Revert "dcache-qos: remove trigger to rescan pools on tag change"

This reverts commit 310889c.

docs/TheBook/src/main/markdown/config-qos-engine.md

@@ -1280,16 +1280,6 @@ be scheduled for scans.
 >
 >   **Use the QoS transition to change existing disk+tape files to tape.**
 
-### Changing pool tags
-
-If a pool's tags are used to determine replica distribution (based on the storage
-unit definition of `onlyOneCopyPer`) and these are changed, QoS will not automatically
-force the pool to be scanned immediately upon restart (it will just be
-scheduled for a restart scan based on the defined grace period).
-
->   If it is desirable to rescan a pool's replicas immediately after its
->   tags have been changed, this must be done manually (see above).
-
 ### Troubleshooting operations
 
 Intervention to rectify qos handling should hopefully be needed infrequently;

modules/dcache-qos/src/main/java/org/dcache/qos/services/scanner/handlers/PoolOpChangeHandler.java

@@ -61,6 +61,7 @@ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
+import diskCacheV111.poolManager.CostModule;
 import diskCacheV111.poolManager.PoolSelectionUnit;
 import diskCacheV111.poolManager.PoolSelectionUnit.SelectionPool;
 import diskCacheV111.poolManager.PoolSelectionUnit.SelectionPoolGroup;
@@ -69,9 +70,11 @@ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 import diskCacheV111.poolManager.StorageUnitInfoExtractor;
 import diskCacheV111.pools.PoolV2Mode;
 import java.util.Collection;
+import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.stream.Collectors;
+import org.dcache.poolmanager.PoolInfo;
 import org.dcache.poolmanager.PoolMonitor;
 import org.dcache.qos.data.PoolQoSStatus;
 import org.dcache.qos.services.scanner.data.PoolFilter;
@@ -114,6 +117,7 @@ public synchronized PoolOpDiff reloadAndScan(PoolMonitor newPoolMonitor) {
                   diff.getPoolsAddedToPoolGroup().removeAll(p);
                   diff.getPoolsRemovedFromPoolGroup().removeAll(p);
                   diff.getModeChanged().remove(p);
+                  diff.getTagsChanged().remove(p);
               });
 
         PoolSelectionUnit currentPsu = newPoolMonitor.getPoolSelectionUnit();
@@ -153,6 +157,16 @@ public synchronized PoolOpDiff reloadAndScan(PoolMonitor newPoolMonitor) {
         LOGGER.trace("Rescanning the pool groups whose marker changed.");
         diff.getMarkerChanged().forEach(g -> scanPoolsOfModifiedPoolGroup(g, currentPsu));
 
+        LOGGER.trace("Rescanning the pools with changed tags.");
+        diff.getTagsChanged().keySet().stream()
+              .map(currentPsu::getPool)
+              .forEach(p -> poolOperationMap.scan(p.getName(),
+                    null,
+                    null,
+                    null,
+                    p.getPoolMode(),
+                    true));
+
         LOGGER.trace("Checking to see if previously uninitialized pools are now ready.");
         poolOperationMap.saveExcluded();
         lastRefresh = System.currentTimeMillis();
@@ -221,6 +235,9 @@ private PoolOpDiff compare(PoolMonitor currentPoolMonitor, PoolMonitor nextPoolM
         LOGGER.trace("comparing pool mode");
         comparePoolMode(diff, commonPools, nextPsu);
 
+        LOGGER.trace("comparing pool tags");
+        comparePoolTags(diff, commonPools, currentPoolMonitor, nextPoolMonitor);
+
         return diff;
     }
 
@@ -307,6 +324,24 @@ private void comparePoolsInPoolGroups(PoolOpDiff diff,
         }
     }
 
+    private void comparePoolTags(PoolOpDiff diff, Set<String> common, PoolMonitor current,
+          PoolMonitor next) {
+        CostModule currentCostModule = current.getCostModule();
+        CostModule nextCostModule = next.getCostModule();
+
+        diff.getNewPools()
+              .forEach(p -> diff.getTagsChanged().put(p, getPoolTags(p, nextCostModule)));
+
+        common.forEach(p -> {
+            Map<String, String> newTags = getPoolTags(p, nextCostModule);
+            Map<String, String> oldTags = getPoolTags(p, currentCostModule);
+            if (oldTags == null || (newTags != null
+                  && !oldTags.equals(newTags))) {
+                diff.getTagsChanged().put(p, newTags);
+            }
+        });
+    }
+
     private Set<String> compareStorageUnits(PoolOpDiff diff,
           PoolSelectionUnit currentPsu,
           PoolSelectionUnit nextPsu) {
@@ -393,6 +428,14 @@ private Set<String> comparePoolGroups(PoolOpDiff diff,
         return Sets.intersection(next, curr);
     }
 
+    private Map<String, String> getPoolTags(String pool, CostModule costModule) {
+        PoolInfo poolInfo = costModule.getPoolInfo(pool);
+        if (poolInfo == null) {
+            return null;
+        }
+        return poolInfo.getTags();
+    }
+
     /**
      * Scans the "new" pool, also making sure all files have the sticky bit.
      */

modules/dcache-qos/src/main/java/org/dcache/qos/services/scanner/handlers/PoolOpDiff.java

@@ -110,6 +110,12 @@ public final class PoolOpDiff {
      */
     private final Map<String, PoolV2Mode> modeChanged = new HashMap<>();
 
+    /*
+     *  (pool, tags)
+     */
+    private final Map<String, Map<String, String>> tagsChanged
+          = new HashMap<>();
+
     public Collection<String> getConstraintsChanged() {
         return constraintsChanged;
     }
@@ -154,6 +160,10 @@ public Multimap<String, String> getPoolsRemovedFromPoolGroup() {
         return poolsRmved;
     }
 
+    public Map<String, Map<String, String>> getTagsChanged() {
+        return tagsChanged;
+    }
+
     public Collection<String> getUninitializedPools() {
         return uninitPools;
     }
@@ -172,7 +182,7 @@ public boolean isEmpty() {
               && newUnits.isEmpty() && oldUnits.isEmpty()
               && poolsAdded.isEmpty() && poolsRmved.isEmpty()
               && unitsAdded.isEmpty() && unitsRmved.isEmpty()
-              && constraintsChanged.isEmpty()
+              && constraintsChanged.isEmpty() && tagsChanged.isEmpty()
               && modeChanged.isEmpty();
     }
 
@@ -189,12 +199,14 @@ public String toString() {
                     "Units Added:          %s\n" +
                     "Units Removed:        %s\n" +
                     "Constraints changed:  %s\n" +
-                    "Mode changed:         %s\n",
+                    "Mode changed:         %s\n" +
+                    "Tags changed:         %s\n",
               newPools, oldPools, uninitPools,
               newGroups, oldGroups,
               newUnits, oldUnits,
               poolsAdded, poolsRmved,
               unitsAdded, unitsRmved,
-              constraintsChanged, modeChanged);
+              constraintsChanged, modeChanged,
+              tagsChanged);
     }
 }