2013-01-03 13:30 UTC+0100 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)

* harbour/src/rtl/hbcom.c
    + added translation for some OS error codes

  * harbour/src/rdd/dbdetach.c
    ! minor correction in comment

  * harbour/doc/xhb-diff.txt
    + added new section:
         THREAD LOCAL WORK AREAS AND CONCURRENT WORK AREA ACCESS

harbour/ChangeLog.txt

@@ -10,6 +10,17 @@
      * Change, ! Fix, % Optimization, + Addition, - Removal, ; Comment
  */
 
+2013-01-03 13:30 UTC+0100 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)
+  * harbour/src/rtl/hbcom.c
+    + added translation for some OS error codes
+
+  * harbour/src/rdd/dbdetach.c
+    ! minor correction in comment
+
+  * harbour/doc/xhb-diff.txt
+    + added new section:
+         THREAD LOCAL WORK AREAS AND CONCURRENT WORK AREA ACCESS
+
 2012-12-28 14:01 UTC+0100 Viktor Szakats (harbour syenar.net)
   * src/rtl/teditor.prg
     ! fix to fix to fix. I'd appreciate if someone else

harbour/doc/xhb-diff.txt

@@ -1980,7 +1980,7 @@ have to be synced by user and automatic synchronization here will
 strongly reduce scalability.
 
 Harbour also support xBase++ compatible MT API with SYNC and CLASS SYNC
-methods, SIGNAL and THREAD classes, workarea zones and thread functions.
+methods, SIGNAL and THREAD classes, work area zones and thread functions.
 It allows to easy port xbase++ code to Harbour. The main difference
 between Harbour and xbase++ is write protection to complex items.
 Harbour gives only read protection so threads can access the same
@@ -2023,11 +2023,10 @@ it in last years. This feature in xHarbour was implemented only in .c
 code generated by xHarbour compiler (-gc[0-3] output) so it was never
 working with .hrb (-gh) files or some interpreters like xBaseScript.
 xHarbour has support for SYNC methods which were designed to replicate
-xBase++ functionality but their real behavior is not xBase++ and Harbour
-compatible at all. It seems to be close to SYNC CLASS method in xBase++
+xBase++ functionality but their real behavior is neither xBase++ nor
+Harbour compatible. It seems to be close to SYNC CLASS methods in xBase++
 and Harbour though it's not exactly the same. There is no support for
-real SYNC methods like in xBase++ and xBase++ MT programming functions
-and classes.
+real xBase++ SYNC methods and xBase++ MT programming functions and classes.
 
 In summary MT mode in xHarbour looks like a work in progress, started few
 years ago and never finished. Instead some other core code modifications
@@ -2052,6 +2051,55 @@ far from current Harbour functionality and quality.
 
 
 
