src/java.base/share/classes/jdk/internal/jimage/ImageStringsReader.java

rev 16767 : 8175561: Memory churn in jimage code affects startup after resource encapsulation changes
Reviewed-by: jlaskey
rev 16768 : imported patch imgstr_oneup

*** 36,45 ****
--- 36,47 ----
   * but also compiled and delivered as part of the jrtfs.jar to support access
   * to the jimage file provided by the shipped JDK by tools running on JDK 8.
   */
  public class ImageStringsReader implements ImageStrings {
      public static final int HASH_MULTIPLIER = 0x01000193;
+     public static final int POSITIVE_MASK = 0x7FFFFFFF;
+ 
      private final BasicImageReader reader;
  
      ImageStringsReader(BasicImageReader reader) {
          this.reader = Objects.requireNonNull(reader);
      }
*** 52,95 ****
      @Override
      public int add(final String string) {
          throw new InternalError("Can not add strings at runtime");
      }
  
!     private static int hashCode(byte[] bytes, int offset, int count, int seed) {
!         Objects.requireNonNull(bytes);
! 
!         if (offset < 0 || count < 0 || offset > bytes.length - count) {
!             throw new IndexOutOfBoundsException("offset=" + offset + ", count=" + count);
!         }
! 
!         int limit = offset + count;
! 
!         if (limit < 0 || limit > bytes.length) {
!             throw new IndexOutOfBoundsException("limit=" + limit);
!         }
! 
!         for (int i = offset; i < limit; i++) {
!             seed = (seed * HASH_MULTIPLIER) ^ (bytes[i] & 0xFF);
!         }
! 
!         return seed & 0x7FFFFFFF;
      }
  
!     public static int hashCode(byte[] bytes, int seed) {
!         return hashCode(bytes, 0, bytes.length, seed);
      }
  
!     public static int hashCode(byte[] bytes) {
!         return hashCode(bytes, 0, bytes.length, HASH_MULTIPLIER);
      }
  
!     public static int hashCode(String string) {
!         return hashCode(string, HASH_MULTIPLIER);
      }
  
!     public static int hashCode(String string, int seed) {
! 
          int slen = string.length();
          byte[] buffer = null;
  
          for (int i = 0; i < slen; i++) {
              char ch = string.charAt(i);
--- 54,84 ----
      @Override
      public int add(final String string) {
          throw new InternalError("Can not add strings at runtime");
      }
  
!     public static int hashCode(String string) {
!         return hashCode(string, HASH_MULTIPLIER);
      }
  
!     public static int hashCode(String string, int seed) {
!         return unmaskedHashCode(string, seed) & POSITIVE_MASK;
      }
  
!     public static int hashCode(String module, String string) {
!         return hashCode(module, string, HASH_MULTIPLIER);
      }
  
!     public static int hashCode(String module, String string, int seed) {
!         seed = unmaskedHashCode("/", seed);
!         seed = unmaskedHashCode(module, seed);
!         seed = unmaskedHashCode("/", seed);
!         seed = unmaskedHashCode(string, seed);
!         return seed & POSITIVE_MASK;
      }
  
!     public static int unmaskedHashCode(String string, int seed) {
          int slen = string.length();
          byte[] buffer = null;
  
          for (int i = 0; i < slen; i++) {
              char ch = string.charAt(i);
*** 118,129 ****
                  seed = (seed * HASH_MULTIPLIER) ^ (0x80);
              } else {
                  seed = (seed * HASH_MULTIPLIER) ^ (uch);
              }
          }
! 
!         return seed & 0x7FFFFFFF;
      }
  
      static int charsFromMUTF8Length(byte[] bytes, int offset, int count) {
          int length = 0;
  
--- 107,117 ----
                  seed = (seed * HASH_MULTIPLIER) ^ (0x80);
              } else {
                  seed = (seed * HASH_MULTIPLIER) ^ (uch);
              }
          }
!         return seed;
      }
  
      static int charsFromMUTF8Length(byte[] bytes, int offset, int count) {
          int length = 0;
  
*** 263,272 ****
--- 251,261 ----
      }
  
      static int mutf8FromStringLength(String s) {
          int length = 0;
          int slen = s.length();
+ 
          for (int i = 0; i < slen; i++) {
              char ch = s.charAt(i);
              int uch = ch & 0xFFFF;
  
              if ((uch & ~0x7F) != 0) {