SL-17483: Make it possible to override width of any ThreadPool.

Introduce CommonControl, which in a running viewer (or any program containing
an LLViewerControlListener instance) gives access to LLViewerControl
functionality, e.g. getting, setting or enumerating control variables --
without introducing a link dependency on newview.

Make ThreadPool's constructor consult CommonControl to check for an override
for the width of the new ThreadPool in the Global (i.e. gSavedSettings)
setting ThreadPoolSizes, and honor that if found.

Introduce static ThreadPool methods getConfiguredWidth(), to query for such an
override on any particular ThreadPool name; and getWidth(), to ask for the
width of an instance if that instance already exists, else the width with
which it *would* be instantiated.

1 files changed, 104 insertions, 0 deletions

diff --git a/indra/llcommon/commoncontrol.cpp b/indra/llcommon/commoncontrol.cpp
new file mode 100644
index 0000000000..2c2a2abeb0
--- /dev/null
+++ b/indra/llcommon/commoncontrol.cpp
@@ -0,0 +1,104 @@
+/**
+ * @file   commoncontrol.cpp
+ * @author Nat Goodspeed
+ * @date   2022-06-08
+ * @brief  Implementation for commoncontrol.
+ * 
+ * $LicenseInfo:firstyear=2022&license=viewerlgpl$
+ * Copyright (c) 2022, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "commoncontrol.h"
+// STL headers
+// std headers
+// external library headers
+// other Linden headers
+#include "llevents.h"
+#include "llsdutil.h"
+
+LLSD LL::CommonControl::access(const LLSD& params)
+{
+    // We can't actually introduce a link-time dependency on llxml, or on any
+    // global LLControlGroup (*koff* gSavedSettings *koff*) but we can issue a
+    // runtime query. If we're running as part of a viewer with
+    // LLViewerControlListener, we can use that to interact with any
+    // instantiated LLControGroup.
+    LLSD response;
+    {
+        LLEventStream reply("reply");
+        LLTempBoundListener connection = reply.listen("listener",
+                     [&response] (const LLSD& event)
+                     {
+                         response = event;
+                         return false;
+                     });
+        LLSD rparams{ params };
+        rparams["reply"] = reply.getName();
+        LLEventPumps::instance().obtain("LLViewerControl").post(rparams);
+    }
+    // LLViewerControlListener responds immediately. If it's listening at all,
+    // it will already have set response.
+    if (! response.isDefined())
+    {
+        LLTHROW(NoListener("No LLViewerControl listener instantiated"));
+    }
+    LLSD error{ response["error"] };
+    if (error.isDefined())
+    {
+        LLTHROW(ParamError(error));
+    }
+    return response;
+}
+
+/// set control group.key to defined default value
+LLSD LL::CommonControl::set_default(const std::string& group, const std::string& key)
+{
+    return access(llsd::map("op", "set",
+                            "group", group, "key", key))["value"];
+}
+
+/// set control group.key to specified value
+LLSD LL::CommonControl::set(const std::string& group, const std::string& key, const LLSD& value)
+{
+    return access(llsd::map("op", "set",
+                            "group", group, "key", key, "value", value))["value"];
+}
+
+/// toggle boolean control group.key
+LLSD LL::CommonControl::toggle(const std::string& group, const std::string& key)
+{
+    return access(llsd::map("op", "toggle",
+                            "group", group, "key", key))["value"];
+}
+
+/// get the definition for control group.key, (! isDefined()) if bad
+/// ["name"], ["type"], ["value"], ["comment"]
+LLSD LL::CommonControl::get_def(const std::string& group, const std::string& key)
+{
+    return access(llsd::map("op", "get",
+                            "group", group, "key", key));
+}
+
+/// get the value of control group.key
+LLSD LL::CommonControl::get(const std::string& group, const std::string& key)
+{
+    return access(llsd::map("op", "get",
+                            "group", group, "key", key))["value"];
+}
+
+/// get defined groups
+std::vector<std::string> LL::CommonControl::get_groups()
+{
+    auto groups{ access(llsd::map("op", "groups"))["groups"] };
+    return { groups.beginArray(), groups.endArray() };
+}
+
+/// get definitions for all variables in group
+LLSD LL::CommonControl::get_vars(const std::string& group)
+{
+    return access(llsd::map("op", "vars", "group", group))["vars"];
+}