Fri, 07 Jan 2011 10:42:32 -0500
7003271: Hotspot should track cumulative Java heap bytes allocated on a per-thread basis
Summary: Track allocated bytes in Thread's, update on TLAB retirement and direct allocation in Eden and tenured, add JNI methods for ThreadMXBean.
Reviewed-by: coleenp, kvn, dholmes, ysr
1 /*
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25 #ifndef SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
26 #define SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
28 #include "jvmtifiles/jvmtiEnv.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/objArrayKlass.hpp"
32 #include "oops/objArrayOop.hpp"
33 #include "prims/jvmtiRedefineClassesTrace.hpp"
34 #include "runtime/vm_operations.hpp"
36 // Introduction:
37 //
38 // The RedefineClasses() API is used to change the definition of one or
39 // more classes. While the API supports redefining more than one class
40 // in a single call, in general, the API is discussed in the context of
41 // changing the definition of a single current class to a single new
42 // class. For clarity, the current class is will always be called
43 // "the_class" and the new class will always be called "scratch_class".
44 //
45 // The name "the_class" is used because there is only one structure
46 // that represents a specific class; redefinition does not replace the
47 // structure, but instead replaces parts of the structure. The name
48 // "scratch_class" is used because the structure that represents the
49 // new definition of a specific class is simply used to carry around
50 // the parts of the new definition until they are used to replace the
51 // appropriate parts in the_class. Once redefinition of a class is
52 // complete, scratch_class is thrown away.
53 //
54 //
55 // Implementation Overview:
56 //
57 // The RedefineClasses() API is mostly a wrapper around the VM op that
58 // does the real work. The work is split in varying degrees between
59 // doit_prologue(), doit() and doit_epilogue().
60 //
61 // 1) doit_prologue() is called by the JavaThread on the way to a
62 // safepoint. It does parameter verification and loads scratch_class
63 // which involves:
64 // - parsing the incoming class definition using the_class' class
65 // loader and security context
66 // - linking scratch_class
67 // - merging constant pools and rewriting bytecodes as needed
68 // for the merged constant pool
69 // - verifying the bytecodes in scratch_class
70 // - setting up the constant pool cache and rewriting bytecodes
71 // as needed to use the cache
72 // - finally, scratch_class is compared to the_class to verify
73 // that it is a valid replacement class
74 // - if everything is good, then scratch_class is saved in an
75 // instance field in the VM operation for the doit() call
76 //
77 // Note: A JavaThread must do the above work.
78 //
79 // 2) doit() is called by the VMThread during a safepoint. It installs
80 // the new class definition(s) which involves:
81 // - retrieving the scratch_class from the instance field in the
82 // VM operation
83 // - house keeping (flushing breakpoints and caches, deoptimizing
84 // dependent compiled code)
85 // - replacing parts in the_class with parts from scratch_class
86 // - adding weak reference(s) to track the obsolete but interesting
87 // parts of the_class
88 // - adjusting constant pool caches and vtables in other classes
89 // that refer to methods in the_class. These adjustments use the
90 // SystemDictionary::classes_do() facility which only allows
91 // a helper method to be specified. The interesting parameters
92 // that we would like to pass to the helper method are saved in
93 // static global fields in the VM operation.
94 // - telling the SystemDictionary to notice our changes
95 //
96 // Note: the above work must be done by the VMThread to be safe.
97 //
98 // 3) doit_epilogue() is called by the JavaThread after the VM op
99 // is finished and the safepoint is done. It simply cleans up
100 // memory allocated in doit_prologue() and used in doit().
101 //
102 //
103 // Constant Pool Details:
104 //
105 // When the_class is redefined, we cannot just replace the constant
106 // pool in the_class with the constant pool from scratch_class because
107 // that could confuse obsolete methods that may still be running.
108 // Instead, the constant pool from the_class, old_cp, is merged with
109 // the constant pool from scratch_class, scratch_cp. The resulting
110 // constant pool, merge_cp, replaces old_cp in the_class.
