Support removing segments outside of live window in HLS

Issue: #223

Change-Id: Ib91c60268d8df9adbaf5f6cac77eaebd6a3edb6e

packager/hls/base/media_playlist.cc

@@ -18,6 +18,7 @@
 #include "packager/file/file.h"
 #include "packager/hls/base/tag.h"
 #include "packager/media/base/language_utils.h"
+#include "packager/media/base/muxer_util.h"
 #include "packager/version/version.h"
 
 namespace shaka {
@@ -577,7 +578,6 @@ void MediaPlaylist::SlideWindow() {
   HlsEntry::EntryType prev_entry_type = HlsEntry::EntryType::kExtInf;
 
   std::list<std::unique_ptr<HlsEntry>>::iterator last = entries_.begin();
-  size_t num_segments_removed = 0;
   for (; last != entries_.end(); ++last) {
     HlsEntry::EntryType entry_type = last->get()->type();
     if (entry_type == HlsEntry::EntryType::kExtKey) {
@@ -588,13 +588,14 @@ void MediaPlaylist::SlideWindow() {
       ++discontinuity_sequence_number_;
     } else {
       DCHECK_EQ(entry_type, HlsEntry::EntryType::kExtInf);
-      const SegmentInfoEntry* segment_info =
-          reinterpret_cast<SegmentInfoEntry*>(last->get());
+      const SegmentInfoEntry& segment_info =
+          *reinterpret_cast<SegmentInfoEntry*>(last->get());
       const double last_segment_end_time =
-          segment_info->start_time() + segment_info->duration();
+          segment_info.start_time() + segment_info.duration();
       if (timeshift_limit < last_segment_end_time)
         break;
-      ++num_segments_removed;
+      RemoveOldSegment(segment_info.start_time());
+      media_sequence_number_++;
     }
     prev_entry_type = entry_type;
   }
@@ -602,7 +603,23 @@ void MediaPlaylist::SlideWindow() {
   // Add key entries back.
   entries_.insert(entries_.begin(), std::make_move_iterator(ext_x_keys.begin()),
                   std::make_move_iterator(ext_x_keys.end()));
-  media_sequence_number_ += num_segments_removed;
+}
+
+void MediaPlaylist::RemoveOldSegment(uint64_t start_time) {
+  if (hls_params_.preserved_segments_outside_live_window == 0)
+    return;
+  if (stream_type_ == MediaPlaylistStreamType::kVideoIFramesOnly)
+    return;
+
+  segments_to_be_removed_.push_back(
+      media::GetSegmentName(media_info_.segment_template(), start_time,
+                            media_sequence_number_, media_info_.bandwidth()));
+  while (segments_to_be_removed_.size() >
+         hls_params_.preserved_segments_outside_live_window) {
+    VLOG(2) << "Deleting " << segments_to_be_removed_.front();
+    File::Delete(segments_to_be_removed_.front().c_str());
+    segments_to_be_removed_.pop_front();
+  }
 }
 
 }  // namespace hls

packager/hls/base/media_playlist.h

@@ -188,8 +188,12 @@ class MediaPlaylist {
   // Remove elements from |entries_| for live profile. Increments
   // |sequence_number_| by the number of segments removed.
   void SlideWindow();
+  // Remove the segment specified by |start_time|. The actual deletion can
+  // happen at a later time depending on the value of
+  // |preserved_segment_outside_live_window| in |hls_params_|.
+  void RemoveOldSegment(uint64_t start_time);
 
-  const HlsParams hls_params_;
+  const HlsParams& hls_params_;
   // Mainly for MasterPlaylist to use these values.
   const std::string file_name_;
   const std::string name_;
@@ -218,6 +222,9 @@ class MediaPlaylist {
   uint32_t target_duration_ = 0;
 
   std::list<std::unique_ptr<HlsEntry>> entries_;
+  // A list to hold the file names of the segments to be removed temporarily.
+  // Once a file is actually removed, it is removed from the list.
+  std::list<std::string> segments_to_be_removed_;
 
