add tryLockMember

tihmstar · Jul 25, 2024 · 2ea3cfe · 2ea3cfe
1 parent 9034af6
commit 2ea3cfe
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Showing 2 changed files with 25 additions and 2 deletions.
diff --git a/include/libgeneral/GuardAccess.hpp b/include/libgeneral/GuardAccess.hpp
@@ -31,6 +31,13 @@ namespace tihmstar {
         void lockMember();
         void unlockMember();
 
+        /*
+            Attempts to lock Member if it is not already locked.
+            Returns true if lock was acquired
+            Returns false if already locked
+         */
+        bool tryLockMember();
+
         //block until someone removed members
         void waitForMemberDrain();
     };

diff --git a/libgeneral/GuardAccess.cpp b/libgeneral/GuardAccess.cpp
@@ -28,11 +28,11 @@ GuardAccess::~GuardAccess(){
 #pragma mark public
 void GuardAccess::addMember(){
     while (true){
-        if (_members.fetch_add(1) >= GuardAccess::maxMembers){
+        if (_members.fetch_add(1) >= GuardAccess::maxMembers-1){
             _members.fetch_sub(1); _leaveEvent.notifyAll();
 
             uint64_t wevent = _leaveEvent.getNextEvent();
-            while (_members>=GuardAccess::maxMembers){
+            while (_members>=GuardAccess::maxMembers-1){
                 _leaveEvent.waitForEvent(wevent);
                 wevent = _leaveEvent.getNextEvent();
             }
@@ -73,6 +73,22 @@ void GuardAccess::unlockMember(){
     _leaveEvent.notifyAll();
 }
 
+bool GuardAccess::tryLockMember(){
+    while (true){
+        if (_members.fetch_add(GuardAccess::maxMembers) >= GuardAccess::maxMembers){
+            _members.fetch_sub(GuardAccess::maxMembers); _leaveEvent.notifyAll();
+            return false;
+        }else{
+            uint64_t wevent = _leaveEvent.getNextEvent();
+            while (_members > GuardAccess::maxMembers){
+                _leaveEvent.waitForEvent(wevent);
+                wevent = _leaveEvent.getNextEvent();
+            }
+            return true;
+        }
+    }
+}
+
 void GuardAccess::waitForMemberDrain(){
     uint64_t wevent = _leaveEvent.getNextEvent();
     _leaveEvent.waitForEvent(wevent);