[GitHub] [maven-resolver] rfscholte commented on a change in pull request #22: Introduce caching for tracking files.

[GitBox <gi...@apache.org>]

rfscholte commented on a change in pull request #22: Introduce caching for tracking files.
URL: https://github.com/apache/maven-resolver/pull/22#discussion_r270969267
 
 

 ##########
 File path: maven-resolver-impl/src/main/java/org/eclipse/aether/internal/impl/TrackingFileManager.java
 ##########
 @@ -131,52 +207,145 @@ public Properties update( File file, Map<String, String> updates )
                 raf.seek( 0 );
                 raf.write( stream.toByteArray() );
                 raf.setLength( raf.getFilePointer() );
+
+                this.entryTs = System.currentTimeMillis();
+                this.lastModifiedTs = file.lastModified();
             }
             catch ( IOException e )
             {
                 LOGGER.warn( "Failed to write tracking file {}", file, e );
             }
             finally
             {
-                release( lock, file );
-                close( raf, file );
+                release( lock );
+                close( raf );
             }
-        }
 
-        return props;
-    }
+            return props;
+        }
 
-    private void release( FileLock lock, File file )
-    {
-        if ( lock != null )
+        private void release( FileLock lock )
         {
-            try
+            if ( lock != null )
             {
-                lock.release();
+                try
+                {
+                    lock.release();
+                }
+                catch ( IOException e )
+                {
+                    LOGGER.warn( "Error releasing lock for tracking file {}", file, e );
+                }
             }
-            catch ( IOException e )
+        }
+
+        private void close( Closeable closeable )
+        {
+            if ( closeable != null )
             {
-                LOGGER.warn( "Error releasing lock for tracking file {}", file, e );
+                try
+                {
+                    closeable.close();
+                }
+                catch ( IOException e )
+                {
+                    LOGGER.warn( "Error closing tracking file {}", file, e );
+                }
             }
         }
-    }
 
-    private void close( Closeable closeable, File file )
-    {
-        if ( closeable != null )
+        private FileLock lock( FileChannel channel, long size, boolean shared ) throws IOException
         {
-            try
+            FileLock lock = null;
+
+            for ( int attempts = 8; attempts >= 0; attempts-- )
             {
-                closeable.close();
+                try
+                {
+                    lock = channel.lock( 0, size, shared );
+                    break;
+                }
+                catch ( OverlappingFileLockException e )
+                {
+                    if ( attempts <= 0 )
+                    {
+                        throw (IOException) new IOException().initCause( e );
+                    }
+                    try
+                    {
+                        Thread.sleep( 50L );
+                    }
+                    catch ( InterruptedException e1 )
+                    {
+                        Thread.currentThread().interrupt();
+                    }
+                }
             }
-            catch ( IOException e )
+
+            if ( lock == null )
             {
-                LOGGER.warn( "Error closing tracking file {}", file, e );
+                throw new IOException( "Could not lock file" );
             }
+
+            return lock;
+        }
+
+    }
+
+    /**
+     * Canonicalized files by their path (the same canonicalized file may be registered under different paths). This
+     * cache is especially useful on Windows platform where canonicalization is relatively expensive.
+     */
+    private static ConcurrentHashMap<String, File> canonicalizedCache = new ConcurrentHashMap<>();
 
 Review comment:
   In case of a cache I would prefer `WeakHashMap` + `Collections.synchronizedMap` 

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