| //===-- main.cpp ------------------------------------------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // This test is intended to create a situation in which one thread will exit |
| // while a breakpoint is being handled in another thread. This may not always |
| // happen because it's possible that the exiting thread will exit before the |
| // breakpoint is hit. The test case should be flexible enough to treat that |
| // as success. |
| |
| #include <pthread.h> |
| #include <unistd.h> |
| #include <atomic> |
| |
| volatile int g_test = 0; |
| |
| // Note that although hogging the CPU while waiting for a variable to change |
| // would be terrible in production code, it's great for testing since it |
| // avoids a lot of messy context switching to get multiple threads synchronized. |
| #define do_nothing() |
| |
| #define pseudo_barrier_wait(bar) \ |
| --bar; \ |
| while (bar > 0) \ |
| do_nothing(); |
| |
| #define pseudo_barrier_init(bar, count) (bar = count) |
| |
| // A barrier to synchronize all the threads except the one that will exit. |
| std::atomic_int g_barrier1; |
| |
| // A barrier to synchronize all the threads including the one that will exit. |
| std::atomic_int g_barrier2; |
| |
| // A barrier to keep the first group of threads from exiting until after the |
| // breakpoint has been passed. |
| std::atomic_int g_barrier3; |
| |
| void * |
| break_thread_func (void *input) |
| { |
| // Wait until the entire first group of threads is running |
| pseudo_barrier_wait(g_barrier1); |
| |
| // Wait for the exiting thread to start |
| pseudo_barrier_wait(g_barrier2); |
| |
| // Do something |
| g_test++; // Set breakpoint here |
| |
| // Synchronize after the breakpoint |
| pseudo_barrier_wait(g_barrier3); |
| |
| // Return |
| return NULL; |
| } |
| |
| void * |
| wait_thread_func (void *input) |
| { |
| // Wait until the entire first group of threads is running |
| pseudo_barrier_wait(g_barrier1); |
| |
| // Wait for the exiting thread to start |
| pseudo_barrier_wait(g_barrier2); |
| |
| // Wait until the breakpoint has been passed |
| pseudo_barrier_wait(g_barrier3); |
| |
| // Return |
| return NULL; |
| } |
| |
| void * |
| exit_thread_func (void *input) |
| { |
| // Sync up with the rest of the threads. |
| pseudo_barrier_wait(g_barrier2); |
| |
| // Try to make sure this thread doesn't exit until the breakpoint is hit. |
| usleep(1); |
| |
| // Return |
| return NULL; |
| } |
| |
| int main () |
| { |
| pthread_t thread_1; |
| pthread_t thread_2; |
| pthread_t thread_3; |
| pthread_t thread_4; |
| pthread_t thread_5; |
| |
| // The first barrier waits for the non-exiting threads to start. |
| // This thread will also participate in that barrier. |
| // The idea here is to guarantee that the exiting thread will be |
| // last in the internal list maintained by the debugger. |
| pseudo_barrier_init(g_barrier1, 5); |
| |
| // The second break synchronyizes thread exection with the breakpoint. |
| pseudo_barrier_init(g_barrier2, 5); |
| |
| // The third barrier keeps the waiting threads around until the breakpoint |
| // has been passed. |
| pseudo_barrier_init(g_barrier3, 4); |
| |
| // Create a thread to hit the breakpoint |
| pthread_create (&thread_1, NULL, break_thread_func, NULL); |
| |
| // Create more threads to slow the debugger down during processing. |
| pthread_create (&thread_2, NULL, wait_thread_func, NULL); |
| pthread_create (&thread_3, NULL, wait_thread_func, NULL); |
| pthread_create (&thread_4, NULL, wait_thread_func, NULL); |
| |
| // Wait for all these threads to get started. |
| pseudo_barrier_wait(g_barrier1); |
| |
| // Create a thread to exit during the breakpoint |
| pthread_create (&thread_5, NULL, exit_thread_func, NULL); |
| |
| // Wait for the threads to finish |
| pthread_join(thread_5, NULL); |
| pthread_join(thread_4, NULL); |
| pthread_join(thread_3, NULL); |
| pthread_join(thread_2, NULL); |
| pthread_join(thread_1, NULL); |
| |
| return 0; |
| } |