MB-36956: Refactor executorpool_test for multiple ExecutorPools

Modify the tests in executorpool_test.cc to facilitate testing more
than just the CB3 ExecutorPool:

- Change test fixtures to Typed Test fixtures (although only
  instantiated with the existing TextExecutorPool).

- Rename getBuckets to getTaskables to better reflect the current,
  more generic form.

- Adjust some tests to not rely on implementation details of
  CB3ExecutorPool.

Change-Id: Ia01595b9bf4c2b6c494f0b32615052b495afc8d9
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/133455
Tested-by: Build Bot <[email protected]>
Reviewed-by: James Harrison <[email protected]>

Author: daverigby

engines/ep/src/cb3_executorpool.cc

@@ -88,7 +88,7 @@ CB3ExecutorPool::CB3ExecutorPool(size_t maxThreads,
       totReadyTasks(0),
       isHiPrioQset(false),
       isLowPrioQset(false),
-      numBuckets(0),
+      numTaskables(0),
       numSleepers(0),
       curWorkers(numTaskSets),
       numWorkers(numTaskSets),
@@ -443,7 +443,7 @@ void CB3ExecutorPool::_registerTaskable(Taskable& taskable) {
         }
 
         taskOwners.insert(&taskable);
-        numBuckets++;
+        numTaskables++;
     }
 
     _startWorkers();
@@ -604,15 +604,15 @@ std::vector<ExTask> CB3ExecutorPool::_stopTaskGroup(
 std::vector<ExTask> CB3ExecutorPool::_unregisterTaskable(Taskable& taskable,
                                                          bool force) {
     EP_LOG_INFO("Unregistering {} taskable {}",
-                (numBuckets == 1) ? "last" : "",
+                (numTaskables == 1) ? "last" : "",
                 taskable.getName());
 
     std::unique_lock<std::mutex> lh(tMutex);
 
     auto rv = _stopTaskGroup(taskable.getGID(), lh, force);
 
     taskOwners.erase(&taskable);
-    if (!(--numBuckets)) {
+    if (!(--numTaskables)) {
         if (!taskLocator.empty()) {
             throw std::logic_error(
                     "CB3ExecutorPool::_unregisterTaskable: "

engines/ep/src/cb3_executorpool.h

@@ -142,6 +142,10 @@ class CB3ExecutorPool : public ExecutorPool {
     std::vector<ExTask> unregisterTaskable(Taskable& taskable,
                                            bool force) override;
 
+    size_t getNumTaskables() const override {
+        return numTaskables;
+    }
+
     void doWorkerStat(EventuallyPersistentEngine* engine,
                       const void* cookie,
                       const AddStatFn& add_stat) override;
@@ -301,7 +305,8 @@ class CB3ExecutorPool : public ExecutorPool {
     TaskQ lpTaskQ; // a vector array of numTaskSets elements for low priority
     bool isLowPrioQset;
 
-    size_t numBuckets;
+    // Numbers of registered taskables.
+    size_t numTaskables;
 
     SyncObject tMutex; // to serialize taskLocator, threadQ, numBuckets access
 

engines/ep/src/executorpool.h

@@ -114,6 +114,9 @@ class ExecutorPool {
     virtual std::vector<ExTask> unregisterTaskable(Taskable& taskable,
                                                    bool force) = 0;
 
+    /// @returns the number of registered Taskables.
+    virtual size_t getNumTaskables() const = 0;
+
     /***************** Task Scheduling **************************************/
 
     /**