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1 | /******************************************************************************* |
2 | * Copyright (c) 2016 École Polytechnique de Montréal | |
3 | * | |
4 | * All rights reserved. This program and the accompanying materials are | |
5 | * made available under the terms of the Eclipse Public License v1.0 which | |
6 | * accompanies this distribution, and is available at | |
7 | * http://www.eclipse.org/legal/epl-v10.html | |
8 | *******************************************************************************/ | |
9 | ||
10 | package org.eclipse.tracecompass.internal.statesystem.core.backend.historytree; | |
11 | ||
12 | import java.io.IOException; | |
13 | import java.nio.ByteBuffer; | |
14 | import java.nio.ByteOrder; | |
15 | import java.nio.channels.ReadableByteChannel; | |
16 | import java.nio.file.Files; | |
17 | import java.nio.file.Path; | |
18 | import java.nio.file.StandardOpenOption; | |
19 | ||
20 | import org.eclipse.jdt.annotation.NonNullByDefault; | |
f4baf640 | 21 | import org.eclipse.tracecompass.internal.statesystem.core.backend.historytree.classic.HistoryTreeClassic; |
9a4c098d GB |
22 | |
23 | /** | |
24 | * Class that contains factory methods to build different types of history trees | |
25 | * | |
26 | * @author Geneviève Bastien | |
27 | */ | |
28 | @NonNullByDefault | |
29 | public final class HistoryTreeFactory { | |
30 | ||
31 | private HistoryTreeFactory() { | |
32 | } | |
33 | ||
34 | /** | |
35 | * Create a new State History from scratch, using a {@link HTConfig} object | |
36 | * for configuration. | |
37 | * | |
38 | * @param conf | |
39 | * The config to use for this History Tree. | |
40 | * @return the new state history tree | |
41 | * @throws IOException | |
42 | * If an error happens trying to open/write to the file | |
43 | * specified in the config | |
44 | */ | |
3a081e85 GB |
45 | public static IHistoryTree createHistoryTree(HTConfig conf) throws IOException { |
46 | return new HistoryTreeClassic(conf); | |
9a4c098d GB |
47 | } |
48 | ||
49 | /** | |
50 | * "Reader" factory : instantiate a SHTree from an existing tree file on | |
51 | * disk | |
52 | * | |
53 | * @param existingStateFile | |
54 | * Path/filename of the history-file we are to open | |
55 | * @param expectedProviderVersion | |
56 | * The expected version of the state provider | |
57 | * @return The history tree | |
58 | * @throws IOException | |
59 | * If an error happens reading the file | |
60 | */ | |
3a081e85 | 61 | public static IHistoryTree createFromFile(Path existingStateFile, int expectedProviderVersion) throws IOException { |
9a4c098d GB |
62 | /* |
63 | * Check the file exists and has a positive length. These verifications | |
64 | * will also be done in the HT's constructor. | |
65 | */ | |
66 | if (!Files.isReadable(existingStateFile)) { | |
67 | throw new IOException("Selected state file does not exist or is not readable."); //$NON-NLS-1$ | |
68 | } | |
69 | if (Files.size(existingStateFile) <= 0) { | |
70 | throw new IOException("Empty target file"); //$NON-NLS-1$ | |
71 | } | |
72 | ||
73 | /* Read the magic number from the history tree file */ | |
74 | ByteBuffer buffer = ByteBuffer.allocate(Integer.BYTES); | |
75 | try (ReadableByteChannel channel = Files.newByteChannel(existingStateFile, StandardOpenOption.READ);) { | |
76 | buffer.order(ByteOrder.LITTLE_ENDIAN); | |
77 | buffer.clear(); | |
78 | channel.read(buffer); | |
79 | buffer.flip(); | |
80 | } | |
81 | ||
82 | /* | |
83 | * Check the magic number to see which history tree class to create | |
84 | */ | |
85 | int magicNumber = buffer.getInt(); | |
86 | switch (magicNumber) { | |
3a081e85 GB |
87 | case HistoryTreeClassic.HISTORY_FILE_MAGIC_NUMBER: |
88 | return new HistoryTreeClassic(existingStateFile.toFile(), expectedProviderVersion); | |
9a4c098d GB |
89 | default: |
90 | throw new IOException("Not a known history tree file"); //$NON-NLS-1$ | |
91 | } | |
92 | } | |
93 | } |