#1147 Drop SingleFilePersistenceHandler in favor of DistributedFilesPersistenceHandler

- Remove SingleFilePersistenceHandler: DistributedFilesPersistenceHandler with segment size 1 can be used instead
- Rename  SegmentFilesPersistenceHolder to DistributedFilesPersistenceHandler
- Rename SeparateFilePersistenceHandler to IndividualFilesPersistenceHandler to match LimboPersistenceType entry
- Add link to limbo page on Wiki in the settings

src/main/java/fr/xephi/authme/data/limbo/persistence/DistributedFilesPersistenceHandler.java

@@ -30,7 +30,7 @@ import java.util.Optional;
  * Persistence handler for LimboPlayer objects by distributing the objects to store
  * in various segments (buckets) based on the start of the player's UUID.
  */
-class SegmentFilesPersistenceHolder implements LimboPersistenceHandler {
+class DistributedFilesPersistenceHandler implements LimboPersistenceHandler {
 
     private static final Type LIMBO_MAP_TYPE = new TypeToken<Map<String, LimboPlayer>>(){}.getType();
 
@@ -39,7 +39,7 @@ class SegmentFilesPersistenceHolder implements LimboPersistenceHandler {
     private final SegmentNameBuilder segmentNameBuilder;
 
     @Inject
-    SegmentFilesPersistenceHolder(@DataFolder File dataFolder, BukkitService bukkitService, Settings settings) {
+    DistributedFilesPersistenceHandler(@DataFolder File dataFolder, BukkitService bukkitService, Settings settings) {
         cacheFolder = new File(dataFolder, "playerdata");
         if (!cacheFolder.exists()) {
             // TODO ljacqu 20170313: Create FileUtils#mkdirs
@@ -100,7 +100,7 @@ class SegmentFilesPersistenceHolder implements LimboPersistenceHandler {
 
     @Override
     public LimboPersistenceType getType() {
-        return LimboPersistenceType.SEGMENT_FILES;
+        return LimboPersistenceType.DISTRIBUTED_FILES;
     }
 
     private void saveEntries(Map<String, LimboPlayer> entries, File file) {
@@ -126,7 +126,11 @@ class SegmentFilesPersistenceHolder implements LimboPersistenceHandler {
 
     private File getPlayerSegmentFile(String uuid) {
         String segment = segmentNameBuilder.createSegmentName(uuid);
-        return new File(cacheFolder, segment + "-limbo.json");
+        return getSegmentFile(segment);
+    }
+
+    private File getSegmentFile(String segmentId) {
+        return new File(cacheFolder, segmentId + "-limbo.json");
     }
 
     /**
@@ -167,7 +171,7 @@ class SegmentFilesPersistenceHolder implements LimboPersistenceHandler {
         ConsoleLogger.info("Saving " + limbosFromOldSegments.size() + " LimboPlayers from old segments into "
             + limboBySegment.size() + " current segments");
         for (Map.Entry<String, Map<String, LimboPlayer>> entry : limboBySegment.entrySet()) {
-            File file = new File(cacheFolder, entry.getKey() + "-limbo.json");
+            File file = getSegmentFile(entry.getKey());
             Map<String, LimboPlayer> limbosToSave = Optional.ofNullable(readLimboPlayers(file))
                 .orElseGet(HashMap::new);
             limbosToSave.putAll(entry.getValue());
@@ -193,7 +197,7 @@ class SegmentFilesPersistenceHolder implements LimboPersistenceHandler {
     }
 
     /**
-     * Deletes files from the current segmenting scheme that are empty.
+     * Deletes segment files that are empty.
      */
     private void deleteEmptyFiles() {
         File[] files = listFiles(cacheFolder);

src/main/java/fr/xephi/authme/data/limbo/persistence/IndividualFilesPersistenceHandler.java

@@ -19,13 +19,13 @@ import java.nio.charset.StandardCharsets;
 /**
  * Saves LimboPlayer objects as JSON into individual files.
  */
-class SeparateFilePersistenceHandler implements LimboPersistenceHandler {
+class IndividualFilesPersistenceHandler implements LimboPersistenceHandler {
 
     private final Gson gson;
     private final File cacheDir;
 
     @Inject
-    SeparateFilePersistenceHandler(@DataFolder File dataFolder, BukkitService bukkitService) {
+    IndividualFilesPersistenceHandler(@DataFolder File dataFolder, BukkitService bukkitService) {
         cacheDir = new File(dataFolder, "playerdata");
         if (!cacheDir.exists() && !cacheDir.isDirectory() && !cacheDir.mkdir()) {
             ConsoleLogger.warning("Failed to create playerdata directory '" + cacheDir + "'");

src/main/java/fr/xephi/authme/data/limbo/persistence/LimboPersistenceType.java

@@ -6,13 +6,10 @@ package fr.xephi.authme.data.limbo.persistence;
 public enum LimboPersistenceType {
 
     /** Store each LimboPlayer in a separate file. */
-    INDIVIDUAL_FILES(SeparateFilePersistenceHandler.class),
+    INDIVIDUAL_FILES(IndividualFilesPersistenceHandler.class),
 
-    /** Store all LimboPlayers in the same file. */
-    SINGLE_FILE(SingleFilePersistenceHandler.class),
-
-    /** Distribute LimboPlayers by segments into a set number of files. */
-    SEGMENT_FILES(SegmentFilesPersistenceHolder.class),
+    /** Store LimboPlayers distributed in a configured number of files. */
+    DISTRIBUTED_FILES(DistributedFilesPersistenceHandler.class),
 
