IMG-46: Call finishFn on download finished (metrics) (#1487)

* Skip goes to processing

* Call finishFn on download finished

* defer DownloadFinished in DownloadSync

asyncbuffer/buffer.go

@@ -14,6 +14,7 @@
 package asyncbuffer
 
 import (
+	"context"
 	"errors"
 	"io"
 	"sync"
@@ -68,15 +69,19 @@ type AsyncBuffer struct {
 
 	paused    *Latch // Paused buffer does not read data beyond threshold
 	chunkCond *Cond  // Ticker that signals when a new chunk is ready
+
+	finishOnce sync.Once
+	finishFn   []context.CancelFunc
 }
 
 // New creates a new AsyncBuffer that reads from the given io.ReadCloser in background
 // and closes it when finished.
-func New(r io.ReadCloser) *AsyncBuffer {
+func New(r io.ReadCloser, finishFn ...context.CancelFunc) *AsyncBuffer {
 	ab := &AsyncBuffer{
 		r:         r,
 		paused:    NewLatch(),
 		chunkCond: NewCond(),
+		finishFn:  finishFn,
 	}
 
 	go ab.readChunks()
@@ -113,6 +118,12 @@ func (ab *AsyncBuffer) readChunks() {
 		if err := ab.r.Close(); err != nil {
 			logrus.WithField("source", "asyncbuffer.AsyncBuffer.readChunks").Warningf("error closing upstream reader: %s", err)
 		}
+
+		ab.finishOnce.Do(func() {
+			for _, fn := range ab.finishFn {
+				fn()
+			}
+		})
 	}()
 
 	// Stop reading if the reader is closed
@@ -391,6 +402,13 @@ func (ab *AsyncBuffer) Close() error {
 	// Release the paused latch so that no goroutines are waiting for it
 	ab.paused.Release()
 
+	// Finish downloading
+	ab.finishOnce.Do(func() {
+		for _, fn := range ab.finishFn {
+			fn()
+		}
+	})
+
 	return nil
 }
 

imagedata/download.go

@@ -1,6 +1,7 @@
 package imagedata
 
 import (
+	"context"
 	"net/http"
 
 	"github.com/imgproxy/imgproxy/v3/config"
@@ -18,16 +19,18 @@ var (
 )
 
 type DownloadOptions struct {
-	Header         http.Header
-	CookieJar      http.CookieJar
-	MaxSrcFileSize int
+	Header           http.Header
+	CookieJar        http.CookieJar
+	MaxSrcFileSize   int
+	DownloadFinished context.CancelFunc
 }
 
 func DefaultDownloadOptions() DownloadOptions {
 	return DownloadOptions{
-		Header:         nil,
-		CookieJar:      nil,
-		MaxSrcFileSize: config.MaxSrcFileSize,
+		Header:           nil,
+		CookieJar:        nil,
+		MaxSrcFileSize:   config.MaxSrcFileSize,
+		DownloadFinished: nil,
 	}
 }
 

imagedata/factory.go

@@ -106,6 +106,10 @@ func sendRequest(ctx context.Context, url string, opts DownloadOptions) (*imagef
 
 // DownloadSync downloads the image synchronously and returns the ImageData and HTTP headers.
 func downloadSync(ctx context.Context, imageURL string, opts DownloadOptions) (ImageData, http.Header, error) {
+	if opts.DownloadFinished != nil {
+		defer opts.DownloadFinished()
+	}
+
 	req, res, h, err := sendRequest(ctx, imageURL, opts)
 	if res != nil {
 		defer res.Body.Close()
@@ -140,10 +144,13 @@ func downloadAsync(ctx context.Context, imageURL string, opts DownloadOptions) (
 	//nolint:bodyclose
 	req, res, h, err := sendRequest(ctx, imageURL, opts)
 	if err != nil {
+		if opts.DownloadFinished != nil {
+			defer opts.DownloadFinished()
+		}
 		return nil, h, err
 	}
 
-	b := asyncbuffer.New(res.Body)
+	b := asyncbuffer.New(res.Body, opts.DownloadFinished)
 
 	format, err := imagetype.Detect(b.Reader())
 	if err != nil {

processing_handler.go

@@ -29,6 +29,7 @@ import (
 	"github.com/imgproxy/imgproxy/v3/processing"
 	"github.com/imgproxy/imgproxy/v3/router"
 	"github.com/imgproxy/imgproxy/v3/security"
+	"github.com/imgproxy/imgproxy/v3/svg"
 	"github.com/imgproxy/imgproxy/v3/vips"
 )
 
@@ -361,15 +362,16 @@ func handleProcessing(reqID string, rw http.ResponseWriter, r *http.Request) {
 	statusCode := http.StatusOK
 
 	originData, originHeaders, err := func() (imagedata.ImageData, http.Header, error) {
-		defer metrics.StartDownloadingSegment(ctx, metrics.Meta{
+		downloadFinished := metrics.StartDownloadingSegment(ctx, metrics.Meta{
 			metrics.MetaSourceImageURL:    metricsMeta[metrics.MetaSourceImageURL],
 			metrics.MetaSourceImageOrigin: metricsMeta[metrics.MetaSourceImageOrigin],
-		})()
+		})
 
 		downloadOpts := imagedata.DownloadOptions{
-			Header:         imgRequestHeader,
-			CookieJar:      nil,
-			MaxSrcFileSize: po.SecurityOptions.MaxSrcFileSize,
+			Header:           imgRequestHeader,
+			CookieJar:        nil,
+			MaxSrcFileSize:   po.SecurityOptions.MaxSrcFileSize,
+			DownloadFinished: downloadFinished,
 		}
 
 		if config.CookiePassthrough {
@@ -468,6 +470,12 @@ func handleProcessing(reqID string, rw http.ResponseWriter, r *http.Request) {
 	}
 
 	if err != nil {
+		// svg_processing is an exception. We use As here because Is does not work with types.
+		var e svg.SanitizeError
+		if errors.As(err, &e) {
+			checkErr(ctx, "svg_processing", e)
+		}
+
 		// First, check if the processing error wasn't caused by an image data error
 		checkErr(ctx, "download", originData.Error())
 

processing_handler_test.go

@@ -341,6 +341,7 @@ func (s *ProcessingHandlerTestSuite) TestErrorSavingToSVG() {
 	res := rw.Result()
 
 	s.Require().Equal(422, res.StatusCode)
+	fmt.Println(io.ReadAll(res.Body)) // Read the body to avoid resource leak
 }
 
 func (s *ProcessingHandlerTestSuite) TestCacheControlPassthroughCacheControl() {