Truncate the counts store file before writing new values

This should fix a problem during counts store rotation when the counts
store file is partially written but it cannot be recognized as
corrupted.  Hence it will be loaded on the next recovery and lead to
inconsistencies.

community/io/src/main/java/org/neo4j/io/fs/DefaultFileSystemAbstraction.java

@@ -195,4 +195,10 @@ public synchronized <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFile
         }
         return clazz.cast( fileSystem );
     }
+
+    @Override
+    public void truncate( File path, long size ) throws IOException
+    {
+        FileUtils.truncateFile( path, size );
+    }
 }

community/io/src/main/java/org/neo4j/io/fs/FileSystemAbstraction.java

@@ -33,47 +33,49 @@
 public interface FileSystemAbstraction
 {
     StoreChannel open( File fileName, String mode ) throws IOException;
-    
+
     OutputStream openAsOutputStream( File fileName, boolean append ) throws IOException;
-    
+
     InputStream openAsInputStream( File fileName ) throws IOException;
-    
+
     Reader openAsReader( File fileName, String encoding ) throws IOException;
-    
+
     Writer openAsWriter( File fileName, String encoding, boolean append ) throws IOException;
-    
+
     FileLock tryLock( File fileName, StoreChannel channel ) throws IOException;
-    
+
     StoreChannel create( File fileName ) throws IOException;
-    
+
     boolean fileExists( File fileName );
-    
+
     boolean mkdir( File fileName );
-    
+
     void mkdirs( File fileName ) throws IOException;
-    
+
     long getFileSize( File fileName );
 
     boolean deleteFile( File fileName );
-    
+
     void deleteRecursively( File directory ) throws IOException;
-    
+
     boolean renameFile( File from, File to ) throws IOException;
-    
+
     File[] listFiles( File directory );
 
     File[] listFiles( File directory, FilenameFilter filter );
 
     boolean isDirectory( File file );
-    
+
     void moveToDirectory( File file, File toDirectory ) throws IOException;
-    
+
     void copyFile( File from, File to ) throws IOException;
-    
+
     void copyRecursively( File fromDirectory, File toDirectory ) throws IOException;
 
     <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFileSystem( Class<K> clazz, Function<Class<K>, K> creator );
 
+    void truncate( File path, long size ) throws IOException;
+
     interface ThirdPartyFileSystem
     {
         void close();

community/io/src/test/java/org/neo4j/adversaries/fs/AdversarialFileSystemAbstraction.java

@@ -203,6 +203,14 @@ public synchronized <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFile
         return (K) fileSystem;
     }
 
+    @Override
+    public void truncate( File path, long size ) throws IOException
+    {
+        adversary.injectFailure( FileNotFoundException.class, IOException.class, IllegalArgumentException.class,
+                SecurityException.class, NullPointerException.class );
+        delegate.truncate( path, size );
+    }
+
     private <K extends ThirdPartyFileSystem> ThirdPartyFileSystem adversarialProxy(
             final ThirdPartyFileSystem fileSystem,
             Class<K> clazz )

community/io/src/test/java/org/neo4j/graphdb/mockfs/DelegatingFileSystemAbstraction.java

@@ -72,6 +72,12 @@ public <K extends FileSystemAbstraction.ThirdPartyFileSystem> K getOrCreateThird
         return delegate.getOrCreateThirdPartyFileSystem( clazz, creator );
     }
 
+    @Override
+    public void truncate( File path, long size ) throws IOException
+    {
+        delegate.truncate( path, size );
+    }
+
     @Override
     public boolean renameFile( File from, File to ) throws IOException
     {

community/io/src/test/java/org/neo4j/graphdb/mockfs/EphemeralFileSystemAbstraction.java

@@ -569,6 +569,17 @@ public synchronized <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFile
         return clazz.cast( fileSystem );
     }
 
+    @Override
+    public void truncate( File file, long size ) throws IOException
+    {
+        EphemeralFileData data = files.get( file );
+        if ( data == null )
+        {
+            throw new FileNotFoundException( "File " + file + " not found" );
+        }
+        data.truncate( size );
+    }
+
     @SuppressWarnings( "serial" )
     private static class FileStillOpenException extends Exception
     {

community/io/src/test/java/org/neo4j/graphdb/mockfs/LimitedFilesystemAbstraction.java

@@ -51,7 +51,7 @@ public StoreChannel open( File fileName, String mode ) throws IOException
     {
         return new LimitedFileChannel( inner.open( fileName, mode ), this );
     }
-    
+
     @Override
     public OutputStream openAsOutputStream( File fileName, boolean append ) throws IOException
     {
@@ -69,7 +69,7 @@ public Reader openAsReader( File fileName, String encoding ) throws IOException
     {
         return new InputStreamReader( openAsInputStream( fileName ), encoding );
     }
-    
+
     @Override
     public Writer openAsWriter( File fileName, String encoding, boolean append ) throws IOException
     {
@@ -106,7 +106,7 @@ public boolean deleteFile( File fileName )
     {
         return inner.deleteFile( fileName );
     }
-    
+
     @Override
     public void deleteRecursively( File directory ) throws IOException
     {
@@ -118,7 +118,7 @@ public boolean mkdir( File fileName )
     {
         return inner.mkdir( fileName );
     }
-    
+
     @Override
     public void mkdirs( File fileName ) throws IOException
     {
@@ -157,25 +157,25 @@ public File[] listFiles( File directory, FilenameFilter filter )
     {
         return inner.listFiles( directory, filter );
     }
-    
+
     @Override
     public boolean isDirectory( File file )
     {
         return inner.isDirectory( file );
     }
-    
+
     @Override
     public void moveToDirectory( File file, File toDirectory ) throws IOException
     {
         inner.moveToDirectory( file, toDirectory );
     }
-    
+
     @Override
     public void copyFile( File from, File to ) throws IOException
     {
         inner.copyFile( from, to );
     }
-    
+
     @Override
     public void copyRecursively( File fromDirectory, File toDirectory ) throws IOException
     {
@@ -188,4 +188,10 @@ public <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFileSystem(
     {
         return inner.getOrCreateThirdPartyFileSystem( clazz, creator );
     }
+
+    @Override
+    public void truncate( File path, long size ) throws IOException
+    {
+        inner.truncate( path, size );
+    }
 }