   // Used by kVideoIFrameOnly playlists to track the i-frames (key frames).
   struct KeyFrameInfo {

packager/hls/base/media_playlist_unittest.cc

@@ -7,6 +7,9 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
+#include "packager/base/strings/stringprintf.h"
+#include "packager/file/file.h"
+#include "packager/file/file_closer.h"
 #include "packager/file/file_test_util.h"
 #include "packager/hls/base/media_playlist.h"
 #include "packager/version/version.h"
@@ -42,10 +45,9 @@ class MediaPlaylistTest : public ::testing::Test {
       : default_file_name_(kDefaultPlaylistFileName),
         default_name_("default_name"),
         default_group_id_("default_group_id") {
-    HlsParams hls_params;
-    hls_params.playlist_type = type;
-    hls_params.time_shift_buffer_depth = kTimeShiftBufferDepth;
-    media_playlist_.reset(new MediaPlaylist(hls_params, default_file_name_,
+    hls_params_.playlist_type = type;
+    hls_params_.time_shift_buffer_depth = kTimeShiftBufferDepth;
+    media_playlist_.reset(new MediaPlaylist(hls_params_, default_file_name_,
                                             default_name_, default_group_id_));
   }
 
@@ -65,9 +67,12 @@ class MediaPlaylistTest : public ::testing::Test {
     valid_video_media_info_.set_reference_time_scale(kTimeScale);
   }
 
+  HlsParams* mutable_hls_params() { return &hls_params_; }
+
   const std::string default_file_name_;
   const std::string default_name_;
   const std::string default_group_id_;
+  HlsParams hls_params_;
   std::unique_ptr<MediaPlaylist> media_playlist_;
 
   MediaInfo valid_video_media_info_;
@@ -870,5 +875,84 @@ TEST_F(IFrameMediaPlaylistTest, MultiSegment) {
   ASSERT_FILE_STREQ(kMemoryFilePath, kExpectedOutput);
 }
 
+namespace {
+const int kNumPreservedSegmentsOutsideLiveWindow = 3;
+const int kMaxNumSegmentsAvailable =
+    kTimeShiftBufferDepth + 1 + kNumPreservedSegmentsOutsideLiveWindow;
+
+const char kSegmentTemplate[] = "memory://$Number$.mp4";
+const char kSegmentTemplateUrl[] = "video/$Number$.mp4";
+const char kStringPrintTemplate[] = "memory://%d.mp4";
+const char kIgnoredSegmentName[] = "ignored_segment_name";
+
+const uint64_t kInitialStartTime = 0;
+const uint64_t kDuration = kTimeScale;
+}  // namespace
+
+class MediaPlaylistDeleteSegmentsTest : public LiveMediaPlaylistTest {
+ public:
+  void SetUp() override {
+    LiveMediaPlaylistTest::SetUp();
+
+    // Create 100 files with the template.
+    for (int i = 1; i <= 100; ++i) {
+      File::WriteStringToFile(
+          base::StringPrintf(kStringPrintTemplate, i).c_str(), "dummy content");
+    }
+
+    valid_video_media_info_.set_segment_template(kSegmentTemplate);
+    valid_video_media_info_.set_segment_template_url(kSegmentTemplateUrl);
+    ASSERT_TRUE(media_playlist_->SetMediaInfo(valid_video_media_info_));
+
+    mutable_hls_params()->preserved_segments_outside_live_window =
+        kNumPreservedSegmentsOutsideLiveWindow;
+  }
+
+  bool SegmentDeleted(const std::string& segment_name) {
+    std::unique_ptr<File, FileCloser> file_closer(
+        File::Open(segment_name.c_str(), "r"));
+    return file_closer.get() == nullptr;
+  }
+};
+
+// Verify that no segments are deleted initially until there are more than
+// |kMaxNumSegmentsAvailable| segments.
+TEST_F(MediaPlaylistDeleteSegmentsTest, NoSegmentsDeletedInitially) {
+  for (int i = 0; i < kMaxNumSegmentsAvailable; ++i) {
+    media_playlist_->AddSegment(kIgnoredSegmentName,
+                                kInitialStartTime + i * kDuration, kDuration,
+                                kZeroByteOffset, kMBytes);
+  }
+  for (int i = 0; i < kMaxNumSegmentsAvailable; ++i) {
+    EXPECT_FALSE(
+        SegmentDeleted(base::StringPrintf(kStringPrintTemplate, i + 1)));
+  }
+}
+
+TEST_F(MediaPlaylistDeleteSegmentsTest, OneSegmentDeleted) {
+  for (int i = 0; i <= kMaxNumSegmentsAvailable; ++i) {
+    media_playlist_->AddSegment(kIgnoredSegmentName,
+                                kInitialStartTime + i * kDuration, kDuration,
+                                kZeroByteOffset, kMBytes);
+  }
+  EXPECT_FALSE(SegmentDeleted(base::StringPrintf(kStringPrintTemplate, 2)));
+  EXPECT_TRUE(SegmentDeleted(base::StringPrintf(kStringPrintTemplate, 1)));
+}
+
+TEST_F(MediaPlaylistDeleteSegmentsTest, ManySegments) {
+  int many_segments = 50;
+  for (int i = 0; i < many_segments; ++i) {
+    media_playlist_->AddSegment(kIgnoredSegmentName,
+                                kInitialStartTime + i * kDuration, kDuration,
+                                kZeroByteOffset, kMBytes);
+  }
+  const int last_available_segment_index =
+      many_segments - kMaxNumSegmentsAvailable + 1;
+  EXPECT_FALSE(SegmentDeleted(
+      base::StringPrintf(kStringPrintTemplate, last_available_segment_index)));
+  EXPECT_TRUE(SegmentDeleted(base::StringPrintf(
+      kStringPrintTemplate, last_available_segment_index - 1)));
+}
+
 }  // namespace hls
 }  // namespace shaka

