Improve async setup code

content/_code-samples/build-a-wallet/py/2_threaded.py

@@ -14,13 +14,15 @@ class XRPLMonitorThread(Thread):
     the main frame to be shown in the UI. Using a thread lets us maintain the
     responsiveness of the UI while doing work in the background.
     """
-    def __init__(self, url, gui, loop):
+    def __init__(self, url, gui):
         Thread.__init__(self, daemon=True)
         # Note: For thread safety, this thread should treat self.gui as
         # read-only; to modify the GUI, use wx.CallAfter(...)
         self.gui = gui
         self.url = url
-        self.loop = loop
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+        self.loop.set_debug(True)
 
     def run(self):
         """
@@ -28,7 +30,6 @@ class XRPLMonitorThread(Thread):
         from the XRPL, sending them to the GUI thread when necessary, and also
         handles making requests to the XRPL when the GUI prompts them.
         """
-        asyncio.set_event_loop(self.loop)
         self.loop.run_forever()
 
     async def watch_xrpl(self):
@@ -71,8 +72,7 @@ class TWaXLFrame(wx.Frame):
         self.build_ui()
 
         # Start background thread for updates from the ledger ------------------
-        self.worker_loop = asyncio.new_event_loop()
+        self.worker = XRPLMonitorThread(url, self)
-        self.worker = XRPLMonitorThread(url, self, self.worker_loop)
         self.worker.start()
         self.run_bg_job(self.worker.watch_xrpl())
 
@@ -92,7 +92,7 @@ class TWaXLFrame(wx.Frame):
         Schedules a job to run asynchronously in the XRPL worker thread.
         The job should be a Future (for example, from calling an async function)
         """
-        task = asyncio.run_coroutine_threadsafe(job, self.worker_loop)
+        task = asyncio.run_coroutine_threadsafe(job, self.worker.loop)
 
     def update_ledger(self, message):
         """

content/_code-samples/build-a-wallet/py/3_account.py

@@ -15,13 +15,15 @@ class XRPLMonitorThread(Thread):
     the main frame to be shown in the UI. Using a thread lets us maintain the
     responsiveness of the UI while doing work in the background.
     """
-    def __init__(self, url, gui, loop):
+    def __init__(self, url, gui):
         Thread.__init__(self, daemon=True)
         # Note: For thread safety, this thread should treat self.gui as
         # read-only; to modify the GUI, use wx.CallAfter(...)
         self.gui = gui
         self.url = url
-        self.loop = loop
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+        self.loop.set_debug(True)
 
     def run(self):
         """
@@ -29,7 +31,6 @@ class XRPLMonitorThread(Thread):
         from the XRPL, sending them to the GUI thread when necessary, and also
         handles making requests to the XRPL when the GUI prompts them.
         """
-        asyncio.set_event_loop(self.loop)
         self.loop.run_forever()
 
     async def watch_xrpl_account(self, address, wallet=None):
@@ -126,8 +127,7 @@ class TWaXLFrame(wx.Frame):
         self.classic_address = address
 
         # Start background thread for updates from the ledger ------------------
-        self.worker_loop = asyncio.new_event_loop()
+        self.worker = XRPLMonitorThread(url, self)
-        self.worker = XRPLMonitorThread(url, self, self.worker_loop)
         self.worker.start()
         self.run_bg_job(self.worker.watch_xrpl_account(address, wallet))
 
@@ -166,7 +166,7 @@ class TWaXLFrame(wx.Frame):
         Schedules a job to run asynchronously in the XRPL worker thread.
         The job should be a Future (for example, from calling an async function)
         """
-        task = asyncio.run_coroutine_threadsafe(job, self.worker_loop)
+        task = asyncio.run_coroutine_threadsafe(job, self.worker.loop)
 
     def toggle_dialog_style(self, event):
         """

