drop python 3.7 support, drop pypy3.7-3.8, add pypy3.10 (except on wi…

…ndows) (#2668)

* drop support for Python 3.7, PyPy3.7 & 3.8. Updates documentation, CI, and code with help of `pyupgrade --py38-plus`.

.github/workflows/ci.yml

@@ -18,16 +18,18 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['3.7', '3.8', '3.9', '3.10', 'pypy-3.8-nightly', 'pypy-3.9-nightly']
+        # pypy-3.10 is failing, see https://github.com/python-trio/trio/issues/2678
+        python: ['3.8', '3.9', '3.10', 'pypy-3.9-nightly'] #, 'pypy-3.10-nightly']
         arch: ['x86', 'x64']
         lsp: ['']
         lsp_extract_file: ['']
         extra_name: ['']
         exclude:
-          - python: 'pypy-3.8-nightly'
-            arch: 'x86'
+          # pypy does not release 32-bit binaries
           - python: 'pypy-3.9-nightly'
             arch: 'x86'
+          #- python: 'pypy-3.10-nightly'
+          #  arch: 'x86'
         include:
           - python: '3.8'
             arch: 'x64'
@@ -65,8 +67,8 @@ jobs:
           # and then finally an actual release version.  actions/setup-python doesn't
           # support this for PyPy presently so we get no help there.
           #
-          # CPython -> 3.9.0-alpha - 3.9.X
-          # PyPy    -> pypy-3.7
+          # 'CPython' -> '3.9.0-alpha - 3.9.X'
+          # 'PyPy'    -> 'pypy-3.9'
           python-version: ${{ fromJSON(format('["{0}", "{1}"]', format('{0}.0-alpha - {0}.X', matrix.python), matrix.python))[startsWith(matrix.python, 'pypy')] }}
           architecture: '${{ matrix.arch }}'
           cache: pip
@@ -92,7 +94,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['pypy-3.7', 'pypy-3.8', 'pypy-3.9', '3.7', '3.8', '3.9', '3.10', '3.11', '3.12-dev', 'pypy-3.8-nightly', 'pypy-3.9-nightly']
+        python: ['pypy-3.9', 'pypy-3.10', '3.8', '3.9', '3.10', '3.11', '3.12-dev', 'pypy-3.9-nightly', 'pypy-3.10-nightly']
         check_formatting: ['0']
         extra_name: ['']
         include:
@@ -143,7 +145,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python: ['3.7', '3.8', '3.9', '3.10', 'pypy-3.8-nightly', 'pypy-3.9-nightly']
+        python: ['3.8', '3.9', '3.10', 'pypy-3.9-nightly', 'pypy-3.10-nightly']
     continue-on-error: >-
       ${{
         (

README.rst

@@ -92,8 +92,9 @@ demonstration of implementing the "Happy Eyeballs" algorithm in an
 older library versus Trio.
 
 **Cool, but will it work on my system?** Probably! As long as you have
-some kind of Python 3.7-or-better (CPython or the latest PyPy3 are
-both fine), and are using Linux, macOS, Windows, or FreeBSD, then Trio
+some kind of Python 3.8-or-better (CPython or [currently maintained versions of
+PyPy3](https://doc.pypy.org/en/latest/faq.html#which-python-versions-does-pypy-implement)
+are both fine), and are using Linux, macOS, Windows, or FreeBSD, then Trio
 will work. Other environments might work too, but those
 are the ones we test on. And all of our dependencies are pure Python,
 except for CFFI on Windows, which has wheels available, so

docs/source/index.rst

@@ -45,7 +45,7 @@ Vital statistics:
 
 * Supported environments: We test on
 
-  - Python: 3.7+ (CPython and PyPy)
+  - Python: 3.8+ (CPython and PyPy)
   - Windows, macOS, Linux (glibc and musl), FreeBSD
 
   Other environments might also work; give it a try and see.

docs/source/reference-core.rst

@@ -974,12 +974,8 @@ work. What we need is something that's *like* a global variable, but
 that can have different values depending on which request handler is
 accessing it.
 
