remove td::this_thread::yield function. usleep_for(1) used instead

benchmark/bench_queue.cpp

@@ -51,7 +51,7 @@ class Backoff {
     if (cnt < 50) {
       return true;
     } else {
-      td::this_thread::yield();
+      td::usleep_for(1);
       return cnt < 500;
     }
   }

td/telegram/net/NetQueryDispatcher.cpp

@@ -194,7 +194,7 @@ Status NetQueryDispatcher::wait_dc_init(DcId dc_id, bool force) {
         return Status::Error("Closing");
       }
 #if !TD_THREAD_UNSUPPORTED
-      td::this_thread::yield();
+      td::usleep_for(1);
 #endif
     }
   }

tdutils/td/utils/AtomicRead.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include "td/utils/common.h"
+#include "td/utils/port/sleep.h"
 #include "td/utils/port/thread.h"
 #include "td/utils/type_traits.h"
 
@@ -20,6 +21,15 @@ template <class T>
 class AtomicRead {
  public:
   void read(T &dest) const {
+    int it = 0;
+    const int wait_each_it = 4;
+    auto wait = [&]() {
+      it++;
+      if (it % wait_each_it == 0) {
+        usleep_for(1);
+      }
+    };
+
     while (true) {
       static_assert(TD_IS_TRIVIALLY_COPYABLE(T), "T must be trivially copyable");
       auto version_before = version.load();
@@ -30,7 +40,7 @@ class AtomicRead {
           break;
         }
       }
-      td::this_thread::yield();
+      wait();
     }
   }
 

tdutils/td/utils/MpmcQueue.h

@@ -14,6 +14,7 @@
 #include "td/utils/format.h"
 #include "td/utils/HazardPointers.h"
 #include "td/utils/logging.h"
+#include "td/utils/port/sleep.h"
 #include "td/utils/port/thread.h"
 #include "td/utils/ScopeGuard.h"
 
@@ -305,7 +306,7 @@ class MpmcQueueOld {
       if (try_pop(value, thread_id)) {
         return value;
       }
-      td::this_thread::yield();
+      td::usleep_for(1);
     }
   }
 
@@ -429,7 +430,7 @@ class MpmcQueue {
       if (try_pop(value, thread_id)) {
         return value;
       }
-      td::this_thread::yield();
+      td::usleep_for(1);
     }
   }
 

tdutils/td/utils/MpmcWaiter.h

@@ -8,6 +8,7 @@
 
 #include "td/utils/common.h"
 #include "td/utils/logging.h"
+#include "td/utils/port/sleep.h"
 #include "td/utils/port/thread.h"
 
 #include <algorithm>
@@ -29,16 +30,17 @@ class MpmcEagerWaiter {
     slot.yields = 0;
     slot.worker_id = worker_id;
   }
+
   void wait(Slot &slot) {
     if (slot.yields < RoundsTillSleepy) {
-      td::this_thread::yield();
+      yield();
       slot.yields++;
     } else if (slot.yields == RoundsTillSleepy) {
       auto state = state_.load(std::memory_order_relaxed);
       if (!State::has_worker(state)) {
         auto new_state = State::with_worker(state, slot.worker_id);
         if (state_.compare_exchange_strong(state, new_state, std::memory_order_acq_rel)) {
-          td::this_thread::yield();
+          yield();
           slot.yields++;
           return;
         }
@@ -47,12 +49,12 @@ class MpmcEagerWaiter {
           return;
         }
       }
-      td::this_thread::yield();
+      yield();
       slot.yields = 0;
     } else if (slot.yields < RoundsTillAsleep) {
       auto state = state_.load(std::memory_order_acquire);
       if (State::still_sleepy(state, slot.worker_id)) {
-        td::this_thread::yield();
+        yield();
         slot.yields++;
         return;
       }
@@ -121,6 +123,10 @@ class MpmcEagerWaiter {
       condition_variable_.notify_all();
     }
   }
+  static void yield() {
+    // whatever, this is better than sched_yield
+    usleep_for(1);
+  }
 };
 
