sync module improvements

sys/apis/sync.lua

@@ -1,26 +1,61 @@
-local syncLocks = { }
+local Sync = {
+  syncLocks = { }
+}
 
 local os = _G.os
 
-return function(obj, fn)
+function Sync.sync(obj, fn)
   local key = tostring(obj)
-  if syncLocks[key] then
+  if Sync.syncLocks[key] then
     local cos = tostring(coroutine.running())
-    table.insert(syncLocks[key], cos)
+    table.insert(Sync.syncLocks[key], cos)
     repeat
       local _, co = os.pullEvent('sync_lock')
     until co == cos
   else
-    syncLocks[key] = { }
+    Sync.syncLocks[key] = { }
   end
   local s, m = pcall(fn)
-  local co = table.remove(syncLocks[key], 1)
+  local co = table.remove(Sync.syncLocks[key], 1)
   if co then
     os.queueEvent('sync_lock', co)
   else
-    syncLocks[key] = nil
+    Sync.syncLocks[key] = nil
   end
   if not s then
     error(m)
   end
 end
+
+function Sync.lock(obj)
+  local key = tostring(obj)
+  if Sync.syncLocks[key] then
+    local cos = tostring(coroutine.running())
+    table.insert(Sync.syncLocks[key], cos)
+    repeat
+      local _, co = os.pullEvent('sync_lock')
+    until co == cos
+  else
+    Sync.syncLocks[key] = { }
+  end
+end
+
+function Sync.release(obj)
+  local key = tostring(obj)
+  if not Sync.syncLocks[key] then
+    error('Sync.release: Lock was not obtained', 2)
+  end
+  local co = table.remove(Sync.syncLocks[key], 1)
+  if co then
+    os.queueEvent('sync_lock', co)
+  else
+    Sync.syncLocks[key] = nil
+  end
+end
+
+function Sync.isLocked(obj)
+  local key = tostring(obj)
+  return not not Sync.syncLocks[key]
+end
+
+return Sync