Implement _thread.RLock (#1922)

* Implement _thread.RLock

* Enable some test_threading tests

* Get tests passing

* Disable test on Mono

* Fix repr

Author: slozier

src/core/IronPython.Modules/_thread.cs

@@ -35,7 +35,7 @@ public static void PerformModuleReload(PythonContext/*!*/ context, PythonDiction
 
         #region Public API Surface
 
-        public static double TIMEOUT_MAX = 0; // TODO: fill this with a proper value
+        public static double TIMEOUT_MAX = Math.Floor(TimeSpan.MaxValue.TotalSeconds);
 
         [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
         public static readonly PythonType LockType = DynamicHelpers.GetPythonTypeFromType(typeof(@lock));
@@ -138,23 +138,33 @@ public static object _set_sentinel(CodeContext context) {
 
         #endregion
 
+#nullable enable
+
         [PythonType, PythonHidden]
         public sealed class @lock {
-            private AutoResetEvent blockEvent;
-            private Thread curHolder;
+            private AutoResetEvent? blockEvent;
+            private Thread? curHolder;
 
             public object __enter__() {
-                acquire(true, -1);
+                acquire();
                 return this;
             }
 
             public void __exit__(CodeContext/*!*/ context, [NotNone] params object[] args) {
                 release(context);
             }
 
-            public bool acquire(bool blocking = true, float timeout = -1) {
+            public bool acquire(bool blocking = true, double timeout = -1) {
+                var timespan = Timeout.InfiniteTimeSpan;
+
+                if (timeout != -1) {
+                    if (!blocking) throw PythonOps.ValueError("can't specify a timeout for a non-blocking call");
+                    if (timeout < 0) throw PythonOps.ValueError("timeout value must be a non-negative number");
+                    timespan = TimeSpan.FromSeconds(timeout);
+                }
+
                 for (; ; ) {
-                    if (Interlocked.CompareExchange<Thread>(ref curHolder, Thread.CurrentThread, null) == null) {
+                    if (Interlocked.CompareExchange(ref curHolder, Thread.CurrentThread, null) is null) {
                         return true;
                     }
                     if (!blocking) {
@@ -166,16 +176,16 @@ public bool acquire(bool blocking = true, float timeout = -1) {
                         CreateBlockEvent();
                         continue;
                     }
-                    if (!blockEvent.WaitOne(timeout < 0 ? Timeout.InfiniteTimeSpan : TimeSpan.FromSeconds(timeout))) {
+                    if (!blockEvent.WaitOne(timespan)) {
                         return false;
                     }
                     GC.KeepAlive(this);
                 }
             }
 
             public void release(CodeContext/*!*/ context) {
-                if (Interlocked.Exchange<Thread>(ref curHolder, null) == null) {
-                    throw PythonExceptions.CreateThrowable((PythonType)context.LanguageContext.GetModuleState("threaderror"), "lock isn't held", null);
+                if (Interlocked.Exchange(ref curHolder, null) is null) {
+                    throw PythonOps.RuntimeError("release unlocked lock");
                 }
                 if (blockEvent != null) {
                     // if this isn't set yet we race, it's handled in Acquire()
@@ -184,18 +194,135 @@ public void release(CodeContext/*!*/ context) {
                 }
             }
 
-            public bool locked() {
-                return curHolder != null;
+            public bool locked()
+                => curHolder is not null;
+
+            public string __repr__() {
+                if (curHolder is null) {
+                    return $"<unlocked _thread.lock object at 0x{IdDispenser.GetId(this):X16}>";
+                }
+                return $"<locked _thread.lock object at 0x{IdDispenser.GetId(this):X16}>";
             }
 
             private void CreateBlockEvent() {
                 AutoResetEvent are = new AutoResetEvent(false);
-                if (Interlocked.CompareExchange<AutoResetEvent>(ref blockEvent, are, null) != null) {
+                if (Interlocked.CompareExchange(ref blockEvent, are, null) is not null) {
                     are.Close();
                 }
             }
         }
 