     /** No persistence to disk. */
     DISABLED(NoOpPersistenceHandler.class);

src/main/java/fr/xephi/authme/data/limbo/persistence/SegmentConfiguration.java

@@ -3,7 +3,7 @@ package fr.xephi.authme.data.limbo.persistence;
 /**
  * Configuration for the total number of segments to use.
  * <p>
- * The {@link SegmentFilesPersistenceHolder} reduces the number of files by assigning each UUID
+ * The {@link DistributedFilesPersistenceHandler} reduces the number of files by assigning each UUID
  * to a segment. This enum allows to define how many segments the UUIDs should be distributed in.
  * <p>
  * Segments are defined by a <b>distribution</b> and a <b>length.</b> The distribution defines
@@ -38,8 +38,8 @@ public enum SegmentConfiguration {
     /** 1. */
     ONE(1, 1),
 
-    ///** 2. */
-    //TWO(2, 1),
+    // /** 2. */
+    // TWO(2, 1),
 
     /** 4. */
     FOUR(4, 1),
@@ -86,7 +86,7 @@ public enum SegmentConfiguration {
     }
 
     /**
-     * @return number of segments to which this configuration will distribute UUIDs
+     * @return number of segments to which this configuration will distribute all UUIDs
      */
     public int getTotalSegments() {
         return (int) Math.pow(distribution, length);

src/main/java/fr/xephi/authme/data/limbo/persistence/SegmentNameBuilder.java

@@ -4,7 +4,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 /**
- * Creates segment names for {@link SegmentFilesPersistenceHolder}.
+ * Creates segment names for {@link DistributedFilesPersistenceHandler}.
  */
 class SegmentNameBuilder {
 

src/main/java/fr/xephi/authme/data/limbo/persistence/SingleFilePersistenceHandler.java

@@ -1,94 +0,0 @@
-package fr.xephi.authme.data.limbo.persistence;
-
-import com.google.common.reflect.TypeToken;
-import com.google.gson.Gson;
-import com.google.gson.GsonBuilder;
-import fr.xephi.authme.ConsoleLogger;
-import fr.xephi.authme.data.limbo.LimboPlayer;
-import fr.xephi.authme.initialization.DataFolder;
-import fr.xephi.authme.service.BukkitService;
-import fr.xephi.authme.util.FileUtils;
-import fr.xephi.authme.util.PlayerUtils;
-import org.bukkit.entity.Player;
-
-import javax.inject.Inject;
-import java.io.File;
-import java.io.FileReader;
-import java.io.FileWriter;
-import java.io.IOException;
-import java.lang.reflect.Type;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
-
-/**
- * Saves all LimboPlayers in one JSON file and keeps the entries in memory.
- */
-class SingleFilePersistenceHandler implements LimboPersistenceHandler {
-
-    private final File cacheFile;
-    private final Gson gson;
-    private Map<String, LimboPlayer> entries;
-
-    @Inject
-    SingleFilePersistenceHandler(@DataFolder File dataFolder, BukkitService bukkitService) {
-        cacheFile = new File(dataFolder, "limbo.json");
-        if (!cacheFile.exists()) {
-            FileUtils.create(cacheFile);
-        }
-
-        gson = new GsonBuilder()
-            .registerTypeAdapter(LimboPlayer.class, new LimboPlayerSerializer())
-            .registerTypeAdapter(LimboPlayer.class, new LimboPlayerDeserializer(bukkitService))
-            .setPrettyPrinting()
-            .create();
-
-        Type type = new TypeToken<ConcurrentMap<String, LimboPlayer>>(){}.getType();
-        try (FileReader fr = new FileReader(cacheFile)) {
-            entries = gson.fromJson(fr, type);
-        } catch (IOException e) {
-            ConsoleLogger.logException("Failed to read from '" + cacheFile + "':", e);
-        }
-
-        if (entries == null) {
-            entries = new ConcurrentHashMap<>();
-        }
-    }
-
-    @Override
-    public LimboPlayer getLimboPlayer(Player player) {
-        return entries.get(PlayerUtils.getUUIDorName(player));
-    }
-
-    @Override
-    public void saveLimboPlayer(Player player, LimboPlayer limbo) {
-        entries.put(PlayerUtils.getUUIDorName(player), limbo);
-        saveEntries("adding '" + player.getName() + "'");
-    }
-
-    @Override
-    public void removeLimboPlayer(Player player) {
-        LimboPlayer entry = entries.remove(PlayerUtils.getUUIDorName(player));
-        if (entry != null) {
-            saveEntries("removing '" + player.getName() + "'");
-        }
-    }
-
-    /**
-     * Saves the entries to the disk.
-     *
-     * @param action the reason for saving (for logging purposes)
-     */
-    private void saveEntries(String action) {
-        try (FileWriter fw = new FileWriter(cacheFile)) {
-            gson.toJson(entries, fw);
-        } catch (IOException e) {
-            ConsoleLogger.logException("Failed saving JSON limbo cache after " + action, e);
-        }
-    }
-
-    @Override
-    public LimboPersistenceType getType() {
-        return LimboPersistenceType.SINGLE_FILE;
-    }
-}