jdk8-mips64-public/hotspot: src/share/vm/oops/symbol.cpp@e1162778c1c8 (annotated)

src/share/vm/oops/symbol.cpp@e1162778c1c8 (annotated)

src/share/vm/oops/symbol.cpp

Thu, 07 Apr 2011 09:53:20 -0700

author: johnc
date: Thu, 07 Apr 2011 09:53:20 -0700
changeset 2781: e1162778c1c8
parent 2497: 3582bf76420e
child 2708: 1d1603768966
permissions: -rw-r--r--

7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes

 /*
  * Copyright (c) 1997, 2009, 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.
  *
  */
 #include "precompiled.hpp"
 #include "oops/oop.inline.hpp"
 #include "oops/symbol.hpp"
 #include "runtime/os.hpp"
 #include "memory/allocation.inline.hpp"
 Symbol::Symbol(const u1* name, int length) : _refcount(0), _length(length) {
   _identity_hash = os::random();
   for (int i = 0; i < _length; i++) {
     byte_at_put(i, name[i]);
   }
 }
 void* Symbol::operator new(size_t size, int len) {
   return (void *) AllocateHeap(object_size(len) * HeapWordSize, "symbol");
 }
 // ------------------------------------------------------------------
 // Symbol::equals
 //
 // Compares the symbol with a string of the given length.
 bool Symbol::equals(const char* str, int len) const {
   int l = utf8_length();
   if (l != len) return false;
   while (l-- > 0) {
     if (str[l] != (char) byte_at(l))
       return false;
   }
   assert(l == -1, "we should be at the beginning");
   return true;
 }
 // ------------------------------------------------------------------
 // Symbol::starts_with
 //
 // Tests if the symbol starts with the specified prefix of the given
 // length.
 bool Symbol::starts_with(const char* prefix, int len) const {
   if (len > utf8_length()) return false;
   while (len-- > 0) {
     if (prefix[len] != (char) byte_at(len))
       return false;
   }
   assert(len == -1, "we should be at the beginning");
   return true;
 }
 // ------------------------------------------------------------------
 // Symbol::index_of
 //
 // Finds if the given string is a substring of this symbol's utf8 bytes.
 // Return -1 on failure.  Otherwise return the first index where str occurs.
 int Symbol::index_of_at(int i, const char* str, int len) const {
   assert(i >= 0 && i <= utf8_length(), "oob");
   if (len <= 0)  return 0;
   char first_char = str[0];
   address bytes = (address) ((Symbol*)this)->base();
   address limit = bytes + utf8_length() - len;  // inclusive limit
   address scan = bytes + i;
   if (scan > limit)
     return -1;
   for (;;) {
     scan = (address) memchr(scan, first_char, (limit + 1 - scan));
     if (scan == NULL)
       return -1;  // not found
     assert(scan >= bytes+i && scan <= limit, "scan oob");
     if (memcmp(scan, str, len) == 0)
       return (int)(scan - bytes);
   }
 }
 char* Symbol::as_C_string(char* buf, int size) const {
   if (size > 0) {
     int len = MIN2(size - 1, utf8_length());
     for (int i = 0; i < len; i++) {
       buf[i] = byte_at(i);
     }
     buf[len] = '\0';
   }
   return buf;
 }
 char* Symbol::as_C_string() const {
   int len = utf8_length();
   char* str = NEW_RESOURCE_ARRAY(char, len + 1);
   return as_C_string(str, len + 1);
 }
 char* Symbol::as_C_string_flexible_buffer(Thread* t,
                                                  char* buf, int size) const {
   char* str;
   int len = utf8_length();
   int buf_len = len + 1;
   if (size < buf_len) {
     str = NEW_RESOURCE_ARRAY(char, buf_len);
   } else {
     str = buf;
   }
   return as_C_string(str, buf_len);
 }
 void Symbol::print_symbol_on(outputStream* st) const {
   st = st ? st : tty;
   int length = UTF8::unicode_length((const char*)bytes(), utf8_length());
   const char *ptr = (const char *)bytes();
   jchar value;
   for (int index = 0; index < length; index++) {
     ptr = UTF8::next(ptr, &value);
     if (value >= 32 && value < 127 || value == '\'' || value == '\\') {
       st->put(value);
     } else {
       st->print("\\u%04x", value);
     }
   }
 }
 jchar* Symbol::as_unicode(int& length) const {
   Symbol* this_ptr = (Symbol*)this;
   length = UTF8::unicode_length((char*)this_ptr->bytes(), utf8_length());
   jchar* result = NEW_RESOURCE_ARRAY(jchar, length);
   if (length > 0) {
     UTF8::convert_to_unicode((char*)this_ptr->bytes(), result, length);
   }
   return result;
 }
 const char* Symbol::as_klass_external_name(char* buf, int size) const {
   if (size > 0) {
     char* str    = as_C_string(buf, size);
     int   length = (int)strlen(str);
     // Turn all '/'s into '.'s (also for array klasses)
     for (int index = 0; index < length; index++) {
       if (str[index] == '/') {
         str[index] = '.';
       }
     }
     return str;
   } else {
     return buf;
   }
 }
 const char* Symbol::as_klass_external_name() const {
   char* str    = as_C_string();
   int   length = (int)strlen(str);
   // Turn all '/'s into '.'s (also for array klasses)
   for (int index = 0; index < length; index++) {
     if (str[index] == '/') {
       str[index] = '.';
     }
   }
   return str;
 }
 void Symbol::print_on(outputStream* st) const {
   if (this == NULL) {
     st->print_cr("NULL");
   } else {
     st->print("Symbol: '");
     print_symbol_on(st);
     st->print("'");
     st->print(" count %d", refcount());
   }
 }
 // The print_value functions are present in all builds, to support the
 // disassembler and error reporting.
 void Symbol::print_value_on(outputStream* st) const {
   if (this == NULL) {
     st->print("NULL");
   } else {
     st->print("'");
     for (int i = 0; i < utf8_length(); i++) {
       st->print("%c", byte_at(i));
     }
     st->print("'");
   }
 }
 void Symbol::increment_refcount() {
   // Only increment the refcount if positive.  If negative either
   // overflow has occurred or it is a permanent symbol in a read only
   // shared archive.
   if (_refcount >= 0) {
     Atomic::inc(&_refcount);
     NOT_PRODUCT(Atomic::inc(&_total_count);)
   }
 }
 void Symbol::decrement_refcount() {
   if (_refcount >= 0) {
     Atomic::dec(&_refcount);
 #ifdef ASSERT
     if (_refcount < 0) {
       print();
       assert(false, "reference count underflow for symbol");
     }
 #endif
   }
 }
 NOT_PRODUCT(int Symbol::_total_count = 0;)

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/oops/symbol.cpp@e1162778c1c8 (annotated)

src/share/vm/oops/symbol.cpp