util: Add type safe GetTime

src/util/time.cpp

@@ -1,5 +1,5 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2018 The Bitcoin Core developers
+// Copyright (c) 2009-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -27,6 +27,20 @@ int64_t GetTime()
     return now;
 }
 
+template <typename T>
+T GetTime()
+{
+    const std::chrono::seconds mocktime{nMockTime.load(std::memory_order_relaxed)};
+
+    return std::chrono::duration_cast<T>(
+        mocktime.count() ?
+            mocktime :
+            std::chrono::microseconds{GetTimeMicros()});
+}
+template std::chrono::seconds GetTime();
+template std::chrono::milliseconds GetTime();
+template std::chrono::microseconds GetTime();
+
 void SetMockTime(int64_t nMockTimeIn)
 {
     nMockTime.store(nMockTimeIn, std::memory_order_relaxed);