perf(export): download in chunks files >= 10 mb

app/lib/download_manager/parallel_download_queue.rb

@@ -15,18 +15,14 @@ module DownloadManager
       hydra = Typhoeus::Hydra.new(max_concurrency: DOWNLOAD_MAX_PARALLEL)
 
       attachments.each do |attachment, path|
-        begin
-          download_one(attachment: attachment,
-                       path_in_download_dir: path,
-                       http_client: hydra)
-        rescue => e
-          on_error.call(attachment, path, e)
-        end
+        download_one(attachment: attachment,
+                      path_in_download_dir: path,
+                      http_client: hydra)
+      rescue => e
+        on_error.call(attachment, path, e)
       end
 
       hydra.run
-
-      GC.start
     end
 
     # can't be used with typhoeus, otherwise block is closed before the request is run by hydra
@@ -38,20 +34,17 @@ module DownloadManager
 
       if attachment.is_a?(ActiveStorage::FakeAttachment)
         attachment_path.write(attachment.file.read, mode: 'wb')
-      else
-        request = Typhoeus::Request.new(attachment.url)
-        request.on_complete do |response|
-          if response.success?
-            attachment_path.open(mode: "wb") do |fd|
-              fd.write(response.body)
-            end
-          else
-            attachment_path.delete if attachment_path.exist? # -> case of retries failed, must cleanup partialy downloaded file
-            on_error.call(attachment, path_in_download_dir, response.code)
-          end
-        end
-        http_client.queue(request)
+        return
       end
+
+      request = Typhoeus::Request.new(attachment.url)
+      if attachment.blob.byte_size < 10.megabytes
+        request_in_whole(request, attachment:, attachment_path:, path_in_download_dir:)
+      else
+        request_in_chunks(request, attachment:, attachment_path:, path_in_download_dir:)
+      end
+
+      http_client.queue(request)
     end
 
     private
@@ -66,5 +59,38 @@ module DownloadManager
 
       basename + ext
     end
+
+    def request_in_whole(request, attachment:, attachment_path:, path_in_download_dir:)
+      request.on_complete do |response|
+        if response.success?
+          attachment_path.open(mode: 'wb') do |fd|
+            fd.write(response.body)
+          end
+        else
+          handle_response_error(response, attachment:, attachment_path:, path_in_download_dir:)
+        end
+      end
+    end
+
+    def request_in_chunks(request, attachment:, attachment_path:, path_in_download_dir:)
+      downloaded_file = attachment_path.open(mode: 'wb')
+
+      request.on_body do |chunk|
+        downloaded_file.write(chunk)
+      end
+
+      request.on_complete do |response|
+        downloaded_file.close
+
+        if !response.success?
+          handle_response_error(response, attachment:, attachment_path:, path_in_download_dir:)
+        end
+      end
+    end
+
+    def handle_response_error(response, attachment:, attachment_path:, path_in_download_dir:)
+      attachment_path.delete if attachment_path.exist? # -> case of retries failed, must cleanup partialy downloaded file
+      on_error.call(attachment, path_in_download_dir, response.code)
+    end
   end
 end

spec/lib/download_manager/parallel_download_queue_spec.rb

@@ -8,8 +8,10 @@ describe DownloadManager::ParallelDownloadQueue do
   after { FileUtils.remove_entry_secure(test_dir) if Dir.exist?(test_dir) }
 
   let(:downloadable_manager) { DownloadManager::ParallelDownloadQueue.new([attachment], download_to_dir) }
+  let(:http_client) { instance_double(Typhoeus::Hydra) }
+
   describe '#download_one' do
-    subject { downloadable_manager.download_one(attachment: attachment, path_in_download_dir: destination, http_client: double) }
+    subject { downloadable_manager.download_one(attachment: attachment, path_in_download_dir: destination, http_client:) }
 
     let(:destination) { 'lol.png' }
     let(:attachment) do
@@ -73,5 +75,47 @@ describe DownloadManager::ParallelDownloadQueue do
         end
       end
     end
+
+    context "download strategies" do
+      subject { super(); http_client.run }
+      let(:byte_size) { 1.kilobyte }
+      let(:file_url) { 'http://example.com/test_file' }
+      let(:destination) { 'test_file.txt' }
+      let(:http_client) { Typhoeus::Hydra.new }
+      let(:blob) { instance_double('ActiveStorage::Blob', byte_size:, url: file_url) }
+      let(:attachment) { double('ActiveStorage::Attachment', blob: blob) }
+
+      before do
+        allow(attachment).to receive(:url).and_return(file_url)
+        stub_request(:get, file_url).to_return(body: file_content, status: 200)
+      end
+
+      context 'for small files using request_in_whole method' do
+        let(:file_content) { 'downloaded content' }
+        it 'downloads the file in whole' do
+          target = Pathname.new(download_to_dir).join(destination)
+          expect { subject }.to change { target.exist? }.from(false).to(true)
+
+          expect(File.read(target)).to eq(file_content)
+        end
+      end
+
+      context 'for large files using request_in_chunks method' do
+        let(:byte_size) { 20.megabytes } # Adjust byte size for large file scenario
+        let(:file_content) { 'downloaded content' * 1000 }
+
+        before do
+          allow(downloadable_manager).to receive(:request_in_chunks).and_call_original
+        end
+
+        it 'downloads the file in chunks' do
+          target = Pathname.new(download_to_dir).join(destination)
+          expect { subject }.to change { target.exist? }.from(false).to(true)
+
+          expect(File.read(target)).to eq(file_content)
+          expect(downloadable_manager).to have_received(:request_in_chunks) # ensure we're taking the chunks code path
+        end
+      end
+    end
   end
 end