packager/hls/public/hls_params.h

@@ -31,6 +31,13 @@ struct HlsParams {
   /// Defines the live window, or the guaranteed duration of the time shifting
   /// buffer for 'live' playlists.
   double time_shift_buffer_depth = 0;
+  /// Segments outside live window (defined by 'time_shift_buffer_depth' above)
+  /// are automatically removed except the latest number of segments defined by
+  /// this parameter. This is needed to accommodate latencies in various stages
+  /// of content serving pipeline, so that the segments stay accessible as they
+  /// may still be accessed by the player.
+  /// The segments are not removed if the value is zero.
+  size_t preserved_segments_outside_live_window = 0;
   /// Defines the key uri for "identity" and "com.apple.streamingkeydelivery"
   /// key formats. Ignored if the playlist is not encrypted or not using the
   /// above key formats.

packager/mpd/base/representation.cc

@@ -498,6 +498,7 @@ void Representation::RemoveSegments(uint64_t start_time,
   }
   while (segments_to_be_removed_.size() >
          mpd_options_.mpd_params.preserved_segments_outside_live_window) {
+    VLOG(2) << "Deleting " << segments_to_be_removed_.front();
     File::Delete(segments_to_be_removed_.front().c_str());
     segments_to_be_removed_.pop_front();
   }

packager/mpd/base/representation.h

@@ -212,7 +212,8 @@ class Representation {
   std::list<ContentProtectionElement> content_protection_elements_;
   // TODO(kqyang): Address sliding window issue with multiple periods.
   std::list<SegmentInfo> segment_infos_;
-  // A temporary list to hold the file names of segments to be removed.
+  // A list to hold the file names of the segments to be removed temporarily.
+  // Once a file is actually removed, it is removed from the list.
   std::list<std::string> segments_to_be_removed_;
 
   const uint32_t id_;

packager/mpd/base/representation_unittest.cc

@@ -27,12 +27,6 @@ namespace {
 
 const uint32_t kAnyRepresentationId = 1;
 
-bool SegmentDeleted(const std::string& segment_name) {
-  std::unique_ptr<File, FileCloser> file_closer(
-      File::Open(segment_name.c_str(), "r"));
-  return file_closer.get() == nullptr;
-}
-
 class MockRepresentationStateChangeListener
     : public RepresentationStateChangeListener {
  public:
@@ -1185,86 +1179,106 @@ TEST_P(TimeShiftBufferDepthTest, ManySegments) {
       XmlNodeEqual(ExpectedXml(expected_s_element, kExpectedStartNumber)));
 }
 
-TEST_P(TimeShiftBufferDepthTest, DeleteSegmentsOutsideOfLiveWindow) {
-  const char kSegmentTemplate[] = "memory://$Number$.mp4";
-  const char kStringPrintTemplate[] = "memory://%d.mp4";
+INSTANTIATE_TEST_CASE_P(InitialStartTime,
+                        TimeShiftBufferDepthTest,
+                        Values(0, 1000));
 
