Fix race condition that could show an empty link preview after send.

signalapp · Aug 5, 2021 · 2bac1a7 · 2bac1a7 · Tursko · Aug 10, 2021
1 parent 80e1b2c
commit 2bac1a7
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Showing 2 changed files with 25 additions and 20 deletions.
diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java
@@ -2846,7 +2846,6 @@ protected void sendComplete(long threadId) {
     attachmentManager.cleanup();
 
     updateLinkPreviewState();
-    linkPreviewViewModel.onSend();
   }
 
   private void sendMessage() {
@@ -2939,13 +2938,14 @@ private void sendMediaMessage(final boolean forceSms, final long expiresIn, fina
       throws InvalidMessageException
   {
     Log.i(TAG, "Sending media message...");
+    List<LinkPreview> linkPreviews = linkPreviewViewModel.onSend();
     sendMediaMessage(recipient.getId(),
                      forceSms,
                      getMessage(),
                      attachmentManager.buildSlideDeck(),
                      inputPanel.getQuote().orNull(),
                      Collections.emptyList(),
-                     linkPreviewViewModel.getActiveLinkPreviews(),
+                     linkPreviews,
                      composeText.getMentions(),
                      expiresIn,
                      viewOnce,

diff --git a/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java b/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java
@@ -53,13 +53,27 @@ public boolean hasLinkPreviewUi() {
     return linkPreviewSafeState.getValue() != null && linkPreviewSafeState.getValue().hasContent();
   }
 
-  public @NonNull List<LinkPreview> getActiveLinkPreviews() {
-    final LinkPreviewState state = linkPreviewSafeState.getValue();
+  /**
+   * Gets the current state for use in the UI, then resets local state to prepare for the next message send.
+   */
+  public @NonNull List<LinkPreview> onSend() {
+    final LinkPreviewState currentState = linkPreviewSafeState.getValue();
 
-    if (state == null || !state.getLinkPreview().isPresent()) {
+    if (activeRequest != null) {
+      activeRequest.cancel();
+      activeRequest = null;
+    }
+
+    userCanceled = false;
+    activeUrl    = null;
+
+    debouncer.clear();
+    linkPreviewState.setValue(LinkPreviewState.forNoLinks());
+
+    if (currentState == null || !currentState.getLinkPreview().isPresent()) {
       return Collections.emptyList();
     } else {
-      return Collections.singletonList(state.getLinkPreview().get());
+      return Collections.singletonList(currentState.getLinkPreview().get());
     }
   }
 
@@ -115,7 +129,11 @@ public void onSuccess(@NonNull LinkPreview linkPreview) {
         public void onError(@NonNull LinkPreviewRepository.Error error) {
           ThreadUtil.runOnMain(() -> {
             if (!userCanceled) {
-              linkPreviewState.setValue(LinkPreviewState.forLinksWithNoPreview(error));
+              if (activeUrl != null) {
+                linkPreviewState.setValue(LinkPreviewState.forLinksWithNoPreview(error));
+              } else {
+                linkPreviewState.setValue(LinkPreviewState.forNoLinks());
+              }
             }
             activeRequest = null;
           });
@@ -145,19 +163,6 @@ public void onTransportChanged(boolean isSms) {
     }
   }
 
-  public void onSend() {
-    if (activeRequest != null) {
-      activeRequest.cancel();
-      activeRequest = null;
-    }
-
-    userCanceled = false;
-    activeUrl    = null;
-
-    debouncer.clear();
-    linkPreviewState.setValue(LinkPreviewState.forNoLinks());
-  }
-
   public void onEnabled() {
     userCanceled = false;
     enabled      = SignalStore.settings().isLinkPreviewsEnabled();