru::Tempfile.new("danbooru-export-dump-#{model.name}-", binmode: true))
+    gzip = Zlib::GzipWriter.new(file)
 
     CurrentUser.scoped(User.anonymous) do
       records.find_each(batch_size: 5_000) do |record|
-        file.puts(record.to_json)
+        gzip.puts(record.to_json)
       end
     end
 
-    file.close # flush zlib footer
+    gzip.finish
     file
   end
 

app/logical/danbooru/http.rb

@@ -171,11 +171,11 @@ module Danbooru
       # Download a file from `url` and return a {MediaFile}.
       #
       # @param url [String] the URL to download
-      # @param file [Tempfile] the file to download the URL to
+      # @param file [Danbooru::Tempfile] the file to download the URL to
       # @raise [DownloadError] if the server returns a non-200 OK response
       # @raise [FileTooLargeError] if the file exceeds Danbooru's maximum download size.
       # @return [Array<(HTTP::Response, MediaFile)>] the HTTP response and the downloaded file
-      def download_media(url, file: Tempfile.new("danbooru-download-", binmode: true))
+      def download_media(url, file: Danbooru::Tempfile.new("danbooru-download-#{url.parameterize.truncate(96)}-", binmode: true))
         response = get(url)
 
         raise DownloadError, "#{url} failed with code #{response.status}" if response.status != 200

app/logical/danbooru/tempfile.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Like Tempfile, but delete the tempfile when it's closed.
+#
+# The Tempfile class in the standard library doesn't delete the file immediately when you call `file.close`. Instead you
+# have to call `file.close!` or `file.unlink` to delete the file, or wait until the object gets garbage collected, which
+# can take a long time. This makes it so that Tempfiles are cleaned up immediately on close.
+module Danbooru
+  class Tempfile < ::Tempfile
+    def close(unlink = true)
+      super
+    end
+  end
+end

app/logical/discord_slash_command/tagme_command.rb

@@ -52,6 +52,8 @@ class DiscordSlashCommand
           },
         }]
       }
+    ensure
+      preview&.close
     end
 
     def get_last_message_with_url(limit: 10)

app/logical/ffmpeg.rb

@@ -22,7 +22,7 @@ class FFmpeg
   #
   # @return [MediaFile] the preview image
   def smart_video_preview
-    vp = Tempfile.new(["video-preview", ".png"], binmode: true)
+    vp = Danbooru::Tempfile.new(["danbooru-video-preview-#{file.md5}-", ".png"], binmode: true)
 
     # https://ffmpeg.org/ffmpeg.html#Main-options
     # https://ffmpeg.org/ffmpeg-filters.html#thumbnail

app/logical/iqdb_client.rb

@@ -101,6 +101,8 @@ class IqdbClient
       preview = media_file.preview!(Danbooru.config.small_image_width, Danbooru.config.small_image_width)
       file = HTTP::FormData::File.new(preview)
       request(:post, "query", form: { file: file }, params: { limit: limit })
+    ensure
+      preview&.close
     end
 
     # Add a post to IQDB.

app/logical/media_file/image.rb

@@ -7,6 +7,11 @@
 class MediaFile::Image < MediaFile
   delegate :thumbnail_image, to: :image
 
+  def close
+    super
+    @preview_frame&.close unless @preview_frame == self
+  end
+
   def dimensions
     image.size
   rescue Vips::Error
@@ -107,7 +112,7 @@ class MediaFile::Image < MediaFile
       resized_image = resized_image.flatten(background: 255)
     end
 
-    output_file = Tempfile.new(["image-preview-#{md5}", ".#{format.to_s}"])
+    output_file = Danbooru::Tempfile.new(["danbooru-image-preview-#{md5}-", ".#{format.to_s}"])
     case format.to_sym
     when :jpeg
       # https://www.libvips.org/API/current/VipsForeignSave.html#vips-jpegsave
@@ -130,14 +135,6 @@ class MediaFile::Image < MediaFile
     preview_frame.resize!(w, h, size: :force, **options)
   end
 
-  def preview_frame
-    if is_animated?
-      FFmpeg.new(self).smart_video_preview
-    else
-      self
-    end
-  end
-
   def is_animated?
     frame_count.to_i > 1
   end
@@ -166,6 +163,8 @@ class MediaFile::Image < MediaFile
     false
   end
 
