MB-48531: Remove CheckpointVisitor

Unused now, all logic moved to ClosedUnrefCheckpointRemoverTask in
previous patches.

Change-Id: I5fe0508bd2cf1660989f6df4f82d72dadceeafcf
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/163268
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>

engines/ep/CMakeLists.txt

@@ -300,7 +300,6 @@ ADD_LIBRARY(ep_objs OBJECT
             src/checkpoint_config.cc
             src/checkpoint_manager.cc
             src/checkpoint_remover.cc
-            src/checkpoint_visitor.cc
             src/conflict_resolution.cc
             src/conn_notifier.cc
             src/connhandler.cc

engines/ep/tests/module_tests/checkpoint_remover_test.cc

@@ -19,7 +19,6 @@
 #include "checkpoint_manager.h"
 #include "checkpoint_remover.h"
 #include "checkpoint_utils.h"
-#include "checkpoint_visitor.h"
 #include "collections/vbucket_manifest_handles.h"
 #include "dcp/response.h"
 #include "test_helpers.h"
@@ -60,39 +59,6 @@ TEST_F(CheckpointRemoverEPTest, GetVBucketsSortedByChkMgrMem) {
     }
 }
 
-/**
- * Check that CheckpointVisitor orders vbuckets to visit by "highest checkpoint
- * mem-usage" order.
- */
-TEST_F(CheckpointRemoverEPTest, CheckpointVisitorVBucketOrder) {
-    std::deque<Vbid> vbuckets;
-    for (uint16_t i = 0; i < 3; i++) {
-        setVBucketStateAndRunPersistTask(Vbid(i), vbucket_state_active);
-        for (uint16_t j = 0; j < i; j++) {
-            std::string doc_key =
-                    "key_" + std::to_string(i) + "_" + std::to_string(j);
-            store_item(Vbid(i), makeStoredDocKey(doc_key), "value");
-        }
-        vbuckets.emplace_back(vbid);
-    }
-
-    std::atomic<bool> stateFinalizer = true;
-    auto visitor = CheckpointVisitor(
-            store, engine->getEpStats(), stateFinalizer, 1 /*memToClear*/);
-    auto comparator = visitor.getVBucketComparator();
-    std::sort(vbuckets.begin(), vbuckets.end(), comparator);
-
-    ASSERT_EQ(3, vbuckets.size());
-    for (size_t i = 1; i < vbuckets.size(); i++) {
-        auto thisVbid = vbuckets[i];
-        auto prevVbid = vbuckets[i - 1];
-        // This vBucket should have a greater memory usage than the one previous
-        // to it in the map
-        ASSERT_GE(store->getVBucket(thisVbid)->getChkMgrMemUsage(),
-                  store->getVBucket(prevVbid)->getChkMgrMemUsage());
-    }
-}
-
 #ifndef WIN32
 /**
  * Check that the CheckpointManager memory usage calculation is correct and
@@ -432,22 +398,18 @@ void CheckpointRemoverEPTest::testExpellingOccursBeforeCursorDropping(
         // Testing ItemExpel
         std::vector<queued_item> items;
         manager->getNextItemsForCursor(cursor.get(), items);
+    } // Testing CursorDrop otherwise
 
-        const auto& remover =
-                std::make_shared<ClosedUnrefCheckpointRemoverTask>(
-                        engine.get(),
-                        engine->getEpStats(),
-                        engine->getConfiguration().getChkRemoverStime());
-        remover->run();
-        getCkptDestroyerTask(vbid).run();
-    } else {
-        // Testing CursorDrop
-        std::atomic<bool> stateFinalizer = false;
-        auto visitor = CheckpointVisitor(
-                store, engine->getEpStats(), stateFinalizer, memToClear);
-        visitor.visitBucket(vb);
-        getCkptDestroyerTask(vbid).run();
+    const auto remover = std::make_shared<ClosedUnrefCheckpointRemoverTask>(
+            engine.get(),
+            engine->getEpStats(),
+            engine->getConfiguration().getChkRemoverStime());
+    remover->run();
+    getCkptDestroyerTask(vbid).run();
 
+    if (moveCursor) {
+        EXPECT_EQ(stats.getNumCheckpoints(), inititalNumCheckpoints);
+    } else {
         EXPECT_LT(stats.getNumCheckpoints(), inititalNumCheckpoints);
     }
 
@@ -961,12 +923,12 @@ TEST_F(CheckpointRemoverEPTest, CheckpointRemovalWithoutCursorDrop) {
     ASSERT_EQ(0, engine->getEpStats().itemsRemovedFromCheckpoints);
     ASSERT_EQ(0, engine->getEpStats().cursorsDropped);
 
-    const auto memToClear = store->getRequiredCheckpointMemoryReduction();
-    EXPECT_GT(memToClear, 0);
-    std::atomic<bool> stateFinalizer = false;
-    auto visitor = CheckpointVisitor(
-            store, engine->getEpStats(), stateFinalizer, memToClear);
-    visitor.visitBucket(vb);
+    ASSERT_GT(store->getRequiredCheckpointMemoryReduction(), 0);
+    const auto remover = std::make_shared<ClosedUnrefCheckpointRemoverTask>(
+            engine.get(),
+            engine->getEpStats(),
+            engine->getConfiguration().getChkRemoverStime());
+    remover->run();
     getCkptDestroyerTask(vbid).run();
 
     EXPECT_EQ(0, store->getRequiredCheckpointMemoryReduction());

executor/fake_executorpool.h

@@ -159,11 +159,8 @@ class CheckedExecutor : public CB3ExecutorThread {
         } else if (getTaskName() ==
                    "Removing closed unreferenced checkpoints from memory") {
             checker = [=](bool taskRescheduled) {
-                // This task _may_ schedule or wake 1 or 2 subsequent tasks.
-                // 1. A CheckpointVisitor, scanning all vbuckets for
-                //    Checkpoints to remove
-                // 2. A CheckpointDestroyer, to destroy checkpoints made
-                //    unreferenced by cursor dropping
+                // This task _may_ schedule or wake a CheckpointDestroyer, to
+                // destroy checkpoints made unreferenced by cursor dropping
                 this->oneExecutes(taskRescheduled, /*min*/ 0, /*max*/ 2);
             };
         } else if (getTaskName() == "Paging out items." ||

executor/tasks.def.h

@@ -86,7 +86,6 @@ TASK(ActiveStreamCheckpointProcessorTask, NONIO_TASK_IDX, 3)
 TASK(ConnNotifierCallback, NONIO_TASK_IDX, 5)
 TASK(CheckpointDestroyerTask, NONIO_TASK_IDX, 6)
 TASK(ClosedUnrefCheckpointRemoverTask, NONIO_TASK_IDX, 6)
-TASK(ClosedUnrefCheckpointRemoverVisitorTask, NONIO_TASK_IDX, 6)
 TASK(VBucketMemoryDeletionTask, NONIO_TASK_IDX, 6)
 TASK(StatCheckpointTask, NONIO_TASK_IDX, 7)
 TASK(StatDCPTask, NONIO_TASK_IDX, 7)