intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 55 insertions, 0 deletions

diff --git a/library/cpp/messagebus/futex_like.cpp b/library/cpp/messagebus/futex_like.cpp
new file mode 100644
index 0000000000..7f965126db
--- /dev/null
+++ b/library/cpp/messagebus/futex_like.cpp
@@ -0,0 +1,55 @@
+#include <util/system/platform.h>
+
+#ifdef _linux_
+#include <sys/syscall.h>
+#include <linux/futex.h>
+
+#if !defined(SYS_futex)
+#define SYS_futex __NR_futex
+#endif
+#endif
+
+#include <errno.h>
+
+#include <util/system/yassert.h>
+
+#include "futex_like.h"
+
+#ifdef _linux_
+namespace {
+    int futex(int* uaddr, int op, int val, const struct timespec* timeout,
+              int* uaddr2, int val3) {
+        return syscall(SYS_futex, uaddr, op, val, timeout, uaddr2, val3);
+    }
+}
+#endif
+
+void TFutexLike::Wake(size_t count) {
+    Y_ASSERT(count > 0);
+#ifdef _linux_
+    if (count > unsigned(Max<int>())) {
+        count = Max<int>();
+    }
+    int r = futex(&Value, FUTEX_WAKE, count, nullptr, nullptr, 0);
+    Y_VERIFY(r >= 0, "futex_wake failed: %s", strerror(errno));
+#else
+    TGuard<TMutex> guard(Mutex);
+    if (count == 1) {
+        CondVar.Signal();
+    } else {
+        CondVar.BroadCast();
+    }
+#endif
+}
+
+void TFutexLike::Wait(int expected) {
+#ifdef _linux_
+    int r = futex(&Value, FUTEX_WAIT, expected, nullptr, nullptr, 0);
+    Y_VERIFY(r >= 0 || errno == EWOULDBLOCK, "futex_wait failed: %s", strerror(errno));
+#else
+    TGuard<TMutex> guard(Mutex);
+    if (expected == Get()) {
+        CondVar.WaitI(Mutex);
+    }
+#endif
+}