From ba6a1df423fd1d91bb4a105af86bf4278bdb3a36 Mon Sep 17 00:00:00 2001
From: Kacper Kasper <kacperkasper@gmail.com>
Date: Sun, 17 Oct 2021 12:35:47 +0200
Subject: [PATCH] MediaPlayer: cache file duration in memory

* SetAttribute() will fail for read-only volumes.
* Duration() is called in playlist's Draw() method.
  Since _CalculateDuration() is very expensive because it parses
  file metadata, it causes visible drawing glitches and playlist is
  almost unusable.
* Mitigates #15221. I don't consider this a fix because first draw
  is still going to block for a long time, but at least scrolling
  works smoothly now. Ideally, file metadata would be parsed
  asynchronously in a separate thread and drawn as it becomes
  available.

Change-Id: If198d61c77a7746bcc0e19b7caeed89ce829c247
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4597
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
---
 src/apps/mediaplayer/playlist/PlaylistItem.cpp | 13 ++++++++++---
 src/apps/mediaplayer/playlist/PlaylistItem.h   |  1 +
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/apps/mediaplayer/playlist/PlaylistItem.cpp b/src/apps/mediaplayer/playlist/PlaylistItem.cpp
index bb96c22f90..c68b1b623a 100644
--- a/src/apps/mediaplayer/playlist/PlaylistItem.cpp
+++ b/src/apps/mediaplayer/playlist/PlaylistItem.cpp
@@ -45,7 +45,8 @@ static vint32 sInstanceCount = 0;
 PlaylistItem::PlaylistItem()
 	:
 	fPlaybackFailed(false),
-	fTrackSupplier(NULL)
+	fTrackSupplier(NULL),
+	fDuration(-1)
 {
 #ifdef DEBUG_INSTANCE_COUNT
 	atomic_add(&sInstanceCount, 1);
@@ -143,8 +144,14 @@ PlaylistItem::Duration()
 {
 	bigtime_t duration;
 	if (GetAttribute(ATTR_INT64_DURATION, duration) != B_OK) {
-		duration = this->_CalculateDuration();
-		SetAttribute(ATTR_INT64_DURATION, duration);
+		if (fDuration == -1) {
+			duration = this->_CalculateDuration();
+			if (SetAttribute(ATTR_INT64_DURATION, duration) != B_OK) {
+				fDuration = duration;
+			}
+		} else {
+			duration = fDuration;
+		}
 	}
 
 	return duration;
diff --git a/src/apps/mediaplayer/playlist/PlaylistItem.h b/src/apps/mediaplayer/playlist/PlaylistItem.h
index 3b1a4bb067..d3abe96f12 100644
--- a/src/apps/mediaplayer/playlist/PlaylistItem.h
+++ b/src/apps/mediaplayer/playlist/PlaylistItem.h
@@ -127,6 +127,7 @@ private:
 			BList				fListeners;
 			bool				fPlaybackFailed;
 			TrackSupplier*		fTrackSupplier;
+			bigtime_t			fDuration;
 };
 
 typedef BReference<PlaylistItem> PlaylistItemRef;