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 /*

  * Copyright (c) 2014, 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/nmethod.hpp"

 #include "gc_implementation/g1/g1CodeCacheRemSet.hpp"

 #include "memory/iterator.hpp"

 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

 G1CodeRootChunk::G1CodeRootChunk() : _top(NULL), _next(NULL), _prev(NULL), _free(NULL) {

   _top = bottom();

 }

 void G1CodeRootChunk::reset() {

   _next = _prev = NULL;

   _free = NULL;

   _top = bottom();

 }

 void G1CodeRootChunk::nmethods_do(CodeBlobClosure* cl) {

   NmethodOrLink* cur = bottom();

   while (cur != _top) {

     if (is_nmethod(cur)) {

       cl->do_code_blob(cur->_nmethod);

     }

     cur++;

   }

 }

 bool G1CodeRootChunk::remove_lock_free(nmethod* method) {

   NmethodOrLink* cur = bottom();

   for (NmethodOrLink* cur = bottom(); cur != _top; cur++) {

     if (cur->_nmethod == method) {

       bool result = Atomic::cmpxchg_ptr(NULL, &cur->_nmethod, method) == method;

       if (!result) {

         // Someone else cleared out this entry.

         return false;

       }

       // The method was cleared. Time to link it into the free list.

       NmethodOrLink* prev_free;

       do {

         prev_free = (NmethodOrLink*)_free;

         cur->_link = prev_free;

       } while (Atomic::cmpxchg_ptr(cur, &_free, prev_free) != prev_free);

       return true;

     }

   }

   return false;

 }

 G1CodeRootChunkManager::G1CodeRootChunkManager() : _free_list(), _num_chunks_handed_out(0) {

   _free_list.initialize();

   _free_list.set_size(G1CodeRootChunk::word_size());

 }

 size_t G1CodeRootChunkManager::fl_mem_size() {

   return _free_list.count() * _free_list.size();

 }

 void G1CodeRootChunkManager::free_all_chunks(FreeList<G1CodeRootChunk>* list) {

   _num_chunks_handed_out -= list->count();

   _free_list.prepend(list);

 }

 void G1CodeRootChunkManager::free_chunk(G1CodeRootChunk* chunk) {

   _free_list.return_chunk_at_head(chunk);

   _num_chunks_handed_out--;

 }

 void G1CodeRootChunkManager::purge_chunks(size_t keep_ratio) {

   size_t keep = _num_chunks_handed_out * keep_ratio / 100;

   if (keep >= (size_t)_free_list.count()) {

     return;

   }

   FreeList<G1CodeRootChunk> temp;

   temp.initialize();

   temp.set_size(G1CodeRootChunk::word_size());

   _free_list.getFirstNChunksFromList((size_t)_free_list.count() - keep, &temp);

   G1CodeRootChunk* cur = temp.get_chunk_at_head();

   while (cur != NULL) {

     delete cur;

     cur = temp.get_chunk_at_head();

   }

 }

 size_t G1CodeRootChunkManager::static_mem_size() {

   return sizeof(G1CodeRootChunkManager);

 }

 G1CodeRootChunk* G1CodeRootChunkManager::new_chunk() {

   G1CodeRootChunk* result = _free_list.get_chunk_at_head();

   if (result == NULL) {

     result = new G1CodeRootChunk();

   }

   _num_chunks_handed_out++;

   result->reset();

   return result;

 }

 #ifndef PRODUCT

 size_t G1CodeRootChunkManager::num_chunks_handed_out() const {

   return _num_chunks_handed_out;

 }

 size_t G1CodeRootChunkManager::num_free_chunks() const {

   return (size_t)_free_list.count();

 }

 #endif

 G1CodeRootChunkManager G1CodeRootSet::_default_chunk_manager;

 void G1CodeRootSet::purge_chunks(size_t keep_ratio) {

   _default_chunk_manager.purge_chunks(keep_ratio);

 }

 size_t G1CodeRootSet::free_chunks_static_mem_size() {

   return _default_chunk_manager.static_mem_size();

 }

 size_t G1CodeRootSet::free_chunks_mem_size() {

   return _default_chunk_manager.fl_mem_size();

 }

 G1CodeRootSet::G1CodeRootSet(G1CodeRootChunkManager* manager) : _manager(manager), _list(), _length(0) {

   if (_manager == NULL) {

     _manager = &_default_chunk_manager;

   }

   _list.initialize();

   _list.set_size(G1CodeRootChunk::word_size());

 }

 G1CodeRootSet::~G1CodeRootSet() {

   clear();

 }

 void G1CodeRootSet::add(nmethod* method) {

   if (!contains(method)) {

     // Find the first chunk thatisn't full.

