feat add Promise

CMakeLists.txt

@@ -124,6 +124,7 @@ if(SLED_BUILD_TESTS)
 		src/any_test.cc
         src/filesystem/path_test.cc
 		src/futures/future_test.cc
+		src/futures/promise_test.cc
         src/log/fmt_test.cc
 		# src/profiling/profiling_test.cc
         src/strings/base64_test.cc

include/sled/synchronization/mutex.h

@@ -134,11 +134,13 @@ public:
     template<typename Predicate>
     inline bool WaitFor(MutexLock &lock, TimeDelta timeout, Predicate &&pred)
     {
+        if (timeout.ns() < 0) { return pred(); }
+
         if (timeout == TimeDelta::PlusInfinity()) {
             cv_.wait(lock.lock_, std::forward<Predicate>(pred));
             return true;
         } else {
-            return cv_.wait_for(lock.lock_, std::chrono::milliseconds(timeout.ms()), std::forward<Predicate>(pred));
+            return cv_.wait_for(lock.lock_, std::chrono::microseconds(timeout.us()), std::forward<Predicate>(pred));
         }
     }
 

include/sled/units/time_delta.h

@@ -43,6 +43,12 @@ public:
         return FromValue(value);
     }
 
+    template<typename T, typename V>
+    inline TimeDelta(std::chrono::duration<T, V> duration)
+    {
+        *this = Micros(std::chrono::duration_cast<std::chrono::microseconds>(duration));
+    }
+
     TimeDelta() = delete;
 
     template<typename T = int64_t>
@@ -69,15 +75,9 @@ public:
         return ToMultiple<1000, T>();
     }
 
-    constexpr int64_t seconds_or(int64_t fallback_value) const
-    {
-        return ToFractionOr<1000000>(fallback_value);
-    }
+    constexpr int64_t seconds_or(int64_t fallback_value) const { return ToFractionOr<1000000>(fallback_value); }
 
-    constexpr int64_t ms_or(int64_t fallback_value) const
-    {
-        return ToFractionOr<1000>(fallback_value);
-    }
+    constexpr int64_t ms_or(int64_t fallback_value) const { return ToFractionOr<1000>(fallback_value); }
 
     constexpr int64_t us_or(int64_t fallback_value) const { return ToValueOr(fallback_value); }
 

src/futures/promise_test.cc

@@ -0,0 +1,21 @@
+#include <gtest/gtest.h>
+#include <sled/futures/promise.h>
+
+TEST(Promise, Basic)
+{
+    auto p = sled::Promise<int>();
+    auto v = p.Then([](int v) {
+                  EXPECT_EQ(v, 1);
+                  return v + 10;
+              })
+                 .Tap([](int v) {
+                     EXPECT_EQ(v, 11);
+                     // no effect
+                     return v + 1;
+                 })
+                 .Then([](int v) {
+                     EXPECT_EQ(v, 11);
+                     return v + 10;
+                 });
+    p.Resolve(1);
+}