-To solve this problem, Python 3.7 added a new module to the standard
-library: :mod:`contextvars`. And not only does Trio have built-in
-support for :mod:`contextvars`, but if you're using an earlier version
-of Python, then Trio makes sure that a backported version of
-:mod:`contextvars` is installed. So you can assume :mod:`contextvars`
-is there and works regardless of what version of Python you're using.
+To solve this problem, Python has a module in the standard
+library: :mod:`contextvars`.
 
 Here's a toy example demonstrating how to use :mod:`contextvars`:
 
@@ -1009,7 +1005,7 @@ Example output (yours may differ slightly):
    request 0: Request received finished
 
 For more information, read the
-`contextvars docs <https://docs.python.org/3.7/library/contextvars.html>`__.
+`contextvars docs <https://docs.python.org/3/library/contextvars.html>`__.
 
 
 .. _synchronization:

docs/source/tutorial.rst

@@ -88,7 +88,7 @@ Okay, ready? Let's get started.
 Before you begin
 ----------------
 
-1. Make sure you're using Python 3.7 or newer.
+1. Make sure you're using Python 3.8 or newer.
 
 2. ``python3 -m pip install --upgrade trio`` (or on Windows, maybe
    ``py -3 -m pip install --upgrade trio`` – `details

newsfragments/2668.removal.rst

@@ -0,0 +1 @@
+Drop support for Python3.7 and PyPy3.7/3.8.

newsfragments/README.rst

@@ -14,6 +14,7 @@ Each file should be named like ``<ISSUE>.<TYPE>.rst``, where
   deprecated features after an appropriate time, go in the
   ``deprecated`` category instead)
 * ``feature``: any new feature that doesn't qualify for ``headline``
+* ``removal``: removing support for old python versions, or other removals with no deprecation period.
 * ``bugfix``
 * ``doc``
 * ``deprecated``

notes-to-self/how-does-windows-so-reuseaddr-work.py

@@ -10,6 +10,7 @@
 modes = ["default", "SO_REUSEADDR", "SO_EXCLUSIVEADDRUSE"]
 bind_types = ["wildcard", "specific"]
 
+
 def sock(mode):
     s = socket.socket(family=socket.AF_INET)
     if mode == "SO_REUSEADDR":
@@ -18,6 +19,7 @@ def sock(mode):
         s.setsockopt(socket.SOL_SOCKET, socket.SO_EXCLUSIVEADDRUSE, 1)
     return s
 
+
 def bind(sock, bind_type):
     if bind_type == "wildcard":
         sock.bind(("0.0.0.0", 12345))
@@ -26,6 +28,7 @@ def bind(sock, bind_type):
     else:
         assert False
 
+
 def table_entry(mode1, bind_type1, mode2, bind_type2):
     with sock(mode1) as sock1:
         bind(sock1, bind_type1)
@@ -41,19 +44,22 @@ def table_entry(mode1, bind_type1, mode2, bind_type2):
         else:
             return "Success"
 
-print("""
+
+print(
+    """
                                                        second bind
                                | """
-+ " | ".join(["%-19s" % mode for mode in modes])
+    + " | ".join(["%-19s" % mode for mode in modes])
 )
 
-print("""                              """, end='')
+print("""                              """, end="")
 for mode in modes:
-    print(" | " + " | ".join(["%8s" % bind_type for bind_type in bind_types]), end='')
+    print(" | " + " | ".join(["%8s" % bind_type for bind_type in bind_types]), end="")
 
