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

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

*** 57,93 ****
  
      ImageStrings getStrings() {
          return strings;
      }
  
-     private static int attributeLength(int data) {
-         return (data & 0x7) + 1;
-     }
- 
-     private static int attributeKind(int data) {
-         return data >>> 3;
-     }
- 
      static long[] decompress(ByteBuffer bytes) {
          Objects.requireNonNull(bytes);
          long[] attributes = new long[ATTRIBUTE_COUNT];
  
          if (bytes != null) {
              while (bytes.hasRemaining()) {
                  int data = bytes.get() & 0xFF;
!                 int kind = attributeKind(data);
  
                  if (kind == ATTRIBUTE_END) {
                      break;
                  }
  
                  if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {
                      throw new InternalError(
                          "Invalid jimage attribute kind: " + kind);
                  }
  
!                 int length = attributeLength(data);
                  long value = 0;
  
                  for (int j = 0; j < length; j++) {
                      value <<= 8;
  
--- 57,85 ----
  
      ImageStrings getStrings() {
          return strings;
      }
  
      static long[] decompress(ByteBuffer bytes) {
          Objects.requireNonNull(bytes);
          long[] attributes = new long[ATTRIBUTE_COUNT];
  
          if (bytes != null) {
              while (bytes.hasRemaining()) {
                  int data = bytes.get() & 0xFF;
!                 int kind = data >>> 3;
  
                  if (kind == ATTRIBUTE_END) {
                      break;
                  }
  
                  if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {
                      throw new InternalError(
                          "Invalid jimage attribute kind: " + kind);
                  }
  
!                 int length = (data & 0x7) + 1;
                  long value = 0;
  
                  for (int j = 0; j < length; j++) {
                      value <<= 8;
  
*** 126,138 ****
  
          return stream.toArray();
       }
  
      public boolean verify(String name) {
          Objects.requireNonNull(name);
  
!         return name.equals(getFullName());
      }
  
      long getAttribute(int kind) {
          if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {
              throw new InternalError(
--- 118,204 ----
  
          return stream.toArray();
       }
  
      public boolean verify(String name) {
+         return verify(name, attributes, strings);
+     }
+ 
+     /**
+      * A simpler verification would be {@code name.equals(getFullName())}, but
+      * by not creating the full name and enabling early returns we allocate
+      * fewer objects. Could possibly be made allocation free by extending
+      * ImageStrings to test if strings at an offset match the name region.
+      */
+     static boolean verify(String name, final long[] attributes,
+             final ImageStrings strings) {
          Objects.requireNonNull(name);
+         final int length = name.length();
+         int index = 0;
+         int moduleOffset = (int)attributes[ATTRIBUTE_MODULE];
+         if (moduleOffset != 0) {
+             String module = strings.get(moduleOffset);
+             final int moduleLen = module.length();
+             index = moduleLen + 1;
+             if (length <= index
+                     || name.charAt(0) != '/'
+                     || !name.regionMatches(1, module, 0, moduleLen)
+                     || name.charAt(index++) != '/') {
+                 return false;
+             }
+         }
  
!         return verifyName(name, index, length, attributes, strings);
!     }
! 
!     static boolean verify(String module, String name,
!                 final long[] attributes, final ImageStrings strings) {
!         Objects.requireNonNull(module);
!         Objects.requireNonNull(name);
!         int moduleOffset = (int)attributes[ATTRIBUTE_MODULE];
!         if (moduleOffset != 0) {
!             if (!module.equals(strings.get(moduleOffset))) {
!                 return false;
!             }
!         }
! 
!         return verifyName(name, 0, name.length(), attributes, strings);
!     }
! 
!     private static boolean verifyName(String name, int index, final int length,
!             final long[] attributes, final ImageStrings strings) {
! 
!         int parentOffset = (int) attributes[ATTRIBUTE_PARENT];
!         if (parentOffset != 0) {
!             String parent = strings.get(parentOffset);
!             final int parentLen = parent.length();
!             if (!name.regionMatches(index, parent, 0, parentLen)) {
!                 return false;
!             }
!             index += parentLen;
!             if (length <= index || name.charAt(index++) != '/') {
!                 return false;
!             }
!         }
!         String base = strings.get((int) attributes[ATTRIBUTE_BASE]);
!         final int baseLen = base.length();
!         if (!name.regionMatches(index, base, 0, baseLen)) {
!             return false;
!         }
!         index += baseLen;
!         int extOffset = (int) attributes[ATTRIBUTE_EXTENSION];
!         if (extOffset != 0) {
!             String extension = strings.get(extOffset);
!             int extLen = extension.length();
!             if (length <= index
!                     || name.charAt(index++) != '.'
!                     || !name.regionMatches(index, extension, 0, extLen)) {
!                 return false;
!             }
!             index += extLen;
!         }
!         return length == index;
      }
  
      long getAttribute(int kind) {
          if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {
              throw new InternalError(