[PATCH v6 03/10] compat/win32: add pthread_cond_timedwait

["Paul Tarjan via GitGitGadget" <gitgitgadget@gmail.com>]

From: Paul Tarjan <github@paulisageek.com>

Add a pthread_cond_timedwait() implementation to the Windows pthread
compatibility layer using SleepConditionVariableCS() with a millisecond
timeout computed from the absolute deadline.

This enables callers to use bounded waits on condition variables
instead of blocking indefinitely with pthread_cond_wait().

Signed-off-by: Paul Tarjan <github@paulisageek.com>
---
 compat/win32/pthread.c | 26 ++++++++++++++++++++++++++
 compat/win32/pthread.h |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/compat/win32/pthread.c b/compat/win32/pthread.c
index 7e93146963..538ef92d9d 100644
--- a/compat/win32/pthread.c
+++ b/compat/win32/pthread.c
@@ -66,3 +66,29 @@ int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 		return err_win_to_posix(GetLastError());
 	return 0;
 }
+
+int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
+			   const struct timespec *abstime)
+{
+	struct timeval now;
+	long long now_ms, deadline_ms;
+	DWORD timeout_ms;
+
+	gettimeofday(&now, NULL);
+	now_ms = (long long)now.tv_sec * 1000 + now.tv_usec / 1000;
+	deadline_ms = (long long)abstime->tv_sec * 1000 +
+		      abstime->tv_nsec / 1000000;
+
+	if (deadline_ms <= now_ms)
+		timeout_ms = 0;
+	else
+		timeout_ms = (DWORD)(deadline_ms - now_ms);
+
+	if (SleepConditionVariableCS(cond, mutex, timeout_ms) == 0) {
+		DWORD err = GetLastError();
+		if (err == ERROR_TIMEOUT)
+			return ETIMEDOUT;
+		return err_win_to_posix(err);
+	}
+	return 0;
+}
diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h
index ccacc5a53b..d80df8d12a 100644
--- a/compat/win32/pthread.h
+++ b/compat/win32/pthread.h
@@ -64,6 +64,8 @@ int win32_pthread_join(pthread_t *thread, void **value_ptr);
 pthread_t pthread_self(void);
 
 int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);
+int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
+			   const struct timespec *abstime);
 
 static inline void NORETURN pthread_exit(void *ret)
 {
-- 
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