-  // Create 100 files with the template.
-  for (int i = 1; i <= 100; ++i) {
-    File::WriteStringToFile(base::StringPrintf(kStringPrintTemplate, i).c_str(),
-                            "dummy content");
+namespace {
+const int kTimeShiftBufferDepth = 2;
+const int kNumPreservedSegmentsOutsideLiveWindow = 3;
+const int kMaxNumSegmentsAvailable =
+    kTimeShiftBufferDepth + 1 + kNumPreservedSegmentsOutsideLiveWindow;
+
+const char kSegmentTemplate[] = "memory://$Number$.mp4";
+const char kSegmentTemplateUrl[] = "video/$Number$.mp4";
+const char kStringPrintTemplate[] = "memory://%d.mp4";
+
+const uint64_t kInitialStartTime = 0;
+const uint64_t kDuration = kDefaultTimeScale;
+const uint64_t kSize = 10;
+const uint64_t kNoRepeat = 0;
+}  // namespace
+
+class RepresentationDeleteSegmentsTest : public SegmentTimelineTestBase {
+ public:
+  void SetUp() override {
+    SegmentTimelineTestBase::SetUp();
+
+    // Create 100 files with the template.
+    for (int i = 1; i <= 100; ++i) {
+      File::WriteStringToFile(
+          base::StringPrintf(kStringPrintTemplate, i).c_str(), "dummy content");
+    }
+
+    MediaInfo media_info = ConvertToMediaInfo(GetDefaultMediaInfo());
+    media_info.set_segment_template(kSegmentTemplate);
+    media_info.set_segment_template_url(kSegmentTemplateUrl);
+    representation_ =
+        CreateRepresentation(media_info, kAnyRepresentationId, NoListener());
+    ASSERT_TRUE(representation_->Init());
+
+    mpd_options_.mpd_params.time_shift_buffer_depth = kTimeShiftBufferDepth;
+    mpd_options_.mpd_params.preserved_segments_outside_live_window =
+        kNumPreservedSegmentsOutsideLiveWindow;
   }
 
-  MediaInfo media_info = ConvertToMediaInfo(GetDefaultMediaInfo());
-  media_info.set_segment_template(kSegmentTemplate);
-  representation_ =
-      CreateRepresentation(media_info, kAnyRepresentationId, NoListener());
-  ASSERT_TRUE(representation_->Init());
+  bool SegmentDeleted(const std::string& segment_name) {
+    std::unique_ptr<File, FileCloser> file_closer(
+        File::Open(segment_name.c_str(), "r"));
+    return file_closer.get() == nullptr;
+  }
+};
 
-  const int kTimeShiftBufferDepth = 2;
-  const int kNumPreservedSegmentsOutsideLiveWindow = 3;
-  const int kMaxNumSegmentsAvailable =
-      kTimeShiftBufferDepth + 1 + kNumPreservedSegmentsOutsideLiveWindow;
-
-  mutable_mpd_options()->mpd_params.time_shift_buffer_depth =
-      kTimeShiftBufferDepth;
-  mutable_mpd_options()->mpd_params.preserved_segments_outside_live_window =
-      kNumPreservedSegmentsOutsideLiveWindow;
-
-  const uint64_t kInitialStartTime = 0;
-  const uint64_t kDuration = kDefaultTimeScale;
-  const uint64_t kSize = 10;
-  const uint64_t kNoRepeat = 0;
-
-  // Verify that no segments are deleted initially until there are more than
-  // |kMaxNumSegmentsAvailable| segments.
-  uint64_t next_start_time = kInitialStartTime;
-  int num_total_segments = 0;
-  int last_available_segment_index = 1;  // No segments are deleted.
+// Verify that no segments are deleted initially until there are more than
+// |kMaxNumSegmentsAvailable| segments.
+TEST_F(RepresentationDeleteSegmentsTest, NoSegmentsDeletedInitially) {
   for (int i = 0; i < kMaxNumSegmentsAvailable; ++i) {
-    AddSegments(next_start_time, kDuration, kSize, kNoRepeat);
-    next_start_time += kDuration;
-    ++num_total_segments;
-
-    EXPECT_FALSE(SegmentDeleted(base::StringPrintf(
-        kStringPrintTemplate, last_available_segment_index)));
+    AddSegments(kInitialStartTime + i * kDuration, kDuration, kSize, kNoRepeat);
   }
+  for (int i = 0; i < kMaxNumSegmentsAvailable; ++i) {
+    EXPECT_FALSE(
+        SegmentDeleted(base::StringPrintf(kStringPrintTemplate, i + 1)));
+  }
+}
 
