Mercurial > hg > truffle
annotate src/share/vm/prims/jvmtiTagMap.hpp @ 1716:be3f9c242c9d
6948538: CMS: BOT walkers can fall into object allocation and initialization cracks
Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode.
Reviewed-by: chrisphi, johnc, poonam
| author | ysr |
|---|---|
| date | Mon, 16 Aug 2010 15:58:42 -0700 |
| parents | c18cbe5936b8 |
| children | f95d63e2154a |
| rev | line source |
|---|---|
| 0 | 1 /* |
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6941466: Oracle rebranding changes for Hotspot repositories
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 25 // JvmtiTagMap | |
| 26 | |
| 27 #ifndef _JAVA_JVMTI_TAG_MAP_H_ | |
| 28 #define _JAVA_JVMTI_TAG_MAP_H_ | |
| 29 | |
| 30 // forward references | |
| 31 class JvmtiTagHashmap; | |
| 32 class JvmtiTagHashmapEntry; | |
| 33 class JvmtiTagHashmapEntryClosure; | |
| 34 | |
| 35 class JvmtiTagMap : public CHeapObj { | |
| 36 private: | |
| 37 | |
| 38 enum{ | |
| 39 n_hashmaps = 2, // encapsulates 2 hashmaps | |
| 40 max_free_entries = 4096 // maximum number of free entries per env | |
| 41 }; | |
| 42 | |
| 43 // memory region for young generation | |
| 44 static MemRegion _young_gen; | |
| 45 static void get_young_generation(); | |
| 46 | |
| 47 JvmtiEnv* _env; // the jvmti environment | |
| 48 Mutex _lock; // lock for this tag map | |
| 49 JvmtiTagHashmap* _hashmap[n_hashmaps]; // the hashmaps | |
| 50 | |
| 51 JvmtiTagHashmapEntry* _free_entries; // free list for this environment | |
| 52 int _free_entries_count; // number of entries on the free list | |
| 53 | |
| 54 // create a tag map | |
| 55 JvmtiTagMap(JvmtiEnv* env); | |
| 56 | |
| 57 // accessors | |
| 58 inline Mutex* lock() { return &_lock; } | |
| 59 inline JvmtiEnv* env() const { return _env; } | |
| 60 | |
| 61 // rehash tags maps for generation start to end | |
| 62 void rehash(int start, int end); | |
| 63 | |
| 64 // indicates if the object is in the young generation | |
| 65 static bool is_in_young(oop o); | |
| 66 | |
| 67 // iterate over all entries in this tag map | |
| 68 void entry_iterate(JvmtiTagHashmapEntryClosure* closure); | |
| 69 | |
| 70 public: | |
| 71 | |
| 72 // indicates if this tag map is locked | |
| 73 bool is_locked() { return lock()->is_locked(); } | |
| 74 | |
| 75 // return the appropriate hashmap for a given object | |
| 76 JvmtiTagHashmap* hashmap_for(oop o); | |
| 77 | |
| 78 // create/destroy entries | |
| 79 JvmtiTagHashmapEntry* create_entry(jweak ref, jlong tag); | |
| 80 void destroy_entry(JvmtiTagHashmapEntry* entry); | |
| 81 | |
| 82 // returns true if the hashmaps are empty | |
| 83 bool is_empty(); | |
| 84 | |
| 85 // return tag for the given environment | |
| 86 static JvmtiTagMap* tag_map_for(JvmtiEnv* env); | |
| 87 | |
| 88 // destroy tag map | |
| 89 ~JvmtiTagMap(); | |
| 90 | |
| 91 // set/get tag | |
| 92 void set_tag(jobject obj, jlong tag); | |
| 93 jlong get_tag(jobject obj); | |
| 94 | |
| 95 // deprecated heap iteration functions | |
| 96 void iterate_over_heap(jvmtiHeapObjectFilter object_filter, | |
| 97 KlassHandle klass, | |
| 98 jvmtiHeapObjectCallback heap_object_callback, | |
| 99 const void* user_data); | |
| 100 | |
| 101 void iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback, | |
| 102 jvmtiStackReferenceCallback stack_ref_callback, | |
| 103 jvmtiObjectReferenceCallback object_ref_callback, | |
| 104 const void* user_data); | |
| 105 | |
| 106 void iterate_over_objects_reachable_from_object(jobject object, | |
| 107 jvmtiObjectReferenceCallback object_reference_callback, | |
| 108 const void* user_data); | |
| 109 | |
| 110 | |
| 111 // advanced (JVMTI 1.1) heap iteration functions | |
| 112 void iterate_through_heap(jint heap_filter, | |
| 113 KlassHandle klass, | |
| 114 const jvmtiHeapCallbacks* callbacks, | |
| 115 const void* user_data); | |
| 116 | |
| 117 void follow_references(jint heap_filter, | |
| 118 KlassHandle klass, | |
| 119 jobject initial_object, | |
| 120 const jvmtiHeapCallbacks* callbacks, | |
| 121 const void* user_data); | |
| 122 | |
| 123 // get tagged objects | |
| 124 jvmtiError get_objects_with_tags(const jlong* tags, jint count, | |
| 125 jint* count_ptr, jobject** object_result_ptr, | |
| 126 jlong** tag_result_ptr); | |
| 127 | |
| 128 // call post-GC to rehash the tag maps. | |
| 129 static void gc_epilogue(bool full); | |
| 130 | |
| 131 // call after referencing processing has completed (CMS) | |
| 132 static void cms_ref_processing_epilogue(); | |
| 133 }; | |
| 134 | |
| 135 #endif /* _JAVA_JVMTI_TAG_MAP_H_ */ |