mirror of
https://github.com/matrix-construct/construct
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38 lines
1.5 KiB
C++
38 lines
1.5 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_CTX_EXCEPTION_HANDLER_H
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namespace ircd::ctx::this_ctx
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{
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struct exception_handler;
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}
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/// An instance of exception_handler must be present to allow a context
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/// switch inside a catch block. This is due to ABI limitations that stack
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/// exceptions with thread-local assumptions and don't expect catch blocks
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/// on the same thread to interleave when we switch the stack.
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///
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/// We first increment the refcount for the caught exception so it remains
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/// intuitively accessible for the rest of the catch block. Then the presence
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/// of this object makes the ABI believe the catch block has ended.
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///
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/// The exception cannot then be rethrown. DO NOT RETHROW THE EXCEPTION.
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///
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struct ircd::ctx::this_ctx::exception_handler
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:std::exception_ptr
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{
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exception_handler() noexcept;
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exception_handler(exception_handler &&) = delete;
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exception_handler(const exception_handler &) = delete;
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exception_handler &operator=(exception_handler &&) = delete;
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exception_handler &operator=(const exception_handler &) = delete;
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};
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