MPD  0.20.6
PosixCond.hxx
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29 
30 #ifndef THREAD_POSIX_COND_HXX
31 #define THREAD_POSIX_COND_HXX
32 
33 #include "PosixMutex.hxx"
34 
35 #include <chrono>
36 
37 #include <sys/time.h>
38 
42 class PosixCond {
43  pthread_cond_t cond;
44 
45 public:
46 #ifdef __GLIBC__
47  /* optimized constexpr constructor for pthread implementations
48  that support it */
49  constexpr PosixCond():cond(PTHREAD_COND_INITIALIZER) {}
50 #else
51  /* slow fallback for pthread implementations that are not
52  compatible with "constexpr" */
54  pthread_cond_init(&cond, nullptr);
55  }
56 
58  pthread_cond_destroy(&cond);
59  }
60 #endif
61 
62  PosixCond(const PosixCond &other) = delete;
63  PosixCond &operator=(const PosixCond &other) = delete;
64 
65  void signal() {
66  pthread_cond_signal(&cond);
67  }
68 
69  void broadcast() {
70  pthread_cond_broadcast(&cond);
71  }
72 
73  void wait(PosixMutex &mutex) {
74  pthread_cond_wait(&cond, &mutex.mutex);
75  }
76 
77 private:
78  bool timed_wait(PosixMutex &mutex, unsigned timeout_ms) {
79  struct timeval now;
80  gettimeofday(&now, nullptr);
81 
82  struct timespec ts;
83  ts.tv_sec = now.tv_sec + timeout_ms / 1000;
84  ts.tv_nsec = (now.tv_usec + (timeout_ms % 1000) * 1000) * 1000;
85  // Keep tv_nsec < 1E9 to prevent return of EINVAL
86  if (ts.tv_nsec >= 1000000000) {
87  ts.tv_nsec -= 1000000000;
88  ts.tv_sec++;
89  }
90 
91  return pthread_cond_timedwait(&cond, &mutex.mutex, &ts) == 0;
92  }
93 
94 public:
95  bool timed_wait(PosixMutex &mutex,
96  std::chrono::steady_clock::duration timeout) {
97  auto timeout_ms = std::chrono::duration_cast<std::chrono::milliseconds>(timeout).count();
98  if (timeout_ms < 0)
99  timeout_ms = 0;
100  else if (timeout_ms > std::numeric_limits<unsigned>::max())
101  timeout_ms = std::numeric_limits<unsigned>::max();
102 
103  return timed_wait(mutex, timeout_ms);
104  }
105 };
106 
107 #endif
bool timed_wait(PosixMutex &mutex, std::chrono::steady_clock::duration timeout)
Definition: PosixCond.hxx:95
Low-level wrapper for a pthread_cond_t.
Definition: PosixCond.hxx:42
void wait(PosixMutex &mutex)
Definition: PosixCond.hxx:73
Low-level wrapper for a pthread_mutex_t.
Definition: PosixMutex.hxx:38
PosixCond & operator=(const PosixCond &other)=delete
void signal()
Definition: PosixCond.hxx:65
void broadcast()
Definition: PosixCond.hxx:69