-  AddSegments(next_start_time, kDuration, kSize, kNoRepeat);
-  next_start_time += kDuration;
-  ++num_total_segments;
-  last_available_segment_index = 2;
-
-  EXPECT_FALSE(SegmentDeleted(
-      base::StringPrintf(kStringPrintTemplate, last_available_segment_index)));
-  EXPECT_TRUE(SegmentDeleted(base::StringPrintf(
-      kStringPrintTemplate, last_available_segment_index - 1)));
-
-  // Verify that there are exactly |kMaxNumSegmentsAvailable| segments
-  // remaining.
-  const uint64_t kRepeat = 10;
-  AddSegments(next_start_time, kDuration, kSize, kRepeat);
-  next_start_time += (kRepeat + 1) * kDuration;
-  num_total_segments += kRepeat + 1;
-  last_available_segment_index =
-      num_total_segments - kMaxNumSegmentsAvailable + 1;
-
-  EXPECT_FALSE(SegmentDeleted(
-      base::StringPrintf(kStringPrintTemplate, last_available_segment_index)));
-  EXPECT_TRUE(SegmentDeleted(base::StringPrintf(
-      kStringPrintTemplate, last_available_segment_index - 1)));
-
-  AddSegments(next_start_time, kDuration, kSize, kNoRepeat);
-  ++last_available_segment_index;
+TEST_F(RepresentationDeleteSegmentsTest, OneSegmentDeleted) {
+  for (int i = 0; i <= kMaxNumSegmentsAvailable; ++i) {
+    AddSegments(kInitialStartTime + i * kDuration, kDuration, kSize, kNoRepeat);
+  }
+  EXPECT_FALSE(SegmentDeleted(base::StringPrintf(kStringPrintTemplate, 2)));
+  EXPECT_TRUE(SegmentDeleted(base::StringPrintf(kStringPrintTemplate, 1)));
+}
 
+// Verify that segments are deleted as expected with many non-repeating
+// segments.
+TEST_F(RepresentationDeleteSegmentsTest, ManyNonRepeatingSegments) {
+  int many_segments = 50;
+  for (int i = 0; i < many_segments; ++i) {
+    AddSegments(kInitialStartTime + i * kDuration, kDuration, kSize, kNoRepeat);
+  }
+  const int last_available_segment_index =
+      many_segments - kMaxNumSegmentsAvailable + 1;
   EXPECT_FALSE(SegmentDeleted(
       base::StringPrintf(kStringPrintTemplate, last_available_segment_index)));
   EXPECT_TRUE(SegmentDeleted(base::StringPrintf(
       kStringPrintTemplate, last_available_segment_index - 1)));
 }
 
-INSTANTIATE_TEST_CASE_P(InitialStartTime,
-                        TimeShiftBufferDepthTest,
-                        Values(0, 1000));
+// Verify that segments are deleted as expected with many repeating segments.
+TEST_F(RepresentationDeleteSegmentsTest, ManyRepeatingSegments) {
+  const int kLoops = 4;
+  const uint64_t kRepeat = 10;
+  for (int i = 0; i < kLoops; ++i) {
+    AddSegments(kInitialStartTime + i * kDuration * (kRepeat + 1), kDuration,
+                kSize, kRepeat);
+  }
+  const int kNumSegments = kLoops * (kRepeat + 1);
+  const int last_available_segment_index =
+      kNumSegments - kMaxNumSegmentsAvailable + 1;
+  EXPECT_FALSE(SegmentDeleted(
+      base::StringPrintf(kStringPrintTemplate, last_available_segment_index)));
+  EXPECT_TRUE(SegmentDeleted(base::StringPrintf(
+      kStringPrintTemplate, last_available_segment_index - 1)));
+}
 
 }  // namespace shaka