aoqi@0: /*
vkempik@8452:  * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "classfile/altHashing.hpp"
aoqi@0: #include "classfile/javaClasses.hpp"
aoqi@0: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
aoqi@0: #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
aoqi@0: #include "gc_implementation/g1/g1StringDedupTable.hpp"
vkempik@8452: #include "gc_implementation/shared/concurrentGCThread.hpp"
aoqi@0: #include "memory/gcLocker.hpp"
aoqi@0: #include "memory/padded.inline.hpp"
aoqi@0: #include "oops/typeArrayOop.hpp"
aoqi@0: #include "runtime/mutexLocker.hpp"
aoqi@0: 
aoqi@0: //
vkempik@8452: // List of deduplication table entries. Links table
aoqi@0: // entries together using their _next fields.
aoqi@0: //
vkempik@8452: class G1StringDedupEntryList : public CHeapObj<mtGC> {
aoqi@0: private:
aoqi@0:   G1StringDedupEntry* _list;
aoqi@0:   size_t              _length;
aoqi@0: 
aoqi@0: public:
vkempik@8452:   G1StringDedupEntryList() :
aoqi@0:     _list(NULL),
aoqi@0:     _length(0) {
aoqi@0:   }
aoqi@0: 
aoqi@0:   void add(G1StringDedupEntry* entry) {
aoqi@0:     entry->set_next(_list);
aoqi@0:     _list = entry;
aoqi@0:     _length++;
aoqi@0:   }
aoqi@0: 
aoqi@0:   G1StringDedupEntry* remove() {
aoqi@0:     G1StringDedupEntry* entry = _list;
aoqi@0:     if (entry != NULL) {
aoqi@0:       _list = entry->next();
aoqi@0:       _length--;
aoqi@0:     }
aoqi@0:     return entry;
aoqi@0:   }
aoqi@0: 
vkempik@8452:   G1StringDedupEntry* remove_all() {
vkempik@8452:     G1StringDedupEntry* list = _list;
vkempik@8452:     _list = NULL;
vkempik@8452:     return list;
vkempik@8452:   }
vkempik@8452: 
aoqi@0:   size_t length() {
aoqi@0:     return _length;
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: //
aoqi@0: // Cache of deduplication table entries. This cache provides fast allocation and
aoqi@0: // reuse of table entries to lower the pressure on the underlying allocator.
aoqi@0: // But more importantly, it provides fast/deferred freeing of table entries. This
aoqi@0: // is important because freeing of table entries is done during stop-the-world
aoqi@0: // phases and it is not uncommon for large number of entries to be freed at once.
aoqi@0: // Tables entries that are freed during these phases are placed onto a freelist in
aoqi@0: // the cache. The deduplication thread, which executes in a concurrent phase, will
aoqi@0: // later reuse or free the underlying memory for these entries.
aoqi@0: //
aoqi@0: // The cache allows for single-threaded allocations and multi-threaded frees.
aoqi@0: // Allocations are synchronized by StringDedupTable_lock as part of a table
aoqi@0: // modification.
aoqi@0: //
aoqi@0: class G1StringDedupEntryCache : public CHeapObj<mtGC> {
aoqi@0: private:
vkempik@8452:   // One cache/overflow list per GC worker to allow lock less freeing of
vkempik@8452:   // entries while doing a parallel scan of the table. Using PaddedEnd to
vkempik@8452:   // avoid false sharing.
vkempik@8452:   size_t                             _nlists;
vkempik@8452:   size_t                             _max_list_length;
vkempik@8452:   PaddedEnd<G1StringDedupEntryList>* _cached;
vkempik@8452:   PaddedEnd<G1StringDedupEntryList>* _overflowed;
aoqi@0: 
aoqi@0: public:
vkempik@8452:   G1StringDedupEntryCache(size_t max_size);
aoqi@0:   ~G1StringDedupEntryCache();
aoqi@0: 
vkempik@8452:   // Set max number of table entries to cache.
vkempik@8452:   void set_max_size(size_t max_size);
vkempik@8452: 
vkempik@8452:   // Get a table entry from the cache, or allocate a new entry if the cache is empty.
aoqi@0:   G1StringDedupEntry* alloc();
aoqi@0: 
vkempik@8452:   // Insert a table entry into the cache.
aoqi@0:   void free(G1StringDedupEntry* entry, uint worker_id);
aoqi@0: 
aoqi@0:   // Returns current number of entries in the cache.
