8079792: GC directory structure cleanup

Reviewed-by: brutisso, stefank, david

hotspot/src/share/vm/gc/g1/g1CodeCacheRemSet.cpp

@@ -0,0 +1,405 @@
+/*
+ * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "code/codeCache.hpp"
+#include "code/nmethod.hpp"
+#include "gc/g1/g1CodeCacheRemSet.hpp"
+#include "gc/g1/heapRegion.hpp"
+#include "memory/heap.hpp"
+#include "memory/iterator.hpp"
+#include "oops/oop.inline.hpp"
+#include "utilities/hashtable.inline.hpp"
+#include "utilities/stack.inline.hpp"
+
+class CodeRootSetTable : public Hashtable<nmethod*, mtGC> {
+  friend class G1CodeRootSetTest;
+  typedef HashtableEntry<nmethod*, mtGC> Entry;
+
+  static CodeRootSetTable* volatile _purge_list;
+
+  CodeRootSetTable* _purge_next;
+
+  unsigned int compute_hash(nmethod* nm) {
+    uintptr_t hash = (uintptr_t)nm;
+    return hash ^ (hash >> 7); // code heap blocks are 128byte aligned
+  }
+
+  void remove_entry(Entry* e, Entry* previous);
+  Entry* new_entry(nmethod* nm);
+
+ public:
+  CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {}
+  ~CodeRootSetTable();
+
+  // Needs to be protected locks
+  bool add(nmethod* nm);
+  bool remove(nmethod* nm);
+
+  // Can be called without locking
+  bool contains(nmethod* nm);
+
+  int entry_size() const { return BasicHashtable<mtGC>::entry_size(); }
+
+  void copy_to(CodeRootSetTable* new_table);
+  void nmethods_do(CodeBlobClosure* blk);
+
+  template<typename CB>
+  int remove_if(CB& should_remove);
+
+  static void purge_list_append(CodeRootSetTable* tbl);
+  static void purge();
+
+  static size_t static_mem_size() {
+    return sizeof(_purge_list);
+  }
+};
+
+CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL;
+
+CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) {
+  unsigned int hash = compute_hash(nm);
+  Entry* entry = (Entry*) new_entry_free_list();
+  if (entry == NULL) {
+    entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC);
+  }
+  entry->set_next(NULL);
+  entry->set_hash(hash);
+  entry->set_literal(nm);
+  return entry;
+}
+
+void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) {
+  int index = hash_to_index(e->hash());
+  assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null");
+
+  if (previous == NULL) {
+    set_entry(index, e->next());
+  } else {
+    previous->set_next(e->next());
+  }
+  free_entry(e);
+}
+
+CodeRootSetTable::~CodeRootSetTable() {
+  for (int index = 0; index < table_size(); ++index) {
+    for (Entry* e = bucket(index); e != NULL; ) {
+      Entry* to_remove = e;
+      // read next before freeing.
+      e = e->next();
+      unlink_entry(to_remove);
+      FREE_C_HEAP_ARRAY(char, to_remove);
+    }
+  }
+  assert(number_of_entries() == 0, "should have removed all entries");
+  free_buckets();
+  for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) {
+    FREE_C_HEAP_ARRAY(char, e);
+  }
+}
+
+bool CodeRootSetTable::add(nmethod* nm) {
+  if (!contains(nm)) {
+    Entry* e = new_entry(nm);
+    int index = hash_to_index(e->hash());
+    add_entry(index, e);
+    return true;
+  }
+  return false;
+}
+
+bool CodeRootSetTable::contains(nmethod* nm) {
+  int index = hash_to_index(compute_hash(nm));
+  for (Entry* e = bucket(index); e != NULL; e = e->next()) {
+    if (e->literal() == nm) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool CodeRootSetTable::remove(nmethod* nm) {
+  int index = hash_to_index(compute_hash(nm));
+  Entry* previous = NULL;
+  for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) {
+    if (e->literal() == nm) {
+      remove_entry(e, previous);
+      return true;
+    }
+  }
+  return false;
+}
+
+void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) {
+  for (int index = 0; index < table_size(); ++index) {
+    for (Entry* e = bucket(index); e != NULL; e = e->next()) {
+      new_table->add(e->literal());
+    }
+  }
+  new_table->copy_freelist(this);
+}
+
+void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) {
+  for (int index = 0; index < table_size(); ++index) {
+    for (Entry* e = bucket(index); e != NULL; e = e->next()) {
+      blk->do_code_blob(e->literal());
+    }
+  }
+}
+
+template<typename CB>
+int CodeRootSetTable::remove_if(CB& should_remove) {
+  int num_removed = 0;
+  for (int index = 0; index < table_size(); ++index) {
+    Entry* previous = NULL;
+    Entry* e = bucket(index);
+    while (e != NULL) {
+      Entry* next = e->next();
+      if (should_remove(e->literal())) {
+        remove_entry(e, previous);
+        ++num_removed;
+      } else {
+        previous = e;
+      }
+      e = next;
+    }
+  }
+  return num_removed;
+}
+
+G1CodeRootSet::~G1CodeRootSet() {
+  delete _table;
+}
+
+CodeRootSetTable* G1CodeRootSet::load_acquire_table() {
+  return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table);
+}
+
+void G1CodeRootSet::allocate_small_table() {
+  _table = new CodeRootSetTable(SmallSize);
+}
+
+void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) {
+  for (;;) {
