35 
  36 bool G1StringDedup::_enabled = false;
  37 
  38 void G1StringDedup::initialize() {
  39   assert(UseG1GC, "String deduplication only available with G1");
  40   if (UseStringDeduplication) {
  41     _enabled = true;
  42     G1StringDedupQueue::create();
  43     G1StringDedupTable::create();
  44     G1StringDedupThread::create();
  45   }
  46 }
  47 
  48 void G1StringDedup::stop() {
  49   assert(is_enabled(), "String deduplication not enabled");
  50   G1StringDedupThread::stop();
  51 }
  52 
  53 bool G1StringDedup::is_candidate_from_mark(oop obj) {
  54   if (java_lang_String::is_instance_inlined(obj)) {
  55     bool from_young = G1CollectedHeap::heap()->heap_region_containing_raw(obj)->is_young();
  56     if (from_young && obj->age() < StringDeduplicationAgeThreshold) {
  57       // Candidate found. String is being evacuated from young to old but has not
  58       // reached the deduplication age threshold, i.e. has not previously been a
  59       // candidate during its life in the young generation.
  60       return true;
  61     }
  62   }
  63 
  64   // Not a candidate
  65   return false;
  66 }
  67 
  68 void G1StringDedup::enqueue_from_mark(oop java_string) {
  69   assert(is_enabled(), "String deduplication not enabled");
  70   if (is_candidate_from_mark(java_string)) {
  71     G1StringDedupQueue::push(0 /* worker_id */, java_string);
  72   }
  73 }
  74 
  75 bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {

  35 
  36 bool G1StringDedup::_enabled = false;
  37 
  38 void G1StringDedup::initialize() {
  39   assert(UseG1GC, "String deduplication only available with G1");
  40   if (UseStringDeduplication) {
  41     _enabled = true;
  42     G1StringDedupQueue::create();
  43     G1StringDedupTable::create();
  44     G1StringDedupThread::create();
  45   }
  46 }
  47 
  48 void G1StringDedup::stop() {
  49   assert(is_enabled(), "String deduplication not enabled");
  50   G1StringDedupThread::stop();
  51 }
  52 
  53 bool G1StringDedup::is_candidate_from_mark(oop obj) {
  54   if (java_lang_String::is_instance_inlined(obj)) {
  55     bool from_young = G1CollectedHeap::heap()->heap_region_containing(obj)->is_young();
  56     if (from_young && obj->age() < StringDeduplicationAgeThreshold) {
  57       // Candidate found. String is being evacuated from young to old but has not
  58       // reached the deduplication age threshold, i.e. has not previously been a
  59       // candidate during its life in the young generation.
  60       return true;
  61     }
  62   }
  63 
  64   // Not a candidate
  65   return false;
  66 }
  67 
  68 void G1StringDedup::enqueue_from_mark(oop java_string) {
  69   assert(is_enabled(), "String deduplication not enabled");
  70   if (is_candidate_from_mark(java_string)) {
  71     G1StringDedupQueue::push(0 /* worker_id */, java_string);
  72   }
  73 }
  74 
  75 bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) {