aoqi@0:   size_t size();
aoqi@0: 
vkempik@8452:   // Deletes overflowed entries.
vkempik@8452:   void delete_overflowed();
aoqi@0: };
aoqi@0: 
vkempik@8452: G1StringDedupEntryCache::G1StringDedupEntryCache(size_t max_size) :
vkempik@8452:   _nlists(MAX2(ParallelGCThreads, (size_t)1)),
vkempik@8452:   _max_list_length(0),
vkempik@8452:   _cached(PaddedArray<G1StringDedupEntryList, mtGC>::create_unfreeable((uint)_nlists)),
vkempik@8452:   _overflowed(PaddedArray<G1StringDedupEntryList, mtGC>::create_unfreeable((uint)_nlists)) {
vkempik@8452:   set_max_size(max_size);
aoqi@0: }
aoqi@0: 
aoqi@0: G1StringDedupEntryCache::~G1StringDedupEntryCache() {
aoqi@0:   ShouldNotReachHere();
aoqi@0: }
aoqi@0: 
vkempik@8452: void G1StringDedupEntryCache::set_max_size(size_t size) {
vkempik@8452:   _max_list_length = size / _nlists;
vkempik@8452: }
vkempik@8452: 
aoqi@0: G1StringDedupEntry* G1StringDedupEntryCache::alloc() {
aoqi@0:   for (size_t i = 0; i < _nlists; i++) {
vkempik@8452:     G1StringDedupEntry* entry = _cached[i].remove();
aoqi@0:     if (entry != NULL) {
aoqi@0:       return entry;
aoqi@0:     }
aoqi@0:   }
aoqi@0:   return new G1StringDedupEntry();
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupEntryCache::free(G1StringDedupEntry* entry, uint worker_id) {
aoqi@0:   assert(entry->obj() != NULL, "Double free");
aoqi@0:   assert(worker_id < _nlists, "Invalid worker id");
vkempik@8452: 
aoqi@0:   entry->set_obj(NULL);
vkempik@10009:   entry->set_hash(0);
vkempik@8452: 
vkempik@8452:   if (_cached[worker_id].length() < _max_list_length) {
vkempik@8452:     // Cache is not full
vkempik@8452:     _cached[worker_id].add(entry);
vkempik@8452:   } else {
vkempik@8452:     // Cache is full, add to overflow list for later deletion
vkempik@8452:     _overflowed[worker_id].add(entry);
vkempik@8452:   }
aoqi@0: }
aoqi@0: 
aoqi@0: size_t G1StringDedupEntryCache::size() {
aoqi@0:   size_t size = 0;
aoqi@0:   for (size_t i = 0; i < _nlists; i++) {
vkempik@8452:     size += _cached[i].length();
aoqi@0:   }
aoqi@0:   return size;
aoqi@0: }
aoqi@0: 
vkempik@8452: void G1StringDedupEntryCache::delete_overflowed() {
vkempik@8452:   double start = os::elapsedTime();
vkempik@8452:   uintx count = 0;
vkempik@8452: 
aoqi@0:   for (size_t i = 0; i < _nlists; i++) {
vkempik@8452:     G1StringDedupEntry* entry;
vkempik@8452: 
vkempik@8452:     {
vkempik@8452:       // The overflow list can be modified during safepoints, therefore
vkempik@8452:       // we temporarily join the suspendible thread set while removing
vkempik@8452:       // all entries from the list.