content/_code-samples/build-a-wallet/py/4_tx_history.py

@@ -18,13 +18,15 @@ class XRPLMonitorThread(Thread):
     the main frame to be shown in the UI. Using a thread lets us maintain the
     responsiveness of the UI while doing work in the background.
     """
-    def __init__(self, url, gui, loop):
+    def __init__(self, url, gui):
         Thread.__init__(self, daemon=True)
         # Note: For thread safety, this thread should treat self.gui as
         # read-only; to modify the GUI, use wx.CallAfter(...)
         self.gui = gui
         self.url = url
-        self.loop = loop
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+        self.loop.set_debug(True)
 
     def run(self):
         """
@@ -32,7 +34,6 @@ class XRPLMonitorThread(Thread):
         from the XRPL, sending them to the GUI thread when necessary, and also
         handles making requests to the XRPL when the GUI prompts them.
         """
-        asyncio.set_event_loop(self.loop)
         self.loop.run_forever()
 
     async def watch_xrpl_account(self, address, wallet=None):
@@ -137,8 +138,7 @@ class TWaXLFrame(wx.Frame):
         self.classic_address = address
 
         # Start background thread for updates from the ledger ------------------
-        self.worker_loop = asyncio.new_event_loop()
+        self.worker = XRPLMonitorThread(url, self)
-        self.worker = XRPLMonitorThread(url, self, self.worker_loop)
         self.worker.start()
         self.run_bg_job(self.worker.watch_xrpl_account(address, wallet))
 
@@ -197,7 +197,7 @@ class TWaXLFrame(wx.Frame):
         Schedules a job to run asynchronously in the XRPL worker thread.
         The job should be a Future (for example, from calling an async function)
         """
-        task = asyncio.run_coroutine_threadsafe(job, self.worker_loop)
+        task = asyncio.run_coroutine_threadsafe(job, self.worker.loop)
 
     def toggle_dialog_style(self, event):
         """

content/_code-samples/build-a-wallet/py/5_send_xrp.py

@@ -18,13 +18,15 @@ class XRPLMonitorThread(Thread):
     the main frame to be shown in the UI. Using a thread lets us maintain the
     responsiveness of the UI while doing work in the background.
     """
-    def __init__(self, url, gui, loop):
+    def __init__(self, url, gui):
         Thread.__init__(self, daemon=True)
         # Note: For thread safety, this thread should treat self.gui as
         # read-only; to modify the GUI, use wx.CallAfter(...)
         self.gui = gui
         self.url = url
-        self.loop = loop
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+        self.loop.set_debug(True)
 
     def run(self):
         """
@@ -32,7 +34,6 @@ class XRPLMonitorThread(Thread):
         from the XRPL, sending them to the GUI thread when necessary, and also
         handles making requests to the XRPL when the GUI prompts them.
         """
-        asyncio.set_event_loop(self.loop)
         self.loop.run_forever()
 
     async def watch_xrpl_account(self, address, wallet=None):
@@ -246,8 +247,7 @@ class TWaXLFrame(wx.Frame):
         self.classic_address = address
 
         # Start background thread for updates from the ledger ------------------
-        self.worker_loop = asyncio.new_event_loop()
+        self.worker = XRPLMonitorThread(url, self)
-        self.worker = XRPLMonitorThread(url, self, self.worker_loop)
         self.worker.start()
         self.run_bg_job(self.worker.watch_xrpl_account(address, wallet))
 
@@ -315,7 +315,7 @@ class TWaXLFrame(wx.Frame):
         Schedules a job to run asynchronously in the XRPL worker thread.
         The job should be a Future (for example, from calling an async function)
         """
-        task = asyncio.run_coroutine_threadsafe(job, self.worker_loop)
+        task = asyncio.run_coroutine_threadsafe(job, self.worker.loop)
 
     def toggle_dialog_style(self, event):
         """

content/_code-samples/build-a-wallet/py/6_verification_and_polish.py

@@ -20,13 +20,15 @@ class XRPLMonitorThread(Thread):
     the main frame to be shown in the UI. Using a thread lets us maintain the
     responsiveness of the UI while doing work in the background.
     """
-    def __init__(self, url, gui, loop):
+    def __init__(self, url, gui):
         Thread.__init__(self, daemon=True)
         # Note: For thread safety, this thread should treat self.gui as
         # read-only; to modify the GUI, use wx.CallAfter(...)
         self.gui = gui
         self.url = url
-        self.loop = loop
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(self.loop)
+        self.loop.set_debug(True)
 
