windows-timedmutex: New module.

* lib/windows-timedmutex.h: New file, based on windows-mutex.h.
* lib/windows-timedmutex.c: New file, based on windows-mutex.c.
* modules/windows-timedmutex: New file.

2 files changed, 275 insertions, 0 deletions

diff --git a/lib/windows-timedmutex.c b/lib/windows-timedmutex.c
new file mode 100644
index 0000000000..20adbfb5b5
--- /dev/null
+++ b/lib/windows-timedmutex.c
@@ -0,0 +1,223 @@
+/* Timed mutexes (native Windows implementation).
+   Copyright (C) 2005-2019 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005, 2019.
+   Based on GCC's gthr-win32.h.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "windows-timedmutex.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+int
+glwthread_timedmutex_init (glwthread_timedmutex_t *mutex)
+{
+  /* Attempt to allocate an auto-reset event object.  */
+  /* CreateEvent
+     <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-createeventa> */
+  HANDLE event = CreateEvent (NULL, FALSE, FALSE, NULL);
+  if (event == INVALID_HANDLE_VALUE)
+    return EAGAIN;
+  mutex->event = event;
+  InitializeCriticalSection (&mutex->lock);
+  mutex->guard.done = 1;
+  return 0;
+}
+
+int
+glwthread_timedmutex_lock (glwthread_timedmutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    {
+      if (InterlockedIncrement (&mutex->guard.started) == 0)
+        {
+          /* This thread is the first one to need this mutex.
+             Initialize it.  */
+          int err = glwthread_timedmutex_init (mutex);
+          if (err != 0)
+            {
+              /* Undo increment.  */
+              InterlockedDecrement (&mutex->guard.started);
+              return err;
+            }
+        }
+      else
+        {
+          /* Don't let mutex->guard.started grow and wrap around.  */
+          InterlockedDecrement (&mutex->guard.started);
+          /* Yield the CPU while waiting for another thread to finish
+             initializing this mutex.  */
+          while (!mutex->guard.done)
+            Sleep (0);
+        }
+    }
+  EnterCriticalSection (&mutex->lock);
+  return 0;
+}
+
+int
+glwthread_timedmutex_trylock (glwthread_timedmutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    {
+      if (InterlockedIncrement (&mutex->guard.started) == 0)
+        {
+          /* This thread is the first one to need this mutex.
+             Initialize it.  */
+          int err = glwthread_timedmutex_init (mutex);
+          if (err != 0)
+            {
+              /* Undo increment.  */
+              InterlockedDecrement (&mutex->guard.started);
+              return err;
+            }
+        }
+      else
+        {
+          /* Don't let mutex->guard.started grow and wrap around.  */
+          InterlockedDecrement (&mutex->guard.started);
+          /* Let another thread finish initializing this mutex, and let it also
+             lock this mutex.  */
+          return EBUSY;
+        }
+    }
+  if (!TryEnterCriticalSection (&mutex->lock))
+    return EBUSY;
+  return 0;
+}
+
+int
+glwthread_timedmutex_timedlock (glwthread_timedmutex_t *mutex,
+                                const struct timespec *abstime)
+{
+  if (!mutex->guard.done)
+    {
+      if (InterlockedIncrement (&mutex->guard.started) == 0)
+        {
+          /* This thread is the first one to need this mutex.
+             Initialize it.  */
+          int err = glwthread_timedmutex_init (mutex);
+          if (err != 0)
+            {
+              /* Undo increment.  */
+              InterlockedDecrement (&mutex->guard.started);
+              return err;
+            }
+        }
+      else
+        {
+          /* Don't let mutex->guard.started grow and wrap around.  */
+          InterlockedDecrement (&mutex->guard.started);
+          /* Yield the CPU while waiting for another thread to finish
+             initializing this mutex.  */
+          while (!mutex->guard.done)
+            Sleep (0);
+        }
+    }
+
+  /* POSIX says:
+      "Under no circumstance shall the function fail with a timeout if
+       the mutex can be locked immediately. The validity of the abstime