+###    THREAD LOCAL WORK AREAS AND CONCURRENT WORK AREA ACCESS    ###
+=====================================================================
+In Harbour and xBase++ work areas are local to the thread. It means
+that each thread has its own independent work areas and aliases.
+Anyhow it's possible to move work area from one thread to other one
+using known from xBase++ zero space. In xBase++ each thread can
+move his work area to zero space using:
+   DbRelease( [<nWorkArea>|<cAlias>], [<bAreaBlock>] ) --> lSuccess
+Then this work area can be attached by other thread using:
+   DbRequest( [<cAlias>], [<lFreeArea>], ; 
+              [<@bAreaBlock>], [<lWait>] ) --> lSuccess 
+In Harbour above functions are available in XPP emulation library.
+There are also core Harbour functions giving this functionality:
+   hb_dbDetach( [<nWorkArea>|<cAlias>], [<xCargo>] ) -> <lSuccess>
+   hb_dbRequest( [<cAlias>], [<lFreeArea>], ;
+                 [<@xCargo>], [<lWait>] ) -> <lSuccess>
+This is very powerful mechanism which allows to concurrently access
+the same tables, i.e. this PP rules illustrates it:
+   #xcommand UNLOCK WORKAREA [<cAlias>] => hb_dbDetach( <cAlias> )
+   #xcommand LOCK WORKAREA <cAlias>   => hb_dbRequest( <cAlias>, .T.,, .T. )
+after opening the table (USE) thread executes
+   UNLOCK WORKAREA
+and move work area to zero space. Then each thread which wants to make
+some operations on work area has to encapsulate it in lock/unlock code,
+i.e.:
+   LOCK WORKAREA "DOCUMENTS"
+      COUNT TO nInvoices FOR year( DOCUMENTS->DATE ) == year( date() )
+   UNLOCK WORKAREA
+
+In xHarbour by default work areas are global to the application and there
+is no protection mechanism against concurrent access so if two threads try
+to access the same work area in the same time they can corrupt internal
+RDD data. It means that for safe concurrent WA access in xHarbour user have
+to create his own protection mechanism (some different version of LOCAL
+WORKAREA / UNLOCK WORKAREA commands using some other synchronization
+methods available in xHarbour, i.e. mutexes).
+Later support for thread local work areas was added to xHarbour but
+without any mechanism which allows to move work area from one thread to
+another. This can be controlled by global SET (SETs are global in xHarbour)
+   _SET_WORKAREAS_SHARED
+Setting it to .T. disables global work areas and switches to thread local
+ones.
+There is no technical or mathematical reason to keep such strange
+implementation because it does not give any new functionality to
+programmer in comparison to xBase++ and Harbour but allows to easy
+corrupt RDD internals.
+
+
+
 ###    HARBOUR TASKS AND MT SUPPORT IN DOS    ###
 =================================================
 Harbour supports threads also in systems without native thread support.

harbour/src/rdd/dbdetach.c

@@ -95,8 +95,8 @@ HB_FUNC( HB_DBDETACH )
 }
 
 /*
- * DbRequest( [<cAlias>], [<lFreeArea>], [<@xCargo>], [<lWait>] )
- *         -> <lSuccess>
+ * hb_dbRequest( [<cAlias>], [<lFreeArea>], [<@xCargo>], [<lWait>] )
+ *          -> <lSuccess>
  */
 HB_FUNC( HB_DBREQUEST )
 {

harbour/src/rtl/hbcom.c

@@ -326,9 +326,19 @@ static void hb_comSetOsError( PHB_COM pCom, HB_BOOL fError )
          pCom->error = HB_COM_ERR_TIMEOUT;
          break;
       case EACCES:
+#if defined( ETXTBSY )
+      case ETXTBSY:
+#endif
+#if defined( EPERM )
+      case EPERM:
+#endif
          pCom->error = HB_COM_ERR_ACCESS;
          break;
       case ENOTTY:
+      case ENOENT:
+#if defined( ENOTDIR )
+      case ENOTDIR:
+#endif
          pCom->error = HB_COM_ERR_NOCOM;
          break;
       default:
@@ -1346,6 +1356,14 @@ static void hb_comSetOsError( PHB_COM pCom, BOOL fError )
       case ERROR_TIMEOUT:
          pCom->error = HB_COM_ERR_TIMEOUT;
          break;
+      case ERROR_ACCESS_DENIED:
+      case ERROR_SHARING_VIOLATION:
+         pCom->error = HB_COM_ERR_BUSY;
+         break;
+      case ERROR_FILE_NOT_FOUND:
+      case ERROR_PATH_NOT_FOUND:
+         pCom->error = HB_COM_ERR_NOCOM;
+         break;
       default:
          pCom->error = HB_COM_ERR_OTHER;
          break;
@@ -2065,6 +2083,17 @@ static void hb_comSetOsError( PHB_COM pCom, APIRET rc )
       case NO_ERROR:
          pCom->error = 0;
          break;
+      case ERROR_TIMEOUT:
+         pCom->error = HB_COM_ERR_TIMEOUT;
+         break;
+      case ERROR_ACCESS_DENIED:
+      case ERROR_SHARING_VIOLATION:
+         pCom->error = HB_COM_ERR_BUSY;
+         break;
+      case ERROR_FILE_NOT_FOUND:
+      case ERROR_PATH_NOT_FOUND:
+         pCom->error = HB_COM_ERR_NOCOM;
+         break;
       default:
          pCom->error = HB_COM_ERR_OTHER;
          break;