1 files changed, 30 insertions, 0 deletions
diff --git a/indra/newview/scripts/lua/ErrorQueue.lua b/indra/newview/scripts/lua/ErrorQueue.lua
new file mode 100644
index 0000000000..a6d4470044
--- /dev/null
+++ b/indra/newview/scripts/lua/ErrorQueue.lua
@@ -0,0 +1,30 @@
+-- ErrorQueue isa WaitQueue with the added feature that a producer can push an
+-- error through the queue. Once that error is dequeued, every consumer will
+-- raise that error.
+
+local WaitQueue = require('WaitQueue')
+
+local ErrorQueue = WaitQueue:new()
+
+function ErrorQueue:Error(message)
+    -- Setting Error() is a marker, like closing the queue. Once we reach the
+    -- error, every subsequent Dequeue() call will raise the same error.
+    self._closed = message
+    self:_wake_waiters()
+end
+
+function ErrorQueue:Dequeue()
+    local value = WaitQueue.Dequeue(self)
+    if value ~= nil then
+        -- queue not yet closed, show caller
+        return value
+    end
+    if self._closed == true then
+        -- WaitQueue:close() sets true: queue has only been closed, tell caller
+        return nil
+    end
+    -- self._closed is a message set by Error()
+    error(self._closed)
+end
+
+return ErrorQueue