111 //
112 // The key part of any merging algorithm is the entry comparison
113 // function so we have to know the types of entries in a constant pool
114 // in order to merge two of them together. Constant pools can contain
115 // up to 12 different kinds of entries; the JVM_CONSTANT_Unicode entry
116 // is not presently used so we only have to worry about the other 11
117 // entry types. For the purposes of constant pool merging, it is
118 // helpful to know that the 11 entry types fall into 3 different
119 // subtypes: "direct", "indirect" and "double-indirect".
120 //
121 // Direct CP entries contain data and do not contain references to
122 // other CP entries. The following are direct CP entries:
123 // JVM_CONSTANT_{Double,Float,Integer,Long,Utf8}
124 //
125 // Indirect CP entries contain 1 or 2 references to a direct CP entry
126 // and no other data. The following are indirect CP entries:
127 // JVM_CONSTANT_{Class,NameAndType,String}
128 //
129 // Double-indirect CP entries contain two references to indirect CP
130 // entries and no other data. The following are double-indirect CP
131 // entries:
132 // JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref}
133 //
134 // When comparing entries between two constant pools, the entry types
135 // are compared first and if they match, then further comparisons are
136 // made depending on the entry subtype. Comparing direct CP entries is
137 // simply a matter of comparing the data associated with each entry.
138 // Comparing both indirect and double-indirect CP entries requires
139 // recursion.
140 //
141 // Fortunately, the recursive combinations are limited because indirect
142 // CP entries can only refer to direct CP entries and double-indirect
143 // CP entries can only refer to indirect CP entries. The following is
144 // an example illustration of the deepest set of indirections needed to
145 // access the data associated with a JVM_CONSTANT_Fieldref entry:
146 //
147 // JVM_CONSTANT_Fieldref {
148 // class_index => JVM_CONSTANT_Class {
149 // name_index => JVM_CONSTANT_Utf8 {
150 // <data-1>
151 // }
152 // }
153 // name_and_type_index => JVM_CONSTANT_NameAndType {
154 // name_index => JVM_CONSTANT_Utf8 {
155 // <data-2>
156 // }
157 // descriptor_index => JVM_CONSTANT_Utf8 {
158 // <data-3>
159 // }
160 // }
161 // }
162 //
163 // The above illustration is not a data structure definition for any
164 // computer language. The curly braces ('{' and '}') are meant to
165 // delimit the context of the "fields" in the CP entry types shown.
166 // Each indirection from the JVM_CONSTANT_Fieldref entry is shown via
167 // "=>", e.g., the class_index is used to indirectly reference a
168 // JVM_CONSTANT_Class entry where the name_index is used to indirectly
169 // reference a JVM_CONSTANT_Utf8 entry which contains the interesting
170 // <data-1>. In order to understand a JVM_CONSTANT_Fieldref entry, we
171 // have to do a total of 5 indirections just to get to the CP entries
172 // that contain the interesting pieces of data and then we have to
173 // fetch the three pieces of data. This means we have to do a total of
174 // (5 + 3) * 2 == 16 dereferences to compare two JVM_CONSTANT_Fieldref
175 // entries.
176 //
177 // Here is the indirection, data and dereference count for each entry
178 // type:
179 //
180 // JVM_CONSTANT_Class 1 indir, 1 data, 2 derefs
181 // JVM_CONSTANT_Double 0 indir, 1 data, 1 deref
182 // JVM_CONSTANT_Fieldref 2 indir, 3 data, 8 derefs
183 // JVM_CONSTANT_Float 0 indir, 1 data, 1 deref
184 // JVM_CONSTANT_Integer 0 indir, 1 data, 1 deref
185 // JVM_CONSTANT_InterfaceMethodref 2 indir, 3 data, 8 derefs
186 // JVM_CONSTANT_Long 0 indir, 1 data, 1 deref
187 // JVM_CONSTANT_Methodref 2 indir, 3 data, 8 derefs
188 // JVM_CONSTANT_NameAndType 1 indir, 2 data, 4 derefs
189 // JVM_CONSTANT_String 1 indir, 1 data, 2 derefs
190 // JVM_CONSTANT_Utf8 0 indir, 1 data, 1 deref
191 //
192 // So different subtypes of CP entries require different amounts of
193 // work for a proper comparison.
