8372179: Remove Unused ConcurrentHashTable::MultiGetHandle

Reviewed-by: dholmes, iwalulya

Author: Thomas Schatzl

src/hotspot/share/utilities/concurrentHashTable.hpp

@@ -451,8 +451,7 @@ class ConcurrentHashTable : public CHeapObj<MT> {
 
   // All callbacks for get are under critical sections. Other callbacks may be
   // under critical section or may have locked parts of table. Calling any
-  // methods on the table during a callback is not supported.Only MultiGetHandle
-  // supports multiple gets.
+  // methods on the table during a callback is not supported.
 
   // Get methods return true on found item with LOOKUP_FUNC and FOUND_FUNC is
   // called.
@@ -538,18 +537,6 @@ class ConcurrentHashTable : public CHeapObj<MT> {
   // Must be done at a safepoint.
   void rehash_nodes_to(Thread* thread, ConcurrentHashTable<CONFIG, MT>* to_cht);
 
-  // Scoped multi getter.
-  class MultiGetHandle : private ScopedCS {
-   public:
-    MultiGetHandle(Thread* thread, ConcurrentHashTable<CONFIG, MT>* cht)
-      : ScopedCS(thread, cht) {}
-    // In the MultiGetHandle scope you can lookup items matching LOOKUP_FUNC.
-    // The VALUEs are safe as long as you never save the VALUEs outside the
-    // scope, e.g. after ~MultiGetHandle().
-    template <typename LOOKUP_FUNC>
-    VALUE* get(LOOKUP_FUNC& lookup_f, bool* grow_hint = nullptr);
-  };
-
  private:
   class BucketsOperation;
 

src/hotspot/share/utilities/concurrentHashTable.inline.hpp

@@ -233,14 +233,6 @@ inline ConcurrentHashTable<CONFIG, MT>::
   GlobalCounter::critical_section_end(_thread, _cs_context);
 }
 
-template <typename CONFIG, MemTag MT>
-template <typename LOOKUP_FUNC>
-inline typename CONFIG::Value* ConcurrentHashTable<CONFIG, MT>::
-  MultiGetHandle::get(LOOKUP_FUNC& lookup_f, bool* grow_hint)
-{
-  return ScopedCS::_cht->internal_get(ScopedCS::_thread, lookup_f, grow_hint);
-}
-
 // HaveDeletables
 template <typename CONFIG, MemTag MT>
 template <typename EVALUATE_FUNC>

test/hotspot/gtest/utilities/test_concurrentHashtable.cpp

@@ -97,7 +97,6 @@ struct Config : public AllStatic {
 };
 
 typedef ConcurrentHashTable<Pointer, mtInternal> SimpleTestTable;
-typedef ConcurrentHashTable<Pointer, mtInternal>::MultiGetHandle SimpleTestGetHandle;
 typedef ConcurrentHashTable<Config, mtInternal> CustomTestTable;
 
 struct SimpleTestLookup {
@@ -345,10 +344,6 @@ static void cht_scope(Thread* thr) {
   SimpleTestLookup stl(val);
   SimpleTestTable* cht = new SimpleTestTable();
   EXPECT_TRUE(cht->insert(thr, stl, val)) << "Insert unique value failed.";
-  {
-    SimpleTestGetHandle get_handle(thr, cht);
-    EXPECT_EQ(*get_handle.get(stl), val) << "Getting a pre-existing value failed.";
-  }
   // We do remove here to make sure the value-handle 'unlocked' the table when leaving the scope.
   EXPECT_TRUE(cht->remove(thr, stl)) << "Removing a pre-existing value failed.";
   EXPECT_FALSE(cht_get_copy(cht, thr, stl) == val) << "Got a removed value.";
@@ -556,7 +551,6 @@ class TestInterface : public AllStatic {
 };
 
 typedef ConcurrentHashTable<TestInterface, mtInternal> TestTable;
-typedef ConcurrentHashTable<TestInterface, mtInternal>::MultiGetHandle TestGetHandle;
 
 struct TestLookup {
   uintptr_t _val;
@@ -788,15 +782,8 @@ class RunnerDeleteInserterThread : public CHTTestThread {
   bool test_loop() {
     for (uintptr_t v = 0x1; v < 0xFFF; v++ ) {
       uintptr_t tv;
-      if (v & 0x1) {
-        TestLookup tl(v);
-        tv = cht_get_copy(_cht, this, tl);
-      } else {
-        TestLookup tl(v);
-        TestGetHandle value_handle(this, _cht);
-        uintptr_t* tmp = value_handle.get(tl);
-        tv = tmp != nullptr ? *tmp : 0;
-      }
+      TestLookup tl(v);
+      tv = cht_get_copy(_cht, this, tl);
       EXPECT_TRUE(tv == 0 || tv == v) << "Got unknown value.";
     }
     return true;