1 files changed, 111 insertions, 11 deletions

diff --git a/indra/llcommon/threadpool.cpp b/indra/llcommon/threadpool.cpp
index d5adf11264..3a9a5a2062 100644
--- a/indra/llcommon/threadpool.cpp
+++ b/indra/llcommon/threadpool.cpp
@@ -17,18 +17,58 @@
 // std headers
 // external library headers
 // other Linden headers
+#include "commoncontrol.h"
 #include "llerror.h"
 #include "llevents.h"
+#include "llsd.h"
 #include "stringize.h"
 
-LL::ThreadPool::ThreadPool(const std::string& name, size_t threads, size_t capacity):
+#include <boost/fiber/algo/round_robin.hpp>
+
+/*****************************************************************************
+*   Custom fiber scheduler for worker threads
+*****************************************************************************/
+// As of 2022-12-06, each of our worker threads only runs a single (default)
+// fiber: we don't launch explicit fibers within worker threads, nor do we
+// anticipate doing so. So a worker thread that's simply waiting for incoming
+// tasks should really sleep a little. Override the default fiber scheduler to
+// implement that.
+struct sleepy_robin: public boost::fibers::algo::round_robin
+{
+    virtual void suspend_until( std::chrono::steady_clock::time_point const&) noexcept
+    {
+#if LL_WINDOWS
+        // round_robin holds a std::condition_variable, and
+        // round_robin::suspend_until() calls
+        // std::condition_variable::wait_until(). On Windows, that call seems
+        // busier than it ought to be. Try just sleeping.
+        Sleep(1);
+#else
+        // currently unused other than windows, but might as well have something here
+        // different units than Sleep(), but we actually just want to sleep for any de-minimis duration
+        usleep(1);
+#endif
+    }
+
+    virtual void notify() noexcept
+    {
+        // Since our Sleep() call above will wake up on its own, we need not
+        // take any special action to wake it.
+    }
+};
+
+/*****************************************************************************
+*   ThreadPoolBase
+*****************************************************************************/
+LL::ThreadPoolBase::ThreadPoolBase(const std::string& name, size_t threads,
+                                   WorkQueueBase* queue):
     super(name),
-    mQueue(name, capacity),
     mName("ThreadPool:" + name),
-    mThreadCount(threads)
+    mThreadCount(getConfiguredWidth(name, threads)),
+    mQueue(queue)
 {}
 
-void LL::ThreadPool::start()
+void LL::ThreadPoolBase::start()
 {
     for (size_t i = 0; i < mThreadCount; ++i)
     {
@@ -56,17 +96,17 @@ void LL::ThreadPool::start()
         });
 }
 
-LL::ThreadPool::~ThreadPool()
+LL::ThreadPoolBase::~ThreadPoolBase()
 {
     close();
 }
 
-void LL::ThreadPool::close()
+void LL::ThreadPoolBase::close()
 {
-    if (! mQueue.isClosed())
+    if (! mQueue->isClosed())
     {
         LL_DEBUGS("ThreadPool") << mName << " closing queue and joining threads" << LL_ENDL;
-        mQueue.close();
+        mQueue->close();
         for (auto& pair: mThreads)
         {
             LL_DEBUGS("ThreadPool") << mName << " waiting on thread " << pair.first << LL_ENDL;
@@ -76,14 +116,74 @@ void LL::ThreadPool::close()
     }
 }
 
-void LL::ThreadPool::run(const std::string& name)
+void LL::ThreadPoolBase::run(const std::string& name)
 {
+#if LL_WINDOWS
+    // Try using sleepy_robin fiber scheduler.
+    boost::fibers::use_scheduling_algorithm<sleepy_robin>();
+#endif // LL_WINDOWS
+
     LL_DEBUGS("ThreadPool") << name << " starting" << LL_ENDL;
     run();
     LL_DEBUGS("ThreadPool") << name << " stopping" << LL_ENDL;
 }
 
-void LL::ThreadPool::run()
+void LL::ThreadPoolBase::run()
+{
+    mQueue->runUntilClose();
+}
+
+//static
+size_t LL::ThreadPoolBase::getConfiguredWidth(const std::string& name, size_t dft)
+{
+    LLSD poolSizes;
+    try
+    {
+        poolSizes = LL::CommonControl::get("Global", "ThreadPoolSizes");
+        // "ThreadPoolSizes" is actually a map containing the sizes of
+        // interest -- or should be, if this process has an
+        // LLViewerControlListener instance and its settings include
+        // "ThreadPoolSizes". If we failed to retrieve it, perhaps we're in a
+        // program that doesn't define that, or perhaps there's no such
+        // setting, or perhaps we're asking too early, before the LLEventAPI
+        // itself has been instantiated. In any of those cases, it seems worth
+        // warning.
+        if (! poolSizes.isDefined())
+        {
+            // Note: we don't warn about absence of an override key for a
+            // particular ThreadPool name, that's fine. This warning is about
+            // complete absence of a ThreadPoolSizes setting, which we expect
+            // in a normal viewer session.
+            LL_WARNS("ThreadPool") << "No 'ThreadPoolSizes' setting for ThreadPool '"
+                                   << name << "'" << LL_ENDL;
+        }
+    }
+    catch (const LL::CommonControl::Error& exc)
+    {
+        // We don't want ThreadPool to *require* LLViewerControlListener.
+        // Just log it and carry on.
+        LL_WARNS("ThreadPool") << "Can't check 'ThreadPoolSizes': " << exc.what() << LL_ENDL;
+    }
+
+    LL_DEBUGS("ThreadPool") << "ThreadPoolSizes = " << poolSizes << LL_ENDL;
+    // LLSD treats an undefined value as an empty map when asked to retrieve a
+    // key, so we don't need this to be conditional.
+    LLSD sizeSpec{ poolSizes[name] };
+    // We retrieve sizeSpec as LLSD, rather than immediately as LLSD::Integer,
+    // so we can distinguish the case when it's undefined.
+    return sizeSpec.isInteger() ? sizeSpec.asInteger() : dft;
+}
+
+//static
+size_t LL::ThreadPoolBase::getWidth(const std::string& name, size_t dft)
 {
-    mQueue.runUntilClose();
+    auto instance{ getInstance(name) };
+    if (instance)
+    {
+        return instance->getWidth();
+    }
+    else
+    {
+        return getConfiguredWidth(name, dft);
+    }
 }