194 //
195 // Now that we've talked about the different entry types and how to
196 // compare them we need to get back to merging. This is not a merge in
197 // the "sort -u" sense or even in the "sort" sense. When we merge two
198 // constant pools, we copy all the entries from old_cp to merge_cp,
199 // preserving entry order. Next we append all the unique entries from
200 // scratch_cp to merge_cp and we track the index changes from the
201 // location in scratch_cp to the possibly new location in merge_cp.
202 // When we are done, any obsolete code that is still running that
203 // uses old_cp should not be able to observe any difference if it
204 // were to use merge_cp. As for the new code in scratch_class, it is
205 // modified to use the appropriate index values in merge_cp before it
206 // is used to replace the code in the_class.
207 //
208 // There is one small complication in copying the entries from old_cp
209 // to merge_cp. Two of the CP entry types are special in that they are
210 // lazily resolved. Before explaining the copying complication, we need
211 // to digress into CP entry resolution.
212 //
213 // JVM_CONSTANT_Class and JVM_CONSTANT_String entries are present in
214 // the class file, but are not stored in memory as such until they are
215 // resolved. The entries are not resolved unless they are used because
216 // resolution is expensive. During class file parsing the entries are
217 // initially stored in memory as JVM_CONSTANT_ClassIndex and
218 // JVM_CONSTANT_StringIndex entries. These special CP entry types
219 // indicate that the JVM_CONSTANT_Class and JVM_CONSTANT_String entries
220 // have been parsed, but the index values in the entries have not been
221 // validated. After the entire constant pool has been parsed, the index
222 // values can be validated and then the entries are converted into
223 // JVM_CONSTANT_UnresolvedClass and JVM_CONSTANT_UnresolvedString
224 // entries. During this conversion process, the UTF8 values that are
225 // indirectly referenced by the JVM_CONSTANT_ClassIndex and
226 // JVM_CONSTANT_StringIndex entries are changed into symbolOops and the
227 // entries are modified to refer to the symbolOops. This optimization
228 // eliminates one level of indirection for those two CP entry types and
229 // gets the entries ready for verification. During class file parsing
230 // it is also possible for JVM_CONSTANT_UnresolvedString entries to be
231 // resolved into JVM_CONSTANT_String entries. Verification expects to
232 // find JVM_CONSTANT_UnresolvedClass and either JVM_CONSTANT_String or
233 // JVM_CONSTANT_UnresolvedString entries and not JVM_CONSTANT_Class
234 // entries.
235 //
236 // Now we can get back to the copying complication. When we copy
237 // entries from old_cp to merge_cp, we have to revert any
238 // JVM_CONSTANT_Class entries to JVM_CONSTANT_UnresolvedClass entries
239 // or verification will fail.
240 //
241 // It is important to explicitly state that the merging algorithm
242 // effectively unresolves JVM_CONSTANT_Class entries that were in the
243 // old_cp when they are changed into JVM_CONSTANT_UnresolvedClass
244 // entries in the merge_cp. This is done both to make verification
245 // happy and to avoid adding more brittleness between RedefineClasses
246 // and the constant pool cache. By allowing the constant pool cache
247 // implementation to (re)resolve JVM_CONSTANT_UnresolvedClass entries
248 // into JVM_CONSTANT_Class entries, we avoid having to embed knowledge
249 // about those algorithms in RedefineClasses.
250 //
251 // Appending unique entries from scratch_cp to merge_cp is straight
252 // forward for direct CP entries and most indirect CP entries. For the
253 // indirect CP entry type JVM_CONSTANT_NameAndType and for the double-
254 // indirect CP entry types, the presence of more than one piece of
255 // interesting data makes appending the entries more complicated.
