Reduce number of clipboard synchronizations

- VncClient will ignore repeated requests to sync clipboard with same text. This happens due to activity lifecycle. - VncViewModel will drop new clip texts from server while previous text is being processed. This should prevent some ANRs.
gujjwal00 · Feb 22, 2024 · 22f3ddd · 22f3ddd
1 parent 971f9ac
commit 22f3ddd
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Showing 2 changed files with 32 additions and 6 deletions.
diff --git a/app/src/main/java/com/gaurav/avnc/viewmodel/VncViewModel.kt b/app/src/main/java/com/gaurav/avnc/viewmodel/VncViewModel.kt
@@ -27,6 +27,7 @@ import com.gaurav.avnc.vnc.Messenger
 import com.gaurav.avnc.vnc.UserCredential
 import com.gaurav.avnc.vnc.VncClient
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.awaitCancellation
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.isActive
@@ -318,8 +319,19 @@ class VncViewModel(val profile: ServerProfile, app: Application) : BaseViewModel
         }
     }
 
+    private var clipReceiverJob: Job? = null
     private fun receiveClipboardText(text: String) {
-        if (pref.server.clipboardSync) launchIO {
+        if (!pref.server.clipboardSync)
+            return
+
+        // This is a protective measure against servers which send every 'selection' made on the server.
+        // Setting clip text involves IPC, so these events can exhaust Binder resources, leading to ANRs.
+        if (clipReceiverJob?.isActive == true) {
+            Log.w(javaClass.simpleName, "Dropping clip text received from server, previous text is still pending")
+            return
+        }
+
+        clipReceiverJob = launchIO {
             setClipboardText(app, text)
         }
     }

diff --git a/app/src/main/java/com/gaurav/avnc/vnc/VncClient.kt b/app/src/main/java/com/gaurav/avnc/vnc/VncClient.kt
@@ -105,6 +105,12 @@ class VncClient(private val observer: Observer) {
     private var autoFBRequestsQueued = true
     private var autoFBRequests = autoFBRequestsQueued
 
+    /**
+     * Value of the most recent cut text sent/received from server
+     */
+    @Volatile
+    private var lastCutText: String? = null
+
     /**
      * Setup different properties for this client.
      *
@@ -195,10 +201,14 @@ class VncClient(private val observer: Observer) {
      * Sends text to remote desktop's clipboard.
      */
     fun sendCutText(text: String) = ifConnectedAndInteractive {
-        if (nativeIsUTF8CutTextSupported(nativePtr))
-            nativeSendCutText(nativePtr, text.toByteArray(StandardCharsets.UTF_8), true)
-        else
-            nativeSendCutText(nativePtr, text.toByteArray(StandardCharsets.ISO_8859_1), false)
+        if (text != lastCutText) {
+            val sent = if (nativeIsUTF8CutTextSupported(nativePtr))
+                nativeSendCutText(nativePtr, text.toByteArray(StandardCharsets.UTF_8), true)
+            else
+                nativeSendCutText(nativePtr, text.toByteArray(StandardCharsets.ISO_8859_1), false)
+            if (sent)
+                lastCutText = text
+        }
     }
 
     /**
@@ -294,7 +304,11 @@ class VncClient(private val observer: Observer) {
     @Keep
     private fun cbGotXCutText(bytes: ByteArray, isUTF8: Boolean) {
         (if (isUTF8) StandardCharsets.UTF_8 else StandardCharsets.ISO_8859_1).let {
-            observer.onGotXCutText(it.decode(ByteBuffer.wrap(bytes)).toString())
+            val cutText = it.decode(ByteBuffer.wrap(bytes)).toString()
+            if (cutText != lastCutText) {
+                lastCutText = cutText
+                observer.onGotXCutText(cutText)
+            }
         }
     }