/** Lets go of any references to a hash map. */
public void forget() {
hashMap = null;
readPos = null;
byteSegmentRef.reset(0, 0);
hasRows = false;
readIndex = 0;
nextTailOffset = -1;
}
/**
* Read the current value.
*
* @return The ByteSegmentRef to the current value read.
*/
private WriteBuffers.ByteSegmentRef internalRead() {
if (!hasList) {
/*
* Single value.
*/
if (readIndex > 0) {
return null;
}
// For a non-list (i.e. single value), the offset is for the variable length long (VLong)
// holding the value length (followed by the key length).
hashMap.writeBuffers.setReadPoint(firstOffset, readPos);
int valueLength = (int) hashMap.writeBuffers.readVLong(readPos);
// The value is before the offset. Make byte segment reference absolute.
byteSegmentRef.reset(firstOffset - valueLength, valueLength);
hashMap.writeBuffers.populateValue(byteSegmentRef);
readIndex++;
return byteSegmentRef;
}
/*
* Multiple values.
*/
if (readIndex == 0) {
// For a list, the value and key lengths of 1st record were overwritten with the
// relative offset to a new list record.
long relativeOffset = hashMap.writeBuffers.readNByteLong(firstOffset, 5, readPos);
// At the beginning of the list record will be the value length.
hashMap.writeBuffers.setReadPoint(firstOffset + relativeOffset, readPos);
int valueLength = (int) hashMap.writeBuffers.readVLong(readPos);
// The value is before the list record offset. Make byte segment reference absolute.
byteSegmentRef.reset(firstOffset - valueLength, valueLength);
hashMap.writeBuffers.populateValue(byteSegmentRef);
readIndex++;
return byteSegmentRef;
}
if (readIndex == 1) {
// We remembered the offset of just after the key length in the list record.
// Read the absolute offset to the 2nd value.
nextTailOffset =
hashMap.writeBuffers.readNByteLong(offsetAfterListRecordKeyLen, 5, readPos);
if (nextTailOffset <= 0) {
throw new Error("Expecting a second value");
}
} else if (nextTailOffset <= 0) {
return null;
}
hashMap.writeBuffers.setReadPoint(nextTailOffset, readPos);
// Get the value length.
int valueLength = (int) hashMap.writeBuffers.readVLong(readPos);
// Now read the relative offset to next record. Next record is always before the
// previous record in the write buffers (see writeBuffers javadoc).
long delta = hashMap.writeBuffers.readVLong(readPos);
long newTailOffset = delta == 0 ? 0 : (nextTailOffset - delta);
// The value is before the value record offset. Make byte segment reference absolute.
byteSegmentRef.reset(nextTailOffset - valueLength, valueLength);
hashMap.writeBuffers.populateValue(byteSegmentRef);
nextTailOffset = newTailOffset;
readIndex++;
return byteSegmentRef;
}