vkempik@8452:       SuspendibleThreadSetJoiner sts_join;
vkempik@8452:       entry = _overflowed[i].remove_all();
vkempik@8452:     }
vkempik@8452: 
vkempik@8452:     // Delete all entries
vkempik@8452:     while (entry != NULL) {
vkempik@8452:       G1StringDedupEntry* next = entry->next();
aoqi@0:       delete entry;
vkempik@8452:       entry = next;
vkempik@8452:       count++;
aoqi@0:     }
aoqi@0:   }
vkempik@8452: 
vkempik@8452:   double end = os::elapsedTime();
vkempik@8452:   if (PrintStringDeduplicationStatistics) {
vkempik@8452:     gclog_or_tty->print_cr("[GC concurrent-string-deduplication, deleted " UINTX_FORMAT " entries, " G1_STRDEDUP_TIME_FORMAT "]", count, end - start);
vkempik@8452:   }
aoqi@0: }
aoqi@0: 
aoqi@0: G1StringDedupTable*      G1StringDedupTable::_table = NULL;
aoqi@0: G1StringDedupEntryCache* G1StringDedupTable::_entry_cache = NULL;
aoqi@0: 
aoqi@0: const size_t             G1StringDedupTable::_min_size = (1 << 10);   // 1024
aoqi@0: const size_t             G1StringDedupTable::_max_size = (1 << 24);   // 16777216
aoqi@0: const double             G1StringDedupTable::_grow_load_factor = 2.0; // Grow table at 200% load
aoqi@0: const double             G1StringDedupTable::_shrink_load_factor = _grow_load_factor / 3.0; // Shrink table at 67% load
aoqi@0: const double             G1StringDedupTable::_max_cache_factor = 0.1; // Cache a maximum of 10% of the table size
aoqi@0: const uintx              G1StringDedupTable::_rehash_multiple = 60;   // Hash bucket has 60 times more collisions than expected
aoqi@0: const uintx              G1StringDedupTable::_rehash_threshold = (uintx)(_rehash_multiple * _grow_load_factor);
aoqi@0: 
aoqi@0: uintx                    G1StringDedupTable::_entries_added = 0;
aoqi@0: uintx                    G1StringDedupTable::_entries_removed = 0;
aoqi@0: uintx                    G1StringDedupTable::_resize_count = 0;
aoqi@0: uintx                    G1StringDedupTable::_rehash_count = 0;
aoqi@0: 
vkempik@10008: G1StringDedupTable::G1StringDedupTable(size_t size, uint64_t hash_seed) :
aoqi@0:   _size(size),
aoqi@0:   _entries(0),
aoqi@0:   _grow_threshold((uintx)(size * _grow_load_factor)),
aoqi@0:   _shrink_threshold((uintx)(size * _shrink_load_factor)),
aoqi@0:   _rehash_needed(false),
aoqi@0:   _hash_seed(hash_seed) {
aoqi@0:   assert(is_power_of_2(size), "Table size must be a power of 2");
aoqi@0:   _buckets = NEW_C_HEAP_ARRAY(G1StringDedupEntry*, _size, mtGC);
aoqi@0:   memset(_buckets, 0, _size * sizeof(G1StringDedupEntry*));
aoqi@0: }
aoqi@0: 
aoqi@0: G1StringDedupTable::~G1StringDedupTable() {
aoqi@0:   FREE_C_HEAP_ARRAY(G1StringDedupEntry*, _buckets, mtGC);
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::create() {
aoqi@0:   assert(_table == NULL, "One string deduplication table allowed");
vkempik@8452:   _entry_cache = new G1StringDedupEntryCache((size_t)(_min_size * _max_cache_factor));
aoqi@0:   _table = new G1StringDedupTable(_min_size);
aoqi@0: }
aoqi@0: 
vkempik@10009: void G1StringDedupTable::add(typeArrayOop value, unsigned int hash, G1StringDedupEntry** list) {
aoqi@0:   G1StringDedupEntry* entry = _entry_cache->alloc();
aoqi@0:   entry->set_obj(value);
vkempik@10009:   entry->set_hash(hash);
aoqi@0:   entry->set_next(*list);
aoqi@0:   *list = entry;
aoqi@0:   _entries++;
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::remove(G1StringDedupEntry** pentry, uint worker_id) {
aoqi@0:   G1StringDedupEntry* entry = *pentry;
aoqi@0:   *pentry = entry->next();
aoqi@0:   _entry_cache->free(entry, worker_id);
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::transfer(G1StringDedupEntry** pentry, G1StringDedupTable* dest) {
aoqi@0:   G1StringDedupEntry* entry = *pentry;
aoqi@0:   *pentry = entry->next();
vkempik@10009:   unsigned int hash = entry->hash();
aoqi@0:   size_t index = dest->hash_to_index(hash);
aoqi@0:   G1StringDedupEntry** list = dest->bucket(index);
aoqi@0:   entry->set_next(*list);
aoqi@0:   *list = entry;
