From 3b08bb1318cd0bf6bc1811b520f9c6934b1aa3bd Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Mon, 12 Jun 2023 14:19:01 +0800
Subject: [PATCH] Fix deadlocks

* java/org/gnu/emacs/EmacsView.java (EmacsView)
(showOnScreenKeyboard, hideOnScreenKeyboard): Don't synchronize.
* java/org/gnu/emacs/EmacsWindow.java (EmacsWindow)
(toggleOnScreenKeyboard): Revert to calling IMM functions from
the main thread.
* src/android.c (struct android_event_container)
(android_pselect_nfds, android_pselect_readfds)
(android_pselect_writefds, android_pselect_exceptfds)
(android_pselect_timeout): Don't make volatile.
(android_wait_event): Run queries if necessary.
---
 java/org/gnu/emacs/EmacsView.java   |  5 +++--
 java/org/gnu/emacs/EmacsWindow.java | 25 ++++++++++++++++--------
 src/android.c                       | 30 ++++++++++++++++++-----------
 3 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/java/org/gnu/emacs/EmacsView.java b/java/org/gnu/emacs/EmacsView.java
index 7fd672233f2..278c6025902 100644
--- a/java/org/gnu/emacs/EmacsView.java
+++ b/java/org/gnu/emacs/EmacsView.java
@@ -590,16 +590,17 @@ public final class EmacsView extends ViewGroup
     super.onAttachedToWindow ();
   }
 
-  public synchronized void
+  public void
   showOnScreenKeyboard ()
   {
     /* Specifying no flags at all tells the system the user asked for
        the input method to be displayed.  */
+
     imManager.showSoftInput (this, 0);
     isCurrentlyTextEditor = true;
   }
 
-  public synchronized void
+  public void
   hideOnScreenKeyboard ()
   {
     imManager.hideSoftInputFromWindow (this.getWindowToken (),
diff --git a/java/org/gnu/emacs/EmacsWindow.java b/java/org/gnu/emacs/EmacsWindow.java
index f5e40e9a2d9..68a18ec2aa7 100644
--- a/java/org/gnu/emacs/EmacsWindow.java
+++ b/java/org/gnu/emacs/EmacsWindow.java
@@ -1201,16 +1201,25 @@ public final class EmacsWindow extends EmacsHandleObject
   }
 
   public void
-  toggleOnScreenKeyboard (boolean on)
+  toggleOnScreenKeyboard (final boolean on)
   {
-    /* InputMethodManager functions are thread safe.  Call
-       `showOnScreenKeyboard' etc from the Emacs thread in order to
-       keep the calls in sync with updates to the input context.  */
+    /* Even though InputMethodManager functions are thread safe,
+       `showOnScreenKeyboard' etc must be called from the UI thread in
+       order to avoid deadlocks if the calls happen in tandem with a
+       call to a synchronizing function within
+       `onCreateInputConnection'.  */
 
-    if (on)
-      view.showOnScreenKeyboard ();
-    else
-      view.hideOnScreenKeyboard ();
+    EmacsService.SERVICE.runOnUiThread (new Runnable () {
+	@Override
+	public void
+	run ()
+	{
+	  if (on)
+	    view.showOnScreenKeyboard ();
+	  else
+	    view.hideOnScreenKeyboard ();	  
+	}
+      });
   }
 
   public String
diff --git a/src/android.c b/src/android.c
index 4414d465107..873d821361c 100644
--- a/src/android.c
+++ b/src/android.c
@@ -272,7 +272,7 @@ void *unused_pointer;
 struct android_event_container
 {
   /* The next and last events in this queue.  */
-  struct android_event_container *volatile next, *last;
+  struct android_event_container *next, *last;
 
   /* The event itself.  */
   union android_event event;
@@ -301,11 +301,11 @@ struct android_event_queue
 };
 
 /* Arguments to pselect used by the select thread.  */
-static volatile int android_pselect_nfds;
-static fd_set *volatile android_pselect_readfds;
-static fd_set *volatile android_pselect_writefds;
-static fd_set *volatile android_pselect_exceptfds;
-static struct timespec *volatile android_pselect_timeout;
+static int android_pselect_nfds;
+static fd_set *android_pselect_readfds;
+static fd_set *android_pselect_writefds;
+static fd_set *android_pselect_exceptfds;
+static struct timespec *android_pselect_timeout;
 
 /* Value of pselect.  */
 static int android_pselect_rc;
@@ -569,12 +569,20 @@ android_pending (void)
   return i;
 }
 
+/* Forward declaration.  */
+
+static void android_check_query (void);
+
 /* Wait for events to become available synchronously.  Return once an
-   event arrives.  */
+   event arrives.  Also, reply to the UI thread whenever it requires a
+   response.  */
 
 void
 android_wait_event (void)
 {
+  /* Run queries from the UI thread to the Emacs thread.  */
+  android_check_query ();
+
   pthread_mutex_lock (&event_queue.mutex);
 
   /* Wait for events to appear if there are none available to
@@ -584,6 +592,10 @@ android_wait_event (void)
 		       &event_queue.mutex);
 
   pthread_mutex_unlock (&event_queue.mutex);
+
+  /* Check for queries again.  If a query is sent after the call to
+     `android_check_query' above, `read_var' will be signaled.  */
+  android_check_query ();
 }
 
 void
@@ -701,10 +713,6 @@ android_write_event (union android_event *event)
    should answer the query ASAP.  */
 static bool android_urgent_query;
 
-/* Forward declaration.  */
-
-static void android_check_query (void);
-
 int
 android_select (int nfds, fd_set *readfds, fd_set *writefds,
 		fd_set *exceptfds, struct timespec *timeout)
-- 
2.39.2