From d6b6c9171f3fd945c4e5e4144923ac831c43c208 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Wed, 4 Dec 2019 22:46:39 -0800
Subject: [PATCH] Include asyncio task information in /-/threads debug page

---
 datasette/app.py                   | 21 ++++++++++++++++++++-
 datasette/templates/show_json.html |  2 +-
 datasette/views/special.py         |  5 ++++-
 docs/introspection.rst             |  8 +++++++-
 tests/test_api.py                  |  9 +++++++++
 5 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/datasette/app.py b/datasette/app.py
index 119d0e19..5c1c3e83 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -2,6 +2,7 @@ import asyncio
 import collections
 import hashlib
 import os
+import re
 import sys
 import threading
 import traceback
@@ -477,12 +478,19 @@ class Datasette:
 
     def threads(self):
         threads = list(threading.enumerate())
-        return {
+        d = {
             "num_threads": len(threads),
             "threads": [
                 {"name": t.name, "ident": t.ident, "daemon": t.daemon} for t in threads
             ],
         }
+        # Only available in Python 3.7+
+        if hasattr(asyncio, "all_tasks"):
+            tasks = asyncio.all_tasks()
+            d.update(
+                {"num_tasks": len(tasks), "tasks": [_cleaner_task_str(t) for t in tasks]}
+            )
+        return d
 
     def table_metadata(self, database, table):
         "Fetch table-specific metadata."
@@ -684,3 +692,14 @@ class DatasetteRouter(AsgiRouter):
             await asgi_send_html(
                 send, await template.render_async(info), status=status, headers=headers
             )
+
+
+_cleaner_task_str_re = re.compile(r"\S*site-packages/")
+
+
+def _cleaner_task_str(task):
+    s = str(task)
+    # This has something like the following in it:
+    # running at /Users/simonw/Dropbox/Development/datasette/venv-3.7.5/lib/python3.7/site-packages/uvicorn/main.py:361>
+    # Clean up everything up to and including site-packages
+    return _cleaner_task_str_re.sub("", s)
diff --git a/datasette/templates/show_json.html b/datasette/templates/show_json.html
index c87ec9f7..b9e49eb2 100644
--- a/datasette/templates/show_json.html
+++ b/datasette/templates/show_json.html
@@ -7,6 +7,6 @@
 {% block content %}
 <h1>{{ filename }}</h1>
 
-<pre>{{ data|tojson(indent=4) }}</pre>
+<pre>{{ data_json }}</pre>
 
 {% endblock %}
diff --git a/datasette/views/special.py b/datasette/views/special.py
index 45e948f6..2b31028d 100644
--- a/datasette/views/special.py
+++ b/datasette/views/special.py
@@ -27,5 +27,8 @@ class JsonDataView(BaseView):
             return await self.render(
                 ["show_json.html"],
                 request=request,
-                context={"filename": self.filename, "data": data},
+                context={
+                    "filename": self.filename,
+                    "data_json": json.dumps(data, indent=4),
+                },
             )
diff --git a/docs/introspection.rst b/docs/introspection.rst
index 02552bab..3cd4a40f 100644
--- a/docs/introspection.rst
+++ b/docs/introspection.rst
@@ -113,7 +113,7 @@ Shows currently attached databases. `Databases example <https://latest.datasette
 /-/threads
 ----------
 
-Shows details of threads. `Threads example <https://latest.datasette.io/-/threads>`_::
+Shows details of threads and ``asyncio`` tasks. `Threads example <https://latest.datasette.io/-/threads>`_::
 
     {
         "num_threads": 2,
@@ -128,5 +128,11 @@ Shows details of threads. `Threads example <https://latest.datasette.io/-/thread
                 "ident": 123145319682048,
                 "name": "Thread-1"
             },
+        ],
+        "num_tasks": 3,
+        "tasks": [
+            "<Task pending coro=<RequestResponseCycle.run_asgi() running at uvicorn/protocols/http/httptools_impl.py:385> cb=[set.discard()]>",
+            "<Task pending coro=<Server.serve() running at uvicorn/main.py:361> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x10365c3d0>()]> cb=[run_until_complete.<locals>.<lambda>()]>",
+            "<Task pending coro=<LifespanOn.main() running at uvicorn/lifespan/on.py:48> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x10364f050>()]>>"
         ]
     }
diff --git a/tests/test_api.py b/tests/test_api.py
index 34eef4ce..cf09c1ba 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -18,6 +18,7 @@ from .fixtures import (  # noqa
 )
 import json
 import pytest
+import sys
 import urllib
 
 
@@ -1229,6 +1230,14 @@ def test_metadata_json(app_client):
     assert METADATA == response.json
 
 
+def test_threads_json(app_client):
+    response = app_client.get("/-/threads.json")
+    expected_keys = {"threads", "num_threads"}
+    if sys.version_info >= (3, 7, 0):
+        expected_keys.update({"tasks", "num_tasks"})
+    assert expected_keys == set(response.json.keys())
+
+
 def test_plugins_json(app_client):
     response = app_client.get("/-/plugins.json")
     assert [