--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/RevlogStream.java	Mon Jan 24 05:33:47 2011 +0100
@@ -0,0 +1,379 @@
+/*
+ * Copyright (c) 2010-2011 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@svnkit.com
+ */
+package org.tmatesoft.hg.internal;
+
+import static org.tmatesoft.hg.repo.HgRepository.TIP;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.zip.DataFormatException;
+import java.util.zip.Inflater;
+
+import org.tmatesoft.hg.core.Nodeid;
+
+
+/**
+ * ? Single RevlogStream per file per repository with accessor to record access session (e.g. with back/forward operations), 
+ * or numerous RevlogStream with separate representation of the underlaying data (cached, lazy ChunkStream)?
+ * 
+ * @see http://mercurial.selenic.com/wiki/Revlog
+ * @see http://mercurial.selenic.com/wiki/RevlogNG
+ *
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class RevlogStream {
+
+	private List<IndexEntry> index; // indexed access highly needed
+	private boolean inline = false;
+	private final File indexFile;
+	private final DataAccessProvider dataAccess;
+
+	// if we need anything else from HgRepo, might replace DAP parameter with HgRepo and query it for DAP.
+	public RevlogStream(DataAccessProvider dap, File indexFile) {
+		this.dataAccess = dap;
+		this.indexFile = indexFile;
+	}
+
+	/*package*/ DataAccess getIndexStream() {
+		return dataAccess.create(indexFile);
+	}
+
+	/*package*/ DataAccess getDataStream() {
+		final String indexName = indexFile.getName();
+		File dataFile = new File(indexFile.getParentFile(), indexName.substring(0, indexName.length() - 1) + "d");
+		return dataAccess.create(dataFile);
+	}
+	
+	public int revisionCount() {
+		initOutline();
+		return index.size();
+	}
+	
+	public int dataLength(int revision) {
+		// XXX in fact, use of iterate() instead of this implementation may be quite reasonable.
+		//
+		final int indexSize = revisionCount();
+		DataAccess daIndex = getIndexStream(); // XXX may supply a hint that I'll need really few bytes of data (although at some offset)
+		if (revision == TIP) {
+			revision = indexSize - 1;
+		}
+		try {
+			int recordOffset = inline ? (int) index.get(revision).offset : revision * REVLOGV1_RECORD_SIZE;
+			daIndex.seek(recordOffset + 12); // 6+2+4
+			int actualLen = daIndex.readInt();
+			return actualLen; 
+		} catch (IOException ex) {
+			ex.printStackTrace(); // log error. FIXME better handling
+			throw new IllegalStateException(ex);
+		} finally {
+			daIndex.done();
+		}
+	}
+	
+	// Perhaps, RevlogStream should be limited to use of plain int revisions for access,
+	// while Nodeids should be kept on the level up, in Revlog. Guess, Revlog better keep
+	// map of nodeids, and once this comes true, we may get rid of this method.
+	// Unlike its counterpart, Revlog#getLocalRevisionNumber, doesn't fail with exception if node not found,
+	// returns a predefined constant instead
+	public int findLocalRevisionNumber(Nodeid nodeid) {
+		// XXX this one may be implemented with iterate() once there's mechanism to stop iterations
+		final int indexSize = revisionCount();
+		DataAccess daIndex = getIndexStream();
+		try {
+			byte[] nodeidBuf = new byte[20];
+			for (int i = 0; i < indexSize; i++) {
+				daIndex.skip(8);
+				int compressedLen = daIndex.readInt();
+				daIndex.skip(20);
+				daIndex.readBytes(nodeidBuf, 0, 20);
+				if (nodeid.equalsTo(nodeidBuf)) {
+					return i;
+				}
+				daIndex.skip(inline ? 12 + compressedLen : 12);
+			}
+		} catch (IOException ex) {
+			ex.printStackTrace(); // log error. FIXME better handling
+			throw new IllegalStateException(ex);
+		} finally {
+			daIndex.done();
+		}
+		return Integer.MIN_VALUE;
+	}
+
+
+	private final int REVLOGV1_RECORD_SIZE = 64;
+
+	// should be possible to use TIP, ALL, or -1, -2, -n notation of Hg
+	// ? boolean needsNodeid
+	public void iterate(int start, int end, boolean needData, Inspector inspector) {
+		initOutline();
+		final int indexSize = index.size();
+		if (indexSize == 0) {
+			return;
+		}
+		if (end == TIP) {
+			end = indexSize - 1;
+		}
+		if (start == TIP) {
+			start = indexSize - 1;
+		}
+		if (start < 0 || start >= indexSize) {
+			throw new IllegalArgumentException("Bad left range boundary " + start);
+		}
+		if (end < start || end >= indexSize) {
+			throw new IllegalArgumentException("Bad right range boundary " + end);
+		}
+		// XXX may cache [start .. end] from index with a single read (pre-read)
+		
+		DataAccess daIndex = null, daData = null;
+		daIndex = getIndexStream();
+		if (needData && !inline) {
+			daData = getDataStream();
+		}
+		try {
+			byte[] nodeidBuf = new byte[20];
+			byte[] lastData = null;
+			int i;
