Implement thread pool for JsonShopConfiguration saves

src/main/java/org/shanerx/tradeshop/TradeShop.java

@@ -37,6 +37,8 @@
 import org.shanerx.tradeshop.data.config.Language;
 import org.shanerx.tradeshop.data.config.Setting;
 import org.shanerx.tradeshop.data.storage.DataStorage;
+import org.shanerx.tradeshop.data.storage.DataType;
+import org.shanerx.tradeshop.data.storage.Json.JsonShopConfiguration;
 import org.shanerx.tradeshop.player.JoinEventListener;
 import org.shanerx.tradeshop.player.Permissions;
 import org.shanerx.tradeshop.shop.ShopSign;
@@ -112,6 +114,8 @@ public void onEnable() {
 
     @Override
     public void onDisable() {
+        varManager.getDataStorage().ensureFinalSave();
+
         if (getListManager() != null)
             getListManager().clearManager();
     }

src/main/java/org/shanerx/tradeshop/data/config/Setting.java

@@ -51,6 +51,7 @@ public enum Setting {
 
     // System Options
     DATA_STORAGE_TYPE(SettingSection.SYSTEM_OPTIONS, "data-storage-type", "FLATFILE"),
+    MAX_SAVE_THREADS(SettingSection.SYSTEM_OPTIONS, "max-save-threads", 1),
     ENABLE_DEBUG(SettingSection.SYSTEM_OPTIONS, "enable-debug", 0),
     CHECK_UPDATES(SettingSection.SYSTEM_OPTIONS, "check-updates", true),
     ALLOW_METRICS(SettingSection.SYSTEM_OPTIONS, "allow-metrics", true),

src/main/java/org/shanerx/tradeshop/data/storage/DataStorage.java

@@ -67,7 +67,6 @@
 public class DataStorage extends Utils {
 
     private transient DataType dataType;
-    public final Map<File, String> saving;
     private final String BROKEN_JSON_START = "}(.*[\"\\w:])";
 
     private final Cache<World, LinkageConfiguration> linkCache = CacheBuilder.newBuilder()
@@ -84,7 +83,6 @@ public class DataStorage extends Utils {
             .build();
 
     public DataStorage(DataType dataType) {
-        saving = new ConcurrentHashMap<>();
         reload(dataType);
     }
 
@@ -131,8 +129,6 @@ public boolean validate() {
                 }
             });
 
-            TradeShop.getPlugin().getDebugger().log("FLATFILE Malformed Files Found: " + correctedFiles.size(), DebugLevels.DATA_ERROR);
-
             //Write corrected malformed files
             if (correctedFiles.size() > 0) {
                 correctedFiles.forEach((k, v) -> {
@@ -314,5 +310,13 @@ protected LinkageConfiguration getLinkageConfiguration(World w) {
 
         throw new NotImplementedException("Data storage type " + dataType + " has not been implemented yet.");
     }
+
+    public void ensureFinalSave() {
+        // for onDisable !!!
+        if (dataType == DataType.FLATFILE) {
+            JsonShopConfiguration.SaveThreadMaster.getInstance().saveEverythingNow();
+        }
+        // SQLITE will have an analogous branch
+    }
 }
 

src/main/java/org/shanerx/tradeshop/data/storage/Json/JsonShopConfiguration.java

@@ -27,21 +27,25 @@
 
 import com.google.common.collect.Sets;
 import com.google.gson.JsonElement;
-import org.bukkit.Bukkit;
+import com.google.gson.JsonObject;
+import org.bukkit.scheduler.BukkitRunnable;
 import org.shanerx.tradeshop.TradeShop;
+import org.shanerx.tradeshop.data.config.Setting;
 import org.shanerx.tradeshop.data.storage.ShopConfiguration;
 import org.shanerx.tradeshop.shop.Shop;
 import org.shanerx.tradeshop.shoplocation.ShopChunk;
 import org.shanerx.tradeshop.shoplocation.ShopLocation;
-import org.shanerx.tradeshop.utils.debug.DebugLevels;
+import org.shanerx.tradeshop.utils.gsonprocessing.GsonProcessor;
+import org.shanerx.tradeshop.utils.objects.Tuple;
 
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.logging.Level;
+import java.util.logging.Logger;
 
 public class JsonShopConfiguration extends JsonConfiguration implements ShopConfiguration {
 
@@ -65,12 +69,8 @@ public void save(Shop shop) {
 
     @Override
     public void remove(ShopLocation loc) {
-        System.out.println("PREV: " + gson.toJson(jsonObj));
-
         if (jsonObj.has(loc.serialize()))
             jsonObj.remove(loc.serialize());
-
-        System.out.println("NOW: " + gson.toJson(jsonObj));
         saveFile();
     }
 
@@ -117,29 +117,7 @@ public int size() {
 
     @Override
     protected void saveFile() {
-        if (PLUGIN.getDataStorage().saving.containsKey(this.file)) {
-            return;
-        }
-
-        final String str = gson.toJson(jsonObj);
-        if (str.isEmpty() || jsonObj.entrySet().isEmpty()) {
-            this.file.delete();
-            return;
-        }
-
-        PLUGIN.getDataStorage().saving.put(this.file, str);
-//        Bukkit.getScheduler().runTaskAsynchronously(TradeShop.getPlugin(), () -> {
-            try {
-                System.out.println("SAVE: " + str);
-                FileWriter fileWriter = new FileWriter(this.file);
-                fileWriter.write(str);
-                fileWriter.flush();
-                fileWriter.close();
-            } catch (IOException e) {
-                PLUGIN.getLogger().log(Level.SEVERE, "Could not save " + this.file.getName() + " file! Data may be lost!", e);
-            }
-            PLUGIN.getDataStorage().saving.remove(this.file);
-//        });
+        SaveThreadMaster.getInstance().enqueue(this.file, this.jsonObj);
     }
 
     @Override
@@ -160,4 +138,123 @@ protected void loadFile() {
             }
         }
     }
+
+    public static class SaveThreadMaster {
+
+        private static SaveThreadMaster singleton;
+
+        private Queue<Tuple<File, JsonObject>> saveQueue;
+        private Set<BukkitRunnable> runningTasks;
+        private Map<File, SaveTask> filesBeingSaved;
+
+        private int maxThreads;
+        private final GsonProcessor gson = new GsonProcessor();
+
+        private SaveThreadMaster() {
+            if (singleton != null) {
+                throw new UnsupportedOperationException("Attempting to create further instance of singleton class SaveThreadMaster!");
+            }
+
+            saveQueue = new ConcurrentLinkedQueue<>();
+            runningTasks = new HashSet<>();
+            filesBeingSaved = new ConcurrentHashMap<>();
+            maxThreads = Math.max(0, Setting.MAX_SAVE_THREADS.getInt());
+
+            singleton = this;
+        }
+
+        public static SaveThreadMaster getInstance() {
+            if (singleton == null) {
+                return new SaveThreadMaster();
+            }
+
+            return singleton;
+        }
+
+        Queue<Tuple<File, JsonObject>> getSaveQueue() {
+            return saveQueue;
+        }
+
+        private SaveTask makeRunnable() {
+            return new SaveTask();
+        }
+
+        void enqueue(File file, JsonObject jsonObj) {
+            if (filesBeingSaved.containsKey(file)) {
+                SaveTask task = filesBeingSaved.get(file);
+                task.enqueue(new Tuple<>(file, jsonObj));
+            } else {
+                saveQueue.add(new Tuple<>(file, jsonObj));
+            }
+
+            if (maxThreads == 0) {
+                makeRunnable().run();
+                if (!saveQueue.isEmpty()) {
+                    throw new IllegalStateException("saveQueue should be empty but has unsaved shop data: " + saveQueue.size());
+                }
+            } else if (runningTasks.size() < maxThreads) {
+                makeRunnable().runTaskAsynchronously(TradeShop.getPlugin());
+            }
+        }
+
+        public void saveEverythingNow() {
+            if (saveQueue.isEmpty()) return;
+            for (int i = 0; i < maxThreads; ++i) {
+                makeRunnable().runTaskAsynchronously(TradeShop.getPlugin());
+            }
+        }
+    }
+
+    static class SaveTask extends BukkitRunnable {
+        private SaveThreadMaster master;
+        private Queue<Tuple<File, JsonObject>> ownQueue;
+
+        SaveTask() {
+            this.master = SaveThreadMaster.getInstance();
+            ownQueue = new ConcurrentLinkedQueue<>();
+        }
+
+        private Tuple<File, JsonObject> pollNext() {
+            if (!ownQueue.isEmpty()) return ownQueue.poll();
+            else return master.getSaveQueue().poll();
+        }
+
+        void enqueue(Tuple<File, JsonObject> elem) {
+            ownQueue.add(elem);
+        }
+
+        @Override
+        public void run() {
+            Logger logger = TradeShop.getPlugin().getLogger();
+            Tuple<File, JsonObject> elem;
+
+            while ((elem = pollNext()) != null) {
+                File file = elem.getLeft();
+                JsonObject jsonObj = elem.getRight();
+                String str = master.gson.toJson(jsonObj);
+
+                if (str.isEmpty() || jsonObj.entrySet().isEmpty()) {
+                    file.delete();
+                    return;
+                }
+
+                try {
+                    FileWriter fileWriter = new FileWriter(file);
+                    fileWriter.write(str);
+                    fileWriter.flush();
+                    fileWriter.close();
+                } catch (IOException e) {
+                    logger.log(Level.SEVERE, "Could not save " + file.getName() + " file! Data may be lost!", e);
+                }
+            }
+
+            // task dies now:
+            master.filesBeingSaved.remove(this);
+        }
+
+        @Override
+        public int hashCode() {
+            return super.getTaskId();
+        }
+    }
 }