Use system wide file locks to synchronize log files.

Sources/Plasma/CoreLib/CMakeLists.txt

@@ -6,6 +6,7 @@ set(CoreLib_SOURCES
     hsExceptions.cpp
     hsExceptionStack.cpp
     hsFastMath.cpp
+    hsFILELock.cpp
     hsGeometry3.cpp
     hsMatrix33.cpp
     hsMatrix44.cpp
@@ -43,6 +44,7 @@ set(CoreLib_HEADERS
     hsExceptions.h
     hsExceptionStack.h
     hsFastMath.h
+    hsFILELock.h
     hsGeometry3.h
     hsLockGuard.h
     hsMatrix44.h

Sources/Plasma/CoreLib/hsFILELock.cpp

@@ -0,0 +1,162 @@
+/*==LICENSE==*
+
+CyanWorlds.com Engine - MMOG client, server and tools
+Copyright (C) 2011  Cyan Worlds, 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 3 of the License, 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 <http://www.gnu.org/licenses/>.
+
+Additional permissions under GNU GPL version 3 section 7
+
+If you modify this Program, or any covered work, by linking or
+combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
+NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
+JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
+(or a modified version of those libraries),
+containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
+PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
+JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
+licensors of this Program grant you additional
+permission to convey the resulting work. Corresponding Source for a
+non-source form of such a combination shall include the source code for
+the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
+work.
+
+You can contact Cyan Worlds, Inc. by email legal@cyan.com
+ or by snail mail at:
+      Cyan Worlds, Inc.
+      14617 N Newport Hwy
+      Mead, WA   99021
+
+*==LICENSE==*/
+
+#include "hsFILELock.h"
+
+#include <string_theory/format>
+#include <system_error>
+
+#include "hsWindows.h"
+#ifdef _MSC_VER
+#   include <io.h>
+#endif
+#ifndef HS_BUILD_FOR_WIN32
+#   include <sys/file.h>
+#endif
+
+bool hsFILELock::ILock(bool block) const
+{
+    if (fRef == nullptr)
+        return true;
+
+#ifdef HS_BUILD_FOR_WIN32
+    OVERLAPPED o{};
+    DWORD flags = LOCKFILE_EXCLUSIVE_LOCK;
+    if (block)
+        flags |= LOCKFILE_FAIL_IMMEDIATELY;
+
+    // Lock only the first byte of the file - we have
+    // to provide the exact same region to UnlockFileEx(),
+    // and this is a mandatory lock. Totally different than
+    // POSIX file locks, which are advisory and operate on
+    // the whole file.
+    BOOL result = LockFileEx(
+#ifdef _MSC_VER
+        (HANDLE)_get_osfhandle(_fileno(fRef)),
+#else
+        (HANDLE)fileno(fRef),
+#endif // _MSC_VER
+        flags,
+        0,
+        1,
+        0,
+        &o
+    );
+    if (result == 0) {
+        DWORD error = GetLastError();
+        if (!block && error == ERROR_IO_PENDING)
+            return false;
+        // BasicLockable requires an exception to indicate that the
+        // lock was not acquired.
+        throw std::system_error(
+            std::error_code(error, std::system_category()),
+            ST::format(
+                "LockFileEx() failed: {}",
+                hsCOMError(hsLastWin32Error, error)
+            ).to_std_string()
+        );
+    }
+
+#else
+    int op = LOCK_EX;
+    if (!block)
+        op |= LOCK_NB;
+    int result = flock(fileno(fRef), op);
+    if (result == -1) {
+        if (!block && errno == EWOULDBLOCK)
+            return false;
+        // BasicLockable requires an exception to indicate that the
+        // lock was not acquired. Even though EINTR is probably not
+        // an error condition, we should still throw to indicate no
+        // lock was acquired.
+        throw std::system_error(
+            std::error_code(errno, std::system_category()),
+            ST::format(
+                "flock() LOCK_EX failed: {}",
+                strerror(errno)
+            ).to_std_string()
+        );
+    }
+#endif // HS_BUILD_FOR_WIN32
+
+    return true;
+}
+
+void hsFILELock::unlock() const
+{
+    if (fRef == nullptr)
+        return;
+
+#ifdef HS_BUILD_FOR_WIN32
+    OVERLAPPED o{};
+    BOOL result = UnlockFileEx(
+#ifdef _MSC_VER
+        (HANDLE)_get_osfhandle(_fileno(fRef)),
+#else
+        (HANDLE)fileno(fRef),
+#endif // _MSC_VER
+        0,
+        1,
+        0,
+        &o
+    );
+    // BasicLockable doesn't allow exceptions to be
+    // thrown in the unlock method.
+    hsAssert(
+        result,
+        ST::format(
+            "UnlockFileEx() failed: {}",
+            hsCOMError(hsLastWin32Error, GetLastError())
+        ).c_str()
+    );
+
+#else
+    int result = flock(fileno(fRef), LOCK_UN);
+    hsAssert(
+        result == 0,
+        ST::format(
+            "flock() LOCK_UN failed: {}",
+            strerror(errno)
+        ).c_str()
+    );
+#endif // HS_BUILD_FOR_WIN32
+}

