change macOS < 10.12 clock to SYSTEM_CLOCK, fixes #2537 (#2538)

* change macOS < 10.12 clock to SYSTEM_CLOCK, fixes #2537

* remove clock_id option from alt_clock_gettime since we always want a monotonic clock.

* update header definition for alt_clock_gettime

* pass clock definition down to host_get_clock_service for macOS < 10.12

* change to monotonic clocks

src/clock.cpp

@@ -60,15 +60,9 @@
 
 int alt_clock_gettime (int clock_id, timespec *ts)
 {
- // The clock_id specified is not supported on this system.
- if (clock_id != CLOCK_REALTIME) {
- errno = EINVAL;
- return -1;
- }
-
  clock_serv_t cclock;
  mach_timespec_t mts;
- host_get_clock_service (mach_host_self (), CALENDAR_CLOCK, &cclock);
+ host_get_clock_service (mach_host_self (), clock_id, &cclock);
  clock_get_time (cclock, &mts);
  mach_port_deallocate (mach_task_self (), cclock);
  ts->tv_sec = mts.tv_sec;
@@ -162,8 +156,8 @@ uint64_t zmq::clock_t::now_us ()
  // Use POSIX clock_gettime function to get precise monotonic time.
  struct timespec tv;
 
-#if defined ZMQ_HAVE_OSX && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 // less than macOS 10.12 
- int rc = alt_clock_gettime (CLOCK_MONOTONIC, &tv);
+#if defined ZMQ_HAVE_OSX && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 // less than macOS 10.12
+ int rc = alt_clock_gettime (SYSTEM_CLOCK, &tv);
 #else
  int rc = clock_gettime (CLOCK_MONOTONIC, &tv);
 #endif
@@ -250,7 +244,7 @@ uint64_t zmq::clock_t::rdtsc ()
 #else
  struct timespec ts;
  #if defined ZMQ_HAVE_OSX && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 // less than macOS 10.12
- alt_clock_gettime (CLOCK_MONOTONIC, &ts);
+ alt_clock_gettime (SYSTEM_CLOCK, &ts);
  #else
  clock_gettime (CLOCK_MONOTONIC, &ts);
  #endif

src/condition_variable.hpp

@@ -81,15 +81,15 @@ namespace zmq
 
 #else
 
-#ifdef ZMQ_HAVE_WINDOWS_TARGET_XP
-#include <condition_variable> 
-#include <mutex> 
-#endif
+#ifdef ZMQ_HAVE_WINDOWS_TARGET_XP
+#include <condition_variable>
+#include <mutex>
+#endif
 
 namespace zmq
 {
 
-#ifndef ZMQ_HAVE_WINDOWS_TARGET_XP
+#ifndef ZMQ_HAVE_WINDOWS_TARGET_XP
  class condition_variable_t
  {
  public:
@@ -133,51 +133,51 @@ namespace zmq
  void operator = (const condition_variable_t&);
  };
 #else
- class condition_variable_t
- {
- public:
- inline condition_variable_t()
- {
-
- }
-
- inline ~condition_variable_t()
- {
-
- }
-
- inline int wait(mutex_t* mutex_, int timeout_)
- {
- std::unique_lock<std::mutex> lck(mtx); // lock mtx
- mutex_->unlock(); // unlock mutex_ 
- int res = 0;
- if(timeout_ == -1) {
- cv.wait(lck); // unlock mtx and wait cv.notify_all(), lock mtx after cv.notify_all()
- } else if (cv.wait_for(lck, std::chrono::milliseconds(timeout_)) == std::cv_status::timeout) {
- // time expired
- errno = EAGAIN;
- res = -1;
- }
- lck.unlock(); // unlock mtx
- mutex_->lock(); // lock mutex_
- return res;
- }
-
- inline void broadcast()
- {
- std::unique_lock<std::mutex> lck(mtx); // lock mtx
- cv.notify_all();
- }
-
- private:
-
- std::condition_variable cv;
- std::mutex mtx;
-
- // Disable copy construction and assignment.
- condition_variable_t(const condition_variable_t&);
- void operator = (const condition_variable_t&);
- };
+ class condition_variable_t
+ {
+ public:
+ inline condition_variable_t()
+ {
+
+ }
+
+ inline ~condition_variable_t()
+ {
+
+ }
+
+ inline int wait(mutex_t* mutex_, int timeout_)
+ {
+ std::unique_lock<std::mutex> lck(mtx); // lock mtx
+ mutex_->unlock(); // unlock mutex_
+ int res = 0;
+ if(timeout_ == -1) {
+ cv.wait(lck); // unlock mtx and wait cv.notify_all(), lock mtx after cv.notify_all()
+ } else if (cv.wait_for(lck, std::chrono::milliseconds(timeout_)) == std::cv_status::timeout) {
+ // time expired
+ errno = EAGAIN;
+ res = -1;
+ }
+ lck.unlock(); // unlock mtx
+ mutex_->lock(); // lock mutex_
+ return res;
+ }
+
+ inline void broadcast()
+ {
+ std::unique_lock<std::mutex> lck(mtx); // lock mtx
+ cv.notify_all();
+ }
+
+ private:
+
+ std::condition_variable cv;
+ std::mutex mtx;
+
+ // Disable copy construction and assignment.
+ condition_variable_t(const condition_variable_t&);
+ void operator = (const condition_variable_t&);
+ };
 
 #endif
 }
@@ -214,9 +214,9 @@ namespace zmq
  struct timespec timeout;
 
 #if defined ZMQ_HAVE_OSX && __MAC_OS_X_VERSION_MIN_REQUIRED < 101200 // less than macOS 10.12
- alt_clock_gettime(CLOCK_REALTIME, &timeout);
+ alt_clock_gettime(SYSTEM_CLOCK, &timeout);
 #else
- clock_gettime(CLOCK_REALTIME, &timeout);
+ clock_gettime(CLOCK_MONOTONIC, &timeout);
 #endif
 
  timeout.tv_sec += timeout_ / 1000;