stasis-bLSM/tuplemerger.cpp

#include "tuplemerger.h"
#include "logstore.h"

// t2 is the newer tuple.
// we return deletes here.  our caller decides what to do with them.
datatuple* tuplemerger::merge(const datatuple *t1, const datatuple *t2)
{
  if(!(t1->isDelete() || t2->isDelete())) {
    return (*merge_fp)(t1,t2);
  } else {
    // if there is at least one tombstone, we return t2 intact.
    // t1 tombstone -> ignore it, and return t2.
    // t2 tombstone -> return a tombstone (like t2).
    return t2->create_copy();
  }
}
/**
 * appends the data in t2 to data from t1
 * 
 * deletes are handled by the tuplemerger::merge function
 * so here neither t1 nor t2 is a delete datatuple
 **/
datatuple* append_merger(const datatuple *t1, const datatuple *t2)
{
	assert(!(t1->isDelete() || t2->isDelete()));
    len_t rawkeylen = t1->rawkeylen();
    len_t datalen = t1->datalen() + t2->datalen();
    byte * data = (byte*)malloc(datalen);
    memcpy(data, t1->data(), t1->datalen());
    memcpy(data + t1->datalen(), t2->data(), t2->datalen());

	return datatuple::create(t1->rawkey(), rawkeylen, data, datalen);
}

/**
 * replaces the data with data from t2
 * 
 * deletes are handled by the tuplemerger::merge function
 * so here neither t1 nor t2 is a delete datatuple
 **/
datatuple* replace_merger(const datatuple *t1, const datatuple *t2)
{
	return t2->create_copy();
}