Adding `NowNanos()` to `tensorflow::Env`.

PiperOrigin-RevId: 206812942

4 files changed, 35 insertions, 21 deletions

diff --git a/tensorflow/core/platform/cloud/gcs_throttle_test.cc b/tensorflow/core/platform/cloud/gcs_throttle_test.cc
index 57193ac405..8f962b92b8 100644
--- a/tensorflow/core/platform/cloud/gcs_throttle_test.cc
+++ b/tensorflow/core/platform/cloud/gcs_throttle_test.cc
@@ -24,14 +24,14 @@ namespace {
 
 class TestTime : public EnvTime {
  public:
-  uint64 NowMicros() override { return now_; }
+  uint64 NowNanos() override { return now_micros_ * kMicrosToNanos; }
 
-  void SetTime(uint64 now_micros) { now_ = now_micros; }
+  void SetTime(uint64 now_micros) { now_micros_ = now_micros; }
 
-  void AdvanceSeconds(int64 secs) { now_ += secs * 1000000L; }
+  void AdvanceSeconds(int64 secs) { now_micros_ += secs * kSecondsToMicros; }
 
  private:
-  uint64 now_ = 1234567890000000ULL;
+  uint64 now_micros_ = 1234567890000000ULL;
 };
 
 class GcsThrottleTest : public ::testing::Test {
diff --git a/tensorflow/core/platform/env_time.h b/tensorflow/core/platform/env_time.h
index 23dbedd60d..b4756ed209 100644
--- a/tensorflow/core/platform/env_time.h
+++ b/tensorflow/core/platform/env_time.h
@@ -25,6 +25,13 @@ namespace tensorflow {
 /// access timer related operations.
 class EnvTime {
  public:
+  static constexpr uint64 kMicrosToNanos = 1000ULL;
+  static constexpr uint64 kMillisToMicros = 1000ULL;
+  static constexpr uint64 kMillisToNanos = 1000ULL * 1000ULL;
+  static constexpr uint64 kSecondsToMillis = 1000ULL;
+  static constexpr uint64 kSecondsToMicros = 1000ULL * 1000ULL;
+  static constexpr uint64 kSecondsToNanos = 1000ULL * 1000ULL * 1000ULL;
+
   EnvTime();
   virtual ~EnvTime() = default;
 
@@ -34,11 +41,14 @@ class EnvTime {
   /// The result of Default() belongs to this library and must never be deleted.
   static EnvTime* Default();
 
+  /// \brief Returns the number of nano-seconds since the Unix epoch.
+  virtual uint64 NowNanos() = 0;
+
   /// \brief Returns the number of micro-seconds since the Unix epoch.
-  virtual uint64 NowMicros() = 0;
+  virtual uint64 NowMicros() { return NowNanos() / kMicrosToNanos; }
 
   /// \brief Returns the number of seconds since the Unix epoch.
-  virtual uint64 NowSeconds() { return NowMicros() / 1000000L; }
+  virtual uint64 NowSeconds() { return NowNanos() / kSecondsToNanos; }
 };
 
 }  // namespace tensorflow
diff --git a/tensorflow/core/platform/posix/env_time.cc b/tensorflow/core/platform/posix/env_time.cc
index 341c585a9e..59a67b17aa 100644
--- a/tensorflow/core/platform/posix/env_time.cc
+++ b/tensorflow/core/platform/posix/env_time.cc
@@ -26,10 +26,11 @@ class PosixEnvTime : public EnvTime {
  public:
   PosixEnvTime() {}
 
-  uint64 NowMicros() override {
-    struct timeval tv;
-    gettimeofday(&tv, nullptr);
-    return static_cast<uint64>(tv.tv_sec) * 1000000 + tv.tv_usec;
+  uint64 NowNanos() override {
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    return (static_cast<uint64>(ts.tv_sec) * kSecondsToNanos +
+            static_cast<uint64>(ts.tv_nsec));
   }
 };
 
diff --git a/tensorflow/core/platform/windows/env_time.cc b/tensorflow/core/platform/windows/env_time.cc
index 16cc9dc675..b1713f695c 100644
--- a/tensorflow/core/platform/windows/env_time.cc
+++ b/tensorflow/core/platform/windows/env_time.cc
@@ -19,6 +19,10 @@ limitations under the License.
 #include <windows.h>
 #include <chrono>
 
+using std::chrono::duration_cast;
+using std::chrono::nanoseconds;
+using std::chrono::system_clock;
+
 namespace tensorflow {
 
 namespace {
@@ -38,18 +42,17 @@ class WindowsEnvTime : public EnvTime {
     }
   }
 
-  uint64 NowMicros() override {
+  uint64 NowNanos() {
     if (GetSystemTimePreciseAsFileTime_ != NULL) {
       // GetSystemTimePreciseAsFileTime function is only available in latest
       // versions of Windows, so we need to check for its existence here.
-      // All std::chrono clocks on Windows proved to return
-      // values that may repeat, which is not good enough for some uses.
+      // All std::chrono clocks on Windows proved to return values that may
+      // repeat, which is not good enough for some uses.
       constexpr int64_t kUnixEpochStartTicks = 116444736000000000i64;
-      constexpr int64_t kFtToMicroSec = 10;
 
-      // This interface needs to return system time and not
-      // just any microseconds because it is often used as an argument
-      // to TimedWait() on condition variable
+      // This interface needs to return system time and not just any time
+      // because it is often used as an argument to TimedWait() on condition
+      // variable.
       FILETIME system_time;
       GetSystemTimePreciseAsFileTime_(&system_time);
 
@@ -58,12 +61,12 @@ class WindowsEnvTime : public EnvTime {
       li.HighPart = system_time.dwHighDateTime;
       // Subtract unix epoch start
       li.QuadPart -= kUnixEpochStartTicks;
-      // Convert to microsecs
-      li.QuadPart /= kFtToMicroSec;
+
+      constexpr int64_t kFtToNanoSec = 100;
+      li.QuadPart *= kFtToNanoSec;
       return li.QuadPart;
     }
-    using namespace std::chrono;
-    return duration_cast<microseconds>(system_clock::now().time_since_epoch())
+    return duration_cast<nanoseconds>(system_clock::now().time_since_epoch())
         .count();
   }