aoqi@0: }
aoqi@0: 
aoqi@0: bool G1StringDedupTable::equals(typeArrayOop value1, typeArrayOop value2) {
aoqi@0:   return (value1 == value2 ||
aoqi@0:           (value1->length() == value2->length() &&
aoqi@0:            (!memcmp(value1->base(T_CHAR),
aoqi@0:                     value2->base(T_CHAR),
aoqi@0:                     value1->length() * sizeof(jchar)))));
aoqi@0: }
aoqi@0: 
vkempik@10009: typeArrayOop G1StringDedupTable::lookup(typeArrayOop value, unsigned int hash,
aoqi@0:                                         G1StringDedupEntry** list, uintx &count) {
aoqi@0:   for (G1StringDedupEntry* entry = *list; entry != NULL; entry = entry->next()) {
vkempik@10009:     if (entry->hash() == hash) {
aoqi@0:       typeArrayOop existing_value = entry->obj();
aoqi@0:       if (equals(value, existing_value)) {
aoqi@0:         // Match found
aoqi@0:         return existing_value;
aoqi@0:       }
aoqi@0:     }
aoqi@0:     count++;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Not found
aoqi@0:   return NULL;
aoqi@0: }
aoqi@0: 
vkempik@10009: typeArrayOop G1StringDedupTable::lookup_or_add_inner(typeArrayOop value, unsigned int hash) {
aoqi@0:   size_t index = hash_to_index(hash);
aoqi@0:   G1StringDedupEntry** list = bucket(index);
aoqi@0:   uintx count = 0;
aoqi@0: 
aoqi@0:   // Lookup in list
aoqi@0:   typeArrayOop existing_value = lookup(value, hash, list, count);
aoqi@0: 
aoqi@0:   // Check if rehash is needed
aoqi@0:   if (count > _rehash_threshold) {
aoqi@0:     _rehash_needed = true;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (existing_value == NULL) {
aoqi@0:     // Not found, add new entry
aoqi@0:     add(value, hash, list);
aoqi@0: 
aoqi@0:     // Update statistics
aoqi@0:     _entries_added++;
aoqi@0:   }
aoqi@0: 
aoqi@0:   return existing_value;
aoqi@0: }
aoqi@0: 
vkempik@10009: unsigned int G1StringDedupTable::hash_code(typeArrayOop value) {
aoqi@0:   unsigned int hash;
aoqi@0:   int length = value->length();
aoqi@0:   const jchar* data = (jchar*)value->base(T_CHAR);
aoqi@0: 
vkempik@10009:   if (use_java_hash()) {
vkempik@10009:     hash = java_lang_String::hash_code(data, length);
vkempik@10009:   } else {
vkempik@10009:     hash = AltHashing::halfsiphash_32(_table->_hash_seed, (const uint16_t*)data, length);
vkempik@10009:   }
aoqi@0:   return hash;
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::deduplicate(oop java_string, G1StringDedupStat& stat) {
aoqi@0:   assert(java_lang_String::is_instance(java_string), "Must be a string");
aoqi@0:   No_Safepoint_Verifier nsv;
aoqi@0: 
aoqi@0:   stat.inc_inspected();
aoqi@0: 
aoqi@0:   typeArrayOop value = java_lang_String::value(java_string);
aoqi@0:   if (value == NULL) {
aoqi@0:     // String has no value
aoqi@0:     stat.inc_skipped();
aoqi@0:     return;
aoqi@0:   }
aoqi@0: 
vkempik@10009:   unsigned int hash = 0;
aoqi@0: 
aoqi@0:   if (use_java_hash()) {
aoqi@0:     // Get hash code from cache
aoqi@0:     hash = java_lang_String::hash(java_string);
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (hash == 0) {
aoqi@0:     // Compute hash
vkempik@10009:     hash = hash_code(value);
aoqi@0:     stat.inc_hashed();
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (use_java_hash() && hash != 0) {
aoqi@0:     // Store hash code in cache
aoqi@0:     java_lang_String::set_hash(java_string, hash);
aoqi@0:   }
aoqi@0: 
aoqi@0:   typeArrayOop existing_value = lookup_or_add(value, hash);
aoqi@0:   if (existing_value == value) {
aoqi@0:     // Same value, already known
aoqi@0:     stat.inc_known();
aoqi@0:     return;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Get size of value array
aoqi@0:   uintx size_in_bytes = value->size() * HeapWordSize;
aoqi@0:   stat.inc_new(size_in_bytes);
aoqi@0: 
aoqi@0:   if (existing_value != NULL) {
aoqi@0:     // Enqueue the reference to make sure it is kept alive. Concurrent mark might
aoqi@0:     // otherwise declare it dead if there are no other strong references to this object.
