Break up the mutex implementation into separate source files, one

each for unix, w32, and os2. (CVS 4312)

FossilOrigin-Name: fc5cd71aef5ac194f51d73350d773d532020967e

1 files changed, 124 insertions, 0 deletions

diff --git a/src/mutex_os2.c b/src/mutex_os2.c
new file mode 100644
index 000000000..b598f5d90
--- /dev/null
+++ b/src/mutex_os2.c
@@ -0,0 +1,124 @@
+/*
+** 2007 August 28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains the C functions that implement mutexes for OS/2
+**
+** $Id: mutex_os2.c,v 1.1 2007/08/28 16:34:43 drh Exp $
+*/
+#include "sqliteInt.h"
+
+
+/*
+** The code in this file is only used if SQLITE_MUTEX_OS2 is defined.
+** See the mutex.h file for details.
+*/
+#ifdef SQLITE_MUTEX_OS2
+
+/**** FIX ME:
+***** This is currently a no-op implementation suitable for use
+***** in single-threaded applications only.  Somebody please replace
+***** this with a real mutex implementation for OS/2.
+****/
+
+/*
+** The mutex object
+*/
+struct sqlite3_mutex {
+  int id;     /* The mutex type */
+  int cnt;    /* Number of entries without a matching leave */
+};
+
+/*
+** The sqlite3_mutex_alloc() routine allocates a new
+** mutex and returns a pointer to it.  If it returns NULL
+** that means that a mutex could not be allocated. 
+*/
+sqlite3_mutex *sqlite3_mutex_alloc(int id){
+  static sqlite3_mutex aStatic[4];
+  sqlite3_mutex *pNew = 0;
+  switch( id ){
+    case SQLITE_MUTEX_FAST:
+    case SQLITE_MUTEX_RECURSIVE: {
+      pNew = sqlite3_malloc(sizeof(*pNew));
+      if( pNew ){
+        pNew->id = id;
+        pNew->cnt = 0;
+      }
+      break;
+    }
+    default: {
+      assert( id-2 >= 0 );
+      assert( id-2 < sizeof(aStatic)/sizeof(aStatic[0]) );
+      pNew = &aStatic[id-2];
+      pNew->id = id;
+      break;
+    }
+  }
+  return pNew;
+}
+
+/*
+** This routine deallocates a previously allocated mutex.
+*/
+void sqlite3_mutex_free(sqlite3_mutex *p){
+  assert( p );
+  assert( p->cnt==0 );
+  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
+  sqlite3_free(p);
+}
+
+/*
+** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
+** to enter a mutex.  If another thread is already within the mutex,
+** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
+** SQLITE_BUSY.  The sqlite3_mutex_try() interface returns SQLITE_OK
+** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
+** be entered multiple times by the same thread.  In such cases the,
+** mutex must be exited an equal number of times before another thread
+** can enter.  If the same thread tries to enter any other kind of mutex
+** more than once, the behavior is undefined.
+*/
+void sqlite3_mutex_enter(sqlite3_mutex *p){
+  assert( p );
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
+  p->cnt++;
+}
+int sqlite3_mutex_try(sqlite3_mutex *p){
+  assert( p );
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
+  p->cnt++;
+  return SQLITE_OK;
+}
+
+/*
+** The sqlite3_mutex_leave() routine exits a mutex that was
+** previously entered by the same thread.  The behavior
+** is undefined if the mutex is not currently entered or
+** is not currently allocated.  SQLite will never do either.
+*/
+void sqlite3_mutex_leave(sqlite3_mutex *p){
+  assert( p );
+  assert( sqlite3_mutex_held(p) );
+  p->cnt--;
+  assert( p->id==SQLITE_MUTEX_RECURSIVE || sqlite3_mutex_notheld(p) );
+}
+
+/*
+** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
+** intended for use inside assert() statements.
+*/
+int sqlite3_mutex_held(sqlite3_mutex *p){
+  return p==0 || p->cnt>0;
+}
+int sqlite3_mutex_notheld(sqlite3_mutex *p){
+  return p==0 || p->cnt==0;
+}
+#endif /* SQLITE_MUTEX_OS2 */