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, 29 insertions, 1 deletions

diff --git a/indra/llcommon/threadpool.h b/indra/llcommon/threadpool.h
index f8eec3b457..b49d511257 100644
--- a/indra/llcommon/threadpool.h
+++ b/indra/llcommon/threadpool.h
@@ -30,8 +30,17 @@ namespace LL
         /**
          * Pass ThreadPool a string name. This can be used to look up the
          * relevant WorkQueue.
+         *
+         * The number of threads you pass sets the compile-time default. But
+         * if the user has overridden the LLSD map in the "ThreadPoolSizes"
+         * setting with a key matching this ThreadPool name, that setting
+         * overrides this parameter.
+         *
+         * Pass an explicit capacity to limit the size of the queue.
+         * Constraining the queue can cause a submitter to block. Do not
+         * constrain any ThreadPool accepting work from the main thread.
          */
-        ThreadPool(const std::string& name, size_t threads=1, size_t capacity=1024);
+        ThreadPool(const std::string& name, size_t threads=1, size_t capacity=1024*1024);
         virtual ~ThreadPool();
 
         /**
@@ -59,6 +68,25 @@ namespace LL
          */
         virtual void run();
 
+        /**
+         * getConfiguredWidth() returns the setting, if any, for the specified
+         * ThreadPool name. Returns dft if the "ThreadPoolSizes" map does not
+         * contain the specified name.
+         */
+        static
+        size_t getConfiguredWidth(const std::string& name, size_t dft=0);
+
+        /**
+         * This getWidth() returns the width of the instantiated ThreadPool
+         * with the specified name, if any. If no instance exists, returns its
+         * getConfiguredWidth() if any. If there's no instance and no relevant
+         * override, return dft. Presumably dft should match the threads
+         * parameter passed to the ThreadPool constructor call that will
+         * eventually instantiate the ThreadPool with that name.
+         */
+        static
+        size_t getWidth(const std::string& name, size_t dft);
+
     private:
         void run(const std::string& name);