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40
41#include "qplatformdefs.h"
42#include "qwaitcondition.h"
43#include "qmutex.h"
44#include "qreadwritelock.h"
45#include "qatomic.h"
46#include "qstring.h"
47#include "qdeadlinetimer.h"
48#include "private/qdeadlinetimer_p.h"
49#include "qelapsedtimer.h"
50#include "private/qcore_unix_p.h"
51
52#include "qmutex_p.h"
53#include "qreadwritelock_p.h"
54
55#include <errno.h>
56#include <sys/time.h>
57#include <time.h>
58
59QT_BEGIN_NAMESPACE
60
61#ifdef Q_OS_ANDROID
62// pthread_condattr_setclock is available only since Android 5.0. On older versions, there's
63// a private function for relative waits (hidden in 5.0).
64// Use weakref so we can determine at runtime whether each of them is present.
65static int local_condattr_setclock(pthread_condattr_t*, clockid_t)
66__attribute__((weakref("pthread_condattr_setclock")));
67
68static int local_cond_timedwait_relative(pthread_cond_t*, pthread_mutex_t *, const timespec *)
69__attribute__((weakref("__pthread_cond_timedwait_relative")));
70#endif
71
72static void report_error(int code, const char *where, const char *what)
73{
74 if (code != 0)
75 qErrnoWarning(code, "%s: %s failure", where, what);
76}
77
78void qt_initialize_pthread_cond(pthread_cond_t *cond, const char *where)
79{
80 pthread_condattr_t condattr;
81
82 pthread_condattr_init(&condattr);
83#if (_POSIX_MONOTONIC_CLOCK-0 >= 0)
84#if defined(Q_OS_ANDROID)
85 if (local_condattr_setclock && QElapsedTimer::clockType() == QElapsedTimer::MonotonicClock)
86 local_condattr_setclock(&condattr, CLOCK_MONOTONIC);
87#elif !defined(Q_OS_MAC)
88 if (QElapsedTimer::clockType() == QElapsedTimer::MonotonicClock)
89 pthread_condattr_setclock(&condattr, CLOCK_MONOTONIC);
90#endif
91#endif
92 report_error(pthread_cond_init(cond, &condattr), where, "cv init");
93 pthread_condattr_destroy(&condattr);
94}
95
96void qt_abstime_for_timeout(timespec *ts, QDeadlineTimer deadline)
97{
98#ifdef Q_OS_MAC
99 // on Mac, qt_gettime() (on qelapsedtimer_mac.cpp) returns ticks related to the Mach absolute time
100 // that doesn't work with pthread
101 // Mac also doesn't have clock_gettime
102 struct timeval tv;
103 qint64 nsec = deadline.remainingTimeNSecs();
104 gettimeofday(&tv, 0);
105 ts->tv_sec = tv.tv_sec + nsec / (1000 * 1000 * 1000);
106 ts->tv_nsec = tv.tv_usec * 1000 + nsec % (1000 * 1000 * 1000);
107
108 normalizedTimespec(*ts);
109#else
110 // depends on QDeadlineTimer's internals!!