community/kernel/src/main/java/org/neo4j/kernel/impl/store/kvstore/KeyValueStoreFileFormat.java

@@ -146,6 +146,12 @@ private KeyValueStoreFile create(
                     "Invalid sizes: keySize=%d, valueSize=%d, format maxSize=%d",
                     keySize, valueSize, maxSize ) );
         }
+
+        if ( fs.fileExists( path ) )
+        {
+            fs.truncate( path, 0 );
+        }
+
         BigEndianByteArrayBuffer key = new BigEndianByteArrayBuffer( new byte[keySize] );
         BigEndianByteArrayBuffer value = new BigEndianByteArrayBuffer( new byte[valueSize] );
         writeFormatSpecifier( value );

community/kernel/src/main/java/org/neo4j/kernel/impl/store/kvstore/KeyValueWriter.java

@@ -265,11 +265,7 @@ static abstract class Writer
 
         abstract void close() throws IOException;
 
-        void writeTrailer( String trailer ) throws IOException
-        {
-            write( UTF8.encode( trailer ) );
-        }
-
+        abstract void writeTrailer( String trailer ) throws IOException;
         static Writer create( FileSystemAbstraction fs, PageCache pages, File path, int pageSize ) throws IOException
         {
             if ( pages == null )
@@ -302,6 +298,12 @@ void write( byte[] data ) throws IOException
             out.write( data );
         }
 
+        @Override
+        void writeTrailer( String trailer ) throws IOException
+        {
+            write( UTF8.encode( trailer ) );
+        }
+
         @Override
         KeyValueStoreFile open( Metadata metadata, int keySize, int valueSize ) throws IOException
         {

community/kernel/src/test/java/org/neo4j/graphdb/mockfs/BreakableFileSystemAbstraction.java

@@ -186,4 +186,9 @@ public <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFileSystem( Class
         return inner.getOrCreateThirdPartyFileSystem( clazz, creator );
     }
 
+    @Override
+    public void truncate( File path, long size ) throws IOException
+    {
+        inner.truncate( path, size );
+    }
 }

community/kernel/src/test/java/org/neo4j/kernel/CannedFileSystemAbstraction.java

@@ -44,7 +44,7 @@ public void run()
         {
         }
     };
-    
+
     public static Runnable callCounter( final AtomicInteger count )
     {
         return new Runnable()
@@ -56,7 +56,7 @@ public void run()
             }
         };
     }
-    
+
     private final boolean fileExists;
     private final IOException cannotCreateStoreDir;
     private final IOException cannotOpenLockFile;
@@ -86,7 +86,7 @@ public StoreChannel open( File fileName, String mode ) throws IOException
 
         return emptyFileChannel;
     }
-    
+
     private final StoreChannel emptyFileChannel = new AbstractStoreChannel()
     {
         @Override
@@ -153,7 +153,7 @@ public void close() throws IOException
         {
             onClose.run();
         }
-        
+
         private IOException unsupported()
         {
             return new IOException( "Unsupported" );
@@ -177,7 +177,7 @@ public Reader openAsReader( File fileName, String encoding ) throws IOException
     {
         throw new UnsupportedOperationException( "TODO" );
     }
-    
+
     @Override
     public Writer openAsWriter( File fileName, String encoding, boolean append ) throws IOException
     {
@@ -191,7 +191,7 @@ public FileLock tryLock( File fileName, StoreChannel channel ) throws IOExceptio
         {
             throw new IOException( "Unable to create lock file " + fileName );
         }
-        
+
         return SYMBOLIC_FILE_LOCK;
     }
 
@@ -262,7 +262,7 @@ public File[] listFiles( File directory, FilenameFilter filter )
     {
         return new File[0];
     }
-    
+
     @Override
     public void moveToDirectory( File file, File toDirectory ) throws IOException
     {
@@ -274,7 +274,7 @@ public void copyFile( File file, File toDirectory ) throws IOException
     {
         throw new UnsupportedOperationException( "TODO" );
     }
-    
+
     @Override
     public void copyRecursively( File fromDirectory, File toDirectory ) throws IOException
     {
@@ -288,6 +288,12 @@ public <K extends ThirdPartyFileSystem> K getOrCreateThirdPartyFileSystem( Class
         throw new UnsupportedOperationException( "not implemented" );
     }
 
+    @Override
+    public void truncate( File path, long size ) throws IOException
+    {
+        throw new UnsupportedOperationException( "TODO" );
+    }
+
     private static final FileLock SYMBOLIC_FILE_LOCK = new FileLock()
     {
         @Override