| /* |
| * Copyright (c) 1997, 2017, 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. |
| * |
| */ |
| |
| #ifndef SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP |
| #define SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP |
| |
| #include "memory/allocation.inline.hpp" |
| #include "oops/symbol.hpp" |
| #include "utilities/hashtable.hpp" |
| |
| // The symbol table holds all Symbol*s and corresponding interned strings. |
| // Symbol*s and literal strings should be canonicalized. |
| // |
| // The interned strings are created lazily. |
| // |
| // It is implemented as an open hash table with a fixed number of buckets. |
| // |
| // %note: |
| // - symbolTableEntrys are allocated in blocks to reduce the space overhead. |
| |
| class BoolObjectClosure; |
| class outputStream; |
| |
| |
| // Class to hold a newly created or referenced Symbol* temporarily in scope. |
| // new_symbol() and lookup() will create a Symbol* if not already in the |
| // symbol table and add to the symbol's reference count. |
| // probe() and lookup_only() will increment the refcount if symbol is found. |
| class TempNewSymbol : public StackObj { |
| Symbol* _temp; |
| |
| public: |
| TempNewSymbol() : _temp(NULL) {} |
| // Creating or looking up a symbol increments the symbol's reference count |
| TempNewSymbol(Symbol *s) : _temp(s) {} |
| |
| // Operator= increments reference count. |
| void operator=(const TempNewSymbol &s) { |
| //clear(); //FIXME |
| _temp = s._temp; |
| if (_temp !=NULL) _temp->increment_refcount(); |
| } |
| |
| // Decrement reference counter so it can go away if it's unique |
| void clear() { if (_temp != NULL) _temp->decrement_refcount(); _temp = NULL; } |
| |
| ~TempNewSymbol() { clear(); } |
| |
| // Operators so they can be used like Symbols |
| Symbol* operator -> () const { return _temp; } |
| bool operator == (Symbol* o) const { return _temp == o; } |
| // Sneaky conversion function |
| operator Symbol*() { return _temp; } |
| }; |
| |
| class SymbolTable : public RehashableHashtable<Symbol*, mtSymbol> { |
| friend class VMStructs; |
| friend class ClassFileParser; |
| |
| private: |
| // The symbol table |
| static SymbolTable* _the_table; |
| |
| // Set if one bucket is out of balance due to hash algorithm deficiency |
| static bool _needs_rehashing; |
| |
| // For statistics |
| static int _symbols_removed; |
| static int _symbols_counted; |
| |
| Symbol* allocate_symbol(const u1* name, int len, bool c_heap, TRAPS); // Assumes no characters larger than 0x7F |
| |
| // Adding elements |
| Symbol* basic_add(int index, u1* name, int len, unsigned int hashValue, |
| bool c_heap, TRAPS); |
| bool basic_add(ClassLoaderData* loader_data, |
| constantPoolHandle cp, int names_count, |
| const char** names, int* lengths, int* cp_indices, |
| unsigned int* hashValues, TRAPS); |
| |
| static void new_symbols(ClassLoaderData* loader_data, |
| constantPoolHandle cp, int names_count, |
| const char** name, int* lengths, |
| int* cp_indices, unsigned int* hashValues, |
| TRAPS) { |
| add(loader_data, cp, names_count, name, lengths, cp_indices, hashValues, THREAD); |
| } |
| |
| Symbol* lookup(int index, const char* name, int len, unsigned int hash); |
| |
| SymbolTable() |
| : RehashableHashtable<Symbol*, mtSymbol>(SymbolTableSize, sizeof (HashtableEntry<Symbol*, mtSymbol>)) {} |
| |
| SymbolTable(HashtableBucket<mtSymbol>* t, int number_of_entries) |
| : RehashableHashtable<Symbol*, mtSymbol>(SymbolTableSize, sizeof (HashtableEntry<Symbol*, mtSymbol>), t, |
| number_of_entries) {} |
| |
| // Arena for permanent symbols (null class loader) that are never unloaded |
| static Arena* _arena; |
| static Arena* arena() { return _arena; } // called for statistics |
| |
| static void initialize_symbols(int arena_alloc_size = 0); |
| |
| static volatile int _parallel_claimed_idx; |
| |
| typedef SymbolTable::BucketUnlinkContext BucketUnlinkContext; |
| // Release any dead symbols. Unlinked bucket entries are collected in the given |
| // context to be freed later. |
| // This allows multiple threads to work on the table at once. |
| static void buckets_unlink(int start_idx, int end_idx, BucketUnlinkContext* context, size_t* memory_total); |
| public: |
| enum { |
| symbol_alloc_batch_size = 8, |
| // Pick initial size based on java -version size measurements |
| symbol_alloc_arena_size = 360*K |
| }; |
| |
| // The symbol table |
| static SymbolTable* the_table() { return _the_table; } |
| |
| // Size of one bucket in the string table. Used when checking for rollover. |
| static uint bucket_size() { return sizeof(HashtableBucket<mtSymbol>); } |
| |
| static void create_table() { |
| assert(_the_table == NULL, "One symbol table allowed."); |
