Add coro.lua to aggregate created coroutines.

1 files changed, 57 insertions, 0 deletions

diff --git a/indra/newview/scripts/lua/coro.lua b/indra/newview/scripts/lua/coro.lua
new file mode 100644
index 0000000000..8f868f5a48
--- /dev/null
+++ b/indra/newview/scripts/lua/coro.lua
@@ -0,0 +1,57 @@
+-- Manage Lua coroutines
+
+local coro = {}
+
+coro._coros = {}
+
+-- Launch a Lua coroutine: create and resume.
+-- Returns:
+-- new coroutine
+-- bool ok
+-- if not ok: error message
+-- if ok:     values yielded or returned
+function coro.launch(func, ...)
+    local co = coroutine.create(func)
+    table.insert(coro._coros, co)
+    return co, coroutine.resume(co, ...)
+end
+
+-- yield to other coroutines even if you don't know whether you're in a
+-- created coroutine or the main coroutine
+function coro.yield(...)
+    if coroutine.running() then
+        -- this is a real coroutine, yield normally
+        return coroutine.yield(...)
+    else
+        -- This is the main coroutine: coroutine.yield() doesn't work.
+        -- But we can take a spin through previously-launched coroutines.
+        -- Walk a copy of coro._coros in case any of these coroutines launches
+        -- another: next() forbids creating new entries during traversal.
+        for co in coro._live_coros_iter, table.clone(coro._coros) do
+            co.resume()
+        end
+    end
+end
+
+-- Walk coro._coros table, returning running or suspended coroutines.
+-- Once a coroutine becomes dead, remove it from _coros and don't return it.
+function coro._live_coros()
+    return coro._live_coros_iter, coro._coros
+end
+
+-- iterator function for _live_coros()
+function coro._live_coros_iter(t, idx)
+    local k, co = next(t, idx)
+    while k and coroutine.status(co) == 'dead' do
+--      t[k] = nil
+        -- See coro.yield(): sometimes we traverse a copy of _coros, but if we
+        -- discover a dead coroutine in that copy, delete it from _coros
+        -- anyway. Deleting it from a temporary copy does nothing.
+        coro._coros[k] = nil
+        coroutine.close(co)
+        k, co = next(t, k)
+    end
+    return co
+end
+
+return coro