diff options
Diffstat (limited to 'src/mongo/stdx/thread.h')
| -rw-r--r-- | src/mongo/stdx/thread.h | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/src/mongo/stdx/thread.h b/src/mongo/stdx/thread.h index 43a7cf52879..fda0e5531e1 100644 --- a/src/mongo/stdx/thread.h +++ b/src/mongo/stdx/thread.h @@ -30,6 +30,9 @@ #pragma once #include <chrono> +#include <csignal> +#include <cstddef> +#include <cstdint> #include <ctime> #include <exception> #include <thread> @@ -37,8 +40,86 @@ #include "mongo/stdx/exception.h" +#if defined(__linux__) || defined(__FreeBSD__) +#define MONGO_HAS_SIGALTSTACK 1 +#else +#define MONGO_HAS_SIGALTSTACK 0 +#endif + namespace mongo { namespace stdx { +namespace support { + +/** + * Manages an alternate stack for signal handlers. + * A dummy implementation is provided on platforms which do not support `sigaltstack`. + */ +class SigAltStackController { +public: +#if MONGO_HAS_SIGALTSTACK + /** Return an object that installs and uninstalls our `_stackStorage` as `sigaltstack`. */ + auto makeInstallGuard() const { + struct Guard { + explicit Guard(const SigAltStackController& controller) : _controller(controller) { + _controller._install(); + } + + ~Guard() { + _controller._uninstall(); + } + + const SigAltStackController& _controller; + }; + return Guard{*this}; + } + +private: + void _install() const { + stack_t ss; + ss.ss_sp = _stackStorage.get(); + ss.ss_flags = 0; + ss.ss_size = kStackSize; + if (sigaltstack(&ss, nullptr)) { + abort(); + } + } + + void _uninstall() const { + stack_t ss; + ss.ss_flags = SS_DISABLE; + if (sigaltstack(&ss, nullptr)) { + abort(); + } + } + + // Signal stack consumption was measured in mongo/util/stacktrace_test. + // 64 kiB is 4X our worst case, so that should be enough. + // . signal handler action + // . --use-libunwind : ----\ ============================= + // . --dbg=on : -\ \ minimal | print | backtrace + // . = = ========|=========|========== + // . N N : 4,344 | 7,144 | 5,096 + // . Y N : 4,424 | 7,528 | 5,160 + // . N Y : 4,344 | 13,048 | 7,352 + // . Y Y : 4,424 | 13,672 | 8,392 + // ( https://jira.mongodb.org/secure/attachment/233569/233569_stacktrace-writeup.txt ) + static constexpr std::size_t kMongoMinSignalStackSize = std::size_t{64} << 10; + + static constexpr std::size_t kStackSize = + std::max(kMongoMinSignalStackSize, std::size_t{MINSIGSTKSZ}); + std::unique_ptr<std::byte[]> _stackStorage = std::make_unique<std::byte[]>(kStackSize); + +#else // !MONGO_HAS_SIGALTSTACK + auto makeInstallGuard() const { + struct Guard { + ~Guard() {} // needed to suppress 'unused variable' warnings. + }; + return Guard{}; + } +#endif // !MONGO_HAS_SIGALTSTACK +}; + +} // namespace support /** * We're wrapping std::thread here, rather than aliasing it, because we'd like @@ -49,6 +130,8 @@ namespace stdx { * of the system failed thread creation (as the exception itself is caught at * the top of the stack). * + * We also want to allocate and install a `sigaltstack` to diagnose stack overflows. + * * We're putting this in stdx, rather than having it as some kind of * mongo::Thread, because the signature and use of the type is otherwise * completely identical. Rather than migrate all callers, it was deemed @@ -86,6 +169,7 @@ public: explicit thread(Function f, Args&&... args) noexcept : ::std::thread::thread( // NOLINT [ + sigAltStackController = support::SigAltStackController(), f = std::move(f), pack = std::make_tuple(std::forward<Args>(args)...) ]() mutable noexcept { @@ -96,6 +180,7 @@ public: ::std::set_terminate( // NOLINT ::mongo::stdx::TerminateHandlerDetailsInterface::dispatch); #endif + auto sigAltStackGuard = sigAltStackController.makeInstallGuard(); return std::apply(std::move(f), std::move(pack)); }) { } |