Merge branch 'rickard/win-cs-mutex/OTP-9671'

* rickard/win-cs-mutex/OTP-9671:
  Use critical sections as mutex implementation on Windows

2 files changed, 111 insertions, 5 deletions

diff --git a/erts/include/internal/ethr_mutex.h b/erts/include/internal/ethr_mutex.h
index a0685ea3c0..86a1e9fbdf 100644
--- a/erts/include/internal/ethr_mutex.h
+++ b/erts/include/internal/ethr_mutex.h
@@ -22,6 +22,23 @@
  * Author: Rickard Green
  */
 
+/*
+ * IMPORTANT note about ethr_cond_signal() and ethr_cond_broadcast()
+ *
+ * POSIX allow a call to `pthread_cond_signal' or `pthread_cond_broadcast'
+ * even though the associated mutex/mutexes isn't/aren't locked by the
+ * caller. We do not allow that by default in order to avoid a performance
+ * penalty on some platforms.
+ *
+ * Mutexes and condition variables can, however, be initialized as POSIX
+ * compliant. When initialized as such ethr_cond_signal(), and
+ * ethr_cond_broadcast() are allowed to be called even though the associated
+ * mutexes aren't locked. This will, however, incur a performance penalty on
+ * some platforms.
+ *
+ * POSIX compliant mutexes and condition variables *need* to be used together.
+ */
+
 #ifndef ETHR_MUTEX_H__
 #define ETHR_MUTEX_H__
 
@@ -40,6 +57,14 @@
 #endif
 #endif
 
+/* #define ETHR_DBG_WIN_MTX_WITH_PTHREADS */
+#ifdef ETHR_DBG_WIN_MTX_WITH_PTHREADS
+typedef pthread_mutex_t CRITICAL_SECTION;
+int TryEnterCriticalSection(CRITICAL_SECTION *);
+void EnterCriticalSection(CRITICAL_SECTION *);
+void LeaveCriticalSection(CRITICAL_SECTION *);
+#endif
+
 #ifdef ETHR_MTX_HARD_DEBUG
 #  ifdef __GNUC__
 #    warning ETHR_MTX_HARD_DEBUG
@@ -140,13 +165,19 @@ struct ethr_mutex_base_ {
 typedef struct {
     int main_spincount;
     int aux_spincount;
+    int posix_compliant;
 } ethr_mutex_opt;
 
+#define ETHR_MUTEX_OPT_DEFAULT_INITER {-1, -1, 0}
+
 typedef struct {
     int main_spincount;
     int aux_spincount;
+    int posix_compliant;
 } ethr_cond_opt;
 
+#define ETHR_COND_OPT_DEFAULT_INITER {-1, -1, 0}
+
 #ifdef ETHR_USE_OWN_MTX_IMPL__
 
 typedef struct ethr_mutex_ ethr_mutex;
@@ -179,7 +210,7 @@ struct ethr_cond_ {
 #endif
 };
 
-#else /* pthread */
+#elif defined(ETHR_PTHREADS) && !defined(ETHR_DBG_WIN_MTX_WITH_PTHREADS)
 
 typedef struct ethr_mutex_ ethr_mutex;
 struct ethr_mutex_ {
@@ -197,7 +228,36 @@ struct ethr_cond_ {
 #endif
 };
 
-#endif /* pthread */
+#elif defined(ETHR_WIN32_THREADS) || defined(ETHR_DBG_WIN_MTX_WITH_PTHREADS)
+#  define ETHR_WIN_MUTEX__
+
+typedef struct ethr_mutex_ ethr_mutex;
+struct ethr_mutex_ {
+    int posix_compliant;
+    CRITICAL_SECTION cs;
+    ethr_ts_event *wakeups;
+    ethr_atomic32_t have_wakeups; /* only when posix compliant */
+    ethr_atomic32_t locked;       /* only when posix compliant */
+    ethr_spinlock_t lock;         /* only when posix compliant */
+#if ETHR_XCHK
+    int initialized;
+#endif
+};
+
+typedef struct ethr_cond_ ethr_cond;
+struct ethr_cond_ {
+    int posix_compliant;
+    CRITICAL_SECTION cs;
+    ethr_ts_event *waiters;
+    int spincount;
+#if ETHR_XCHK
+    int initialized;
+#endif
+};
+
+#else
+#  error "no mutex implementation"
+#endif
 
 int ethr_mutex_init_opt(ethr_mutex *, ethr_mutex_opt *);
 int ethr_mutex_init(ethr_mutex *);
@@ -573,7 +633,7 @@ ETHR_INLINE_MTX_FUNC_NAME_(ethr_mutex_unlock)(ethr_mutex *mtx)
 
 #endif /* ETHR_TRY_INLINE_FUNCS */
 
-#else /* pthread_mutex */
+#elif defined(ETHR_PTHREADS) && !defined(ETHR_DBG_WIN_MTX_WITH_PTHREADS)
 
 #if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_MUTEX_IMPL__)
 
@@ -605,7 +665,54 @@ ETHR_INLINE_MTX_FUNC_NAME_(ethr_mutex_unlock)(ethr_mutex *mtx)
 
 #endif /* ETHR_TRY_INLINE_FUNCS */
 
-#endif /* pthread_mutex */
+#elif defined(ETHR_WIN32_THREADS) || defined(ETHR_DBG_WIN_MTX_WITH_PTHREADS)
+
+#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_MUTEX_IMPL__)
+
+static ETHR_INLINE int
+ETHR_INLINE_MTX_FUNC_NAME_(ethr_mutex_trylock)(ethr_mutex *mtx)
+{
+    if (!TryEnterCriticalSection(&mtx->cs))
+	return EBUSY;
+    if (mtx->posix_compliant)
+	ethr_atomic32_set(&mtx->locked, 1);
+    return 0;
+}
+
+static ETHR_INLINE void
+ETHR_INLINE_MTX_FUNC_NAME_(ethr_mutex_lock)(ethr_mutex *mtx)
+{
+    EnterCriticalSection(&mtx->cs);
+    if (mtx->posix_compliant)
+	ethr_atomic32_set(&mtx->locked, 1);
+}
+
+void ethr_mutex_cond_wakeup__(ethr_mutex *mtx);
+
+static ETHR_INLINE void
+ETHR_INLINE_MTX_FUNC_NAME_(ethr_mutex_unlock)(ethr_mutex *mtx)
+{
+    if (mtx->posix_compliant) {
+	ethr_atomic32_set_mb(&mtx->locked, 0);
+	if (ethr_atomic32_read_acqb(&mtx->have_wakeups))
+	    goto cond_wakeup;
+	else
+	    goto leave_cs;
+    }
+
+    if (mtx->wakeups) {
+    cond_wakeup:
+	ethr_mutex_cond_wakeup__(mtx);
+    }
+    else {
+    leave_cs:
+	LeaveCriticalSection(&mtx->cs);
+    }
+}
+
+#endif /* ETHR_TRY_INLINE_FUNCS */
+
+#endif
 
 #ifdef ETHR_USE_OWN_RWMTX_IMPL__
 
diff --git a/erts/include/internal/ethread.h b/erts/include/internal/ethread.h
index 8ad0ded144..142c26c0ca 100644
--- a/erts/include/internal/ethread.h
+++ b/erts/include/internal/ethread.h
@@ -191,7 +191,6 @@ typedef DWORD ethr_tsd_key;
 #undef ETHR_HAVE_ETHR_SIG_FUNCS
 
 #define ETHR_USE_OWN_RWMTX_IMPL__
-#define ETHR_USE_OWN_MTX_IMPL__
 
 #define ETHR_YIELD() (Sleep(0), 0)