SLS: skip to next working slide on problem

When a slide cannot be encoded, skip to the next slide that works.

To prevent an infinite loop, no skipping is done when the last slide of
the slide store doesn't work and also no earlier slide of it worked.

2 files changed, 32 insertions, 15 deletions

diff --git a/src/odr-padenc.cpp b/src/odr-padenc.cpp
index 6506012..94f3d68 100644
--- a/src/odr-padenc.cpp
+++ b/src/odr-padenc.cpp
@@ -350,23 +350,38 @@ int PadEncoder::EncodeSlide(bool skip_if_already_queued) {
         return 0;
     }
 
-    // try to read slides dir (if present)
-    if (slides.Empty()) {
-        if (!slides.InitFromDir(options.sls_dir))
-            return 1;
-    }
-
-    // if slides available, encode the first one
-    if (!slides.Empty()) {
-        slide_metadata_t slide = slides.GetSlide();
-
-        if (!sls_encoder.encodeSlide(slide.filepath, slide.fidx, options.raw_slides))
-            fprintf(stderr, "ODR-PadEnc Error: cannot encode file '%s'\n", slide.filepath.c_str());
+    // usually invoked once
+    for(;;) {
+        // try to read slides dir (if present)
+        if (slides.Empty()) {
+            if (!slides.InitFromDir(options.sls_dir))
+                return 1;
+            slides_success = false;
+        }
 
-        if (options.erase_after_tx) {
-            if (unlink(slide.filepath.c_str()) == -1)
-                perror(("ODR-PadEnc Error: erasing file '" + slide.filepath +"' failed").c_str());
+        // if slides available, encode the first one
+        if (!slides.Empty()) {
+            slide_metadata_t slide = slides.GetSlide();
+
+            if (sls_encoder.encodeSlide(slide.filepath, slide.fidx, options.raw_slides)) {
+                slides_success = true;
+                if (options.erase_after_tx) {
+                    if (unlink(slide.filepath.c_str()) == -1)
+                        perror(("ODR-PadEnc Error: erasing file '" + slide.filepath +"' failed").c_str());
+                }
+            } else {
+                /* skip to next slide, except this is the last slide and so far
+                 * no slide worked, to prevent an infinite loop and because
+                 * re-reading the slides dir just moments later won't result in
+                 * a different amount of slides. */
+                bool skipping = !(slides.Empty() && !slides_success);
+                fprintf(stderr, "ODR-PadEnc Error: cannot encode file '%s'; %s\n", slide.filepath.c_str(), skipping ? "skipping" : "giving up for now");
+                if (skipping)
+                    continue;
+            }
         }
+
+        break;
     }
 
     return 0;
diff --git a/src/odr-padenc.h b/src/odr-padenc.h
index 46290f5..9d941a4 100644
--- a/src/odr-padenc.h
+++ b/src/odr-padenc.h
@@ -90,6 +90,7 @@ protected:
     DLSEncoder dls_encoder;
     SLSEncoder sls_encoder;
     SlideStore slides;
+    bool slides_success;
     int curr_dls_file;
     int output_fd;
     steady_clock::time_point run_timeline;
@@ -101,6 +102,7 @@ protected:
         pad_packetizer(PADPacketizer(options.padlen)),
         dls_encoder(DLSEncoder(&pad_packetizer)),
         sls_encoder(SLSEncoder(&pad_packetizer)),
+        slides_success(false),
         curr_dls_file(0),
         output_fd(-1),
         run_timeline(steady_clock::now()),