| _the_table = new SymbolTable(); |
| initialize_symbols(symbol_alloc_arena_size); |
| } |
| |
| static void create_table(HashtableBucket<mtSymbol>* t, int length, |
| int number_of_entries) { |
| assert(_the_table == NULL, "One symbol table allowed."); |
| |
| // If CDS archive used a different symbol table size, use that size instead |
| // which is better than giving an error. |
| SymbolTableSize = length/bucket_size(); |
| |
| _the_table = new SymbolTable(t, number_of_entries); |
| // if CDS give symbol table a default arena size since most symbols |
| // are already allocated in the shared misc section. |
| initialize_symbols(); |
| } |
| |
| static unsigned int hash_symbol(const char* s, int len); |
| |
| static Symbol* lookup(const char* name, int len, TRAPS); |
| // lookup only, won't add. Also calculate hash. |
| static Symbol* lookup_only(const char* name, int len, unsigned int& hash); |
| // Only copy to C string to be added if lookup failed. |
| static Symbol* lookup(const Symbol* sym, int begin, int end, TRAPS); |
| |
| static void release(Symbol* sym); |
| |
| // Look up the address of the literal in the SymbolTable for this Symbol* |
| static Symbol** lookup_symbol_addr(Symbol* sym); |
| |
| // jchar (utf16) version of lookups |
| static Symbol* lookup_unicode(const jchar* name, int len, TRAPS); |
| static Symbol* lookup_only_unicode(const jchar* name, int len, unsigned int& hash); |
| |
| static void add(ClassLoaderData* loader_data, |
| constantPoolHandle cp, int names_count, |
| const char** names, int* lengths, int* cp_indices, |
| unsigned int* hashValues, TRAPS); |
| |
| // Release any dead symbols |
| static void unlink() { |
| int processed = 0; |
| int removed = 0; |
| unlink(&processed, &removed); |
| } |
| static void unlink(int* processed, int* removed); |
| // Release any dead symbols, possibly parallel version |
| static void possibly_parallel_unlink(int* processed, int* removed); |
| |
| // iterate over symbols |
| static void symbols_do(SymbolClosure *cl); |
| |
| // Symbol creation |
| static Symbol* new_symbol(const char* utf8_buffer, int length, TRAPS) { |
| assert(utf8_buffer != NULL, "just checking"); |
| return lookup(utf8_buffer, length, THREAD); |
| } |
| static Symbol* new_symbol(const char* name, TRAPS) { |
| return new_symbol(name, (int)strlen(name), THREAD); |
| } |
| static Symbol* new_symbol(const Symbol* sym, int begin, int end, TRAPS) { |
| assert(begin <= end && end <= sym->utf8_length(), "just checking"); |
| return lookup(sym, begin, end, THREAD); |
| } |
| |
| // Create a symbol in the arena for symbols that are not deleted |
| static Symbol* new_permanent_symbol(const char* name, TRAPS); |
| |
| // Symbol lookup |
| static Symbol* lookup(int index, const char* name, int len, TRAPS); |
| |
| // Needed for preloading classes in signatures when compiling. |
| // Returns the symbol is already present in symbol table, otherwise |
| // NULL. NO ALLOCATION IS GUARANTEED! |
| static Symbol* probe(const char* name, int len) { |
| unsigned int ignore_hash; |
| return lookup_only(name, len, ignore_hash); |
| } |
| static Symbol* probe_unicode(const jchar* name, int len) { |
| unsigned int ignore_hash; |
| return lookup_only_unicode(name, len, ignore_hash); |
| } |
| |
| // Histogram |
| static void print_histogram() PRODUCT_RETURN; |
| static void print() PRODUCT_RETURN; |
| |
| // Debugging |
| static void verify(); |
| static void dump(outputStream* st); |
| |
| // Sharing |
| static void copy_buckets(char** top, char*end) { |
| the_table()->Hashtable<Symbol*, mtSymbol>::copy_buckets(top, end); |
| } |
| static void copy_table(char** top, char*end) { |
| the_table()->Hashtable<Symbol*, mtSymbol>::copy_table(top, end); |
| } |
| static void reverse(void* boundary = NULL) { |
| the_table()->Hashtable<Symbol*, mtSymbol>::reverse(boundary); |
| } |
| |
| // Rehash the symbol table if it gets out of balance |
| static void rehash_table(); |
| static bool needs_rehashing() { return _needs_rehashing; } |
| // Parallel chunked scanning |
| static void clear_parallel_claimed_index() { _parallel_claimed_idx = 0; } |
| static int parallel_claimed_index() { return _parallel_claimed_idx; } |
| }; |
| |
| class StringTable : public RehashableHashtable<oop, mtSymbol> { |
| friend class VMStructs; |
| |
| private: |
| // The string table |
| static StringTable* _the_table; |
| |
| // Set if one bucket is out of balance due to hash algorithm deficiency |
| static bool _needs_rehashing; |
| |
| // Claimed high water mark for parallel chunked scanning |
| static volatile int _parallel_claimed_idx; |
| |
| static oop intern(Handle string_or_null, jchar* chars, int length, TRAPS); |
