Better flatfile purge performance; sync flatdb access ...

... to avoid data loss

src/main/java/com/gmail/nossr50/database/FlatfileDatabaseManager.java

@@ -13,6 +13,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
 
 import com.gmail.nossr50.mcMMO;
@@ -32,6 +33,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
 
     private final long UPDATE_WAIT_TIME = 600000L; // 10 minutes
     private final File usersFile;
+    private static final Object fileWritingLock = new Object();
 
     protected FlatfileDatabaseManager() {
         usersFile = new File(mcMMO.getUsersFilePath());
@@ -48,9 +50,8 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
         FileWriter out = null;
         String usersFilePath = mcMMO.getUsersFilePath();
 
-        // Rationale for doing a file read instead of using the cached values:
+        // This code is O(n) instead of O(n²)
-        // If mulitple users need be removed, this only opens the file once as
+        synchronized (fileWritingLock) {
-        // opposed to calling removeUser which opens the file once each time.
             try {
                 in = new BufferedReader(new FileReader(usersFilePath));
                 StringBuilder writer = new StringBuilder();
@@ -110,6 +111,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                     }
                 }
             }
+        }
 
         mcMMO.p.getLogger().info("Purged " + purgedUsers + " users from the database.");
     }
@@ -120,9 +122,61 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
 
         mcMMO.p.getLogger().info("Purging old users...");
 
-        for (OfflinePlayer player : mcMMO.p.getServer().getOfflinePlayers()) {
+
-            if (!player.isOnline() && (currentTime - player.getLastPlayed() > PURGE_TIME && removeUser(player.getName()))) {
+        BufferedReader in = null;
+        FileWriter out = null;
+        String usersFilePath = mcMMO.getUsersFilePath();
+
+        // This code is O(n) instead of O(n²)
+        synchronized (fileWritingLock) {
+            try {
+                in = new BufferedReader(new FileReader(usersFilePath));
+                StringBuilder writer = new StringBuilder();
+                String line = "";
+
+                while ((line = in.readLine()) != null) {
+                    String[] character = line.split(":");
+                    String name = character[0];
+                    OfflinePlayer player = Bukkit.getOfflinePlayer(name);
+                    boolean old = true;
+                    if (player != null) {
+                        old = (currentTime - player.getLastPlayed()) > PURGE_TIME;
+                    }
+
+                    if (!old) {
+                        writer.append(line);
+                    }
+                    else {
                         removedPlayers++;
+                        Misc.profileCleanup(name);
+                    }
+                }
+
+                // Write the new file
+                out = new FileWriter(usersFilePath);
+                out.write(writer.toString());
+            }
+            catch (IOException e) {
+                mcMMO.p.getLogger().severe("Exception while reading " + usersFilePath + " (Are you sure you formatted it correctly?)" + e.toString());
+            }
+            finally {
+                if (in != null) {
+                    try {
+                        in.close();
+                    }
+                    catch (IOException ex) {
+                        ex.printStackTrace();
+                    }
+                }
+
+                if (out != null) {
+                    try {
+                        out.close();
+                    }
+                    catch (IOException ex) {
+                        ex.printStackTrace();
+                    }
+                }
             }
         }
 
@@ -136,6 +190,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
         FileWriter out = null;
         String usersFilePath = mcMMO.getUsersFilePath();
 
+        synchronized (fileWritingLock) {
             try {
                 in = new BufferedReader(new FileReader(usersFilePath));
                 StringBuilder writer = new StringBuilder();
@@ -177,6 +232,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                     }
                 }
             }
+        }
 
         Misc.profileCleanup(playerName);
 
@@ -190,6 +246,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
         FileWriter out = null;
         String usersFilePath = mcMMO.getUsersFilePath();
 
+        synchronized (fileWritingLock) {
             try {
                 // Open the file
                 in = new BufferedReader(new FileReader(usersFilePath));
@@ -276,6 +333,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                 }
             }
         }
+    }
 
     public List<PlayerStat> readLeaderboard(String skillName, int pageNumber, int statsPerPage) {
         updateLeaderboards();
@@ -300,6 +358,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
     }
 
     public void newUser(String playerName) {
+        synchronized (fileWritingLock) {
             try {
                 // Open the file to write the player
                 BufferedWriter out = new BufferedWriter(new FileWriter(mcMMO.getUsersFilePath(), true));
@@ -354,10 +413,12 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                 e.printStackTrace();
             }
         }
+    }
 
     public PlayerProfile loadPlayerProfile(String playerName, boolean create) {
         FileReader file = null;
         BufferedReader in = null;
+        synchronized (fileWritingLock) {
             try {
                 // Open the user file
                 file = new FileReader(mcMMO.getUsersFilePath());
@@ -390,6 +451,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                     e.printStackTrace();
                 }
             }
+        }
 
         if (create) {
             newUser(playerName);
@@ -402,6 +464,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
         FileReader file = null;
         BufferedReader in = null;
 
+        synchronized (fileWritingLock) {
             try {
                 // Open the user file
                 file = new FileReader(mcMMO.getUsersFilePath());
@@ -435,6 +498,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                 }
             }
         }
+    }
 
     public boolean checkConnected() {
         // Not implemented
@@ -444,6 +508,8 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
     public List<String> getStoredUsers() {
         ArrayList<String> users = new ArrayList<String>();
         BufferedReader in = null;
+
+        synchronized (fileWritingLock) {
             try {
                 // Open the user file
                 FileReader file = new FileReader(mcMMO.getUsersFilePath());
@@ -465,6 +531,7 @@ public final class FlatfileDatabaseManager implements DatabaseManager {
                     e.printStackTrace();
                 }
             }
+        }
         return users;
     }