kitaev@213: /*
kitaev@213:  * Copyright (c) 2010-2011 TMate Software Ltd
kitaev@213:  *  
kitaev@213:  * This program is free software; you can redistribute it and/or modify
kitaev@213:  * it under the terms of the GNU General Public License as published by
kitaev@213:  * the Free Software Foundation; version 2 of the License.
kitaev@213:  *
kitaev@213:  * This program is distributed in the hope that it will be useful,
kitaev@213:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
kitaev@213:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
kitaev@213:  * GNU General Public License for more details.
kitaev@213:  *
kitaev@213:  * For information on how to redistribute this software under
kitaev@213:  * the terms of a license other than GNU General Public License
kitaev@213:  * contact TMate Software at support@hg4j.com
kitaev@213:  */
kitaev@213: package org.tmatesoft.hg.internal;
kitaev@213: 
kitaev@213: import java.io.File;
kitaev@213: import java.io.FileInputStream;
kitaev@213: import java.io.IOException;
kitaev@213: import java.nio.ByteBuffer;
kitaev@213: import java.nio.MappedByteBuffer;
kitaev@213: import java.nio.channels.FileChannel;
kitaev@213: 
kitaev@213: import org.tmatesoft.hg.core.HgBadStateException;
kitaev@213: 
kitaev@213: /**
kitaev@213:  * 
kitaev@213:  * @author Artem Tikhomirov
kitaev@213:  * @author TMate Software Ltd.
kitaev@213:  */
kitaev@213: public class DataAccessProvider {
kitaev@213: 
kitaev@213: 	private final int mapioMagicBoundary;
kitaev@213: 	private final int bufferSize;
kitaev@213: 
kitaev@213: 	public DataAccessProvider() {
kitaev@213: 		this(100 * 1024, 8 * 1024);
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	public DataAccessProvider(int mapioBoundary, int regularBufferSize) {
kitaev@213: 		mapioMagicBoundary = mapioBoundary;
kitaev@213: 		bufferSize = regularBufferSize;
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	public DataAccess create(File f) {
kitaev@213: 		if (!f.exists()) {
kitaev@213: 			return new DataAccess();
kitaev@213: 		}
kitaev@213: 		try {
kitaev@213: 			FileChannel fc = new FileInputStream(f).getChannel();
kitaev@213: 			int flen = (int) fc.size();
kitaev@213: 			if (fc.size() - flen != 0) {
kitaev@213: 				throw new HgBadStateException("Files greater than 2Gb are not yet supported");
kitaev@213: 			}
kitaev@213: 			if (flen > mapioMagicBoundary) {
kitaev@213: 				// TESTS: bufLen of 1024 was used to test MemMapFileAccess
kitaev@213: 				return new MemoryMapFileAccess(fc, flen, mapioMagicBoundary);
kitaev@213: 			} else {
kitaev@213: 				// XXX once implementation is more or less stable,
kitaev@213: 				// may want to try ByteBuffer.allocateDirect() to see
kitaev@213: 				// if there's any performance gain. 
kitaev@213: 				boolean useDirectBuffer = false;
kitaev@213: 				// TESTS: bufferSize of 100 was used to check buffer underflow states when readBytes reads chunks bigger than bufSize
kitaev@213: 				return new FileAccess(fc, flen, bufferSize, useDirectBuffer);
kitaev@213: 			}
kitaev@213: 		} catch (IOException ex) {
kitaev@213: 			// unlikely to happen, we've made sure file exists.
kitaev@213: 			ex.printStackTrace(); // FIXME log error
kitaev@213: 		}
kitaev@213: 		return new DataAccess(); // non-null, empty.
