io.crums.model.CrumRecord Maven / Gradle / Ivy
/*
* Copyright 2020 Babak Farhang
*/
package io.crums.model;
import java.nio.ByteBuffer;
/**
* A record of the life of a witnessed hash. A witnessed hash goes through 3 phases, 2 of which are
* represented by instances of this class.
*
*
* - Created. A crum, that is just a hash/utc pair, enters the database.
* - Trailed. The crum enters a Merkle tree.
* - Trimmed. The crum and its associated Merkle are purged from the database. The only
* artifact of the crum remaining in the database is the root of the Merkle tree it was in
* (to which a valid instance of this class is forever provably linked to).
*
*
* An instance of this class represents of the first 2 states of a crum.
*
*/
public abstract class CrumRecord {
/**
* Determines whether the record has a crum trail. A CrumRecord begins life without a trail.
*
* @return true iff {@linkplain #trail()} doesn't return null.
*
* @see #trail()
*/
public abstract boolean isTrailed();
/**
* Returns the record's crum (hash/utc pair).
*
* @return never null
*/
public abstract Crum crum();
/**
* Returns the crum trail, or null if it doesn't have one. (A crum has a trail once it's made it into a Merkle tree.)
*
* @return possibly null
* @see #isTrailed()
*/
public abstract CrumTrail trail();
/**
* Instances are equal if their crums are equal and are both trailed.
*
* @see #hashCode()
*/
@Override
public final boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof CrumRecord))
return false;
CrumRecord other = (CrumRecord) o;
boolean equ = (isTrailed() == other.isTrailed()) && crum().equals(other.crum());
// boolean insanity = equ && isTrailed() && !trail().equals(other.trail());
assert !(equ && isTrailed() && !trail().equals(other.trail()));
return equ;
}
/**
* Consistent with {@linkplain #equals(Object)}.
*/
@Override
public final int hashCode() {
return crum().hashCode();
}
/**
* Returns the time witnessed.
*
* @return {@code crum().utc()}
*/
public final long utc() {
return crum().utc();
}
/**
* Returns the hash witnessed.
*
* @return {@code crum().hash()}
*/
public final ByteBuffer hash() {
return crum().hash();
}
/**
* Returns the {@linkplain #hash() hash} in hexadecimal representation.
*/
public final String hashHex() {
return crum().hashHex();
}
}