     G1CodeRootChunk* cur = _list.head();

     while (cur != NULL) {

       if (!cur->is_full()) {

         break;

       }

       cur = cur->next();

     }

     // All chunks are full, get a new chunk.

     if (cur == NULL) {

       cur = new_chunk();

       _list.return_chunk_at_head(cur);

     }

     // Add the nmethod.

     bool result = cur->add(method);

     guarantee(result, err_msg("Not able to add nmethod "PTR_FORMAT" to newly allocated chunk.", method));

     _length++;

   }

 }

 void G1CodeRootSet::remove_lock_free(nmethod* method) {

   G1CodeRootChunk* found = find(method);

   if (found != NULL) {

     bool result = found->remove_lock_free(method);

     if (result) {

       Atomic::dec_ptr((volatile intptr_t*)&_length);

     }

   }

   assert(!contains(method), err_msg(PTR_FORMAT" still contains nmethod "PTR_FORMAT, this, method));

 }

 nmethod* G1CodeRootSet::pop() {

   while (true) {

     G1CodeRootChunk* cur = _list.head();

     if (cur == NULL) {

       assert(_length == 0, "when there are no chunks, there should be no elements");

       return NULL;

     }

     nmethod* result = cur->pop();

     if (result != NULL) {

       _length--;

       return result;

     } else {

       free(_list.get_chunk_at_head());

     }

   }

 }

 G1CodeRootChunk* G1CodeRootSet::find(nmethod* method) {

   G1CodeRootChunk* cur = _list.head();

   while (cur != NULL) {

     if (cur->contains(method)) {

       return cur;

     }

     cur = (G1CodeRootChunk*)cur->next();

   }

   return NULL;

 }

 void G1CodeRootSet::free(G1CodeRootChunk* chunk) {

   free_chunk(chunk);

 }

 bool G1CodeRootSet::contains(nmethod* method) {

   return find(method) != NULL;

 }

 void G1CodeRootSet::clear() {

   free_all_chunks(&_list);

   _length = 0;

 }

 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {

   G1CodeRootChunk* cur = _list.head();

   while (cur != NULL) {

     cur->nmethods_do(blk);

     cur = (G1CodeRootChunk*)cur->next();

   }

 }

 size_t G1CodeRootSet::static_mem_size() {

   return sizeof(G1CodeRootSet);

 }

 size_t G1CodeRootSet::mem_size() {

   return G1CodeRootSet::static_mem_size() + _list.count() * _list.size();

 }

 #ifndef PRODUCT

 void G1CodeRootSet::test() {

   G1CodeRootChunkManager mgr;

   assert(mgr.num_chunks_handed_out() == 0, "Must not have handed out chunks yet");

   assert(G1CodeRootChunkManager::static_mem_size() > sizeof(void*),

          err_msg("The chunk manager's static memory usage seems too small, is only "SIZE_FORMAT" bytes.", G1CodeRootChunkManager::static_mem_size()));

   // The number of chunks that we allocate for purge testing.

   size_t const num_chunks = 10;

   {

     G1CodeRootSet set1(&mgr);

     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 seems too small, is only "SIZE_FORMAT" bytes", G1CodeRootSet::static_mem_size()));

     set1.add((nmethod*)1);

     assert(mgr.num_chunks_handed_out() == 1,

            err_msg("Must have allocated and handed out one chunk, but handed out "

                    SIZE_FORMAT" chunks", mgr.num_chunks_handed_out()));

     assert(set1.length() == 1, err_msg("Added exactly one element, but set contains "

                                        SIZE_FORMAT" elements", set1.length()));

     // G1CodeRootChunk::word_size() is larger than G1CodeRootChunk::num_entries which

     // we cannot access.

     for (uint i = 0; i < G1CodeRootChunk::word_size() + 1; i++) {

       set1.add((nmethod*)1);

     }

     assert(mgr.num_chunks_handed_out() == 1,

            err_msg("Duplicate detection must have prevented allocation of further "

                    "chunks but allocated "SIZE_FORMAT, mgr.num_chunks_handed_out()));

     assert(set1.length() == 1,

            err_msg("Duplicate detection should not have increased the set size but "