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	// DOESN'T WORK YET 
kitaev@213: 	private static class MemoryMapFileAccess extends DataAccess {
kitaev@213: 		private FileChannel fileChannel;
kitaev@213: 		private final int size;
kitaev@213: 		private long position = 0; // always points to buffer's absolute position in the file
kitaev@213: 		private final int memBufferSize;
kitaev@213: 		private MappedByteBuffer buffer;
kitaev@213: 
kitaev@213: 		public MemoryMapFileAccess(FileChannel fc, int channelSize, int /*long?*/ bufferSize) {
kitaev@213: 			fileChannel = fc;
kitaev@213: 			size = channelSize;
kitaev@213: 			memBufferSize = bufferSize;
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public boolean isEmpty() {
kitaev@213: 			return position + (buffer == null ? 0 : buffer.position()) >= size;
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public int length() {
kitaev@213: 			return size;
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public DataAccess reset() throws IOException {
kitaev@213: 			seek(0);
kitaev@213: 			return this;
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public void seek(int offset) {
kitaev@213: 			assert offset >= 0;
kitaev@213: 			// offset may not necessarily be further than current position in the file (e.g. rewind) 
kitaev@213: 			if (buffer != null && /*offset is within buffer*/ offset >= position && (offset - position) < buffer.limit()) {
kitaev@213: 				buffer.position((int) (offset - position));
kitaev@213: 			} else {
kitaev@213: 				position = offset;
kitaev@213: 				buffer = null;
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public void skip(int bytes) throws IOException {
kitaev@213: 			assert bytes >= 0;
kitaev@213: 			if (buffer == null) {
kitaev@213: 				position += bytes;
kitaev@213: 				return;
kitaev@213: 			}
kitaev@213: 			if (buffer.remaining() > bytes) {
kitaev@213: 				buffer.position(buffer.position() + bytes);
kitaev@213: 			} else {
kitaev@213: 				position += buffer.position() + bytes;
kitaev@213: 				buffer = null;
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		private void fill() throws IOException {
kitaev@213: 			if (buffer != null) {
kitaev@213: 				position += buffer.position(); 
kitaev@213: 			}
kitaev@213: 			long left = size - position;
kitaev@213: 			buffer = fileChannel.map(FileChannel.MapMode.READ_ONLY, position, left < memBufferSize ? left : memBufferSize);
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public void readBytes(byte[] buf, int offset, int length) throws IOException {
kitaev@213: 			if (buffer == null || !buffer.hasRemaining()) {
kitaev@213: 				fill();
kitaev@213: 			}
kitaev@213: 			// XXX in fact, we may try to create a MappedByteBuffer of exactly length size here, and read right away
kitaev@213: 			while (length > 0) {
kitaev@213: 				int tail = buffer.remaining();
kitaev@213: 				if (tail == 0) {
kitaev@213: 					throw new IOException();
kitaev@213: 				}
kitaev@213: 				if (tail >= length) {
kitaev@213: 					buffer.get(buf, offset, length);
kitaev@213: 				} else {
kitaev@213: 					buffer.get(buf, offset, tail);
kitaev@213: 					fill();
kitaev@213: 				}
kitaev@213: 				offset += tail;
kitaev@213: 				length -= tail;
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public byte readByte() throws IOException {
kitaev@213: 			if (buffer == null || !buffer.hasRemaining()) {
kitaev@213: 				fill();
kitaev@213: 			}
kitaev@213: 			if (buffer.hasRemaining()) {
kitaev@213: 				return buffer.get();
kitaev@213: 			}
kitaev@213: 			throw new IOException();
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public void done() {
kitaev@213: 			buffer = null;
kitaev@213: 			if (fileChannel != null) {
kitaev@213: 				try {
kitaev@213: 					fileChannel.close();
kitaev@213: 				} catch (IOException ex) {
kitaev@213: 					ex.printStackTrace(); // log debug
kitaev@213: 				}
kitaev@213: 				fileChannel = null;
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 	}
kitaev@213: 
kitaev@213: 	// (almost) regular file access - FileChannel and buffers.
kitaev@213: 	private static class FileAccess extends DataAccess {
kitaev@213: 		private FileChannel fileChannel;
kitaev@213: 		private final int size;
kitaev@213: 		private ByteBuffer buffer;
kitaev@213: 		private int bufferStartInFile = 0; // offset of this.buffer in the file.
