Initial version

code/threads/synchlist.cc

@@ -0,0 +1,101 @@
+// synchlist.cc
+//      Routines for synchronized access to a list.
+//
+//      Implemented by surrounding the List abstraction
+//      with synchronization routines.
+//
+//      Implemented in "monitor"-style -- surround each procedure with a
+//      lock acquire and release pair, using condition signal and wait for
+//      synchronization.
+//
+// Copyright (c) 1992-1993 The Regents of the University of California.
+// All rights reserved.  See copyright.h for copyright notice and limitation 
+// of liability and disclaimer of warranty provisions.
+
+#include "copyright.h"
+#include "synchlist.h"
+
+//----------------------------------------------------------------------
+// SynchList::SynchList
+//      Allocate and initialize the data structures needed for a 
+//      synchronized list, empty to start with.
+//      Elements can now be added to the list.
+//----------------------------------------------------------------------
+
+SynchList::SynchList ()
+{
+    list = new List ();
+    lock = new Lock ("list lock");
+    listEmpty = new Condition ("list empty cond");
+}
+
+//----------------------------------------------------------------------
+// SynchList::~SynchList
+//      De-allocate the data structures created for synchronizing a list. 
+//----------------------------------------------------------------------
+
+SynchList::~SynchList ()
+{
+    delete list;
+    list = NULL;
+    delete lock;
+    lock = NULL;
+    delete listEmpty;
+    listEmpty = NULL;
+}
+
+//----------------------------------------------------------------------
+// SynchList::Append
+//      Append an "item" to the end of the list.  Wake up anyone
+//      waiting for an element to be appended.
+//
+//      "item" is the thing to put on the list, it can be a pointer to 
+//              anything.
+//----------------------------------------------------------------------
+
+void
+SynchList::Append (void *item)
+{
+    lock->Acquire ();		// enforce mutual exclusive access to the list 
+    list->Append (item);
+    listEmpty->Signal (lock);	// wake up a waiter, if any
+    lock->Release ();
+}
+
+//----------------------------------------------------------------------
+// SynchList::Remove
+//      Remove an "item" from the beginning of the list.  Wait if
+//      the list is empty.
+// Returns:
+//      The removed item. 
+//----------------------------------------------------------------------
+
+void *
+SynchList::Remove ()
+{
+    void *item;
+
+    lock->Acquire ();		// enforce mutual exclusion
+    while (list->IsEmpty ())
+	listEmpty->Wait (lock);	// wait until list isn't empty
+    item = list->Remove ();
+    ASSERT (item != NULL);
+    lock->Release ();
+    return item;
+}
+
+//----------------------------------------------------------------------
+// SynchList::Mapcar
+//      Apply function to every item on the list.  Obey mutual exclusion
+//      constraints.
+//
+//      "func" is the procedure to be applied.
+//----------------------------------------------------------------------
+
+void
+SynchList::Mapcar (VoidFunctionPtr func)
+{
+    lock->Acquire ();
+    list->Mapcar (func);
+    lock->Release ();
+}