| oop basic_add(int index, Handle string_or_null, jchar* name, int len, |
| unsigned int hashValue, TRAPS); |
| |
| oop lookup(int index, jchar* chars, int length, unsigned int hashValue); |
| |
| // Apply the give oop closure to the entries to the buckets |
| // in the range [start_idx, end_idx). |
| static void buckets_oops_do(OopClosure* f, int start_idx, int end_idx); |
| |
| typedef StringTable::BucketUnlinkContext BucketUnlinkContext; |
| // Unlink or apply the give oop closure to the entries to the buckets |
| // in the range [start_idx, end_idx). Unlinked bucket entries are collected in the given |
| // context to be freed later. |
| // This allows multiple threads to work on the table at once. |
| static void buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, BucketUnlinkContext* context); |
| |
| StringTable() : RehashableHashtable<oop, mtSymbol>((int)StringTableSize, |
| sizeof (HashtableEntry<oop, mtSymbol>)) {} |
| |
| StringTable(HashtableBucket<mtSymbol>* t, int number_of_entries) |
| : RehashableHashtable<oop, mtSymbol>((int)StringTableSize, sizeof (HashtableEntry<oop, mtSymbol>), t, |
| number_of_entries) {} |
| public: |
| // The string table |
| static StringTable* the_table() { return _the_table; } |
| |
| // Size of one bucket in the string table. Used when checking for rollover. |
| static uint bucket_size() { return sizeof(HashtableBucket<mtSymbol>); } |
| |
| static void create_table() { |
| assert(_the_table == NULL, "One string table allowed."); |
| _the_table = new StringTable(); |
| } |
| |
| // GC support |
| // Delete pointers to otherwise-unreachable objects. |
| static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f) { |
| int processed = 0; |
| int removed = 0; |
| unlink_or_oops_do(cl, f, &processed, &removed); |
| } |
| static void unlink(BoolObjectClosure* cl) { |
| int processed = 0; |
| int removed = 0; |
| unlink_or_oops_do(cl, NULL, &processed, &removed); |
| } |
| static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f, int* processed, int* removed); |
| static void unlink(BoolObjectClosure* cl, int* processed, int* removed) { |
| unlink_or_oops_do(cl, NULL, processed, removed); |
| } |
| // Serially invoke "f->do_oop" on the locations of all oops in the table. |
| static void oops_do(OopClosure* f); |
| |
| // Possibly parallel versions of the above |
| static void possibly_parallel_unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f, int* processed, int* removed); |
| static void possibly_parallel_unlink(BoolObjectClosure* cl, int* processed, int* removed) { |
| possibly_parallel_unlink_or_oops_do(cl, NULL, processed, removed); |
| } |
| static void possibly_parallel_oops_do(OopClosure* f); |
| |
| // Hashing algorithm, used as the hash value used by the |
| // StringTable for bucket selection and comparison (stored in the |
| // HashtableEntry structures). This is used in the String.intern() method. |
| static unsigned int hash_string(const jchar* s, int len); |
| |
| // Internal test. |
| static void test_alt_hash() PRODUCT_RETURN; |
| |
| // Probing |
| static oop lookup(Symbol* symbol); |
| static oop lookup(jchar* chars, int length); |
| |
| // Interning |
| static oop intern(Symbol* symbol, TRAPS); |
| static oop intern(oop string, TRAPS); |
| static oop intern(const char *utf8_string, TRAPS); |
| |
| // Debugging |
| static void verify(); |
| static void dump(outputStream* st); |
| |
| enum VerifyMesgModes { |
| _verify_quietly = 0, |
| _verify_with_mesgs = 1 |
| }; |
| |
| enum VerifyRetTypes { |
| _verify_pass = 0, |
| _verify_fail_continue = 1, |
| _verify_fail_done = 2 |
| }; |
| |
| static VerifyRetTypes compare_entries(int bkt1, int e_cnt1, |
| HashtableEntry<oop, mtSymbol>* e_ptr1, |
| int bkt2, int e_cnt2, |
| HashtableEntry<oop, mtSymbol>* e_ptr2); |
| static VerifyRetTypes verify_entry(int bkt, int e_cnt, |
| HashtableEntry<oop, mtSymbol>* e_ptr, |
| VerifyMesgModes mesg_mode); |
| static int verify_and_compare_entries(); |
| |
| // Sharing |
| static void copy_buckets(char** top, char*end) { |
| the_table()->Hashtable<oop, mtSymbol>::copy_buckets(top, end); |
| } |
| static void copy_table(char** top, char*end) { |
| the_table()->Hashtable<oop, mtSymbol>::copy_table(top, end); |
| } |
| static void reverse() { |
| the_table()->Hashtable<oop, mtSymbol>::reverse(); |
| } |
| |
| // Rehash the symbol table if it gets out of balance |
| static void rehash_table(); |
| static bool needs_rehashing() { return _needs_rehashing; } |
| |
| // Parallel chunked scanning |
| static void clear_parallel_claimed_index() { _parallel_claimed_idx = 0; } |
| static int parallel_claimed_index() { return _parallel_claimed_idx; } |
| }; |
| #endif // SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP |