1 files changed, 80 insertions, 0 deletions
diff --git a/absl/time/internal/get_current_time_ios.inc b/absl/time/internal/get_current_time_ios.inc
new file mode 100644
index 000000000000..f3db32bf7854
--- /dev/null
+++ b/absl/time/internal/get_current_time_ios.inc
@@ -0,0 +1,80 @@
+#include "absl/time/clock.h"
+
+#include <sys/time.h>
+#include <ctime>
+#include <cstdint>
+
+#include "absl/base/internal/raw_logging.h"
+
+// These are not defined in the Xcode 7.3.1 SDK Headers.
+// Once we are no longer supporting Xcode 7.3.1 we can
+// remove these.
+#ifndef __WATCHOS_3_0
+#define __WATCHOS_3_0 30000
+#endif
+
+#ifndef __TVOS_10_0
+#define __TVOS_10_0 100000
+#endif
+
+#ifndef __IPHONE_10_0
+#define __IPHONE_10_0 100000
+#endif
+
+#ifndef __MAC_10_12
+#define __MAC_10_12 101200
+#endif
+
+namespace absl {
+namespace time_internal {
+
+static int64_t GetCurrentTimeNanosFromSystem() {
+#if (__MAC_OS_X_VERSION_MAX_ALLOWED >= __MAC_10_12) ||    \
+    (__IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_10_0) || \
+    (__WATCH_OS_VERSION_MAX_ALLOWED >= __WATCHOS_3_0) ||  \
+    (__TV_OS_VERSION_MAX_ALLOWED >= __TVOS_10_0)
+  // clock_gettime_nsec_np is not defined on SDKs before Xcode 8.0.
+  // This preprocessor logic is based upon __CLOCK_AVAILABILITY in
+  // usr/include/time.h. Once we are no longer supporting Xcode 7.3.1 we can
+  // remove this #if.
+  // We must continue to check if it is defined until we are sure that ALL the
+  // platforms we are shipping on support it.
+  // clock_gettime_nsec_np is preferred because it may give higher accuracy than
+  // gettimeofday in future Apple operating systems.
+  // Currently (macOS 10.12/iOS 10.2) clock_gettime_nsec_np accuracy is
+  // microsecond accuracy (i.e. equivalent to gettimeofday).
+  if (&clock_gettime_nsec_np != nullptr) {
+    return clock_gettime_nsec_np(CLOCK_REALTIME);
+  }
+#endif
+#if (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) &&            \
+     (__MAC_OS_X_VERSION_MIN_REQUIRED < __MAC_10_12)) ||    \
+    (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) &&           \
+     (__IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_10_0)) || \
+    (defined(__WATCH_OS_VERSION_MIN_REQUIRED) &&            \
+     (__WATCH_OS_VERSION_MIN_REQUIRED < __WATCHOS_3_0)) ||  \
+    (defined(__TV_OS_VERSION_MIN_REQUIRED) &&               \
+     (__TV_OS_VERSION_MIN_REQUIRED < __TVOS_10_0))
+  // We need this block in 2 different cases:
+  // a) where we are compiling with Xcode 7 in which case the block above
+  //    will not be compiled in, and this is the only block executed.
+  // b) where we are compiling with Xcode 8+ but supporting operating systems
+  //    that do not define clock_gettime_nsec_np, so this is in effect
+  //    an else block to the block above.
+  // This block will not be compiled if the min supported version is
+  // guaranteed to supply clock_gettime_nsec_np.
+  //
+  // Once we know that clock_gettime_nsec_np is in the SDK *AND* exists on
+  // all the platforms we support, we can remove both this block and alter the
+  // block above to just call clock_gettime_nsec_np directly.
+  const int64_t kNanosPerSecond = 1000 * 1000 * 1000;
+  const int64_t kNanosPerMicrosecond = 1000;
+  struct timeval tp;
+  ABSL_RAW_CHECK(gettimeofday(&tp, nullptr) == 0, "Failed gettimeofday");
+  return (int64_t{tp.tv_sec} * kNanosPerSecond +
+          int64_t{tp.tv_usec} * kNanosPerMicrosecond);
+#endif
+}
+
+}  // namespace time_internal
+}  // namespace absl