256 //
257 // For the JVM_CONSTANT_{Double,Float,Integer,Long,Utf8} entry types,
258 // the entry is simply copied from scratch_cp to the end of merge_cp.
259 // If the index in scratch_cp is different than the destination index
260 // in merge_cp, then the change in index value is tracked.
261 //
262 // Note: the above discussion for the direct CP entries also applies
263 // to the JVM_CONSTANT_Unresolved{Class,String} entry types.
264 //
265 // For the JVM_CONSTANT_{Class,String} entry types, since there is only
266 // one data element at the end of the recursion, we know that we have
267 // either one or two unique entries. If the JVM_CONSTANT_Utf8 entry is
268 // unique then it is appended to merge_cp before the current entry.
269 // If the JVM_CONSTANT_Utf8 entry is not unique, then the current entry
270 // is updated to refer to the duplicate entry in merge_cp before it is
271 // appended to merge_cp. Again, any changes in index values are tracked
272 // as needed.
273 //
274 // Note: the above discussion for JVM_CONSTANT_{Class,String} entry
275 // types is theoretical. Since those entry types have already been
276 // optimized into JVM_CONSTANT_Unresolved{Class,String} entry types,
277 // they are handled as direct CP entries.
278 //
279 // For the JVM_CONSTANT_NameAndType entry type, since there are two
280 // data elements at the end of the recursions, we know that we have
281 // between one and three unique entries. Any unique JVM_CONSTANT_Utf8
282 // entries are appended to merge_cp before the current entry. For any
283 // JVM_CONSTANT_Utf8 entries that are not unique, the current entry is
284 // updated to refer to the duplicate entry in merge_cp before it is
285 // appended to merge_cp. Again, any changes in index values are tracked
286 // as needed.
287 //
288 // For the JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref} entry
289 // types, since there are two indirect CP entries and three data
290 // elements at the end of the recursions, we know that we have between
291 // one and six unique entries. See the JVM_CONSTANT_Fieldref diagram
292 // above for an example of all six entries. The uniqueness algorithm
293 // for the JVM_CONSTANT_Class and JVM_CONSTANT_NameAndType entries is
294 // covered above. Any unique entries are appended to merge_cp before
295 // the current entry. For any entries that are not unique, the current
296 // entry is updated to refer to the duplicate entry in merge_cp before
297 // it is appended to merge_cp. Again, any changes in index values are
298 // tracked as needed.
299 //
300 //
301 // Other Details:
302 //
303 // Details for other parts of RedefineClasses need to be written.
304 // This is a placeholder section.
305 //
306 //
307 // Open Issues (in no particular order):
308 //
309 // - How do we serialize the RedefineClasses() API without deadlocking?
310 //
311 // - SystemDictionary::parse_stream() was called with a NULL protection
312 // domain since the initial version. This has been changed to pass
313 // the_class->protection_domain(). This change has been tested with
314 // all NSK tests and nothing broke, but what will adding it now break
315 // in ways that we don't test?
316 //
317 // - GenerateOopMap::rewrite_load_or_store() has a comment in its
318 // (indirect) use of the Relocator class that the max instruction
319 // size is 4 bytes. goto_w and jsr_w are 5 bytes and wide/iinc is
320 // 6 bytes. Perhaps Relocator only needs a 4 byte buffer to do
321 // what it does to the bytecodes. More investigation is needed.
322 //
323 // - java.lang.Object methods can be called on arrays. This is
324 // implemented via the arrayKlassOop vtable which we don't
325 // update. For example, if we redefine java.lang.Object.toString(),
326 // then the new version of the method will not be called for array
327 // objects.
328 //
329 // - How do we know if redefine_single_class() and the guts of
330 // instanceKlass are out of sync? I don't think this can be
331 // automated, but we should probably order the work in
332 // redefine_single_class() to match the order of field
333 // definitions in instanceKlass. We also need to add some
334 // comments about keeping things in sync.