-print("""
+print(
+    """
 first bind                     -----------------------------------------------------------------"""
-#            default | wildcard |    INUSE |  Success |   ACCESS |  Success |    INUSE |  Success
+    #            default | wildcard |    INUSE |  Success |   ACCESS |  Success |    INUSE |  Success
 )
 
 for i, mode1 in enumerate(modes):
@@ -63,6 +69,8 @@ def table_entry(mode1, bind_type1, mode2, bind_type2):
             for l, bind_type2 in enumerate(bind_types):
                 entry = table_entry(mode1, bind_type1, mode2, bind_type2)
                 row.append(entry)
-                #print(mode1, bind_type1, mode2, bind_type2, entry)
-        print("{:>19} | {:>8} | ".format(mode1, bind_type1)
-              + " | ".join(["%8s" % entry for entry in row]))
+                # print(mode1, bind_type1, mode2, bind_type2, entry)
+        print(
+            f"{mode1:>19} | {bind_type1:>8} | "
+            + " | ".join(["%8s" % entry for entry in row])
+        )

notes-to-self/reopen-pipe.py

@@ -3,12 +3,13 @@
 import time
 import tempfile
 
+
 def check_reopen(r1, w):
     try:
         print("Reopening read end")
-        r2 = os.open("/proc/self/fd/{}".format(r1), os.O_RDONLY)
+        r2 = os.open(f"/proc/self/fd/{r1}", os.O_RDONLY)
 
-        print("r1 is {}, r2 is {}".format(r1, r2))
+        print(f"r1 is {r1}, r2 is {r2}")
 
         print("checking they both can receive from w...")
 
@@ -36,11 +37,12 @@ def check_reopen(r1, w):
         def sleep_then_write():
             time.sleep(1)
             os.write(w, b"c")
+
         threading.Thread(target=sleep_then_write, daemon=True).start()
         assert os.read(r1, 1) == b"c"
         print("r1 definitely seems to be in blocking mode")
     except Exception as exc:
-        print("ERROR: {!r}".format(exc))
+        print(f"ERROR: {exc!r}")
 
 
 print("-- testing anonymous pipe --")
@@ -63,6 +65,6 @@ def sleep_then_write():
 
 print("-- testing socketpair --")
 import socket
+
 rs, ws = socket.socketpair()
 check_reopen(rs.fileno(), ws.fileno())
-

notes-to-self/schedule-timing.py

@@ -4,16 +4,18 @@
 LOOPS = 0
 RUNNING = True
 
+
 async def reschedule_loop(depth):
     if depth == 0:
         global LOOPS
         while RUNNING:
             LOOPS += 1
             await trio.sleep(0)
-            #await trio.lowlevel.cancel_shielded_checkpoint()
+            # await trio.lowlevel.cancel_shielded_checkpoint()
     else:
         await reschedule_loop(depth - 1)
 
+
 async def report_loop():
     global RUNNING
     try:
@@ -25,13 +27,15 @@ async def report_loop():
             end_count = LOOPS
             loops = end_count - start_count
             duration = end_time - start_time
-            print("{} loops/sec".format(loops / duration))
+            print(f"{loops / duration} loops/sec")
     finally:
         RUNNING = False
 
+
 async def main():
     async with trio.open_nursery() as nursery:
         nursery.start_soon(reschedule_loop, 10)
         nursery.start_soon(report_loop)
 
+
 trio.run(main)

notes-to-self/socketpair-buffering.py

@@ -32,6 +32,6 @@
     except BlockingIOError:
         pass
 
-    print("setsockopt bufsize {}: {}".format(bufsize, i))
+    print(f"setsockopt bufsize {bufsize}: {i}")
     a.close()
     b.close()

notes-to-self/ssl-handshake/ssl-handshake.py

@@ -8,6 +8,7 @@
 server_ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
 server_ctx.load_cert_chain("trio-test-1.pem")
 
+
 def _ssl_echo_serve_sync(sock):
     try:
         wrapped = server_ctx.wrap_socket(sock, server_side=True)
@@ -20,16 +21,19 @@ def _ssl_echo_serve_sync(sock):
     except BrokenPipeError:
         pass
 
+
 @contextmanager
 def echo_server_connection():
     client_sock, server_sock = socket.socketpair()
     with client_sock, server_sock:
         t = threading.Thread(
-            target=_ssl_echo_serve_sync, args=(server_sock,), daemon=True)
+            target=_ssl_echo_serve_sync, args=(server_sock,), daemon=True
+        )
         t.start()
 
         yield client_sock
 
+
 class ManuallyWrappedSocket:
     def __init__(self, ctx, sock, **kwargs):
         self.incoming = ssl.MemoryBIO()
@@ -82,21 +86,23 @@ def unwrap(self):
 def wrap_socket_via_wrap_socket(ctx, sock, **kwargs):
     return ctx.wrap_socket(sock, do_handshake_on_connect=False, **kwargs)
 
