jdk8-mips64-public/hotspot: src/share/vm/classfile/symbolTable.hpp@01522ca68fc7 (annotated)

src/share/vm/classfile/symbolTable.hpp@01522ca68fc7 (annotated)

src/share/vm/classfile/symbolTable.hpp

Tue, 18 Jun 2013 12:31:07 -0700

author: johnc
date: Tue, 18 Jun 2013 12:31:07 -0700
changeset 5277: 01522ca68fc7
parent 5196: 8dbc025ff709
child 5743: 63147986a428
permissions: -rw-r--r--

8015237: Parallelize string table scanning during strong root processing
Summary: Parallelize the scanning of the intern string table by having each GC worker claim a given number of buckets. Changes were also reviewed by Per Liden <per.liden@oracle.com>.
Reviewed-by: tschatzl, stefank, twisti

 /*
  * Copyright (c) 1997, 2013, 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 Hashtable<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);
   }
   // Table size
   enum {
     symbol_table_size = 20011
   };
   Symbol* lookup(int index, const char* name, int len, unsigned int hash);
   SymbolTable()
     : Hashtable<Symbol*, mtSymbol>(symbol_table_size, sizeof (HashtableEntry<Symbol*, mtSymbol>)) {}
   SymbolTable(HashtableBucket<mtSymbol>* t, int number_of_entries)
     : Hashtable<Symbol*, mtSymbol>(symbol_table_size, 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);
 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; }
   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.");
     assert(length == symbol_table_size * sizeof(HashtableBucket<mtSymbol>),
            "bad shared symbol 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();
   // 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; }
 };
 class StringTable : public Hashtable<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_do(OopClosure* f, int start_idx, int end_idx);
   StringTable() : Hashtable<oop, mtSymbol>((int)StringTableSize,
                               sizeof (HashtableEntry<oop, mtSymbol>)) {}
   StringTable(HashtableBucket<mtSymbol>* t, int number_of_entries)
     : Hashtable<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);
   static void unlink(BoolObjectClosure* cl) {
     unlink_or_oops_do(cl, NULL);
   }
   // Serially invoke "f->do_oop" on the locations of all oops in the table.
   static void oops_do(OopClosure* f);
   // Possibly parallel version of the above
   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);
   // 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; }
 };
 #endif // SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/classfile/symbolTable.hpp@01522ca68fc7 (annotated)

src/share/vm/classfile/symbolTable.hpp