+  private
+
   # @return [Vips::Image] the Vips image object for the file
   def image
     Vips::Image.new_from_file(file.path, fail: false).autorot
@@ -175,5 +174,15 @@ class MediaFile::Image < MediaFile
     FFmpeg.new(self)
   end
 
-  memoize :image, :video, :preview_frame, :dimensions, :error, :metadata, :is_corrupt?, :is_animated_gif?, :is_animated_png?
+  def preview_frame
+    @preview_frame ||= begin
+      if is_animated?
+        FFmpeg.new(self).smart_video_preview
+      else
+        self
+      end
+    end
+  end
+
+  memoize :image, :video, :dimensions, :error, :metadata, :is_corrupt?, :is_animated_gif?, :is_animated_png?
 end

app/logical/media_file/ugoira.rb

@@ -17,8 +17,9 @@ class MediaFile::Ugoira < MediaFile
   end
 
   def close
-    file.close
-    preview_frame.close
+    super
+    @preview_frame&.close
+    # XXX should clean up `convert` too
   end
 
   def metadata
@@ -52,7 +53,7 @@ class MediaFile::Ugoira < MediaFile
     raise RuntimeError, "can't convert ugoira to webm: no ugoira frame data was provided" unless frame_delays.present?
 
     Danbooru::Archive.extract!(file) do |tmpdir, filenames|
-      output_file = Tempfile.new(["ugoira-conversion", ".webm"], binmode: true)
+      output_file = Danbooru::Tempfile.new(["danbooru-ugoira-conversion-#{md5}-", ".webm"], binmode: true)
 
       # Duplicate last frame to avoid it being displayed only for a very short amount of time.
       last_file_name = File.basename(filenames.last)
@@ -90,8 +91,8 @@ class MediaFile::Ugoira < MediaFile
   private
 
   def preview_frame
-    FFmpeg.new(convert).smart_video_preview
+    @preview_frame ||= FFmpeg.new(convert).smart_video_preview
   end
 
-  memoize :preview_frame, :dimensions, :convert, :metadata
+  memoize :dimensions, :convert, :metadata
 end

app/logical/media_file/video.rb

@@ -10,6 +10,11 @@ class MediaFile::Video < MediaFile
     :audio_stream, :audio_streams, :silence_duration, :silence_percentage, :average_loudness,
     :peak_loudness, :loudness_range, :error, to: :video
 
+  def close
+    super
+    @preview_frame&.close
+  end
+
   def dimensions
     [video.width, video.height]
   end
@@ -65,8 +70,8 @@ class MediaFile::Video < MediaFile
   end
 
   def preview_frame
-    video.smart_video_preview
+    @preview_frame ||= video.smart_video_preview
   end
 
-  memoize :video, :preview_frame, :dimensions, :metadata, :duration, :has_audio?
+  memoize :video, :dimensions, :metadata, :duration, :has_audio?
 end

app/logical/post_replacement_processor.rb

@@ -53,6 +53,8 @@ class PostReplacementProcessor
   rescue Exception => exception
     replacement.errors.add(:base, exception.message)
     raise ActiveRecord::Rollback
+  ensure
+    media_file&.close
   end
 
   def rescale_notes(post)

app/logical/storage_manager/rclone.rb

@@ -27,7 +27,7 @@ class StorageManager::Rclone < StorageManager
   end
 
   def open(path)
-    file = Tempfile.new(binmode: true)
+    file = Danbooru::Tempfile.new(binmode: true)
     rclone "copyto", key(path), file.path
     file
   end

app/models/media_asset.rb

@@ -68,6 +68,8 @@ class MediaAsset < ApplicationRecord
       file = convert_file(original_file)
       storage_service.store(file, file_path)
       backup_storage_service.store(file, file_path)
+    ensure
+      file&.close
     end
 
     def trash_file!

app/models/upload_media_asset.rb

@@ -112,6 +112,8 @@ class UploadMediaAsset < ApplicationRecord
     update!(status: :active)
   rescue Exception => e
     update!(status: :failed, error: e.message)
+  ensure
+    media_file&.close
   end
 
   def update_upload_status