Refactor MetaAccumulator to be a little more sane

bukkit/src/main/java/me/lucko/luckperms/bukkit/vault/VaultChatHook.java

@@ -262,8 +262,8 @@ public class VaultChatHook extends AbstractVaultChat {
 
             // find the max inherited priority & add 10
             MetaAccumulator metaAccumulator = holder.accumulateMeta(null, createContextForWorldSet(world));
-            int priority = (type == ChatMetaType.PREFIX ? metaAccumulator.getPrefixes() : metaAccumulator.getSuffixes()).keySet().stream()
+            metaAccumulator.complete();
-                    .mapToInt(e -> e).max().orElse(0) + 10;
+            int priority = metaAccumulator.getChatMeta(type).keySet().stream().mapToInt(e -> e).max().orElse(0) + 10;
 
             Node.Builder chatMetaNode = NodeFactory.buildChatMetaNode(type, priority, value);
             chatMetaNode.setServer(this.permissionHook.getVaultServer());

common/src/main/java/me/lucko/luckperms/common/caching/type/MetaAccumulator.java

@@ -44,12 +44,14 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.SortedMap;
 import java.util.TreeMap;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * Holds temporary mutable meta whilst this object is passed up the
  * inheritance tree to accumulate meta from parents
  */
 public class MetaAccumulator {
+
     public static MetaAccumulator makeFromConfig(LuckPermsPlugin plugin) {
         return new MetaAccumulator(
                 new SimpleMetaStack(plugin.getConfiguration().get(ConfigKeys.PREFIX_FORMATTING_OPTIONS), ChatMetaType.PREFIX),
@@ -57,6 +59,18 @@ public class MetaAccumulator {
         );
     }
 
+    /**
+     * Represents the current state of a {@link MetaAccumulator}.
+     */
+    private enum State {
+        /** Marks that the accumulator is still gaining (accumulating) new data. */
+        ACCUMULATING,
+        /** Marks that the process of gaining (accumulating) new data is complete. */
+        COMPLETE
+    }
+
+    private final AtomicReference<State> state = new AtomicReference<>(State.ACCUMULATING);
+
     private final ListMultimap<String, String> meta;
     private final SortedMap<Integer, String> prefixes;
     private final SortedMap<Integer, String> suffixes;
@@ -75,7 +89,34 @@ public class MetaAccumulator {
         this.suffixStack = suffixStack;
     }
 
+    private void ensureState(State state) {
+        if (this.state.get() != state) {
+            throw new IllegalStateException("State must be " + state + ", but is actually " + this.state.get());
+        }
+    }
+
+    /**
+     * "Completes" the accumulator, preventing any further changes.
+     *
+     * Also performs some final processing on the accumulators state, before
+     * data is read.
+     */
+    public void complete() {
+        if (!this.state.compareAndSet(State.ACCUMULATING, State.COMPLETE)) {
+            return;
+        }
+
+        // perform final changes
+        if (!this.meta.containsKey(NodeTypes.WEIGHT_KEY) && this.weight != 0) {
+            this.meta.put(NodeTypes.WEIGHT_KEY, String.valueOf(this.weight));
+        }
+    }
+
+    // accumulate methods
+
     public void accumulateNode(LocalizedNode n) {
+        ensureState(State.ACCUMULATING);
+
         n.getTypeData(MetaType.KEY).ifPresent(metaType ->
                 this.meta.put(metaType.getKey(), metaType.getValue())
         );
@@ -92,60 +133,60 @@ public class MetaAccumulator {
     }
 
     public void accumulateMeta(String key, String value) {
+        ensureState(State.ACCUMULATING);
         this.meta.put(key, value);
     }
 
     public void accumulateWeight(int weight) {
+        ensureState(State.ACCUMULATING);
         this.weight = Math.max(this.weight, weight);
     }
 
-    // We can assume that if this method is being called, this holder is effectively finalized.
+    // read methods
-    // (it's not going to accumulate more nodes)
-    // Therefore, it should be ok to set the weight meta key, if not already present.
-    public ListMultimap<String, String> getMeta() {
-        if (!this.meta.containsKey(NodeTypes.WEIGHT_KEY) && this.weight != 0) {
-            this.meta.put(NodeTypes.WEIGHT_KEY, String.valueOf(this.weight));
-        }
 
+    public ListMultimap<String, String> getMeta() {
+        ensureState(State.COMPLETE);
         return this.meta;
     }
 
     public Map<Integer, String> getChatMeta(ChatMetaType type) {
+        ensureState(State.COMPLETE);
         return type == ChatMetaType.PREFIX ? this.prefixes : this.suffixes;
     }
 
-    public MetaStack getStack(ChatMetaType type) {
-        return type == ChatMetaType.PREFIX ? this.prefixStack : this.suffixStack;
-    }
-
     public SortedMap<Integer, String> getPrefixes() {
+        ensureState(State.COMPLETE);
         return this.prefixes;
     }
 
     public SortedMap<Integer, String> getSuffixes() {
+        ensureState(State.COMPLETE);
         return this.suffixes;
     }
 
     public int getWeight() {
+        ensureState(State.COMPLETE);
         return this.weight;
     }
 
     public MetaStack getPrefixStack() {
+        ensureState(State.COMPLETE);
         return this.prefixStack;
     }
 
     public MetaStack getSuffixStack() {
+        ensureState(State.COMPLETE);
         return this.suffixStack;
     }
 
