import org.apache.cassandra.db.ClockAndCount; //导入依赖的package包/类
/**
 * Returns the clock and the count associated with the given counter id, or (0, 0) if no such shard is present.
 */
@VisibleForTesting
public ClockAndCount getClockAndCountOf(ByteBuffer context, CounterId id)
{
    int position = findPositionOf(context, id);
    if (position == -1)
        return ClockAndCount.BLANK;

    long clock = context.getLong(position + CounterId.LENGTH);
    long count = context.getLong(position + CounterId.LENGTH + CLOCK_LENGTH);
    return ClockAndCount.create(clock, count);
}
 

import org.apache.cassandra.db.ClockAndCount; //导入依赖的package包/类
@Test
public void testGetGlockAndCountOf()
{
    ContextState state = ContextState.allocate(3, 3, 3);

    state.writeGlobal(CounterId.fromInt(1), 1L, 1L);
    state.writeRemote(CounterId.fromInt(2), 2L, 2L);
    state.writeLocal( CounterId.fromInt(3), 3L, 3L);
    state.writeGlobal(CounterId.fromInt(4), 4L, 4L);
    state.writeRemote(CounterId.fromInt(5), 5L, 5L);
    state.writeLocal( CounterId.fromInt(6), 6L, 6L);
    state.writeGlobal(CounterId.fromInt(7), 7L, 7L);
    state.writeRemote(CounterId.fromInt(8), 8L, 8L);
    state.writeLocal(CounterId.fromInt(9), 9L, 9L);

    assertEquals(ClockAndCount.create(1L, 1L), cc.getClockAndCountOf(state.context, CounterId.fromInt(1)));
    assertEquals(ClockAndCount.create(2L, 2L), cc.getClockAndCountOf(state.context, CounterId.fromInt(2)));
    assertEquals(ClockAndCount.create(3L, 3L), cc.getClockAndCountOf(state.context, CounterId.fromInt(3)));
    assertEquals(ClockAndCount.create(4L, 4L), cc.getClockAndCountOf(state.context, CounterId.fromInt(4)));
    assertEquals(ClockAndCount.create(5L, 5L), cc.getClockAndCountOf(state.context, CounterId.fromInt(5)));
    assertEquals(ClockAndCount.create(6L, 6L), cc.getClockAndCountOf(state.context, CounterId.fromInt(6)));
    assertEquals(ClockAndCount.create(7L, 7L), cc.getClockAndCountOf(state.context, CounterId.fromInt(7)));
    assertEquals(ClockAndCount.create(8L, 8L), cc.getClockAndCountOf(state.context, CounterId.fromInt(8)));
    assertEquals(ClockAndCount.create(9L, 9L), cc.getClockAndCountOf(state.context, CounterId.fromInt(9)));

    assertEquals(ClockAndCount.create(0L, 0L), cc.getClockAndCountOf(state.context, CounterId.fromInt(0)));
    assertEquals(ClockAndCount.create(0L, 0L), cc.getClockAndCountOf(state.context, CounterId.fromInt(10)));
    assertEquals(ClockAndCount.create(0L, 0L), cc.getClockAndCountOf(state.context, CounterId.fromInt(15)));
    assertEquals(ClockAndCount.create(0L, 0L), cc.getClockAndCountOf(state.context, CounterId.fromInt(20)));
}
 

import org.apache.cassandra.db.ClockAndCount; //导入依赖的package包/类
/**
 * Returns the clock and the count associated with the local counter id, or (0, 0) if no such shard is present.
 */
public ClockAndCount getLocalClockAndCount(ByteBuffer context)
{
    return getClockAndCountOf(context, CounterId.getLocalId());
}