[Android] BrowserProvider: Lock mediabrowser

[Geoffrey Métais]

vlc-android | branch: master | Geoffrey Métais <geoffrey.metais at gmail.com> | Mon Dec 17 11:34:28 2018 +0100| [204fd906e056a23150eeb7837670c35e5b489d87] | committer: Geoffrey Métais

BrowserProvider: Lock mediabrowser

Prevents ConcurrentModificationException

> https://code.videolan.org/videolan/vlc-android/commit/204fd906e056a23150eeb7837670c35e5b489d87
---

 .../org/videolan/vlc/providers/BrowserProvider.kt  | 29 ++++++++++++++--------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/vlc-android/src/org/videolan/vlc/providers/BrowserProvider.kt b/vlc-android/src/org/videolan/vlc/providers/BrowserProvider.kt
index 7dc4e7605..0c7cb0626 100644
--- a/vlc-android/src/org/videolan/vlc/providers/BrowserProvider.kt
+++ b/vlc-android/src/org/videolan/vlc/providers/BrowserProvider.kt
@@ -30,6 +30,8 @@ import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.channels.actor
 import kotlinx.coroutines.channels.mapNotNullTo
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 import org.videolan.libvlc.Media
 import org.videolan.libvlc.util.MediaBrowser
 import org.videolan.libvlc.util.MediaBrowser.EventListener
@@ -50,6 +52,7 @@ abstract class BrowserProvider(val context: Context, val dataset: LiveDataset<Me
 
     override val coroutineContext = Dispatchers.Main.immediate
 
+    private val mutex= Mutex()
     protected var mediabrowser: MediaBrowser? = null
 
     private val foldersContentMap = androidx.collection.SimpleArrayMap<MediaLibraryItem, MutableList<MediaLibraryItem>>()
@@ -133,7 +136,7 @@ abstract class BrowserProvider(val context: Context, val dataset: LiveDataset<Me
         val directories: MutableList<MediaWrapper> = ArrayList()
         val files: MutableList<MediaWrapper> = ArrayList()
         foldersContentMap.clear()
-        initBrowser()
+        mutex.withLock { initBrowser() }
         var currentParsedPosition = -1
         loop@ while (++currentParsedPosition < currentMediaList.size) {
             if (!isActive) {
@@ -154,7 +157,7 @@ abstract class BrowserProvider(val context: Context, val dataset: LiveDataset<Me
             }
             // request parsing
             browserChannel = Channel(Channel.UNLIMITED)
-            mediabrowser?.browse(current.uri, 0)
+            mutex.withLock { mediabrowser?.browse(current.uri, 0) }
             // retrieve subitems
             for (media in browserChannel) {
                 val mw = findMedia(media) ?: continue
@@ -218,12 +221,14 @@ abstract class BrowserProvider(val context: Context, val dataset: LiveDataset<Me
     }
 
     private fun requestBrowsing(url: String?) = launch(Dispatchers.IO) {
-        initBrowser()
-        mediabrowser?.let {
-            if (url != null) it.browse(Uri.parse(url), getFlags())
-            else {
-                it.changeEventListener(this at BrowserProvider)
-                it.discoverNetworkShares()
+        mutex.withLock {
+            initBrowser()
+            mediabrowser?.let {
+                if (url != null) it.browse(Uri.parse(url), getFlags())
+                else {
+                    it.changeEventListener(this at BrowserProvider)
+                    it.discoverNetworkShares()
+                }
             }
         }
     }
@@ -235,9 +240,11 @@ abstract class BrowserProvider(val context: Context, val dataset: LiveDataset<Me
         launch(Dispatchers.IO) {
             if (this at BrowserProvider::browserChannel.isInitialized) browserChannel.close()
             job?.cancelAndJoin()
-            mediabrowser?.let {
-                it.release()
-                mediabrowser = null
+            mutex.withLock {
+                mediabrowser?.let {
+                    it.release()
+                    mediabrowser = null
+                }
             }
         }
     }