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package org.dcache.resilience.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Set;
import java.util.stream.Collectors;
import diskCacheV111.poolManager.CostModule;
import diskCacheV111.poolManager.PoolSelectionUnit;
import diskCacheV111.poolManager.PoolSelectionUnit.SelectionLink;
import diskCacheV111.poolManager.PoolSelectionUnit.SelectionPool;
import diskCacheV111.poolManager.PoolSelectionUnit.SelectionPoolGroup;
import diskCacheV111.poolManager.PoolSelectionUnit.SelectionUnitGroup;
import diskCacheV111.poolManager.StorageUnit;
/**
* <p>Utilities for finding storage unit info relevant to resilient pool group
* operations.</p>
*/
public final class StorageUnitInfoExtractor {
/**
* @param resilientOnly return only resilient groups.
* @return all the pool groups to which this storage unit is linked.
*/
public static Collection<String> getPoolGroupsFor(String unitName,
PoolSelectionUnit psu,
boolean resilientOnly) {
return psu.getPoolGroups().values().stream()
.filter((g) -> (resilientOnly ? g.isResilient() : true) &&
hasStorageUnit(g.getName(), unitName, psu))
.map(SelectionPoolGroup::getName)
.collect(Collectors.toList());
}
/**
* @return all the resilient pool groups to which this storage unit is linked.
*/
public static Collection<String> getResilientGroupsFor(String unitName,
PoolSelectionUnit psu) {
return getPoolGroupsFor(unitName, psu, true);
}
/**
* @return all the storage units linked to this pool group.
*/
public static Collection<StorageUnit> getStorageUnitsInGroup(String name,
PoolSelectionUnit psu) {
Collection<StorageUnit> units = new ArrayList<>();
psu.getLinksPointingToPoolGroup(name).stream()
.map(SelectionLink::getUnitGroupsTargetedBy)
.flatMap(Collection::stream)
.map(SelectionUnitGroup::getMemeberUnits)
.flatMap(Collection::stream)
.filter(StorageUnit.class::isInstance)
.map(StorageUnit.class::cast)
.forEach(units::add);
return units;
}
/**
* @return true if the pool group has at least one storage group
* associated with it via a link, and the storage group overrides the
* pool group resilience settings for required number of copies
* (via a non-<code>null</code> value).
*/
public static boolean hasResilientStorageUnit(String poolGroup,
PoolSelectionUnit psu) {
return getStorageUnitsInGroup(poolGroup, psu).stream()
.filter((u) -> u.getRequiredCopies() > 1)
.findAny().isPresent();
}
/**
* <p>Checks to make sure that resilient storage unit constraints can
* be met by all resilient groups to which it is linked.</p>
*/
public static void verifyCanBeSatisfied(StorageUnit unit,
PoolSelectionUnit psu,
CostModule module) {
Collection<String> groups = getResilientGroupsFor(unit.getName(), psu);
int storageRequired = unit.getRequiredCopies();
Collection<String> onlyOneCopyPer = unit.getOnlyOneCopyPer();
for (String group: groups) {
verify(group, new CostModuleLocationExtractor(onlyOneCopyPer, module),
storageRequired, psu);
}
}
private static Set<SelectionPoolGroup> getNonResilientGroups(PoolSelectionUnit psu) {
return psu.getPoolGroups().values().stream()
.filter((g) -> !g.isResilient())
.collect(Collectors.toSet());
}
private static boolean hasStorageUnit(String poolGroup,
String storageUnit,
PoolSelectionUnit psu) {
return getStorageUnitsInGroup(poolGroup, psu).stream()
.filter((sunit) -> sunit.getName().equals(storageUnit))
.findAny().isPresent();
}
/**
* @param poolGroup to which storage unit is linked.
* @param extractor configured for the specific tag constraints.
* @param required specific to this storage unit.
* @throws IllegalStateException upon encountering the first set of
* constraints which cannot be met.
*/
private static void verify(String poolGroup,
CostModuleLocationExtractor extractor,
int required,
PoolSelectionUnit psu) throws IllegalStateException {
Set<String> members = psu.getPoolsByPoolGroup(poolGroup).stream()
.map(SelectionPool::getName)
.collect(Collectors.toSet());
for (int i = 0; i < required; i++) {
Collection<String> candidates
= extractor.getCandidateLocations(members);
if (candidates.isEmpty()) {
String message = String.format("At %s replicas, the ability for "
+ "pool group %s to distribute replicas according to "
+ "requirements is exceeded.", i, poolGroup);
throw new IllegalStateException(message);
}
String selected = RandomSelectionStrategy.SELECTOR.apply(candidates);
members.remove(selected);
extractor.addSeenTagsFor(selected);
}
}
private StorageUnitInfoExtractor() {
}
}