111 static_assert(QDeadlineTimerNanosecondsInT2);
112 ts->tv_sec = deadline._q_data().first;
113 ts->tv_nsec = deadline._q_data().second;
114#endif
115}
116
117class QWaitConditionPrivate
118{
119public:
120 pthread_mutex_t mutex;
121 pthread_cond_t cond;
122 int waiters;
123 int wakeups;
124
125 int wait_relative(QDeadlineTimer deadline)
126 {
127 timespec ti;
128#ifdef Q_OS_ANDROID
129 if (!local_condattr_setclock && local_cond_timedwait_relative) {
130 qint64 nsec = deadline.remainingTimeNSecs();
131 ti.tv_sec = nsec / (1000 * 1000 * 1000);
132 ti.tv_nsec = nsec - ti.tv_sec * 1000 * 1000 * 1000;
133 return local_cond_timedwait_relative(&cond, &mutex, &ti);
134 }
135#endif
136 qt_abstime_for_timeout(&ti, deadline);
137 return pthread_cond_timedwait(&cond, &mutex, &ti);
138 }
139
140 bool wait(QDeadlineTimer deadline)
141 {
142 int code;
143 forever {
144 if (!deadline.isForever()) {
145 code = wait_relative(deadline);
146 } else {
147 code = pthread_cond_wait(&cond, &mutex);
148 }
149 if (code == 0 && wakeups == 0) {
150 // many vendors warn of spurious wakeups from
151 // pthread_cond_wait(), especially after signal delivery,
152 // even though POSIX doesn't allow for it... sigh
153 continue;
154 }
155 break;
156 }
157
158 Q_ASSERT_X(waiters > 0, "QWaitCondition::wait", "internal error (waiters)");
159 --waiters;
160 if (code == 0) {
161 Q_ASSERT_X(wakeups > 0, "QWaitCondition::wait", "internal error (wakeups)");
162 --wakeups;
163 }
164 report_error(pthread_mutex_unlock(&mutex), "QWaitCondition::wait()", "mutex unlock");
165
166 if (code && code != ETIMEDOUT)
167 report_error(code, "QWaitCondition::wait()", "cv wait");
168
169 return (code == 0);
170 }
171};
172
173QWaitCondition::QWaitCondition()
174{
175 d = new QWaitConditionPrivate;
176 report_error(pthread_mutex_init(&d->mutex, nullptr), "QWaitCondition", "mutex init");
177 qt_initialize_pthread_cond(&d->cond, "QWaitCondition");
178 d->waiters = d->wakeups = 0;
179}
180
181QWaitCondition::~QWaitCondition()
182{
183 report_error(pthread_cond_destroy(&d->cond), "QWaitCondition", "cv destroy");
184 report_error(pthread_mutex_destroy(&d->mutex), "QWaitCondition", "mutex destroy");
185 delete d;
186}
187
188void QWaitCondition::wakeOne()
189{
190 report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wakeOne()", "mutex lock");
191 d->wakeups = qMin(d->wakeups + 1, d->waiters);
192 report_error(pthread_cond_signal(&d->cond), "QWaitCondition::wakeOne()", "cv signal");
193 report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeOne()", "mutex unlock");
194}
195
196void QWaitCondition::wakeAll()
197{
198 report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wakeAll()", "mutex lock");
199 d->wakeups = d->waiters;
200 report_error(pthread_cond_broadcast(&d->cond), "QWaitCondition::wakeAll()", "cv broadcast");
201 report_error(pthread_mutex_unlock(&d->mutex), "QWaitCondition::wakeAll()", "mutex unlock");
202}
203
204bool QWaitCondition::wait(QMutex *mutex, unsigned long time)
205{
206 if (time == std::numeric_limits<unsigned long>::max())
207 return wait(mutex, QDeadlineTimer(QDeadlineTimer::Forever));
208 return wait(mutex, QDeadlineTimer(time));
209}
210
211bool QWaitCondition::wait(QMutex *mutex, QDeadlineTimer deadline)
212{
213 if (!mutex)
214 return false;
215
216 report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wait()", "mutex lock");
217 ++d->waiters;
218 mutex->unlock();
219
220 bool returnValue = d->wait(deadline);
221
222 mutex->lock();
223
224 return returnValue;
225}
226
227bool QWaitCondition::wait(QReadWriteLock *readWriteLock, unsigned long time)
228{
229 if (time == std::numeric_limits<unsigned long>::max())
230 return wait(readWriteLock, QDeadlineTimer(QDeadlineTimer::Forever));
231 return wait(readWriteLock, QDeadlineTimer(time));
232}
233
234bool QWaitCondition::wait(QReadWriteLock *readWriteLock, QDeadlineTimer deadline)
235{
236 if (!readWriteLock)
237 return false;
238 auto previousState = readWriteLock->stateForWaitCondition();
239 if (previousState == QReadWriteLock::Unlocked)
240 return false;
241 if (previousState == QReadWriteLock::RecursivelyLocked) {
242 qWarning("QWaitCondition: cannot wait on QReadWriteLocks with recursive lockForWrite()");
243 return false;
244 }
245
246 report_error(pthread_mutex_lock(&d->mutex), "QWaitCondition::wait()", "mutex lock");
247 ++d->waiters;
248
249 readWriteLock->unlock();
250
251 bool returnValue = d->wait(deadline);
252
253 if (previousState == QReadWriteLock::LockedForWrite)
254 readWriteLock->lockForWrite();
255 else
256 readWriteLock->lockForRead();
257
258 return returnValue;
259}
260
261QT_END_NAMESPACE
262