335 //
336 // - set_new_constant_pool() is huge and we should consider refactoring
337 // it into smaller chunks of work.
338 //
339 // - The exception table update code in set_new_constant_pool() defines
340 // const values that are also defined in a local context elsewhere.
341 // The same literal values are also used in elsewhere. We need to
342 // coordinate a cleanup of these constants with Runtime.
343 //
345 class VM_RedefineClasses: public VM_Operation {
346 private:
347 // These static fields are needed by SystemDictionary::classes_do()
348 // facility and the adjust_cpool_cache_and_vtable() helper:
349 static objArrayOop _old_methods;
350 static objArrayOop _new_methods;
351 static methodOop* _matching_old_methods;
352 static methodOop* _matching_new_methods;
353 static methodOop* _deleted_methods;
354 static methodOop* _added_methods;
355 static int _matching_methods_length;
356 static int _deleted_methods_length;
357 static int _added_methods_length;
358 static klassOop _the_class_oop;
360 // The instance fields are used to pass information from
361 // doit_prologue() to doit() and doit_epilogue().
362 jint _class_count;
363 const jvmtiClassDefinition *_class_defs; // ptr to _class_count defs
365 // This operation is used by both RedefineClasses and
366 // RetransformClasses. Indicate which.
367 JvmtiClassLoadKind _class_load_kind;
369 // _index_map_count is just an optimization for knowing if
370 // _index_map_p contains any entries.
371 int _index_map_count;
372 intArray * _index_map_p;
373 // ptr to _class_count scratch_classes
374 instanceKlassHandle * _scratch_classes;
375 jvmtiError _res;
377 // Performance measurement support. These timers do not cover all
378 // the work done for JVM/TI RedefineClasses() but they do cover
379 // the heavy lifting.
380 elapsedTimer _timer_rsc_phase1;
381 elapsedTimer _timer_rsc_phase2;
382 elapsedTimer _timer_vm_op_prologue;
384 // These routines are roughly in call order unless otherwise noted.
386 // Load the caller's new class definition(s) into _scratch_classes.
387 // Constant pool merging work is done here as needed. Also calls
388 // compare_and_normalize_class_versions() to verify the class
389 // definition(s).
390 jvmtiError load_new_class_versions(TRAPS);
392 // Verify that the caller provided class definition(s) that meet
393 // the restrictions of RedefineClasses. Normalize the order of
394 // overloaded methods as needed.
395 jvmtiError compare_and_normalize_class_versions(
396 instanceKlassHandle the_class, instanceKlassHandle scratch_class);
398 // Swap annotations[i] with annotations[j]
399 // Used by compare_and_normalize_class_versions() when normalizing
400 // overloaded methods or changing idnum as when adding or deleting methods.
401 void swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class);
403 // Figure out which new methods match old methods in name and signature,
404 // which methods have been added, and which are no longer present
405 void compute_added_deleted_matching_methods();
407 // Change jmethodIDs to point to the new methods
408 void update_jmethod_ids();
410 // In addition to marking methods as obsolete, this routine
411 // records which methods are EMCP (Equivalent Module Constant
412 // Pool) in the emcp_methods BitMap and returns the number of
413 // EMCP methods via emcp_method_count_p. This information is
414 // used when information about the previous version of the_class
415 // is squirreled away.
416 void check_methods_and_mark_as_obsolete(BitMap *emcp_methods,
417 int * emcp_method_count_p);
418 void transfer_old_native_function_registrations(instanceKlassHandle the_class);
420 // Unevolving classes may point to methods of the_class directly
421 // from their constant pool caches, itables, and/or vtables. We
422 // use the SystemDictionary::classes_do() facility and this helper
423 // to fix up these pointers.
