[libc-commits] [libc] [libc][arc4random][patch 2/n] add ABA protected MPMCStack (PR #151361)

[Schrodinger ZHU Yifan via libc-commits]

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@@ -0,0 +1,119 @@
+#include "src/__support/CPP/atomic.h"
+#include "src/__support/mpmc_stack.h"
+#include "src/pthread/pthread_create.h"
+#include "src/pthread/pthread_join.h"
+#include "test/IntegrationTest/test.h"
+
+using namespace LIBC_NAMESPACE;
+
+void smoke_test() {
+  MPMCStack<int> stack;
+  for (int i = 0; i <= 100; ++i)
+    if (!stack.push(i))
+      __builtin_trap();
+  for (int i = 100; i >= 0; --i)
+    if (*stack.pop() != i)
+      __builtin_trap();
+  if (stack.pop())
+    __builtin_trap(); // Should be empty now.
+}
+
+void multithread_test() {
+  constexpr static size_t NUM_THREADS = 5;
+  constexpr static size_t NUM_PUSHES = 100;
+  struct State {
+    MPMCStack<size_t> stack;
+    cpp::Atomic<size_t> counter = 0;
+    cpp::Atomic<bool> flags[NUM_PUSHES];
+  } state;
+  pthread_t threads[NUM_THREADS];
+  for (size_t i = 0; i < NUM_THREADS; ++i) {
+    LIBC_NAMESPACE::pthread_create(
+        &threads[i], nullptr,
+        [](void *arg) -> void * {
+          State *state = static_cast<State *>(arg);
+          for (;;) {
+            size_t current = state->counter.fetch_add(1);
+            if (current >= NUM_PUSHES)
+              break;
+            if (!state->stack.push(current))
+              __builtin_trap();
+          }
+          while (auto res = state->stack.pop())
+            state->flags[res.value()].store(true);
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SchrodingerZhu wrote:

It is a test anyway.

https://github.com/llvm/llvm-project/pull/151361