+			boolean extraReadsToBaseRev = false;
+			if (needData && index.get(start).baseRevision < start) {
+				i = index.get(start).baseRevision;
+				extraReadsToBaseRev = true;
+			} else {
+				i = start;
+			}
+			
+			daIndex.seek(inline ? (int) index.get(i).offset : i * REVLOGV1_RECORD_SIZE);
+			for (; i <= end; i++ ) {
+				long l = daIndex.readLong();
+				@SuppressWarnings("unused")
+				long offset = l >>> 16;
+				@SuppressWarnings("unused")
+				int flags = (int) (l & 0X0FFFF);
+				int compressedLen = daIndex.readInt();
+				int actualLen = daIndex.readInt();
+				int baseRevision = daIndex.readInt();
+				int linkRevision = daIndex.readInt();
+				int parent1Revision = daIndex.readInt();
+				int parent2Revision = daIndex.readInt();
+				// Hg has 32 bytes here, uses 20 for nodeid, and keeps 12 last bytes empty
+				daIndex.readBytes(nodeidBuf, 0, 20);
+				daIndex.skip(12);
+				byte[] data = null;
+				if (needData) {
+					byte[] dataBuf = new byte[compressedLen];
+					if (inline) {
+						daIndex.readBytes(dataBuf, 0, compressedLen);
+					} else {
+						daData.seek(index.get(i).offset);
+						daData.readBytes(dataBuf, 0, compressedLen);
+					}
+					if (dataBuf[0] == 0x78 /* 'x' */) {
+						try {
+							Inflater zlib = new Inflater(); // XXX Consider reuse of Inflater, and/or stream alternative
+							zlib.setInput(dataBuf, 0, compressedLen);
+							byte[] result = new byte[actualLen*2]; // FIXME need to use zlib.finished() instead 
+							int resultLen = zlib.inflate(result);
+							zlib.end();
+							data = new byte[resultLen];
+							System.arraycopy(result, 0, data, 0, resultLen);
+						} catch (DataFormatException ex) {
+							ex.printStackTrace();
+							data = new byte[0]; // FIXME need better failure strategy
+						}
+					} else if (dataBuf[0] == 0x75 /* 'u' */) {
+						data = new byte[dataBuf.length - 1];
+						System.arraycopy(dataBuf, 1, data, 0, data.length);
+					} else {
+						// XXX Python impl in fact throws exception when there's not 'x', 'u' or '0'
+						// but I don't see reason not to return data as is 
+						data = dataBuf;
+					}
+					// XXX 
+					if (baseRevision != i) { // XXX not sure if this is the right way to detect a patch
+						// this is a patch
+						LinkedList<PatchRecord> patches = new LinkedList<PatchRecord>();
+						int patchElementIndex = 0;
+						do {
+							PatchRecord pr = PatchRecord.read(data, patchElementIndex);
+							patches.add(pr);
+							patchElementIndex += 12 + pr.len;
+						} while (patchElementIndex < data.length);
+						//
+						byte[] baseRevContent = lastData;
+						data = apply(baseRevContent, actualLen, patches);
+					}
+				} else {
+					if (inline) {
+						daIndex.skip(compressedLen);
+					}
+				}
+				if (!extraReadsToBaseRev || i >= start) {
+					inspector.next(i, actualLen, baseRevision, linkRevision, parent1Revision, parent2Revision, nodeidBuf, data);
+				}
+				lastData = data;
+			}
+		} catch (IOException ex) {
+			throw new IllegalStateException(ex); // FIXME need better handling
+		} finally {
+			daIndex.done();
+			if (daData != null) {
+				daData.done();
+			}
+		}
+	}
+	
+	private void initOutline() {
+		if (index != null && !index.isEmpty()) {
+			return;
+		}
+		ArrayList<IndexEntry> res = new ArrayList<IndexEntry>();
+		DataAccess da = getIndexStream();
+		try {
+			int versionField = da.readInt();
+			da.readInt(); // just to skip next 2 bytes of offset + flags
+			final int INLINEDATA = 1 << 16;
+			inline = (versionField & INLINEDATA) != 0;
+			long offset = 0; // first offset is always 0, thus Hg uses it for other purposes
+			while(true) {
+				int compressedLen = da.readInt();
+				// 8+4 = 12 bytes total read here
+				@SuppressWarnings("unused")
+				int actualLen = da.readInt();
+				int baseRevision = da.readInt();
+				// 12 + 8 = 20 bytes read here
+//				int linkRevision = di.readInt();
+//				int parent1Revision = di.readInt();
+//				int parent2Revision = di.readInt();
+//				byte[] nodeid = new byte[32];
+				if (inline) {
+					res.add(new IndexEntry(offset + REVLOGV1_RECORD_SIZE * res.size(), baseRevision));
+					da.skip(3*4 + 32 + compressedLen); // Check: 44 (skip) + 20 (read) = 64 (total RevlogNG record size)
+				} else {
+					res.add(new IndexEntry(offset, baseRevision));
+					da.skip(3*4 + 32);
+				}
+				if (da.isEmpty()) {
+					// fine, done then
+					res.trimToSize();
+					index = res;
+					break;
+				} else {
+					// start reading next record
+					long l = da.readLong();
+					offset = l >>> 16;
+				}
+			}
+		} catch (IOException ex) {
+			ex.printStackTrace(); // log error
+			// too bad, no outline then.
