Ensure Debug Help library calls on Windows are made in as thread-safe a manner as possible by wrapping them in a scoped lock. #40815
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grynspan
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Jan 12, 2022
grynspan
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Jan 12, 2022
| /// calls into it from the Swift runtime and stdlib should route through this | ||
| /// function. | ||
| SWIFT_RUNTIME_STDLIB_SPI | ||
| bool _swift_withDebugHelpLibrary( |
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This function should be exported so that it can be used by other Swift libraries in the repo if needed. It's not sufficient for those libraries to do their own locking; they would need to use the same lock to ensure thread safety.
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@swift-ci please test |
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aboood880
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grynspan
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| /// On Windows, the Debug Help library (DbgHelp.lib) is not thread-safe. All | ||
| /// calls into it from the Swift runtime and stdlib should route through this | ||
| /// function. | ||
| template < |
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And this is where I'd put my if constexpr… if I had one. (Only available in C++17, must use std::enable_if in its absence.)
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compnerd
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… a manner as possible by wrapping them in a scoped lock.
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Ensure Debug Help library calls on Windows are made in as thread-safe a manner as possible by wrapping them in a scoped lock.
According to the Win32 documentation, the functions in the Debug Help library (DbgHelp.lib) are not thread-safe. That means that calling them across threads may blow up the process.
While we don't have a mechanism to control the use of this library outside the runtime/stdlib, we can at least ensure that all uses of it within the runtime/stdlib are thread-safe. We do so by exposing a new C++ runtime function,
swift::withDebugHelpLibrary(), that callers can invoke. This function acquires a lock and ensuresSymInitialize()has been called and has succeeded before any work is done that relies on the library.