[1450] | 1 | // License: GPL. For details, see LICENSE file.
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| 2 | package org.openstreetmap.josm.io;
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| 3 |
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| 4 | import java.io.BufferedInputStream;
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| 5 | import java.io.BufferedOutputStream;
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| 6 | import java.io.File;
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| 7 | import java.io.FileInputStream;
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| 8 | import java.io.FileOutputStream;
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[2986] | 9 | import java.io.IOException;
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[1450] | 10 |
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| 11 | import org.openstreetmap.josm.Main;
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[5874] | 12 | import org.openstreetmap.josm.tools.Utils;
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[1450] | 13 |
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[1610] | 14 | /**
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| 15 | * Use this class if you want to cache and store a single file that gets updated regularly.
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| 16 | * Unless you flush() it will be kept in memory. If you want to cache a lot of data and/or files,
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| 17 | * use CacheFiles
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[4709] | 18 | * @param <T> a {@link Throwable} that may be thrown during {@link #updateData()},
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| 19 | * use {@link RuntimeException} if no exception must be handled.
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[1610] | 20 | * @author xeen
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| 21 | *
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| 22 | */
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[4709] | 23 | public abstract class CacheCustomContent<T extends Throwable> {
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[1450] | 24 | /**
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| 25 | * Common intervals
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| 26 | */
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[6889] | 27 | public static final int INTERVAL_ALWAYS = -1;
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| 28 | public static final int INTERVAL_HOURLY = 60*60;
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| 29 | public static final int INTERVAL_DAILY = INTERVAL_HOURLY * 24;
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| 30 | public static final int INTERVAL_WEEKLY = INTERVAL_DAILY * 7;
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| 31 | public static final int INTERVAL_MONTHLY = INTERVAL_WEEKLY * 4;
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| 32 | public static final int INTERVAL_NEVER = Integer.MAX_VALUE;
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[1610] | 33 |
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[1450] | 34 | /**
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[1610] | 35 | * Where the data will be stored
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[1450] | 36 | */
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| 37 | private byte[] data = null;
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[1610] | 38 |
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[1450] | 39 | /**
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| 40 | * The ident that identifies the stored file. Includes file-ending.
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| 41 | */
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[6889] | 42 | private final String ident;
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[1610] | 43 |
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[1450] | 44 | /**
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| 45 | * The (file-)path where the data will be stored
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| 46 | */
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[6889] | 47 | private final File path;
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[1610] | 48 |
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[1450] | 49 | /**
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| 50 | * How often to update the cached version
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| 51 | */
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[6889] | 52 | private final int updateInterval;
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[1610] | 53 |
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[1450] | 54 | /**
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| 55 | * This function will be executed when an update is required. It has to be implemented by the
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| 56 | * inheriting class and should use a worker if it has a long wall time as the function is
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| 57 | * executed in the current thread.
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| 58 | * @return the data to cache
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| 59 | */
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[4709] | 60 | protected abstract byte[] updateData() throws T;
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[1610] | 61 |
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[1450] | 62 | /**
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| 63 | * This function serves as a comfort hook to perform additional checks if the cache is valid
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| 64 | * @return True if the cached copy is still valid
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| 65 | */
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| 66 | protected boolean isCacheValid() {
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| 67 | return true;
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[1610] | 68 | }
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| 69 |
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[1450] | 70 | /**
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| 71 | * Initializes the class. Note that all read data will be stored in memory until it is flushed
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[1610] | 72 | * by flushData().
