clang-tools-extra/clangd/support/ThreadCrashReporter.h

   1 //===--- ThreadCrashReporter.h - Thread local signal handling ----*- C++-*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_SUPPORT_THREADCRASHREPORTER_H
  10 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_SUPPORT_THREADCRASHREPORTER_H
  11
  12 #include "llvm/ADT/FunctionExtras.h"
  13
  14 namespace clang {
  15 namespace clangd {
  16
  17 /// Allows setting per-thread abort/kill signal callbacks, to print additional
  18 /// information about the crash depending on which thread got signalled.
  19 class ThreadCrashReporter {
  20 public:
  21   using SignalCallback = llvm::unique_function<void(void)>;
  22
  23   /// Registers the callback as the first one in thread-local callback chain.
  24   ///
  25   /// Asserts if the current thread's callback is already set. The callback is
  26   /// likely to be invoked in a signal handler. Most LLVM signal handling is not
  27   /// strictly async-signal-safe. However reporters should avoid accessing data
  28   /// structures likely to be in a bad state on crash.
  29   ThreadCrashReporter(SignalCallback ThreadLocalCallback);
  30   /// Resets the current thread's callback to nullptr.
  31   ~ThreadCrashReporter();
  32
  33   /// Moves are disabled to ease nesting and escaping considerations.
  34   ThreadCrashReporter(ThreadCrashReporter &&RHS) = delete;
  35   ThreadCrashReporter(const ThreadCrashReporter &) = delete;
  36   ThreadCrashReporter &operator=(ThreadCrashReporter &&) = delete;
  37   ThreadCrashReporter &operator=(const ThreadCrashReporter &) = delete;
  38
  39   /// Calls all currently-active ThreadCrashReporters for the current thread.
  40   ///
  41   /// To be called from sys::AddSignalHandler() callback. Any signal filtering
  42   /// is the responsibility of the caller. While this function is intended to be
  43   /// called from signal handlers, it is not strictly async-signal-safe - see
  44   /// constructor comment.
  45   ///
  46   /// When several reporters are nested, the callbacks are called in LIFO order.
  47   static void runCrashHandlers();
  48
  49 private:
  50   SignalCallback Callback;
  51   /// Points to the next reporter up the stack.
  52   ThreadCrashReporter *Next;
  53 };
  54
  55 } // namespace clangd
  56 } // namespace clang
  57
  58 #endif