Optimize FiberQueue for large number of fibers

javatools/src/main/java/org/xvm/runtime/Fiber.java

@@ -208,6 +208,10 @@ public ObjectHandle getAsyncSection()
      */
     public void setStatus(FiberStatus status, long cOps)
         {
+        if (m_status == FiberStatus.Waiting)
+            {
+            f_context.f_queueSuspended.exitWait();
+            }
         switch (m_status = status)
             {
             default:
@@ -220,6 +224,8 @@ public void setStatus(FiberStatus status, long cOps)
                 break;
 
             case Waiting:
+                f_context.f_queueSuspended.enterWait();
+                // fall through
             case Paused:
                 long cNanos = f_context.f_container.nanoTime() - m_nanoStarted;
                 m_nanoStarted = 0;
@@ -541,10 +547,26 @@ public Frame getBlocker()
 
     /**
      * Set or clear the frame that blocks this fiber's execution.
+     *
+     * @param frameBlocker  null if no blocker exists or the blocker fiber itself
+     * @param lStamp        if no blocker exists, the "wait exit stamp", otherwise the "wait enter
+     *                      stamp" of the fiber queue when this check occurred
      */
-    protected void setBlocker(Frame frameBlocker)
+    protected void setBlocker(Frame frameBlocker, long lStamp)
         {
         m_frameBlocker = frameBlocker;
+        m_lLastStamp   = lStamp;
+        }
+
+    /**
+     * @return true iff there were no wait status changes on the FiberQueue that would change
+     *              the blocker computation result for the fiber
+     */
+    protected boolean noChange(long lLastEnterStamp, long lLastExitStamp)
+        {
+        return m_frameBlocker == null
+            ? lLastEnterStamp == m_lLastStamp
+            : lLastExitStamp  == m_lLastStamp;
         }
 
 
@@ -785,6 +807,11 @@ public int proceed(Frame frameCaller)
      */
     private Frame m_frameBlocker;
 
+    /**
+     * THe FiberQueue stamp of the last time it looked for blockers for this fiber.
+     */
+    private long m_lLastStamp;
+
     /**
      * The counter used to create fibers ids.
      */

javatools/src/main/java/org/xvm/runtime/FiberQueue.java

@@ -19,6 +19,12 @@ public class FiberQueue
     private int m_ixTail = 0;  // past the tail - insertion point
     private int m_cSize  = 0;
 
+    // this value increases every time any fiber that belong to this queue enters the "Waiting" state
+    private long m_lWaitEnterStamp = 0;
+
+    // this value increases every time any fiber that belong to this queue exits the "Waiting" state
+    private long m_lWaitExitStamp = 0;
+
     public FiberQueue(ServiceContext ctx)
         {
         f_context = ctx;
@@ -129,6 +135,22 @@ public Frame getAny()
         return null;
         }
 
+    /**
+     * Called when any fiber changes its state to {@link FiberStatus#Waiting}
+     */
+    protected void enterWait()
+        {
+        m_lWaitEnterStamp++;
+        }
+
+    /**
+     * Called when any fiber changes its state from {@link FiberStatus#Waiting} to any other.
+     */
+    protected void exitWait()
+        {
+        m_lWaitExitStamp++;
+        }
+
     /**
      * Report on the status of the fiber queue. Temporary: for debugging only.
      */
@@ -254,8 +276,19 @@ private boolean canResume(Fiber fiber)
      *
      * @return true iff there are any non-concurrent waiting frames
      */
+static int HIT = 0;
+static int ALL = 0;
     private boolean isAnyNonConcurrentWaiting(Fiber fiberCandidate)
         {
+//if (++ALL % 100_000 == 0)
+//    {
+//    System.err.println("*** hits=" + HIT + " out of " + ALL);
+//    }
+        if (fiberCandidate.noChange(m_lWaitEnterStamp, m_lWaitExitStamp))
+            {
+//++HIT;
+            return fiberCandidate.getBlocker() != null;
+            }
         Frame[] aFrame      = m_aFrame;
         Fiber   fiberCaller = fiberCandidate.getCaller();
 
@@ -267,21 +300,19 @@ private boolean isAnyNonConcurrentWaiting(Fiber fiberCandidate)
                 }
 
             Fiber fiber = frame.f_fiber;
-            if (fiber != fiberCandidate)
+            if (fiber != fiberCandidate &&
+                    fiber.getStatus() == FiberStatus.Waiting)
                 {
-                if (fiber.getStatus() == FiberStatus.Waiting)
+                if (frame.isSafeStack() ||
+                    fiberCaller != null && fiberCaller.isContinuationOf(fiber))
                     {
-                    if (frame.isSafeStack() ||
-                        fiberCaller != null && fiberCaller.isContinuationOf(fiber))
-                        {
-                        continue;
-                        }
-                    fiberCandidate.setBlocker(frame);
-                    return true;
+                    continue;
                     }
+                fiberCandidate.setBlocker(frame, m_lWaitExitStamp);
+                return true;
                 }
             }
-        fiberCandidate.setBlocker(null);
+        fiberCandidate.setBlocker(null, m_lWaitEnterStamp);
         return false;
         }
 

javatools/src/main/java/org/xvm/runtime/ServiceContext.java

@@ -2405,7 +2405,7 @@ public interface TypeSupplier
     /**
      * The queue of suspended fibers.
      */
-    private final FiberQueue f_queueSuspended = new FiberQueue(this);
+    protected final FiberQueue f_queueSuspended = new FiberQueue(this);
 
     /**
      * The reentrancy policy. Must be the same names as in natural Service.Synchronicity.