     @Override
     public String toString() {
         return "MetaAccumulator(" +
-                "meta=" + this.getMeta() + ", " +
+                "meta=" + this.meta + ", " +
-                "prefixes=" + this.getPrefixes() + ", " +
+                "prefixes=" + this.prefixes + ", " +
-                "suffixes=" + this.getSuffixes() + ", " +
+                "suffixes=" + this.suffixes + ", " +
-                "weight=" + this.getWeight() + ", " +
+                "weight=" + this.weight + ", " +
-                "prefixStack=" + this.getPrefixStack() + ", " +
+                "prefixStack=" + this.prefixStack + ", " +
-                "suffixStack=" + this.getSuffixStack() + ")";
+                "suffixStack=" + this.suffixStack + ")";
     }
 }

common/src/main/java/me/lucko/luckperms/common/caching/type/MetaCache.java

@@ -39,8 +39,6 @@ import me.lucko.luckperms.common.metastacking.MetaStack;
 import java.util.List;
 import java.util.Map;
 import java.util.SortedMap;
-import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import javax.annotation.Nonnull;
 
@@ -48,7 +46,6 @@ import javax.annotation.Nonnull;
  * Holds cached meta for a given context
  */
 public class MetaCache implements MetaData {
-    private final ReadWriteLock lock = new ReentrantReadWriteLock();
 
     /**
      * The contexts this container is holding data for
@@ -67,51 +64,40 @@ public class MetaCache implements MetaData {
     }
 
     public void loadMeta(MetaAccumulator meta) {
-        this.lock.writeLock().lock();
+        meta.complete();
-        try {
-            this.metaMultimap = ImmutableListMultimap.copyOf(meta.getMeta());
 
-            //noinspection unchecked
+        this.metaMultimap = ImmutableListMultimap.copyOf(meta.getMeta());
-            Map<String, List<String>> metaMap = (Map) this.metaMultimap.asMap();
-            ImmutableMap.Builder<String, String> metaMapBuilder = ImmutableMap.builder();
 
-            for (Map.Entry<String, List<String>> e : metaMap.entrySet()) {
+        //noinspection unchecked
-                if (e.getValue().isEmpty()) {
+        Map<String, List<String>> metaMap = (Map) this.metaMultimap.asMap();
-                    continue;
+        ImmutableMap.Builder<String, String> metaMapBuilder = ImmutableMap.builder();
-                }
 
-                // take the value which was accumulated first
+        for (Map.Entry<String, List<String>> e : metaMap.entrySet()) {
-                metaMapBuilder.put(e.getKey(), e.getValue().get(0));
+            if (e.getValue().isEmpty()) {
+                continue;
             }
-            this.meta = metaMapBuilder.build();
 
-            this.prefixes = ImmutableSortedMap.copyOfSorted(meta.getPrefixes());
+            // take the value which was accumulated first
-            this.suffixes = ImmutableSortedMap.copyOfSorted(meta.getSuffixes());
+            metaMapBuilder.put(e.getKey(), e.getValue().get(0));
-            this.prefixStack = meta.getPrefixStack();
-            this.suffixStack = meta.getSuffixStack();
-        } finally {
-            this.lock.writeLock().unlock();
         }
+        this.meta = metaMapBuilder.build();
+
+        this.prefixes = ImmutableSortedMap.copyOfSorted(meta.getPrefixes());
+        this.suffixes = ImmutableSortedMap.copyOfSorted(meta.getSuffixes());
+        this.prefixStack = meta.getPrefixStack();
+        this.suffixStack = meta.getSuffixStack();
     }
 
     @Override
     public String getPrefix() {
-        this.lock.readLock().lock();
+        MetaStack prefixStack = this.prefixStack;
-        try {
+        return prefixStack == null ? null : prefixStack.toFormattedString();
-            return this.prefixStack == null ? null : this.prefixStack.toFormattedString();
-        } finally {
-            this.lock.readLock().unlock();
-        }
     }
 
     @Override
     public String getSuffix() {
-        this.lock.readLock().lock();
+        MetaStack suffixStack = this.suffixStack;
-        try {
+        return suffixStack == null ? null : suffixStack.toFormattedString();
-            return this.suffixStack == null ? null : this.suffixStack.toFormattedString();
-        } finally {
-            this.lock.readLock().unlock();
-        }
     }
 
     @Nonnull

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaSetChatMeta.java

@@ -107,6 +107,7 @@ public class MetaSetChatMeta extends SharedSubCommand {
         // determine the priority to set at
         if (priority == Integer.MIN_VALUE) {
             MetaAccumulator metaAccumulator = holder.accumulateMeta(null, Contexts.of(context, Contexts.global().getSettings()));
+            metaAccumulator.complete();
             priority = metaAccumulator.getChatMeta(this.type).keySet().stream().mapToInt(e -> e).max().orElse(0) + 1;
 
             if (holder instanceof Group) {

common/src/main/java/me/lucko/luckperms/common/commands/generic/meta/MetaSetTempChatMeta.java

@@ -118,6 +118,7 @@ public class MetaSetTempChatMeta extends SharedSubCommand {
         // determine the priority to set at
         if (priority == Integer.MIN_VALUE) {
             MetaAccumulator metaAccumulator = holder.accumulateMeta(null, Contexts.of(context, Contexts.global().getSettings()));
+            metaAccumulator.complete();
             priority = metaAccumulator.getChatMeta(this.type).keySet().stream().mapToInt(e -> e).max().orElse(0) + 1;
 
             if (holder instanceof Group) {

sponge/src/main/java/me/lucko/luckperms/sponge/service/internal/HolderSubjectData.java

@@ -362,6 +362,7 @@ public class HolderSubjectData implements LPSubjectData {
             ));
 
             MetaAccumulator metaAccumulator = this.holder.accumulateMeta(null, Contexts.of(contexts, Contexts.global().getSettings()));
+            metaAccumulator.complete();
             int priority = metaAccumulator.getChatMeta(type).keySet().stream().mapToInt(e -> e).max().orElse(0);
             priority += 10;