[Android] Replace shared StringBuilders to avoid threading conflicts

[Robert Stone]

vlc-android | branch: master | Robert Stone <rhstone at gmail.com> | Wed Dec  2 20:26:40 2020 -0800| [c5a2d5da8f8317381d283f53d04560c0febb8b94] | committer: Robert Stone

Replace shared StringBuilders to avoid threading conflicts

> https://code.videolan.org/videolan/vlc-android/commit/c5a2d5da8f8317381d283f53d04560c0febb8b94
---

 .../vlc-android/src/org/videolan/vlc/MediaParsingService.kt   | 11 ++++-------
 .../src/org/videolan/vlc/gui/helpers/NotificationHelper.kt    |  6 +-----
 .../vlc-android/src/org/videolan/vlc/gui/view/FastScroller.kt |  9 +--------
 3 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/application/vlc-android/src/org/videolan/vlc/MediaParsingService.kt b/application/vlc-android/src/org/videolan/vlc/MediaParsingService.kt
index 5f580365f..0dc3399de 100644
--- a/application/vlc-android/src/org/videolan/vlc/MediaParsingService.kt
+++ b/application/vlc-android/src/org/videolan/vlc/MediaParsingService.kt
@@ -84,7 +84,6 @@ class MediaParsingService : LifecycleService(), DevicesDiscoveryCb {
     private var serviceLock = false
     @Volatile
     private var discoverTriggered = false
-    internal val sb = StringBuilder()
     private lateinit var actions : SendChannel<MLAction>
     private lateinit var notificationActor : SendChannel<Notification>
 
@@ -343,13 +342,11 @@ class MediaParsingService : LifecycleService(), DevicesDiscoveryCb {
         if (lastNotificationTime == -1L || currentTime - lastNotificationTime < NOTIFICATION_DELAY) return
         lastNotificationTime = currentTime
         val discovery = withContext(Dispatchers.Default) {
-            sb.setLength(0)
-            when {
-                parsing > 0 -> sb.append(getString(R.string.ml_parse_media)).append(' ').append(parsing).append("%")
-                currentDiscovery != null -> sb.append(getString(R.string.ml_discovering)).append(' ').append(Uri.decode(currentDiscovery?.removeFileProtocole()))
-                else -> sb.append(getString(R.string.ml_parse_media))
+            val progressText = when {
+                parsing > 0 -> getString(R.string.ml_parse_media) + " " + parsing + "%"
+                currentDiscovery != null -> getString(R.string.ml_discovering) + " " + Uri.decode(currentDiscovery?.removeFileProtocole())
+                else -> getString(R.string.ml_parse_media)
             }
-            val progressText = sb.toString()
             if (!isActive) return at withContext ""
             if (lastNotificationTime != -1L) {
                 try {
diff --git a/application/vlc-android/src/org/videolan/vlc/gui/helpers/NotificationHelper.kt b/application/vlc-android/src/org/videolan/vlc/gui/helpers/NotificationHelper.kt
index c31a95389..11cc1e7e3 100644
--- a/application/vlc-android/src/org/videolan/vlc/gui/helpers/NotificationHelper.kt
+++ b/application/vlc-android/src/org/videolan/vlc/gui/helpers/NotificationHelper.kt
@@ -48,8 +48,6 @@ private const val RECOMMENDATION_CHANNEL_ID = "vlc_recommendations"
 
 object NotificationHelper {
     const val TAG = "VLC/NotificationHelper"
-
-    private val sb = StringBuilder()
     const val VLC_DEBUG_CHANNEL = "vlc_debug"
 
     private val notificationIntent = Intent()
@@ -61,14 +59,12 @@ object NotificationHelper {
 
         val piStop = MediaButtonReceiver.buildMediaButtonPendingIntent(ctx, PlaybackStateCompat.ACTION_STOP)
         val builder = NotificationCompat.Builder(ctx, PLAYBACK_SERVICE_CHANNEL_ID)
-        sb.setLength(0)
-        sb.append(title).append(" - ").append(artist)
         builder.setSmallIcon(if (video) R.drawable.ic_notif_video else R.drawable.ic_notif_audio)
                 .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
                 .setContentTitle(title)
                 .setContentText(getMediaDescription(artist, album))
                 .setLargeIcon(cover)
-                .setTicker(sb.toString())
+                .setTicker("$title - $artist")
                 .setAutoCancel(!playing)
                 .setOngoing(playing)
                 .setCategory(NotificationCompat.CATEGORY_TRANSPORT)
diff --git a/application/vlc-android/src/org/videolan/vlc/gui/view/FastScroller.kt b/application/vlc-android/src/org/videolan/vlc/gui/view/FastScroller.kt
index 3d5e7fc0a..b74c622ec 100644
--- a/application/vlc-android/src/org/videolan/vlc/gui/view/FastScroller.kt
+++ b/application/vlc-android/src/org/videolan/vlc/gui/view/FastScroller.kt
@@ -97,7 +97,6 @@ class FastScroller : LinearLayout, Observer<HeadersIndex> {
     private var lastVerticalOffset: Int = 0
     private var tryCollapseAppbarOnNextScroll = false
     private var tryExpandAppbarOnNextScroll = false
-    private val sb = StringBuilder()
 
     private val handler = object : WeakHandler<FastScroller>(this) {
         override fun handleMessage(msg: Message) {
@@ -349,18 +348,12 @@ class FastScroller : LinearLayout, Observer<HeadersIndex> {
 
     private val actor = scope.actor<Unit>(capacity = Channel.CONFLATED) {
         for (evt in channel) if (fastScrolling) {
-            sb.setLength(0)
             //ItemDecoration has to be taken into account so we add 1 for the sticky header
             val position = layoutManager.findFirstVisibleItemPosition() + 1
             if (BuildConfig.DEBUG) Log.d(TAG, "findFirstVisibleItemPosition $position")
             val pos = provider.getPositionForSection(position)
             val sectionforPosition = provider.getSectionforPosition(pos)
-            if (sectionforPosition.isNotEmpty()) bubble.text = withContext(Dispatchers.Default) {
-                sb.append(' ')
-                        .append(sectionforPosition)
-                        .append(' ')
-                        .toString()
-            }
+            if (sectionforPosition.isNotEmpty()) bubble.text = " $sectionforPosition "
             delay(100L)
         }
     }