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[1450] | 73 | * @param ident
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| 74 | * @param updateInterval
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| 75 | */
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| 76 | public CacheCustomContent(String ident, int updateInterval) {
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| 77 | this.ident = ident;
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| 78 | this.updateInterval = updateInterval;
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[4810] | 79 | this.path = new File(Main.pref.getCacheDirectory(), ident);
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[1450] | 80 | }
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[1610] | 81 |
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[1450] | 82 | /**
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| 83 | * Updates data if required
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| 84 | * @return Returns the data
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| 85 | */
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[4709] | 86 | public byte[] updateIfRequired() throws T {
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[6102] | 87 | if (Main.pref.getInteger("cache." + ident, 0) + updateInterval < System.currentTimeMillis()/1000
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[1450] | 88 | || !isCacheValid())
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| 89 | return updateForce();
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| 90 | return getData();
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| 91 | }
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[1610] | 92 |
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[1450] | 93 | /**
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| 94 | * Updates data if required
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| 95 | * @return Returns the data as string
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| 96 | */
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[4709] | 97 | public String updateIfRequiredString() throws T {
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[6102] | 98 | if (Main.pref.getInteger("cache." + ident, 0) + updateInterval < System.currentTimeMillis()/1000
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[1450] | 99 | || !isCacheValid())
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| 100 | return updateForceString();
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| 101 | return getDataString();
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| 102 | }
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[1610] | 103 |
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[1450] | 104 | /**
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| 105 | * Executes an update regardless of updateInterval
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| 106 | * @return Returns the data
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| 107 | */
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[4709] | 108 | public byte[] updateForce() throws T {
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[1450] | 109 | this.data = updateData();
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| 110 | saveToDisk();
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[6102] | 111 | Main.pref.putInteger("cache." + ident, (int)(System.currentTimeMillis()/1000));
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[1450] | 112 | return data;
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| 113 | }
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[1610] | 114 |
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[1450] | 115 | /**
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| 116 | * Executes an update regardless of updateInterval
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| 117 | * @return Returns the data as String
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| 118 | */
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[4709] | 119 | public String updateForceString() throws T {
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[1450] | 120 | updateForce();
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[6552] | 121 | return new String(data, Utils.UTF_8);
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[1450] | 122 | }
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| 123 |
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| 124 | /**
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| 125 | * Returns the data without performing any updates
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| 126 | * @return the data
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| 127 | */
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[4709] | 128 | public byte[] getData() throws T {
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[4810] | 129 | if (data == null) {
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[1450] | 130 | loadFromDisk();
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[2986] | 131 | }
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[1450] | 132 | return data;
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| 133 | }
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[1610] | 134 |
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[1450] | 135 | /**
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| 136 | * Returns the data without performing any updates
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| 137 | * @return the data as String
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| 138 | */
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[4709] | 139 | public String getDataString() throws T {
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[6552] | 140 | return new String(getData(), Utils.UTF_8);
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[1450] | 141 | }
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| 142 |
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| 143 | /**
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[1610] | 144 | * Tries to load the data using the given ident from disk. If this fails, data will be updated
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[1450] | 145 | */
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[4709] | 146 | private void loadFromDisk() throws T {
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[4810] | 147 | if (Main.applet)
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[1450] | 148 | this.data = updateForce();
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[3947] | 149 | else {
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[5874] | 150 | BufferedInputStream input = null;
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[3947] | 151 | try {
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[5874] | 152 | input = new BufferedInputStream(new FileInputStream(path));
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[3947] | 153 | this.data = new byte[input.available()];
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| 154 | input.read(this.data);
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[4810] | 155 | } catch (IOException e) {
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[3947] | 156 | this.data = updateForce();
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[5874] | 157 | } finally {
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| 158 | Utils.close(input);
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[3947] | 159 | }
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[1450] | 160 | }
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| 161 | }
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[1610] | 162 |
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[1450] | 163 | /**
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| 164 | * Stores the data to disk
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| 165 | */
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| 166 | private void saveToDisk() {
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[4810] | 167 | if (Main.applet)
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[3947] | 168 | return;
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[5874] | 169 | BufferedOutputStream output = null;
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[1450] | 170 | try {
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[5874] | 171 | output = new BufferedOutputStream(new FileOutputStream(path));
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[1450] | 172 | output.write(this.data);
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| 173 | output.flush();
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[2986] | 174 | } catch(Exception e) {
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[6643] | 175 | Main.error(e);
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[5874] | 176 | } finally {
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| 177 | Utils.close(output);
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[2986] | 178 | }
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[1610] | 179 | }
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| 180 |
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[1450] | 181 | /**
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| 182 | * Flushes the data from memory. Class automatically reloads it from disk or updateData() if
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| 183 | * required
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| 184 | */
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| 185 | public void flushData() {
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| 186 | data = null;
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| 187 | }
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| 188 | }
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