6990754: Use native memory and reference counting to implement SymbolTable

Move symbols from permgen into C heap and reference count them

Reviewed-by: never, acorn, jmasa, stefank

hotspot/src/share/vm/oops/symbol.cpp

@@ -0,0 +1,231 @@
+/*
+ * 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;)