aoqi@0:     G1SATBCardTableModRefBS::enqueue(existing_value);
aoqi@0: 
aoqi@0:     // Existing value found, deduplicate string
aoqi@0:     java_lang_String::set_value(java_string, existing_value);
aoqi@0: 
aoqi@0:     if (G1CollectedHeap::heap()->is_in_young(value)) {
aoqi@0:       stat.inc_deduped_young(size_in_bytes);
aoqi@0:     } else {
aoqi@0:       stat.inc_deduped_old(size_in_bytes);
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: G1StringDedupTable* G1StringDedupTable::prepare_resize() {
aoqi@0:   size_t size = _table->_size;
aoqi@0: 
aoqi@0:   // Check if the hashtable needs to be resized
aoqi@0:   if (_table->_entries > _table->_grow_threshold) {
aoqi@0:     // Grow table, double the size
aoqi@0:     size *= 2;
aoqi@0:     if (size > _max_size) {
aoqi@0:       // Too big, don't resize
aoqi@0:       return NULL;
aoqi@0:     }
aoqi@0:   } else if (_table->_entries < _table->_shrink_threshold) {
aoqi@0:     // Shrink table, half the size
aoqi@0:     size /= 2;
aoqi@0:     if (size < _min_size) {
aoqi@0:       // Too small, don't resize
aoqi@0:       return NULL;
aoqi@0:     }
aoqi@0:   } else if (StringDeduplicationResizeALot) {
aoqi@0:     // Force grow
aoqi@0:     size *= 2;
aoqi@0:     if (size > _max_size) {
aoqi@0:       // Too big, force shrink instead
aoqi@0:       size /= 4;
aoqi@0:     }
aoqi@0:   } else {
aoqi@0:     // Resize not needed
aoqi@0:     return NULL;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Update statistics
aoqi@0:   _resize_count++;
aoqi@0: 
vkempik@8452:   // Update max cache size
vkempik@8452:   _entry_cache->set_max_size((size_t)(size * _max_cache_factor));
vkempik@8452: 
aoqi@0:   // Allocate the new table. The new table will be populated by workers
aoqi@0:   // calling unlink_or_oops_do() and finally installed by finish_resize().
aoqi@0:   return new G1StringDedupTable(size, _table->_hash_seed);
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::finish_resize(G1StringDedupTable* resized_table) {
aoqi@0:   assert(resized_table != NULL, "Invalid table");
aoqi@0: 
aoqi@0:   resized_table->_entries = _table->_entries;
aoqi@0: 
aoqi@0:   // Free old table
aoqi@0:   delete _table;
aoqi@0: 
aoqi@0:   // Install new table
aoqi@0:   _table = resized_table;
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl, uint worker_id) {
aoqi@0:   // The table is divided into partitions to allow lock-less parallel processing by
aoqi@0:   // multiple worker threads. A worker thread first claims a partition, which ensures
aoqi@0:   // exclusive access to that part of the table, then continues to process it. To allow
aoqi@0:   // shrinking of the table in parallel we also need to make sure that the same worker
aoqi@0:   // thread processes all partitions where entries will hash to the same destination
aoqi@0:   // partition. Since the table size is always a power of two and we always shrink by
aoqi@0:   // dividing the table in half, we know that for a given partition there is only one
aoqi@0:   // other partition whoes entries will hash to the same destination partition. That
aoqi@0:   // other partition is always the sibling partition in the second half of the table.
aoqi@0:   // For example, if the table is divided into 8 partitions, the sibling of partition 0
aoqi@0:   // is partition 4, the sibling of partition 1 is partition 5, etc.