+       parameter need not be checked if the mutex can be locked
+       immediately."
+     Therefore start the loop with a TryEnterCriticalSection call.  */
+  for (;;)
+    {
+      if (TryEnterCriticalSection (&mutex->lock))
+        break;
+
+      {
+        struct timeval currtime;
+        DWORD timeout;
+        DWORD result;
+
+        gettimeofday (&currtime, NULL);
+
+        /* Wait until another thread signals the event or until the
+           abstime passes.  */
+        if (currtime.tv_sec > abstime->tv_sec)
+          timeout = 0;
+        else
+          {
+            unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
+            timeout = seconds * 1000;
+            if (timeout / 1000 != seconds) /* overflow? */
+              timeout = INFINITE;
+            else
+              {
+                long milliseconds =
+                  abstime->tv_nsec / 1000000 - currtime.tv_usec / 1000;
+                if (milliseconds >= 0)
+                  {
+                    timeout += milliseconds;
+                    if (timeout < milliseconds) /* overflow? */
+                      timeout = INFINITE;
+                  }
+                else
+                  {
+                    if (timeout >= - milliseconds)
+                      timeout -= (- milliseconds);
+                    else
+                      timeout = 0;
+                  }
+              }
+          }
+        if (timeout == 0)
+          return ETIMEDOUT;
+
+        /* WaitForSingleObject
+           <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-waitforsingleobject> */
+        result = WaitForSingleObject (mutex->event, timeout);
+        if (result == WAIT_FAILED)
+          abort ();
+        if (result == WAIT_TIMEOUT)
+          return ETIMEDOUT;
+        /* Another thread has just unlocked the mutex.  We have good chances at
+           locking it now.  */
+      }
+    }
+  return 0;
+}
+
+int
+glwthread_timedmutex_unlock (glwthread_timedmutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    return EINVAL;
+  LeaveCriticalSection (&mutex->lock);
+  /* Notify one of the threads that were waiting with a timeout.  */
+  /* SetEvent
+     <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-setevent> */
+  SetEvent (mutex->event);
+  return 0;
+}
+
+int
+glwthread_timedmutex_destroy (glwthread_timedmutex_t *mutex)
+{
+  if (!mutex->guard.done)
+    return EINVAL;
+  DeleteCriticalSection (&mutex->lock);
+  /* CloseHandle
+     <https://docs.microsoft.com/en-us/windows/desktop/api/handleapi/nf-handleapi-closehandle> */
+  CloseHandle (mutex->event);
+  mutex->guard.done = 0;
+  return 0;
+}
diff --git a/lib/windows-timedmutex.h b/lib/windows-timedmutex.h
new file mode 100644
index 0000000000..268c391f5d
--- /dev/null
+++ b/lib/windows-timedmutex.h
@@ -0,0 +1,52 @@
+/* Timed mutexes (native Windows implementation).
+   Copyright (C) 2005-2019 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2005, 2019.
+   Based on GCC's gthr-win32.h.  */
+
+#ifndef _WINDOWS_TIMEDMUTEX_H
+#define _WINDOWS_TIMEDMUTEX_H
+
+#define WIN32_LEAN_AND_MEAN  /* avoid including junk */
+#include <windows.h>
+
+#include <time.h>
+
+#include "windows-spinlock.h"
+
+typedef struct
+        {
+          glwthread_spinlock_t guard; /* protects the initialization */
+          HANDLE event;
+          CRITICAL_SECTION lock;
+        }
+        glwthread_timedmutex_t;
+
+#define GLWTHREAD_TIMEDMUTEX_INIT { GLWTHREAD_SPINLOCK_INIT }
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int glwthread_timedmutex_init (glwthread_timedmutex_t *mutex);
+extern int glwthread_timedmutex_lock (glwthread_timedmutex_t *mutex);
+extern int glwthread_timedmutex_trylock (glwthread_timedmutex_t *mutex);
+extern int glwthread_timedmutex_timedlock (glwthread_timedmutex_t *mutex,
+                                           const struct timespec *abstime);
+extern int glwthread_timedmutex_unlock (glwthread_timedmutex_t *mutex);
+extern int glwthread_timedmutex_destroy (glwthread_timedmutex_t *mutex);
+
+#endif /* _WINDOWS_TIMEDMUTEX_H */