424 static void adjust_cpool_cache_and_vtable(klassOop k_oop, oop loader, TRAPS);
426 // Install the redefinition of a class
427 void redefine_single_class(jclass the_jclass,
428 instanceKlassHandle scratch_class, TRAPS);
430 // Increment the classRedefinedCount field in the specific instanceKlass
431 // and in all direct and indirect subclasses.
432 void increment_class_counter(instanceKlass *ik, TRAPS);
434 // Support for constant pool merging (these routines are in alpha
435 // order):
436 void append_entry(constantPoolHandle scratch_cp, int scratch_i,
437 constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
438 int find_new_index(int old_index);
439 bool is_unresolved_class_mismatch(constantPoolHandle cp1, int index1,
440 constantPoolHandle cp2, int index2);
441 bool is_unresolved_string_mismatch(constantPoolHandle cp1, int index1,
442 constantPoolHandle cp2, int index2);
443 void map_index(constantPoolHandle scratch_cp, int old_index, int new_index);
444 bool merge_constant_pools(constantPoolHandle old_cp,
445 constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
446 int *merge_cp_length_p, TRAPS);
447 jvmtiError merge_cp_and_rewrite(instanceKlassHandle the_class,
448 instanceKlassHandle scratch_class, TRAPS);
449 u2 rewrite_cp_ref_in_annotation_data(
450 typeArrayHandle annotations_typeArray, int &byte_i_ref,
451 const char * trace_mesg, TRAPS);
452 bool rewrite_cp_refs(instanceKlassHandle scratch_class, TRAPS);
453 bool rewrite_cp_refs_in_annotation_struct(
454 typeArrayHandle class_annotations, int &byte_i_ref, TRAPS);
455 bool rewrite_cp_refs_in_annotations_typeArray(
456 typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS);
457 bool rewrite_cp_refs_in_class_annotations(
458 instanceKlassHandle scratch_class, TRAPS);
459 bool rewrite_cp_refs_in_element_value(
460 typeArrayHandle class_annotations, int &byte_i_ref, TRAPS);
461 bool rewrite_cp_refs_in_fields_annotations(
462 instanceKlassHandle scratch_class, TRAPS);
463 void rewrite_cp_refs_in_method(methodHandle method,
464 methodHandle * new_method_p, TRAPS);
465 bool rewrite_cp_refs_in_methods(instanceKlassHandle scratch_class, TRAPS);
466 bool rewrite_cp_refs_in_methods_annotations(
467 instanceKlassHandle scratch_class, TRAPS);
468 bool rewrite_cp_refs_in_methods_default_annotations(
469 instanceKlassHandle scratch_class, TRAPS);
470 bool rewrite_cp_refs_in_methods_parameter_annotations(
471 instanceKlassHandle scratch_class, TRAPS);
472 void rewrite_cp_refs_in_stack_map_table(methodHandle method, TRAPS);
473 void rewrite_cp_refs_in_verification_type_info(
474 address& stackmap_addr_ref, address stackmap_end, u2 frame_i,
475 u1 frame_size, TRAPS);
476 void set_new_constant_pool(instanceKlassHandle scratch_class,
477 constantPoolHandle scratch_cp, int scratch_cp_length, bool shrink, TRAPS);
479 void flush_dependent_code(instanceKlassHandle k_h, TRAPS);
481 static void check_class(klassOop k_oop, oop initiating_loader, TRAPS) PRODUCT_RETURN;
483 static void dump_methods() PRODUCT_RETURN;
485 public:
486 VM_RedefineClasses(jint class_count,
487 const jvmtiClassDefinition *class_defs,
488 JvmtiClassLoadKind class_load_kind);
489 VMOp_Type type() const { return VMOp_RedefineClasses; }
490 bool doit_prologue();
491 void doit();
492 void doit_epilogue();
494 bool allow_nested_vm_operations() const { return true; }
495 jvmtiError check_error() { return _res; }
497 // Modifiable test must be shared between IsModifiableClass query
498 // and redefine implementation
499 static bool is_modifiable_class(oop klass_mirror);
500 };
502 #endif // SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP