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+++ b/CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/include/kj/threadlocal.h	Tue Mar 18 17:55:14 2025 -0400
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+// Copyright (c) 2014, Jason Choy <jjwchoy@gmail.com>
+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#pragma once
+
+// This file declares a macro `KJ_THREADLOCAL_PTR` for declaring thread-local pointer-typed
+// variables.  Use like:
+//     KJ_THREADLOCAL_PTR(MyType) foo = nullptr;
+// This is equivalent to:
+//     thread_local MyType* foo = nullptr;
+// This can only be used at the global scope.
+//
+// AVOID USING THIS.  Use of thread-locals is discouraged because they often have many of the same
+// properties as singletons: http://www.object-oriented-security.org/lets-argue/singletons
+//
+// Also, thread-locals tend to be hostile to event-driven code, which can be particularly
+// surprising when using fibers (all fibers in the same thread will share the same threadlocals,
+// even though they do not share a stack).
+//
+// That said, thread-locals are sometimes needed for runtime logistics in the KJ framework.  For
+// example, the current exception callback and current EventLoop are stored as thread-local
+// pointers.  Since KJ only ever needs to store pointers, not values, we avoid the question of
+// whether these values' destructors need to be run, and we avoid the need for heap allocation.
+
+#include "common.h"
+
+KJ_BEGIN_HEADER
+
+namespace kj {
+
+#if __GNUC__
+
+#define KJ_THREADLOCAL_PTR(type) static __thread type*
+// GCC's __thread is lighter-weight than thread_local and is good enough for our purposes.
+//
+// TODO(cleanup): The above comment was written many years ago. Is it still true? Shouldn't the
+//   compiler be smart enough to optimize a thread_local of POD type?
+
+#else
+
+#define KJ_THREADLOCAL_PTR(type) static thread_local type*
+
+#endif // KJ_USE_PTHREAD_TLS
+
+}  // namespace kj
+
+KJ_END_HEADER