Restore BauweltMember cache and notify all dev servers on member changes

getBauMember never read its cache after the Exposed migration, so every
scoreboard render hit the DB (Too many connections, #479). Cache by
(bauwelt, member) incl. negative results, evict on addMember/remove, and
send BaumemberUpdatePacket to the Bauserver and all dev servers (also on
addmember). BauMemberUpdate clears the cache itself to not depend on
handler order.

CommonCore/SQL/src/de/steamwar/sql/BauweltMember.kt

@@ -30,6 +30,7 @@ import org.jetbrains.exposed.v1.dao.CompositeEntity
 import org.jetbrains.exposed.v1.dao.CompositeEntityClass
 import org.jetbrains.exposed.v1.jdbc.insertIgnore
 import java.util.*
+import java.util.concurrent.ConcurrentHashMap
 
 object BauweltMemberTable : CompositeIdTable("BauweltMember") {
     val bauweltId = reference("BauweltID", SteamwarUserTable).index()
@@ -48,10 +49,12 @@ object BauweltMemberTable : CompositeIdTable("BauweltMember") {
 
 class BauweltMember(id: EntityID<CompositeID>) : CompositeEntity(id) {
     companion object : CompositeEntityClass<BauweltMember>(BauweltMemberTable) {
-        private val cache = mutableMapOf<Int, BauweltMember>()
+        // Keyed by (bauweltId, memberId). Optional.empty() caches "is not a member", which is the
+        // common case for spectators and would otherwise hit the DB on every permission check.
+        private val cache = ConcurrentHashMap<Pair<Int, Int>, Optional<BauweltMember>>()
 
         private fun cache(member: BauweltMember) =
-            cache.put(member.memberID, member)
+            cache.put(member.bauweltID to member.memberID, Optional.of(member))
 
         @JvmStatic
         fun clear() =
@@ -75,20 +78,20 @@ class BauweltMember(id: EntityID<CompositeID>) : CompositeEntity(id) {
                     it[worldEdit] = false
                     it[world] = false
                 }
-            }
+            }.also { cache.remove(ownerId.value to newMemberId.value) }
 
         @JvmStatic
         @Deprecated("Use getBauMember(bauwelt: Int, member: Int)")
         fun getBauMember(bauwelt: UUID, member: UUID) =
-            useDb {
-                find { (bauweltId eq SteamwarUser.get(bauwelt)!!.id) and (BauweltMemberTable.memberId eq SteamwarUser.get(member)!!.id) }.firstOrNull()?.also { cache(it) }
-            }
+            getBauMember(SteamwarUser.get(bauwelt)!!.id.value, SteamwarUser.get(member)!!.id.value)
 
         @JvmStatic
-        fun getBauMember(bauwelt: Int, member: Int) =
-            useDb {
-                find { (bauweltId eq bauwelt) and (BauweltMemberTable.memberId eq member) }.firstOrNull()?.also { cache(it) }
-            }
+        fun getBauMember(bauwelt: Int, member: Int): BauweltMember? =
+            cache.computeIfAbsent(bauwelt to member) {
+                Optional.ofNullable(useDb {
+                    find { (bauweltId eq bauwelt) and (BauweltMemberTable.memberId eq member) }.firstOrNull()
+                })
+            }.orElse(null)
 
         @JvmStatic
         @Deprecated("Use getMembers(bauwelt: Int)")
@@ -140,8 +143,11 @@ class BauweltMember(id: EntityID<CompositeID>) : CompositeEntity(id) {
     fun isWorld() =
         world
 
-    fun remove() =
+    fun remove() {
+        val key = bauweltID to memberID
         useDb {
             delete()
         }
+        cache.remove(key)
+    }
 }