 class MpmcSleepyWaiter {
@@ -208,7 +214,7 @@ class MpmcSleepyWaiter {
     }
     if (slot.state_ == Slot::Search) {
       if (slot.yield_cnt++ < 10 && false) {
-        td::this_thread::yield();
+        // TODO some sleep backoff is possible
         return;
       }
 

tdutils/td/utils/SpinLock.h

@@ -6,6 +6,7 @@
 //
 #pragma once
 
+#include "td/utils/port/sleep.h"
 #include "td/utils/port/thread.h"
 
 #include <atomic>
@@ -30,7 +31,7 @@ class SpinLock {
         //TODO pause
         return true;
       } else {
-        td::this_thread::yield();
+        usleep_for(1);
         return true;
       }
     }

tdutils/td/utils/port/detail/ThreadPthread.cpp

@@ -88,9 +88,6 @@ int ThreadPthread::do_pthread_create(pthread_t *thread, const pthread_attr_t *at
 }
 
 namespace this_thread_pthread {
-void yield() {
-  sched_yield();
-}
 ThreadPthread::id get_id() {
   return pthread_self();
 }

tdutils/td/utils/port/detail/ThreadPthread.h

@@ -83,7 +83,6 @@ class ThreadPthread {
 };
 
 namespace this_thread_pthread {
-void yield();
 ThreadPthread::id get_id();
 }  // namespace this_thread_pthread
 }  // namespace detail

tdutils/td/utils/port/detail/ThreadStl.h

@@ -70,7 +70,9 @@ class ThreadStl {
     return std::forward<T>(v);
   }
 };
-namespace this_thread_stl = std::this_thread;
+namespace this_thread_stl {
+using std::this_thread::get_id;
+}  // namespace this_thread_stl
 }  // namespace detail
 }  // namespace td
 

tdutils/td/utils/queue.h

@@ -32,7 +32,7 @@ class Backoff {
     if (cnt < 1) {  // 50
       return true;
     } else {
-      td::this_thread::yield();
+      td::usleep_for(1);
       return cnt < 3;  // 500
     }
   }
@@ -47,7 +47,7 @@ class InfBackoff {
     if (cnt < 50) {
       return true;
     } else {
-      td::this_thread::yield();
+      td::usleep_for(1);
       return true;
     }
   }

tdutils/td/utils/tests.h

@@ -10,12 +10,14 @@
 #include "td/utils/Context.h"
 #include "td/utils/format.h"
 #include "td/utils/logging.h"
+#include "td/utils/port/sleep.h"
 #include "td/utils/port/thread.h"
 #include "td/utils/Slice.h"
 #include "td/utils/Status.h"
 
 #include <atomic>
 #include <functional>
+#include <mutex>
 #include <utility>
 
 namespace td {
@@ -126,12 +128,12 @@ class RegisterTest {
   }
 };
 
-class Stage {
+class StageWait {
  public:
   void wait(uint64 need) {
     value_.fetch_add(1, std::memory_order_release);
     while (value_.load(std::memory_order_acquire) < need) {
-      td::this_thread::yield();
+      usleep_for(1);
     }
   };
 
@@ -139,6 +141,26 @@ class Stage {
   std::atomic<uint64> value_{0};
 };
 
+class StageMutex {
+ public:
+  void wait(uint64 need) {
+    std::unique_lock<std::mutex> lock{mutex_};
+    value_++;
+    if (value_ == need) {
+      cond_.notify_all();
+      return;
+    }
+    cond_.wait(lock, [&] { return value_ >= need; });
+  };
+
+ private:
+  std::mutex mutex_;
+  std::condition_variable cond_;
+  uint64 value_{0};
+};
+
+using Stage = StageMutex;
+
 string rand_string(int from, int to, size_t len);
 
 vector<string> rand_split(Slice str);