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Class grendel.storage.MessageID

java.lang.Object
   |
   +----grendel.storage.MessageID

This class represents a Message-ID. It does not contain the ID itself: there is no way to reconstruct the original string from this object; however, it contains a hash of that string which should be sufficiently unique so that the odds of a collision are 1 in 2^32 (since it is a 64-bit hash.)

We store the hash instead of the original string because it takes up significantly less memory, and in order to do threading, we tend to need a huge number of Message-IDs in memory at once.

See Also: MessageIDTable

class  MessageID
     extends java.lang.Object
{
          // Fields 1
     long hash;

          // Constructors 4
     MessageID();
     MessageID(byte[], int, int);
     MessageID(String);
     MessageID(long);

          // Methods 4
     public boolean equals(Object);
     protected long hashBytes(byte[], int, int);
     public int hashCode();
     public String toString();
}

• hash

   long hash

• MessageID

   MessageID() 

Constructs a MessageID object with a null hash.

• MessageID

   MessageID(long hash) 

Constructs a MessageID object with the given hash.

• MessageID

   MessageID(byte[] bytes, 
             int start, 
             int length) 

Constructs a MessageID object for the given sub-sequence of bytes. A pointer to the bytes is not retained.

• MessageID

   MessageID(String chars) 

• toString

   public String toString() 

Converts it to a string, for debugging.

Overrides:

toString in class Object

• hashCode

   public int hashCode() 

Overrides:

hashCode in class Object

• equals

   public boolean equals(Object x) 

Overrides:

equals in class Object

• hashBytes

   protected long hashBytes(byte[] bytes, 
                            int start, 
                            int length) 

Computes a 64-bit hash of the given subsequence of bytes.

Note: this hash value is written out to mail summary files by the MailSummaryFileGrendel class. If the hash algorithm is changed, it will invalidate all existing mail summary files, and necessitate a change of the file format version number.

See Also: MailSummaryFileGrendel

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