kitaev@213: 
kitaev@213: 		public FileAccess(FileChannel fc, int channelSize, int bufferSizeHint, boolean useDirect) {
kitaev@213: 			fileChannel = fc;
kitaev@213: 			size = channelSize;
kitaev@213: 			final int capacity = size < bufferSizeHint ? size : bufferSizeHint;
kitaev@213: 			buffer = useDirect ? ByteBuffer.allocateDirect(capacity) : ByteBuffer.allocate(capacity);
kitaev@213: 			buffer.flip(); // or .limit(0) to indicate it's empty
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public boolean isEmpty() {
kitaev@213: 			return bufferStartInFile + buffer.position() >= size;
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public int length() {
kitaev@213: 			return size;
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public DataAccess reset() throws IOException {
kitaev@213: 			seek(0);
kitaev@213: 			return this;
kitaev@213: 		}
kitaev@213: 		
kitaev@213: 		@Override
kitaev@213: 		public void seek(int offset) throws IOException {
kitaev@213: 			if (offset > size) {
kitaev@213: 				throw new IllegalArgumentException();
kitaev@213: 			}
kitaev@213: 			if (offset < bufferStartInFile + buffer.limit() && offset >= bufferStartInFile) {
kitaev@213: 				buffer.position((int) (offset - bufferStartInFile));
kitaev@213: 			} else {
kitaev@213: 				// out of current buffer, invalidate it (force re-read) 
kitaev@213: 				// XXX or ever re-read it right away?
kitaev@213: 				bufferStartInFile = offset;
kitaev@213: 				buffer.clear();
kitaev@213: 				buffer.limit(0); // or .flip() to indicate we switch to reading
kitaev@213: 				fileChannel.position(offset);
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public void skip(int bytes) throws IOException {
kitaev@213: 			final int newPos = buffer.position() + bytes;
kitaev@213: 			if (newPos >= 0 && newPos < buffer.limit()) {
kitaev@213: 				// no need to move file pointer, just rewind/seek buffer 
kitaev@213: 				buffer.position(newPos);
kitaev@213: 			} else {
kitaev@213: 				//
kitaev@213: 				seek(bufferStartInFile + newPos);
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		private boolean fill() throws IOException {
kitaev@213: 			if (!buffer.hasRemaining()) {
kitaev@213: 				bufferStartInFile += buffer.limit();
kitaev@213: 				buffer.clear();
kitaev@213: 				if (bufferStartInFile < size) { // just in case there'd be any exception on EOF, not -1 
kitaev@213: 					fileChannel.read(buffer);
kitaev@213: 					// may return -1 when EOF, but empty will reflect this, hence no explicit support here   
kitaev@213: 				}
kitaev@213: 				buffer.flip();
kitaev@213: 			}
kitaev@213: 			return buffer.hasRemaining();
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public void readBytes(byte[] buf, int offset, int length) throws IOException {
kitaev@213: 			if (!buffer.hasRemaining()) {
kitaev@213: 				fill();
kitaev@213: 			}
kitaev@213: 			while (length > 0) {
kitaev@213: 				int tail = buffer.remaining();
kitaev@213: 				if (tail == 0) {
kitaev@213: 					throw new IOException(); // shall not happen provided stream contains expected data and no attempts to read past isEmpty() == true are made.
kitaev@213: 				}
kitaev@213: 				if (tail >= length) {
kitaev@213: 					buffer.get(buf, offset, length);
kitaev@213: 				} else {
kitaev@213: 					buffer.get(buf, offset, tail);
kitaev@213: 					fill();
kitaev@213: 				}
kitaev@213: 				offset += tail;
kitaev@213: 				length -= tail;
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public byte readByte() throws IOException {
kitaev@213: 			if (buffer.hasRemaining()) {
kitaev@213: 				return buffer.get();
kitaev@213: 			}
kitaev@213: 			if (fill()) {
kitaev@213: 				return buffer.get();
kitaev@213: 			}
kitaev@213: 			throw new IOException();
kitaev@213: 		}
kitaev@213: 
kitaev@213: 		@Override
kitaev@213: 		public void done() {
kitaev@213: 			if (buffer != null) {
kitaev@213: 				buffer = null;
kitaev@213: 			}
kitaev@213: 			if (fileChannel != null) {
kitaev@213: 				try {
kitaev@213: 					fileChannel.close();
kitaev@213: 				} catch (IOException ex) {
kitaev@213: 					ex.printStackTrace(); // log debug
kitaev@213: 				}
kitaev@213: 				fileChannel = null;
kitaev@213: 			}
kitaev@213: 		}
kitaev@213: 	}
kitaev@213: }