Performance & Concurrency Improvements to Permissions

Modifying of permissions was only half protected, enabling concurrency
issues to occur if permissions were modified async.

While no plugin really should be doing that, modifying operations
are not heavily called, so they are safe to add synchronization to.

Now, all modification API's will be synchronized ensuring safety.

Additionally, hasPermission was victim to a common java newbie mistake
of calling if (containsKey(k)) return get(k), resulting in 2 map lookups.

Optimized it to simply be a single get call cutting permission map
lookups in half.

Spigot-API-Patches/0150-Performance-Concurrency-Improvements-to-Permissions.patch

@@ -0,0 +1,114 @@
+From ebe3ab3a42a6d51c060849d75fdaba854bb6dc89 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Thu, 13 Sep 2018 20:51:50 -0400
+Subject: [PATCH] Performance & Concurrency Improvements to Permissions
+
+Modifying of permissions was only half protected, enabling concurrency
+issues to occur if permissions were modified async.
+
+While no plugin really should be doing that, modifying operations
+are not heavily called, so they are safe to add synchronization to.
+
+Now, all modification API's will be synchronized ensuring safety.
+
+Additionally, hasPermission was victim to a common java newbie mistake
+of calling if (containsKey(k)) return get(k), resulting in 2 map lookups.
+
+Optimized it to simply be a single get call cutting permission map
+lookups in half.
+
+diff --git a/src/main/java/org/bukkit/permissions/PermissibleBase.java b/src/main/java/org/bukkit/permissions/PermissibleBase.java
+index d4cb00a82..486f69f86 100644
+--- a/src/main/java/org/bukkit/permissions/PermissibleBase.java
++++ b/src/main/java/org/bukkit/permissions/PermissibleBase.java
+@@ -68,8 +68,11 @@ public class PermissibleBase implements Permissible {
+ 
+         String name = inName.toLowerCase(java.util.Locale.ENGLISH);
+ 
+-        if (isPermissionSet(name)) {
+-            return permissions.get(name).getValue();
++        // Paper start
++        PermissionAttachmentInfo info = permissions.get(name);
++        if (info != null) {
++            return info.getValue();
++            // Paper end
+         } else {
+             Permission perm = Bukkit.getServer().getPluginManager().getPermission(name);
+ 
+@@ -88,13 +91,16 @@ public class PermissibleBase implements Permissible {
+ 
+         String name = perm.getName().toLowerCase(java.util.Locale.ENGLISH);
+ 
+-        if (isPermissionSet(name)) {
+-            return permissions.get(name).getValue();
++        // Paper start
++        PermissionAttachmentInfo info = permissions.get(name);
++        if (info != null) {
++            return info.getValue();
+         }
++        // Paper end
+         return perm.getDefault().getValue(isOp());
+     }
+ 
+-    public PermissionAttachment addAttachment(Plugin plugin, String name, boolean value) {
++    public synchronized PermissionAttachment addAttachment(Plugin plugin, String name, boolean value) { // Paper - synchronized
+         if (name == null) {
+             throw new IllegalArgumentException("Permission name cannot be null");
+         } else if (plugin == null) {
+@@ -111,7 +117,7 @@ public class PermissibleBase implements Permissible {
+         return result;
+     }
+ 
+-    public PermissionAttachment addAttachment(Plugin plugin) {
++    public synchronized PermissionAttachment addAttachment(Plugin plugin) { // Paper - synchronized
+         if (plugin == null) {
+             throw new IllegalArgumentException("Plugin cannot be null");
+         } else if (!plugin.isEnabled()) {
+@@ -126,7 +132,7 @@ public class PermissibleBase implements Permissible {
+         return result;
+     }
+ 
+-    public void removeAttachment(PermissionAttachment attachment) {
++    public synchronized void removeAttachment(PermissionAttachment attachment) { // Paper - synchronized
+         if (attachment == null) {
+             throw new IllegalArgumentException("Attachment cannot be null");
+         }
+@@ -145,7 +151,7 @@ public class PermissibleBase implements Permissible {
+         }
+     }
+ 
+-    public void recalculatePermissions() {
++    public synchronized void recalculatePermissions() { // Paper - synchronized
+         clearPermissions();
+         Set<Permission> defaults = Bukkit.getServer().getPluginManager().getDefaultPermissions(isOp());
+         Bukkit.getServer().getPluginManager().subscribeToDefaultPerms(isOp(), parent);
+@@ -192,7 +198,7 @@ public class PermissibleBase implements Permissible {
+         }
+     }
+ 
+-    public PermissionAttachment addAttachment(Plugin plugin, String name, boolean value, int ticks) {
++    public synchronized PermissionAttachment addAttachment(Plugin plugin, String name, boolean value, int ticks) { // Paper - synchronized
+         if (name == null) {
+             throw new IllegalArgumentException("Permission name cannot be null");
+         } else if (plugin == null) {
+@@ -210,7 +216,7 @@ public class PermissibleBase implements Permissible {
+         return result;
+     }
+ 
+-    public PermissionAttachment addAttachment(Plugin plugin, int ticks) {
++    public synchronized PermissionAttachment addAttachment(Plugin plugin, int ticks) { // Paper - synchronized
+         if (plugin == null) {
+             throw new IllegalArgumentException("Plugin cannot be null");
+         } else if (!plugin.isEnabled()) {
+@@ -228,7 +234,7 @@ public class PermissibleBase implements Permissible {
+         }
+     }
+ 
+-    public Set<PermissionAttachmentInfo> getEffectivePermissions() {
++    public synchronized Set<PermissionAttachmentInfo> getEffectivePermissions() { // Paper - synchronized
+         return new HashSet<PermissionAttachmentInfo>(permissions.values());
+     }
+ 
+-- 
+2.18.0
+