+
 def wrap_socket_via_wrap_bio(ctx, sock, **kwargs):
     return ManuallyWrappedSocket(ctx, sock, **kwargs)
 
 
 for wrap_socket in [
-        wrap_socket_via_wrap_socket,
-        wrap_socket_via_wrap_bio,
+    wrap_socket_via_wrap_socket,
+    wrap_socket_via_wrap_bio,
 ]:
-    print("\n--- checking {} ---\n".format(wrap_socket.__name__))
+    print(f"\n--- checking {wrap_socket.__name__} ---\n")
 
     print("checking with do_handshake + correct hostname...")
     with echo_server_connection() as client_sock:
         client_ctx = ssl.create_default_context(cafile="trio-test-CA.pem")
         wrapped = wrap_socket(
-            client_ctx, client_sock, server_hostname="trio-test-1.example.org")
+            client_ctx, client_sock, server_hostname="trio-test-1.example.org"
+        )
         wrapped.do_handshake()
         wrapped.sendall(b"x")
         assert wrapped.recv(1) == b"x"
@@ -107,7 +113,8 @@ def wrap_socket_via_wrap_bio(ctx, sock, **kwargs):
     with echo_server_connection() as client_sock:
         client_ctx = ssl.create_default_context(cafile="trio-test-CA.pem")
         wrapped = wrap_socket(
-            client_ctx, client_sock, server_hostname="trio-test-2.example.org")
+            client_ctx, client_sock, server_hostname="trio-test-2.example.org"
+        )
         try:
             wrapped.do_handshake()
         except Exception:
@@ -119,7 +126,8 @@ def wrap_socket_via_wrap_bio(ctx, sock, **kwargs):
     with echo_server_connection() as client_sock:
         client_ctx = ssl.create_default_context(cafile="trio-test-CA.pem")
         wrapped = wrap_socket(
-            client_ctx, client_sock, server_hostname="trio-test-2.example.org")
+            client_ctx, client_sock, server_hostname="trio-test-2.example.org"
+        )
         # We forgot to call do_handshake
         # But the hostname is wrong so something had better error out...
         sent = b"x"

notes-to-self/sslobject.py

@@ -15,14 +15,16 @@
 soutb = ssl.MemoryBIO()
 sso = server_ctx.wrap_bio(sinb, soutb, server_side=True)
 
+
 @contextmanager
 def expect(etype):
     try:
         yield
     except etype:
         pass
     else:
-        raise AssertionError("expected {}".format(etype))
+        raise AssertionError(f"expected {etype}")
+
 
 with expect(ssl.SSLWantReadError):
     cso.do_handshake()

notes-to-self/thread-closure-bug-demo.py

@@ -8,18 +8,21 @@
 
 COUNT = 100
 
+
 def slow_tracefunc(frame, event, arg):
     # A no-op trace function that sleeps briefly to make us more likely to hit
     # the race condition.
     time.sleep(0.01)
     return slow_tracefunc
 
+
 def run_with_slow_tracefunc(fn):
     # settrace() only takes effect when you enter a new frame, so we need this
     # little dance:
     sys.settrace(slow_tracefunc)
     return fn()
 
+
 def outer():
     x = 0
     # We hide the done variable inside a list, because we want to use it to
@@ -46,13 +49,14 @@ def traced_looper():
     t.start()
 
     for i in range(COUNT):
-        print("after {} increments, x is {}".format(i, x))
+        print(f"after {i} increments, x is {x}")
         x += 1
         time.sleep(0.01)
 
     done[0] = True
     t.join()
 
-    print("Final discrepancy: {} (should be 0)".format(COUNT - x))
+    print(f"Final discrepancy: {COUNT - x} (should be 0)")
+
 
 outer()