private boolean shouldLoadFurtherValues(final FDate key, final boolean newMinKey) {
if (furtherValues.isEmpty()) {
final V tail = lastValuesFromFurtherValues.getTail();
if (tail == null) {
return true;
}
final V head = lastValuesFromFurtherValues.getHead();
final FDate tailKey = extractKey(key, tail);
final FDate headKey = extractKey(key, head);
final boolean isEndReachedAnyway =
tailKey.equals(maxKeyInDB)
&& key.isBeforeOrEqualTo(maxKeyInDB)
&& headKey.isBeforeOrEqualTo(key);
return !isEndReachedAnyway;
}
final boolean keyIsBeforeMinKeyFromLoadFurtherValues =
newMinKey && key.isBefore(minKeyInDBFromLoadFurtherValues);
if (keyIsBeforeMinKeyFromLoadFurtherValues) {
return true;
}
final boolean newMinKeyFromDBMayFindNewValues =
isMinKeyInDBFromLoadFurtherValues() && key.compareTo(minKeyInDB) <= -1 && newMinKey;
if (newMinKeyFromDBMayFindNewValues) {
return true;
}
return false;
}
private boolean isPotentiallyAlreadyEvicted(final FDate key, final V value) {
final boolean isEvictedBeforeCurrentFurtherValues =
(value == null || extractKey(key, value).isAfter(key))
&& (key.isAfter(minKeyInDB) || key.isAfter(minKeyInDBFromLoadFurtherValues));
if (isEvictedBeforeCurrentFurtherValues) {
return true;
}
final boolean mightBeEvictedAfterFurtherValues = value != null && furtherValues.isEmpty();
if (mightBeEvictedAfterFurtherValues) {
final FDate valueKey = extractKey(key, value);
final boolean isEvictedAfterCurrentFurtherValues =
valueKey.isBefore(key) && valueKey.isBeforeOrEqualTo(maxKeyInDB);
if (isEvictedAfterCurrentFurtherValues) {
return true;
}
}
return false;
}
private V searchInFurtherValues(final FDate key) {
// Take the first matching value from the sorted list
// Search for the newest value
V prevValue = (V) null;
FDate prevKey = null;
if (!lastValuesFromFurtherValues.isEmpty()) {
// though maybe use the last one for smaller increments than the data itself is loaded
for (final V lastValueFromFurtherValues : lastValuesFromFurtherValues) {
final FDate keyLastValueFromFurtherValues = extractKey(key, lastValueFromFurtherValues);
if (keyLastValueFromFurtherValues.isBeforeOrEqualTo(key)) {
prevValue = lastValueFromFurtherValues;
prevKey = keyLastValueFromFurtherValues;
} else {
// only go to further values if it might be possible that those are useable
return prevValue;
}
}
}
final FDate earliestStartOfLoadFurtherValues = determineEaliestStartOfLoadFurtherValues(key);
while (furtherValues.size() > 0) {
final V newValue = furtherValues.getHead();
final FDate newValueKey = extractKey(key, newValue);
final int compare = key.compareTo(newValueKey);
if (compare < 0) {
// key < newValueKey
// run over the key we wanted
break;
} else if (compare == 0) {
// key == newValueKey
// This is the value we searched for! It will later be added with the db key to the cache.
pushLastValueFromFurtherValues();
return newValue;
} else {
// key > newValueKey
// put this value into the cache; gaps do not get filled here, so that the max size of the
// cache does not get reached prematurely
put(newValueKey, newValue, prevKey, prevValue);
pushLastValueFromFurtherValues();
// continue with the next one
prevValue = newValue;
prevKey = newValueKey;
if (furtherValues.isEmpty()
&& newValueKey.isBefore(maxKeyInDB)
&& key.isBefore(maxKeyInDB)
&& maxKeyInDBFromLoadFurtherValues.isBefore(maxKeyInDB)) {
final FDate timeForLoadFurtherValues =
FDates.max(newValueKey, earliestStartOfLoadFurtherValues);
Assertions.checkState(
eventuallyLoadFurtherValues(
"searchInFurtherValues", newValueKey, timeForLoadFurtherValues, false, true));
if (!furtherValues.isEmpty()) {
pushLastValueFromFurtherValues();
if (!timeForLoadFurtherValues.equals(newValue)) {
// do not distort prev/next lookup when using earlisetStartOfLoadFurtherValues, thus
// reset those
prevValue = null;
prevKey = null;
}
}
}
}
}
return prevValue;
}