+        [PythonType]
+        public sealed class RLock {
+            private AutoResetEvent? blockEvent;
+            private Thread? curHolder;
+            private int count;
+
+            public object __enter__() {
+                acquire();
+                return this;
+            }
+
+            public void __exit__(CodeContext/*!*/ context, [NotNone] params object[] args) {
+                release();
+            }
+
+            public bool acquire(bool blocking = true, double timeout = -1) {
+                var timespan = Timeout.InfiniteTimeSpan;
+
+                if (timeout != -1) {
+                    if (!blocking) throw PythonOps.ValueError("can't specify a timeout for a non-blocking call");
+                    if (timeout < 0) throw PythonOps.ValueError("timeout value must be a non-negative number");
+                    timespan = TimeSpan.FromSeconds(timeout);
+                }
+
+                var currentThread = Thread.CurrentThread;
+
+                for (; ; ) {
+                    var previousThread = Interlocked.CompareExchange(ref curHolder, currentThread, null);
+                    if (previousThread == currentThread) {
+                        count++;
+                        return true;
+                    }
+                    if (previousThread is null) {
+                        count = 1;
+                        return true;
+                    }
+                    if (!blocking) {
+                        return false;
+                    }
+                    if (blockEvent is null) {
+                        // try again in case someone released us, checked the block
+                        // event and discovered it was null so they didn't set it.
+                        CreateBlockEvent();
+                        continue;
+                    }
+                    if (!blockEvent.WaitOne(timespan)) {
+                        return false;
+                    }
+                    GC.KeepAlive(this);
+                }
+            }
+
+            public void release() {
+                var currentThread = Thread.CurrentThread;
+
+                if (curHolder != currentThread) {
+                    throw PythonOps.RuntimeError("cannot release un-acquired lock");
+                }
+                if (--count > 0) {
+                    return;
+                }
+
+                if (Interlocked.Exchange(ref curHolder, null) is null) {
+                    throw PythonOps.RuntimeError("release unlocked lock");
+                }
+                if (blockEvent is not null) {
+                    // if this isn't set yet we race, it's handled in acquire()
+                    blockEvent.Set();
+                    GC.KeepAlive(this);
+                }
+            }
+
+            public string __repr__() {
+                if (curHolder is null) {
+                    return $"<unlocked _thread.RLock object owner=0 count=0 at 0x{IdDispenser.GetId(this):X16}>";
+                }
+                return $"<locked _thread.RLock object owner={curHolder?.ManagedThreadId} count={count} at 0x{IdDispenser.GetId(this):X16}>";
+            }
+
+            public void _acquire_restore([NotNone] PythonTuple state) {
+                acquire();
+                count = (int)state[0]!;
+                curHolder = (Thread?)state[1];
+            }
+
+            public PythonTuple _release_save() {
+                var count = Interlocked.Exchange(ref this.count, 0);
+                if (count == 0) {
+                    throw PythonOps.RuntimeError("cannot release un-acquired lock");
+                }
+
+                // release
+                var owner = Interlocked.Exchange(ref curHolder, null);
+                blockEvent?.Set();
+
+                return PythonTuple.MakeTuple(count, owner);
+            }
+
+            public bool _is_owned()
+                => curHolder == Thread.CurrentThread;
+
+            private void CreateBlockEvent() {
+                AutoResetEvent are = new AutoResetEvent(false);
+                if (Interlocked.CompareExchange(ref blockEvent, are, null) != null) {
+                    are.Close();
+                }
+            }
+        }
+
+#nullable restore
+
         #region Internal Implementation details
 
         private static Thread CreateThread(CodeContext/*!*/ context, ThreadStart start) {

src/core/IronPython.StdLib/lib/test/script_helper.py

@@ -39,6 +39,11 @@ def _interpreter_requires_environment():
     """
     global __cached_interp_requires_environment
     if __cached_interp_requires_environment is None:
+        # https://github.com/IronLanguages/ironpython3/issues/1440
+        if sys.implementation.name == "ironpython":
+            __cached_interp_requires_environment = True
+            return True
+
         # Try running an interpreter with -E to see if it works or not.
         try:
             subprocess.check_call([sys.executable, '-E',

tests/IronPython.Tests/Cases/CPythonCasesManifest.ini

@@ -924,7 +924,7 @@ Ignore=true
 [CPython.test_threadedtempfile]
 RetryCount=2 # https://github.com/IronLanguages/ironpython3/issues/1063
 
-[CPython.test_threading]
+[CPython.test_threading] # IronPython.test_threading_stdlib
 Ignore=true
 
 [CPython.test_threading_local]

tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini

@@ -131,6 +131,9 @@ Reason=Unstable - https://github.com/IronLanguages/ironpython3/issues/1037
 Ignore=true
 Reason=StackOverflowException - https://github.com/IronLanguages/ironpython2/issues/182
 
+[IronPython.test_threading_stdlib]
+IsolationLevel=PROCESS
+
 [IronPython.test_threadsafety]
 Ignore=true
 

tests/suite/test_threading_stdlib.py

@@ -0,0 +1,39 @@
+# Licensed to the .NET Foundation under one or more agreements.
+# The .NET Foundation licenses this file to you under the Apache 2.0 License.
+# See the LICENSE file in the project root for more information.
+
+##
+## Run selected tests from test_threading from StdLib
+##
+
+from iptest import is_ironpython, is_mono, generate_suite, run_test
+
+import test.test_threading
+
+def load_tests(loader, standard_tests, pattern):
+    tests = loader.loadTestsFromModule(test.test_threading)
+
+    if is_ironpython:
+        failing_tests = []
+
+        skip_tests = [
+            test.test_threading.SubinterpThreadingTests('test_threads_join'), # ImportError: No module named '_testcapi'
+            test.test_threading.SubinterpThreadingTests('test_threads_join_2'), # ImportError: No module named '_testcapi'
+            test.test_threading.ThreadTests('test_PyThreadState_SetAsyncExc'), # AttributeError: function PyThreadState_SetAsyncExc is not defined
+            test.test_threading.ThreadTests('test_enumerate_after_join'), # AttributeError: 'module' object has no attribute 'getswitchinterval'
+            test.test_threading.ThreadTests('test_finalize_runnning_thread'), # AssertionError: 1 != 42
+            test.test_threading.ThreadTests('test_finalize_with_trace'), # AssertionError
+            test.test_threading.ThreadTests('test_no_refcycle_through_target'), # AttributeError: 'module' object has no attribute 'getrefcount'
+        ]
+
+        if is_mono:
+            skip_tests += [
+                test.test_threading.ThreadJoinOnShutdown('test_4_daemon_threads'), # SystemError: Thread was being aborted
+            ]
+
+        return generate_suite(tests, failing_tests, skip_tests)
+
+    else:
+        return tests
+
+run_test(__name__)