+			index = Collections.emptyList();
+		} finally {
+			da.done();
+		}
+		
+	}
+	
+
+	// perhaps, package-local or protected, if anyone else from low-level needs them
+	// XXX think over if we should keep offset in case of separate data file - we read the field anyway. Perhaps, distinct entry classes for Inline and non-inline indexes?
+	private static class IndexEntry {
+		public final long offset; // for separate .i and .d - copy of index record entry, for inline index - actual offset of the record in the .i file (record entry + revision * record size))
+		//public final int length; // data past fixed record (need to decide whether including header size or not), and whether length is of compressed data or not
+		public final int baseRevision;
+
+		public IndexEntry(long o, int baseRev) {
+			offset = o;
+			baseRevision = baseRev;
+		}
+	}
+
+	// mpatch.c : apply()
+	// FIXME need to implement patch merge (fold, combine, gather and discard from aforementioned mpatch.[c|py]), also see Revlog and Mercurial PDF
+	public/*for HgBundle; until moved to better place*/static byte[] apply(byte[] baseRevisionContent, int outcomeLen, List<PatchRecord> patch) {
+		int last = 0, destIndex = 0;
+		if (outcomeLen == -1) {
+			outcomeLen = baseRevisionContent.length;
+			for (PatchRecord pr : patch) {
+				outcomeLen += pr.start - last + pr.len;
+				last = pr.end;
+			}
+			outcomeLen -= last;
+			last = 0;
+		}
+		byte[] rv = new byte[outcomeLen];
+		for (PatchRecord pr : patch) {
+			System.arraycopy(baseRevisionContent, last, rv, destIndex, pr.start-last);
+			destIndex += pr.start - last;
+			System.arraycopy(pr.data, 0, rv, destIndex, pr.data.length);
+			destIndex += pr.data.length;
+			last = pr.end;
+		}
+		System.arraycopy(baseRevisionContent, last, rv, destIndex, baseRevisionContent.length - last);
+		return rv;
+	}
+
+	// @see http://mercurial.selenic.com/wiki/BundleFormat, in Changelog group description
+	public static class PatchRecord {
+		/*
+		   Given there are pr1 and pr2:
+		     pr1.start to pr1.end will be replaced with pr's data (of pr1.len)
+		     pr1.end to pr2.start gets copied from base
+		 */
+		public int start, end, len;
+		public byte[] data;
+
+		// TODO consider PatchRecord that only records data position (absolute in data source), and acquires data as needed 
+		private PatchRecord(int p1, int p2, int length, byte[] src) {
+			start = p1;
+			end = p2;
+			len = length;
+			data = src;
+		}
+
+		/*package-local*/ static PatchRecord read(byte[] data, int offset) {
+			final int x = offset; // shorthand
+			int p1 =  ((data[x] & 0xFF)<< 24)    | ((data[x+1] & 0xFF) << 16) | ((data[x+2] & 0xFF) << 8)  | (data[x+3] & 0xFF);
+			int p2 =  ((data[x+4] & 0xFF) << 24) | ((data[x+5] & 0xFF) << 16) | ((data[x+6] & 0xFF) << 8)  | (data[x+7] & 0xFF);
+			int len = ((data[x+8] & 0xFF) << 24) | ((data[x+9] & 0xFF) << 16) | ((data[x+10] & 0xFF) << 8) | (data[x+11] & 0xFF);
+			byte[] dataCopy = new byte[len];
+			System.arraycopy(data, x+12, dataCopy, 0, len);
+			return new PatchRecord(p1, p2, len, dataCopy);
+		}
+
+		public /*for HgBundle*/ static PatchRecord read(DataAccess da) throws IOException {
+			int p1 = da.readInt();
+			int p2 = da.readInt();
+			int len = da.readInt();
+			byte[] src = new byte[len];
+			da.readBytes(src, 0, len);
+			return new PatchRecord(p1, p2, len, src);
+		}
+	}
+
+	// FIXME byte[] data might be too expensive, for few usecases it may be better to have intermediate Access object (when we don't need full data 
+	// instantly - e.g. calculate hash, or comparing two revisions
+	public interface Inspector {
+		// XXX boolean retVal to indicate whether to continue?
+		// TODO specify nodeid and data length, and reuse policy (i.e. if revlog stream doesn't reuse nodeid[] for each call) 
+		void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[/*20*/] nodeid, byte[] data);
+	}
+}