Implement Firebird::Semaphore class for Windows and POSIX.

Those platforms which do not have POSIX semaphores (Solaris ?) may need to
implement this class using BSD or SYSV stuff.

src/common/classes/semaphore.h

@@ -0,0 +1,132 @@
+/*
+ *	PROGRAM:		Client/Server Common Code
+ *	MODULE:			semaphore.h
+ *	DESCRIPTION:	Semaphore lock
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ * You may obtain a copy of the Licence at
+ * http://www.gnu.org/licences/lgpl.html
+ * 
+ * As a special exception this file can also be included in modules
+ * with other source code as long as that source code has been 
+ * released under an Open Source Initiative certificed licence.  
+ * More information about OSI certification can be found at: 
+ * http://www.opensource.org 
+ * 
+ * This module 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 Lesser General Public Licence for more details.
+ * 
+ * This module was created by members of the firebird development 
+ * team.  All individual contributions remain the Copyright (C) of 
+ * those individuals and all rights are reserved.  Contributors to 
+ * this file are either listed below or can be obtained from a CVS 
+ * history command.
+ *
+ *  Created by: Nickolay Samofatov <skidder@bssys.com>
+ *
+ *  Contributor(s):
+ * 
+ *
+ *  $Id: semaphore.h,v 1.1 2003-09-16 20:45:31 skidder Exp $
+ *
+ */
+
+#ifndef SEMAPHORE_H
+#define SEMAPHORE_H
+
+#ifdef WIN_NT
+
+#include <windows.h>
+#include <limits.h>
+
+namespace Firebird {
+
+class Semaphore {
+private:
+	HANDLE hSemaphore;
+public:
+	Semaphore() { 
+		hSemaphore = CreateSemaphore(NULL, 0 /*initial count*/, 
+			INT_MAX, NULL); 
+	}
+	~Semaphore() { CloseHandle(hSemaphore); }	
+
+	bool tryEnter(int seconds = 0) {
+		DWORD result = WaitForSingleObject(
+			hSemaphore, seconds >= 0 ? seconds*1000 : INFINITE);
+		if (result == WAIT_FAILED)
+			system_call_failed::raise();
+		return result != WAIT_TIMEOUT;
+	}
+
+	void release(SLONG count = 1) {
+		if (!ReleaseSemaphore(hSemaphore, count, NULL))
+			system_call_failed::raise();
+	}
+};
+
+
+}
+
+#else
+
+#ifdef MULTI_THREAD
+
+#include <semaphore.h>
+#include <errno.h>
+
+namespace Firebird {
+
+class Semaphore {
+private:
+	sem_t sem;
+public:
+	Semaphore() {
+		if (sem_init(&sem, 0, 0) == -1)
+			system_call_failed::raise();
+	}
+	~Semaphore() {
+		if (sem_destroy(&sem) == -1)
+			system_call_failed::raise();
+	}
+	bool tryEnter(int seconds = 0) {
+		if (seconds == 0) {
+			if (sem_trywait(&sem) != -1) return true;
+			if (errno == EAGAIN) return false;
+			system_call_failed::raise();
+		} else if (seconds < 0) {
+			if (sem_wait(&sem) == -1)
+				system_call_failed::raise();
+		} else {
+			struct timespec timeout;
+			timeout.tv_sec = time() + seconds;
+			timeout.tv_nsec = 0;
+			if (sem_timedwait(&sem, &timeout) == 0) return true;
+			if (errno == ETIMEOUT) return false;
+			system_call_failed::raise();
+		}
+		return false;
+	}
+	void enter() {
+		if (sem_wait(&sem) == -1)
+			system_call_failed::raise();
+	}
+	void release(SLONG count = 1) {
+		for (int i = 0; i < count; i++)
+			if (sem_post(&sem) == -1)
+				system_call_failed::raise();
+	}
+};
+
+}
+
+#endif /*MULTI_THREAD*/
+
+#endif /*!WIN_NT*/
+
+#endif