Sources/Plasma/CoreLib/hsFILELock.h

@@ -0,0 +1,83 @@
+/*==LICENSE==*
+
+CyanWorlds.com Engine - MMOG client, server and tools
+Copyright (C) 2011  Cyan Worlds, 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 3 of the License, 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 <http://www.gnu.org/licenses/>.
+
+Additional permissions under GNU GPL version 3 section 7
+
+If you modify this Program, or any covered work, by linking or
+combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
+NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
+JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
+(or a modified version of those libraries),
+containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
+PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
+JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
+licensors of this Program grant you additional
+permission to convey the resulting work. Corresponding Source for a
+non-source form of such a combination shall include the source code for
+the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
+work.
+
+You can contact Cyan Worlds, Inc. by email legal@cyan.com
+ or by snail mail at:
+      Cyan Worlds, Inc.
+      14617 N Newport Hwy
+      Mead, WA   99021
+
+*==LICENSE==*/
+
+#ifndef hsFILELock_inc
+#define hsFILELock_inc
+
+#include "HeadSpin.h"
+
+/**
+ * Acquire a platform dependent lock on the underlying file handle.
+ * \remarks On Windows, file locks are obligatory. Any attempts to
+ * read/write from/to the locked region will be denied. The region
+ * that this method locks is an implementation detail. On unix-like
+ * platforms, locks are advisory, and reads/writes from/to the locked
+ * region will succeed. Therefore, file locks should be treated as
+ * advisory at best (they won't stop someone from making a mess), and
+ * mandatory at worst (they can cause reads/writes to fail).
+ * \note This class meets the requirements of `Lockable`.
+ */
+class hsFILELock
+{
+    FILE* fRef;
+
+    bool ILock(bool block) const;
+
+public:
+    hsFILELock() = delete;
+    hsFILELock(const hsFILELock&) = delete;
+    hsFILELock(hsFILELock&& mv)
+        : fRef(mv.fRef)
+    {
+        mv.fRef = nullptr;
+    }
+    hsFILELock(FILE* f) : fRef(f) { }
+
+    void lock() const { ILock(true); }
+
+    [[nodiscard]]
+    bool try_lock() const { return ILock(false); }
+
+    void unlock() const;
+};
+
+#endif

Sources/Plasma/PubUtilLib/plStatusLog/plStatusLog.cpp

@@ -58,6 +58,7 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
 #include "plStatusLog.h"
 #include "plEncryptLogLine.h"
 
+#include "hsFILELock.h"
 #include "plProduct.h"
 #include "hsThread.h"
 #include "hsTimer.h"
@@ -259,20 +260,17 @@ bool plStatusLogMgr::DumpLogs( const plFileName &newFolderName )
 uint32_t plStatusLog::fLoggingOff = false;
 
 plStatusLog::plStatusLog( uint8_t numDisplayLines, const plFileName &filename, uint32_t flags )
-    : fFileHandle(), fSema(), fSize(), fForceLog(), fMaxNumLines(numDisplayLines),
+    : fFileHandle(), fSize(), fForceLog(), fMaxNumLines(numDisplayLines),
       fDisplayPointer()
 {
     if (filename.IsValid())
     {
         fFilename = filename;
-        fSema = new hsGlobalSemaphore(1, fFilename.AsString().c_str());
     }
     else
     {
         fFilename = "";
         flags |= kDontWriteFile;
-
-        fSema = new hsGlobalSemaphore(1);
     }
 
     fOrigFlags = fFlags = flags;
@@ -366,9 +364,6 @@ void    plStatusLog::IFini()
     if (fBack != nullptr || fNext != nullptr)
         IUnlink();
 
-    if (fSema)
-        delete fSema;
-
     delete [] fLines;
     delete [] fColors;
 }
@@ -431,7 +426,8 @@ bool plStatusLog::IAddLine(const ST::string& line, uint32_t color)
         return true;
 
     /// Scroll pointers up
-    fSema->Wait();
+    hsFILELock fileLock(fFileHandle);
+    hsLockGuard(fileLock);
 
     if (fMaxNumLines > 0)
     {
@@ -448,8 +444,6 @@ bool plStatusLog::IAddLine(const ST::string& line, uint32_t color)
 
     bool ret = IPrintLineToFile(line);
 
-    fSema->Signal();
-
     return ret;
 }
 

Sources/Plasma/PubUtilLib/plStatusLog/plStatusLog.h

@@ -57,7 +57,6 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
 #define _plStatusLog_h
 
 #include "HeadSpin.h"
-#include "hsThread.h"
 #include "plFileSystem.h"
 #include "plLoggable.h"
 
@@ -88,7 +87,6 @@ class plStatusLog : public plLog
         plFileName   fFilename;
         ST::string*  fLines;
         uint32_t*    fColors;
-        hsGlobalSemaphore* fSema;
         FILE*        fFileHandle;
         uint32_t     fSize;
         bool         fForceLog;