Merge pull request #169 from Lignum/fd-limit

Configurable file descriptor limit

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -127,6 +127,7 @@ public class ComputerCraft
 
     public static int computerSpaceLimit = 1000 * 1000;
     public static int floppySpaceLimit = 125 * 1000;
+    public static int maximumFilesOpen = 128;
 
     // Blocks and Items
     public static class Blocks
@@ -184,6 +185,7 @@ public class ComputerCraft
 
         public static Property computerSpaceLimit;
         public static Property floppySpaceLimit;
+        public static Property maximumFilesOpen;
 
     }
 
@@ -260,6 +262,9 @@ public class ComputerCraft
         Config.turtlesNeedFuel = Config.config.get( Configuration.CATEGORY_GENERAL, "turtlesNeedFuel", turtlesNeedFuel );
         Config.turtlesNeedFuel.setComment( "Set whether Turtles require fuel to move" );
 
+        Config.maximumFilesOpen = Config.config.get(Configuration.CATEGORY_GENERAL, "maximumFilesOpen", maximumFilesOpen);
+        Config.maximumFilesOpen.setComment( "How many files a computer can have open at the same time" );
+
         Config.turtleFuelLimit = Config.config.get( Configuration.CATEGORY_GENERAL, "turtleFuelLimit", turtleFuelLimit );
         Config.turtleFuelLimit.setComment( "The fuel limit for Turtles" );
 
@@ -303,6 +308,7 @@ public class ComputerCraft
 
         computerSpaceLimit = Config.computerSpaceLimit.getInt();
         floppySpaceLimit = Config.floppySpaceLimit.getInt();
+        maximumFilesOpen = Math.max( 0, Config.maximumFilesOpen.getInt() );
 
         turtlesNeedFuel = Config.turtlesNeedFuel.getBoolean();
         turtleFuelLimit = Config.turtleFuelLimit.getInt();

src/main/java/dan200/computercraft/core/filesystem/FileSystem.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.core.filesystem;
 
+import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.filesystem.IMount;
 import dan200.computercraft.api.filesystem.IWritableMount;
 
@@ -289,8 +290,8 @@ public class FileSystem
         }
     }
 
-    private Map<String, MountWrapper> m_mounts = new HashMap<String, MountWrapper>();
+    private final Map<String, MountWrapper> m_mounts = new HashMap<String, MountWrapper>();
-    private Set<IMountedFile> m_openFiles = new HashSet<IMountedFile>();
+    private final Set<IMountedFile> m_openFiles = new HashSet<IMountedFile>();
     
     public FileSystem( String rootLabel, IMount rootMount ) throws FileSystemException
     {
@@ -650,6 +651,41 @@ public class FileSystem
         }
     }
 
+    private synchronized <T extends IMountedFile> T openFile(T file, Closeable handle) throws FileSystemException
+    {
+        synchronized( m_openFiles )
+        {
+            if( m_openFiles.size() >= ComputerCraft.maximumFilesOpen )
+            {
+                if( handle != null )
+                {
+                    try {
+                        handle.close();
+                    } catch ( IOException ignored ) {
+                        // shrug
+                    }
+                }
+                throw new FileSystemException("Too many files already open");
+            }
+
+            m_openFiles.add( file );
+            return file;
+        }
+    }
+
+    private synchronized void closeFile( IMountedFile file, Closeable handle ) throws IOException
+    {
+        synchronized( m_openFiles )
+        {
+            m_openFiles.remove( file );
+
+            if( handle != null )
+            {
+                handle.close();
+            }
+        }
+    }
+    
     public synchronized IMountedFileNormal openForRead( String path ) throws FileSystemException
     {
         path = sanitizePath ( path );
@@ -684,11 +720,7 @@ public class FileSystem
                 @Override
                 public void close() throws IOException
                 {
-                    synchronized( m_openFiles )
+                    closeFile( this, reader );
-                    {
-                        m_openFiles.remove( this );
-                        reader.close();
-                    }
                 }
                 
                 @Override
@@ -697,11 +729,7 @@ public class FileSystem
                     throw new UnsupportedOperationException();
                 }
             };
-            synchronized( m_openFiles )
+            return openFile( file, reader );
-            {
-                m_openFiles.add( file );
-            }
-            return file;
         }
         return null;
     }
@@ -744,11 +772,7 @@ public class FileSystem
                 @Override
                 public void close() throws IOException
                 {
-                    synchronized( m_openFiles )
+                    closeFile( this, writer );
-                    {
-                        m_openFiles.remove( this );
-                        writer.close();
-                    }
                 }
                 
                 @Override
@@ -757,11 +781,7 @@ public class FileSystem
                     writer.flush();
                 }
             };
-            synchronized( m_openFiles )
+            return openFile( file, writer );
-            {
-                m_openFiles.add( file );
-            }
-            return file;
         }
         return null;
     }
@@ -790,11 +810,7 @@ public class FileSystem
                 @Override
                 public void close() throws IOException
                 {
-                    synchronized( m_openFiles )
+                    closeFile( this, stream );
-                    {
-                        m_openFiles.remove( this );
-                        stream.close();
-                    }
                 }
                 
                 @Override
@@ -803,11 +819,7 @@ public class FileSystem
                     throw new UnsupportedOperationException();
                 }
             };
-            synchronized( m_openFiles )
+            return openFile( file, stream );
-            {
-                m_openFiles.add( file );
-            }
-            return file;
         }
         return null;
     }
@@ -836,11 +848,7 @@ public class FileSystem
                 @Override
                 public void close() throws IOException
                 {
-                    synchronized( m_openFiles )
+                    closeFile( this, stream );
-                    {
-                        m_openFiles.remove( this );
-                        stream.close();
-                    }
                 }
                 
                 @Override
@@ -849,11 +857,7 @@ public class FileSystem
                     stream.flush();
                 }
             };
-            synchronized( m_openFiles )
+            return openFile( file, stream );
-            {
-                m_openFiles.add( file );
-            }
-            return file;
         }
         return null;
     }

src/main/resources/assets/computercraft/lang/en_US.lang

@@ -56,3 +56,4 @@ gui.computercraft:config.turtle_fuel_limit=Turtle fuel limit
 gui.computercraft:config.advanced_turtle_fuel_limit=Advanced Turtle fuel limit
 gui.computercraft:config.turtles_obey_block_protection=Turtles obey block protection
 gui.computercraft:config.turtles_can_push=Turtles can push entities
+gui.computercraft:config.maximum_files_open=Maximum files open per computer