aoqi@0:   size_t table_half = _table->_size / 2;
aoqi@0: 
aoqi@0:   // Let each partition be one page worth of buckets
aoqi@0:   size_t partition_size = MIN2(table_half, os::vm_page_size() / sizeof(G1StringDedupEntry*));
aoqi@0:   assert(table_half % partition_size == 0, "Invalid partition size");
aoqi@0: 
aoqi@0:   // Number of entries removed during the scan
aoqi@0:   uintx removed = 0;
aoqi@0: 
aoqi@0:   for (;;) {
aoqi@0:     // Grab next partition to scan
aoqi@0:     size_t partition_begin = cl->claim_table_partition(partition_size);
aoqi@0:     size_t partition_end = partition_begin + partition_size;
aoqi@0:     if (partition_begin >= table_half) {
aoqi@0:       // End of table
aoqi@0:       break;
aoqi@0:     }
aoqi@0: 
aoqi@0:     // Scan the partition followed by the sibling partition in the second half of the table
aoqi@0:     removed += unlink_or_oops_do(cl, partition_begin, partition_end, worker_id);
aoqi@0:     removed += unlink_or_oops_do(cl, table_half + partition_begin, table_half + partition_end, worker_id);
aoqi@0:   }
aoqi@0: 
vkempik@8452:   // Delayed update to avoid contention on the table lock
aoqi@0:   if (removed > 0) {
aoqi@0:     MutexLockerEx ml(StringDedupTable_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:     _table->_entries -= removed;
aoqi@0:     _entries_removed += removed;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: uintx G1StringDedupTable::unlink_or_oops_do(G1StringDedupUnlinkOrOopsDoClosure* cl,
aoqi@0:                                             size_t partition_begin,
aoqi@0:                                             size_t partition_end,
aoqi@0:                                             uint worker_id) {
aoqi@0:   uintx removed = 0;
aoqi@0:   for (size_t bucket = partition_begin; bucket < partition_end; bucket++) {
aoqi@0:     G1StringDedupEntry** entry = _table->bucket(bucket);
aoqi@0:     while (*entry != NULL) {
aoqi@0:       oop* p = (oop*)(*entry)->obj_addr();
aoqi@0:       if (cl->is_alive(*p)) {
aoqi@0:         cl->keep_alive(p);
aoqi@0:         if (cl->is_resizing()) {
aoqi@0:           // We are resizing the table, transfer entry to the new table
aoqi@0:           _table->transfer(entry, cl->resized_table());
aoqi@0:         } else {
aoqi@0:           if (cl->is_rehashing()) {
aoqi@0:             // We are rehashing the table, rehash the entry but keep it
aoqi@0:             // in the table. We can't transfer entries into the new table
aoqi@0:             // at this point since we don't have exclusive access to all
aoqi@0:             // destination partitions. finish_rehash() will do a single
aoqi@0:             // threaded transfer of all entries.
aoqi@0:             typeArrayOop value = (typeArrayOop)*p;
vkempik@10009:             unsigned int hash = hash_code(value);
vkempik@10009:             (*entry)->set_hash(hash);
aoqi@0:           }
aoqi@0: 
aoqi@0:           // Move to next entry
aoqi@0:           entry = (*entry)->next_addr();
aoqi@0:         }
aoqi@0:       } else {
aoqi@0:         // Not alive, remove entry from table
aoqi@0:         _table->remove(entry, worker_id);
aoqi@0:         removed++;
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   return removed;
aoqi@0: }
aoqi@0: 
aoqi@0: G1StringDedupTable* G1StringDedupTable::prepare_rehash() {
aoqi@0:   if (!_table->_rehash_needed && !StringDeduplicationRehashALot) {
aoqi@0:     // Rehash not needed
aoqi@0:     return NULL;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Update statistics
aoqi@0:   _rehash_count++;
aoqi@0: 
aoqi@0:   // Compute new hash seed
aoqi@0:   _table->_hash_seed = AltHashing::compute_seed();
aoqi@0: 
aoqi@0:   // Allocate the new table, same size and hash seed
aoqi@0:   return new G1StringDedupTable(_table->_size, _table->_hash_seed);
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::finish_rehash(G1StringDedupTable* rehashed_table) {
aoqi@0:   assert(rehashed_table != NULL, "Invalid table");
aoqi@0: 
aoqi@0:   // Move all newly rehashed entries into the correct buckets in the new table
aoqi@0:   for (size_t bucket = 0; bucket < _table->_size; bucket++) {
aoqi@0:     G1StringDedupEntry** entry = _table->bucket(bucket);
aoqi@0:     while (*entry != NULL) {
aoqi@0:       _table->transfer(entry, rehashed_table);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   rehashed_table->_entries = _table->_entries;
aoqi@0: 
aoqi@0:   // Free old table
aoqi@0:   delete _table;
aoqi@0: 
aoqi@0:   // Install new table
aoqi@0:   _table = rehashed_table;
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::verify() {
aoqi@0:   for (size_t bucket = 0; bucket < _table->_size; bucket++) {
aoqi@0:     // Verify entries
aoqi@0:     G1StringDedupEntry** entry = _table->bucket(bucket);
aoqi@0:     while (*entry != NULL) {
aoqi@0:       typeArrayOop value = (*entry)->obj();
aoqi@0:       guarantee(value != NULL, "Object must not be NULL");
aoqi@0:       guarantee(Universe::heap()->is_in_reserved(value), "Object must be on the heap");
aoqi@0:       guarantee(!value->is_forwarded(), "Object must not be forwarded");
aoqi@0:       guarantee(value->is_typeArray(), "Object must be a typeArrayOop");
vkempik@10009:       unsigned int hash = hash_code(value);
vkempik@10009:       guarantee((*entry)->hash() == hash, "Table entry has inorrect hash");
aoqi@0:       guarantee(_table->hash_to_index(hash) == bucket, "Table entry has incorrect index");
aoqi@0:       entry = (*entry)->next_addr();
aoqi@0:     }
aoqi@0: 
aoqi@0:     // Verify that we do not have entries with identical oops or identical arrays.
