Add metric to count I/O polling

core/jvm/src/main/scala/cats/effect/unsafe/WorkerThread.scala

@@ -427,6 +427,7 @@ private[effect] final class WorkerThread[P <: AnyRef](
       while (!done.get()) {
         // Park the thread until further notice.
         val start = System.nanoTime()
+        metrics.incrementPolledCount()
         val polled = system.poll(_poller, -1, reportFailure)
         now = System.nanoTime() // update now
         metrics.addIdleTime(now - start)
@@ -462,6 +463,7 @@ private[effect] final class WorkerThread[P <: AnyRef](
 
           if (nanos > 0L) {
             val start = now
+            metrics.incrementPolledCount()
             val polled = system.poll(_poller, nanos, reportFailure)
             // we already parked and time passed, so update time again
             // it doesn't matter if we timed out or were awakened, the update is free-ish
@@ -579,6 +581,7 @@ private[effect] final class WorkerThread[P <: AnyRef](
           // Clean up any externally canceled timers
           sleepers.packIfNeeded()
           // give the polling system a chance to discover events
+          metrics.incrementPolledCount()
           system.poll(_poller, 0, reportFailure)
 
           // Obtain a fiber or batch of fibers from the external queue.
@@ -981,6 +984,10 @@ private[effect] object WorkerThread {
     def getParkedCount(): Long = parkedCount
     def incrementParkedCount(): Unit = parkedCount += 1
 
+    private[this] var polledCount: Long = 0
+    def getPolledCount(): Long = polledCount
+    def incrementPolledCount(): Unit = polledCount += 1
+
     private[this] var blockingCount: Long = 0
     def getBlockingCount(): Long = blockingCount
     def incrementBlockingCount(): Unit = blockingCount += 1

core/jvm/src/main/scala/cats/effect/unsafe/metrics/WorkStealingPoolMetrics.scala

@@ -108,6 +108,11 @@ trait WorkerThreadMetrics {
    */
   def parkedCount(): Long
 
+  /**
+   * The total number of times that this WorkerThread has polled for I/O events.
+   */
+  def polledCount(): Long
+
   /**
    * The total number of times that this WorkerThread has switched to a blocking thread and been
    * replaced.
@@ -262,6 +267,7 @@ object WorkStealingPoolMetrics {
     private val metrics = wstp.metrices(idx)
     def idleTime(): Long = metrics.getIdleTime()
     def parkedCount(): Long = metrics.getParkedCount()
+    def polledCount(): Long = metrics.getPolledCount()
     def blockingCount(): Long = metrics.getBlockingCount()
     def respawnCount(): Long = metrics.getBlockingCount()