+    table->_purge_next = _purge_list;
+    CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next);
+    if (old == table->_purge_next) {
+      break;
+    }
+  }
+}
+
+void CodeRootSetTable::purge() {
+  CodeRootSetTable* table = _purge_list;
+  _purge_list = NULL;
+  while (table != NULL) {
+    CodeRootSetTable* to_purge = table;
+    table = table->_purge_next;
+    delete to_purge;
+  }
+}
+
+void G1CodeRootSet::move_to_large() {
+  CodeRootSetTable* temp = new CodeRootSetTable(LargeSize);
+
+  _table->copy_to(temp);
+
+  CodeRootSetTable::purge_list_append(_table);
+
+  OrderAccess::release_store_ptr(&_table, temp);
+}
+
+
+void G1CodeRootSet::purge() {
+  CodeRootSetTable::purge();
+}
+
+size_t G1CodeRootSet::static_mem_size() {
+  return CodeRootSetTable::static_mem_size();
+}
+
+void G1CodeRootSet::add(nmethod* method) {
+  bool added = false;
+  if (is_empty()) {
+    allocate_small_table();
+  }
+  added = _table->add(method);
+  if (_length == Threshold) {
+    move_to_large();
+  }
+  if (added) {
+    ++_length;
+  }
+}
+
+bool G1CodeRootSet::remove(nmethod* method) {
+  bool removed = false;
+  if (_table != NULL) {
+    removed = _table->remove(method);
+  }
+  if (removed) {
+    _length--;
+    if (_length == 0) {
+      clear();
+    }
+  }
+  return removed;
+}
+
+bool G1CodeRootSet::contains(nmethod* method) {
+  CodeRootSetTable* table = load_acquire_table();
+  if (table != NULL) {
+    return table->contains(method);
+  }
+  return false;
+}
+
+void G1CodeRootSet::clear() {
+  delete _table;
+  _table = NULL;
+  _length = 0;
+}
+
+size_t G1CodeRootSet::mem_size() {
+  return sizeof(*this) +
+      (_table != NULL ? sizeof(CodeRootSetTable) + _table->entry_size() * _length : 0);
+}
+
+void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {
+  if (_table != NULL) {
+    _table->nmethods_do(blk);
+  }
+}
+
+class CleanCallback : public StackObj {
+  class PointsIntoHRDetectionClosure : public OopClosure {
+    HeapRegion* _hr;
+   public:
+    bool _points_into;
+    PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {}
+
+    void do_oop(narrowOop* o) {
+      do_oop_work(o);
+    }
+
+    void do_oop(oop* o) {
+      do_oop_work(o);
+    }
+
+    template <typename T>
+    void do_oop_work(T* p) {
+      if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) {
+        _points_into = true;
+      }
+    }
+  };
+
+  PointsIntoHRDetectionClosure _detector;
+  CodeBlobToOopClosure _blobs;
+
+ public:
+  CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {}
+
+  bool operator() (nmethod* nm) {
+    _detector._points_into = false;
+    _blobs.do_code_blob(nm);
+    return !_detector._points_into;
+  }
+};
+
+void G1CodeRootSet::clean(HeapRegion* owner) {
+  CleanCallback should_clean(owner);
+  if (_table != NULL) {
+    int removed = _table->remove_if(should_clean);
+    assert((size_t)removed <= _length, "impossible");
+    _length -= removed;
+  }
+  if (_length == 0) {
+    clear();
+  }
+}
+
+#ifndef PRODUCT
+
+class G1CodeRootSetTest {
+ public:
+  static void test() {
+    {
+      G1CodeRootSet set1;
+      assert(set1.is_empty(), "Code root set must be initially empty but is not.");
+
+      assert(G1CodeRootSet::static_mem_size() == sizeof(void*),
+          err_msg("The code root set's static memory usage is incorrect, "SIZE_FORMAT" bytes", G1CodeRootSet::static_mem_size()));
+
+      set1.add((nmethod*)1);
+      assert(set1.length() == 1, err_msg("Added exactly one element, but set contains "
+          SIZE_FORMAT" elements", set1.length()));
+
+      const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1;
+
+      for (size_t i = 1; i <= num_to_add; i++) {
+        set1.add((nmethod*)1);
+      }
+      assert(set1.length() == 1,
+          err_msg("Duplicate detection should not have increased the set size but "
+              "is "SIZE_FORMAT, set1.length()));
+
+      for (size_t i = 2; i <= num_to_add; i++) {
+        set1.add((nmethod*)(uintptr_t)(i));
+      }
+      assert(set1.length() == num_to_add,
+          err_msg("After adding in total "SIZE_FORMAT" distinct code roots, they "
+              "need to be in the set, but there are only "SIZE_FORMAT,
+              num_to_add, set1.length()));
+
+      assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
+
+      size_t num_popped = 0;
+      for (size_t i = 1; i <= num_to_add; i++) {
+        bool removed = set1.remove((nmethod*)i);
+        if (removed) {
+          num_popped += 1;
+        } else {
+          break;
+        }
+      }
+      assert(num_popped == num_to_add,
+          err_msg("Managed to pop "SIZE_FORMAT" code roots, but only "SIZE_FORMAT" "
+              "were added", num_popped, num_to_add));
+      assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
+
+      G1CodeRootSet::purge();
+
+      assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables");
+
+    }
+
+  }
+};
+
+void TestCodeCacheRemSet_test() {
+  G1CodeRootSetTest::test();
+}
+
+#endif