                    "is "SIZE_FORMAT, set1.length()));

     size_t num_total_after_add = G1CodeRootChunk::word_size() + 1;

     for (size_t i = 0; i < num_total_after_add - 1; i++) {

       set1.add((nmethod*)(uintptr_t)(2 + i));

     }

     assert(mgr.num_chunks_handed_out() > 1,

            "After adding more code roots, more than one additional chunk should have been handed out");

     assert(set1.length() == num_total_after_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_total_after_add, set1.length()));

     size_t num_popped = 0;

     while (set1.pop() != NULL) {

       num_popped++;

     }

     assert(num_popped == num_total_after_add,

            err_msg("Managed to pop "SIZE_FORMAT" code roots, but only "SIZE_FORMAT" "

                    "were added", num_popped, num_total_after_add));

     assert(mgr.num_chunks_handed_out() == 0,

            err_msg("After popping all elements, all chunks must have been returned "

                    "but there are still "SIZE_FORMAT" additional", mgr.num_chunks_handed_out()));

     mgr.purge_chunks(0);

     assert(mgr.num_free_chunks() == 0,

            err_msg("After purging everything, the free list must be empty but still "

                    "contains "SIZE_FORMAT" chunks", mgr.num_free_chunks()));

     // Add some more handed out chunks.

     size_t i = 0;

     while (mgr.num_chunks_handed_out() < num_chunks) {

       set1.add((nmethod*)i);

       i++;

     }

     {

       // Generate chunks on the free list.

       G1CodeRootSet set2(&mgr);

       size_t i = 0;

       while (mgr.num_chunks_handed_out() < (num_chunks * 2)) {

         set2.add((nmethod*)i);

         i++;

       }

       // Exit of the scope of the set2 object will call the destructor that generates

       // num_chunks elements on the free list.

     }

     assert(mgr.num_chunks_handed_out() == num_chunks,

            err_msg("Deletion of the second set must have resulted in giving back "

                    "those, but there are still "SIZE_FORMAT" additional handed out, expecting "

                    SIZE_FORMAT, mgr.num_chunks_handed_out(), num_chunks));

     assert(mgr.num_free_chunks() == num_chunks,

            err_msg("After freeing "SIZE_FORMAT" chunks, they must be on the free list "

                    "but there are only "SIZE_FORMAT, num_chunks, mgr.num_free_chunks()));

     size_t const test_percentage = 50;

     mgr.purge_chunks(test_percentage);

     assert(mgr.num_chunks_handed_out() == num_chunks,

            err_msg("Purging must not hand out chunks but there are "SIZE_FORMAT,

                    mgr.num_chunks_handed_out()));

     assert(mgr.num_free_chunks() == (size_t)(mgr.num_chunks_handed_out() * test_percentage / 100),

            err_msg("Must have purged "SIZE_FORMAT" percent of "SIZE_FORMAT" chunks"

                    "but there are "SIZE_FORMAT, test_percentage, num_chunks,

                    mgr.num_free_chunks()));

     // Purge the remainder of the chunks on the free list.

     mgr.purge_chunks(0);

     assert(mgr.num_free_chunks() == 0, "Free List must be empty");

     assert(mgr.num_chunks_handed_out() == num_chunks,

            err_msg("Expected to be "SIZE_FORMAT" chunks handed out from the first set "

                    "but there are "SIZE_FORMAT, num_chunks, mgr.num_chunks_handed_out()));

     // Exit of the scope of the set1 object will call the destructor that generates

     // num_chunks additional elements on the free list.

    }

   assert(mgr.num_chunks_handed_out() == 0,

          err_msg("Deletion of the only set must have resulted in no chunks handed "

                  "out, but there is still "SIZE_FORMAT" handed out", mgr.num_chunks_handed_out()));

   assert(mgr.num_free_chunks() == num_chunks,

          err_msg("After freeing "SIZE_FORMAT" chunks, they must be on the free list "

                  "but there are only "SIZE_FORMAT, num_chunks, mgr.num_free_chunks()));

   // Restore initial state.

   mgr.purge_chunks(0);

   assert(mgr.num_free_chunks() == 0, "Free List must be empty");

   assert(mgr.num_chunks_handed_out() == 0, "No additional elements must have been handed out yet");

 }

 void TestCodeCacheRemSet_test() {

   G1CodeRootSet::test();

 }

 #endif