aoqi@0:     // We only need to compare entries in the same bucket. If the same oop or an
aoqi@0:     // identical array has been inserted more than once into different/incorrect
aoqi@0:     // buckets the verification step above will catch that.
aoqi@0:     G1StringDedupEntry** entry1 = _table->bucket(bucket);
aoqi@0:     while (*entry1 != NULL) {
aoqi@0:       typeArrayOop value1 = (*entry1)->obj();
aoqi@0:       G1StringDedupEntry** entry2 = (*entry1)->next_addr();
aoqi@0:       while (*entry2 != NULL) {
aoqi@0:         typeArrayOop value2 = (*entry2)->obj();
vkempik@10009:         guarantee(!equals(value1, value2), "Table entries must not have identical arrays");
aoqi@0:         entry2 = (*entry2)->next_addr();
aoqi@0:       }
aoqi@0:       entry1 = (*entry1)->next_addr();
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
vkempik@8452: void G1StringDedupTable::clean_entry_cache() {
vkempik@8452:   _entry_cache->delete_overflowed();
aoqi@0: }
aoqi@0: 
aoqi@0: void G1StringDedupTable::print_statistics(outputStream* st) {
aoqi@0:   st->print_cr(
aoqi@0:     "   [Table]\n"
kevinw@9327:     "      [Memory Usage: " G1_STRDEDUP_BYTES_FORMAT_NS "]\n"
kevinw@9327:     "      [Size: " SIZE_FORMAT ", Min: " SIZE_FORMAT ", Max: " SIZE_FORMAT "]\n"
kevinw@9327:     "      [Entries: " UINTX_FORMAT ", Load: " G1_STRDEDUP_PERCENT_FORMAT_NS ", Cached: " UINTX_FORMAT ", Added: " UINTX_FORMAT ", Removed: " UINTX_FORMAT "]\n"
kevinw@9327:     "      [Resize Count: " UINTX_FORMAT ", Shrink Threshold: " UINTX_FORMAT "(" G1_STRDEDUP_PERCENT_FORMAT_NS "), Grow Threshold: " UINTX_FORMAT "(" G1_STRDEDUP_PERCENT_FORMAT_NS ")]\n"
vkempik@10009:     "      [Rehash Count: " UINTX_FORMAT ", Rehash Threshold: " UINTX_FORMAT ", Hash Seed: " UINT64_FORMAT "]\n"
kevinw@9327:     "      [Age Threshold: " UINTX_FORMAT "]",
aoqi@0:     G1_STRDEDUP_BYTES_PARAM(_table->_size * sizeof(G1StringDedupEntry*) + (_table->_entries + _entry_cache->size()) * sizeof(G1StringDedupEntry)),
aoqi@0:     _table->_size, _min_size, _max_size,
aoqi@0:     _table->_entries, (double)_table->_entries / (double)_table->_size * 100.0, _entry_cache->size(), _entries_added, _entries_removed,
aoqi@0:     _resize_count, _table->_shrink_threshold, _shrink_load_factor * 100.0, _table->_grow_threshold, _grow_load_factor * 100.0,
aoqi@0:     _rehash_count, _rehash_threshold, _table->_hash_seed,
aoqi@0:     StringDeduplicationAgeThreshold);
aoqi@0: }