     def run(self):
         """
@@ -34,7 +36,6 @@ class XRPLMonitorThread(Thread):
         from the XRPL, sending them to the GUI thread when necessary, and also
         handles making requests to the XRPL when the GUI prompts them.
         """
-        asyncio.set_event_loop(self.loop)
         self.loop.run_forever()
 
     async def watch_xrpl_account(self, address, wallet=None):
@@ -400,8 +401,7 @@ class TWaXLFrame(wx.Frame):
         self.classic_address = address
 
         # Start background thread for updates from the ledger ------------------
-        self.worker_loop = asyncio.new_event_loop()
+        self.worker = XRPLMonitorThread(url, self)
-        self.worker = XRPLMonitorThread(url, self, self.worker_loop)
         self.worker.start()
         self.run_bg_job(self.worker.watch_xrpl_account(address, wallet))
 
@@ -469,7 +469,7 @@ class TWaXLFrame(wx.Frame):
         Schedules a job to run asynchronously in the XRPL worker thread.
         The job should be a Future (for example, from calling an async function)
         """
-        task = asyncio.run_coroutine_threadsafe(job, self.worker_loop)
+        task = asyncio.run_coroutine_threadsafe(job, self.worker.loop)
 
     def toggle_dialog_style(self, event):
         """

content/tutorials/build-apps/build-a-desktop-wallet-in-python.md

@@ -103,9 +103,11 @@ Then, the code for the monitor thread is as follows (put this in the same file a
 
 {{ include_code("_code-samples/build-a-wallet/py/2_threaded.py", language="py", start_with="class XRPLMonitorThread", end_before="class TWaXLFrame") }}
 
-This code defines a `Thread` subclass for the worker. When the thread is created, it starts an event loop, which means it's waiting for async tasks and functions to be created. The `watch_xrpl()` function is an example of a such a task (which the GUI thread starts when it's ready): connects to the XRP Ledger, then calls the [subscribe method][] to be notified whenever a new ledger is validated. It uses the immediate response _and_ all later subscription stream messages to trigger updates of the GUI.
+This code defines a `Thread` subclass for the worker. When the thread starts, it sets up an event loop, which waits for async tasks to be created and run. The code uses [asyncio's Debug Mode](https://docs.python.org/3/library/asyncio-dev.html#asyncio-debug-mode) so that the console shows any errors that occur in async tasks.
 
-**Tip:** Define worker jobs like this using `async def` instead of `def` so that you can use the `await` keyword in them; you need to use `await` to get the response to the [`AsyncWebsocketClient.request()` method](https://xrpl-py.readthedocs.io/en/stable/source/xrpl.asyncio.clients.html#xrpl.asyncio.clients.AsyncWebsocketClient.request). Normally, you would also need to use `await` or something similar to get the response to functions defined with `async def` too; but, in this app the `run_bg_job()` helper takes care of that in a different way.
+The `watch_xrpl()` function is an example of a such a task (which the GUI thread starts when it's ready): it connects to the XRP Ledger, then calls the [subscribe method][] to be notified whenever a new ledger is validated. It uses the immediate response _and_ all later subscription stream messages to trigger updates of the GUI.
+
+**Tip:** Define worker jobs like this using `async def` instead of `def` so that you can use the `await` keyword in them; you need to use `await` to get the response to the [`AsyncWebsocketClient.request()` method](https://xrpl-py.readthedocs.io/en/stable/source/xrpl.asyncio.clients.html#xrpl.asyncio.clients.AsyncWebsocketClient.request). Normally, you would also need to use `await` or something similar to get the response from any function you define with `async def`; but, in this app, the `run_bg_job()` helper takes care of that in a different way.
 
 Update the code for the main thread and GUI frame to look like this: