src/java.base/share/classes/java/io/ObjectStreamField.java

rev 17455 : 8184603: Create ObjectStreamField signature lazily when possible
Reviewed-by: rriggs, chegar, alanb, shade

*** 43,62 ****
      implements Comparable<Object>
  {
  
      /** field name */
      private final String name;
!     /** canonical JVM signature of field type */
      private final String signature;
      /** field type (Object.class if unknown non-primitive type) */
      private final Class<?> type;
      /** whether or not to (de)serialize field values as unshared */
      private final boolean unshared;
      /** corresponding reflective field object, if any */
      private final Field field;
      /** offset of field value in enclosing field group */
!     private int offset = 0;
  
      /**
       * Create a Serializable field with the specified type.  This field should
       * be documented with a <code>serialField</code> tag.
       *
--- 43,64 ----
      implements Comparable<Object>
  {
  
      /** field name */
      private final String name;
!     /** canonical JVM signature of field type, if given */
      private final String signature;
      /** field type (Object.class if unknown non-primitive type) */
      private final Class<?> type;
+     /** lazily constructed signature for the type, if no explicit signature */
+     private String typeSignature;
      /** whether or not to (de)serialize field values as unshared */
      private final boolean unshared;
      /** corresponding reflective field object, if any */
      private final Field field;
      /** offset of field value in enclosing field group */
!     private int offset;
  
      /**
       * Create a Serializable field with the specified type.  This field should
       * be documented with a <code>serialField</code> tag.
       *
*** 89,100 ****
              throw new NullPointerException();
          }
          this.name = name;
          this.type = type;
          this.unshared = unshared;
!         signature = getClassSignature(type).intern();
!         field = null;
      }
  
      /**
       * Creates an ObjectStreamField representing a field with the given name,
       * signature and unshared setting.
--- 91,102 ----
              throw new NullPointerException();
          }
          this.name = name;
          this.type = type;
          this.unshared = unshared;
!         this.field = null;
!         this.signature = null;
      }
  
      /**
       * Creates an ObjectStreamField representing a field with the given name,
       * signature and unshared setting.
*** 104,114 ****
              throw new NullPointerException();
          }
          this.name = name;
          this.signature = signature.intern();
          this.unshared = unshared;
!         field = null;
  
          switch (signature.charAt(0)) {
              case 'Z': type = Boolean.TYPE; break;
              case 'B': type = Byte.TYPE; break;
              case 'C': type = Character.TYPE; break;
--- 106,116 ----
              throw new NullPointerException();
          }
          this.name = name;
          this.signature = signature.intern();
          this.unshared = unshared;
!         this.field = null;
  
          switch (signature.charAt(0)) {
              case 'Z': type = Boolean.TYPE; break;
              case 'B': type = Byte.TYPE; break;
              case 'C': type = Character.TYPE; break;
*** 240,260 ****
       *
       * @return  the typecode of the serializable field
       */
      // REMIND: deprecate?
      public char getTypeCode() {
!         return signature.charAt(0);
      }
  
      /**
       * Return the JVM type signature.
       *
       * @return  null if this field has a primitive type.
       */
      // REMIND: deprecate?
      public String getTypeString() {
!         return isPrimitive() ? null : signature;
      }
  
      /**
       * Offset of field within instance data.
       *
--- 242,262 ----
       *
       * @return  the typecode of the serializable field
       */
      // REMIND: deprecate?
      public char getTypeCode() {
!         return getSignature().charAt(0);
      }
  
      /**
       * Return the JVM type signature.
       *
       * @return  null if this field has a primitive type.
       */
      // REMIND: deprecate?
      public String getTypeString() {
!         return isPrimitive() ? null : getSignature();
      }
  
      /**
       * Offset of field within instance data.
       *
*** 282,292 ****
       *
       * @return  true if and only if this field corresponds to a primitive type
       */
      // REMIND: deprecate?
      public boolean isPrimitive() {
!         char tcode = signature.charAt(0);
          return ((tcode != 'L') && (tcode != '['));
      }
  
      /**
       * Returns boolean value indicating whether or not the serializable field
--- 284,294 ----
       *
       * @return  true if and only if this field corresponds to a primitive type
       */
      // REMIND: deprecate?
      public boolean isPrimitive() {
!         char tcode = getTypeCode();
          return ((tcode != 'L') && (tcode != '['));
      }
  
      /**
       * Returns boolean value indicating whether or not the serializable field
*** 318,328 ****
  
      /**
       * Return a string that describes this field.
       */
      public String toString() {
!         return signature + ' ' + name;
      }
  
      /**
       * Returns field represented by this ObjectStreamField, or null if
       * ObjectStreamField is not associated with an actual field.
--- 320,330 ----
  
      /**
       * Return a string that describes this field.
       */
      public String toString() {
!         return getSignature() + ' ' + name;
      }
  
      /**
       * Returns field represented by this ObjectStreamField, or null if
       * ObjectStreamField is not associated with an actual field.
*** 334,341 ****
--- 336,354 ----
      /**
       * Returns JVM type signature of field (similar to getTypeString, except
       * that signature strings are returned for primitive fields as well).
       */
      String getSignature() {
+         if (signature != null) {
              return signature;
          }
+ 
+         String sig = typeSignature;
+         // This lazy calculation is safe since signature can be null iff one
+         // of the public constructors are used, in which case type is always
+         // initialized to the exact type we want the signature to represent.
+         if (sig == null) {
+             typeSignature = sig = getClassSignature(type).intern();
+         }
+         return sig;
+     }
  }