1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.tools;
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3 | import static org.openstreetmap.josm.tools.I18n.tr;
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4 |
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5 | import java.text.MessageFormat;
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6 | import java.util.ArrayList;
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7 | import java.util.List;
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8 | import java.util.function.Supplier;
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9 |
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10 | import org.openstreetmap.josm.Main;
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11 |
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12 | /**
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13 | * This class allows all components of JOSM to register reclaimable amounts to memory.
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14 | * <p>
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15 | * It can be used to hold imagery caches or other data that can be reconstructed form disk/web if required.
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16 | * <p>
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17 | * Reclaimable storage implementations may be added in the future.
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18 | *
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19 | * @author Michael Zangl
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20 | * @since 10588
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21 | */
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22 | public class MemoryManager {
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23 | /**
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24 | * assumed minimum JOSM memory footprint
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25 | */
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26 | private static final long JOSM_CORE_FOOTPRINT = 50L * 1024L * 1024L;
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27 |
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28 | private static final MemoryManager INSTANCE = new MemoryManager();
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29 |
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30 | private final ArrayList<MemoryHandle<?>> activeHandles = new ArrayList<>();
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31 |
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32 | protected MemoryManager() {
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33 | }
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34 |
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35 | /**
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36 | * Allocates a basic, fixed memory size.
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37 | * <p>
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38 | * If there is enough free memory, the factory is used to procude one element which is then returned as memory handle.
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39 | * <p>
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40 | * You should invoke {@link MemoryHandle#free()} if you do not need that handle any more.
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41 | * @param <T> The content type of the memory-
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42 | * @param name A name for the memory area. Only used for debugging.
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43 | * @param maxBytes The maximum amount of bytes the content may have
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44 | * @param factory The factory to use to procude the content if there is sufficient memory.
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45 | * @return A memory handle to the content.
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46 | * @throws NotEnoughMemoryException If there is not enough memory to allocate.
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47 | */
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48 | public synchronized <T> MemoryHandle<T> allocateMemory(String name, long maxBytes, Supplier<T> factory) throws NotEnoughMemoryException {
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49 | if (isAvailable(maxBytes)) {
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50 | T content = factory.get();
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51 | if (content == null) {
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52 | throw new IllegalArgumentException("Factory did not return a content element.");
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53 | }
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54 | Main.info(MessageFormat.format("Allocate for {0}: {1} MB of memory. Available: {2} MB.",
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55 | name, maxBytes / 1024 / 1024, getAvailableMemory() / 1024 / 1024));
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56 | MemoryHandle<T> handle = new ManualFreeMemoryHandle<>(name, content, maxBytes);
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57 | activeHandles.add(handle);
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58 | return handle;
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59 | } else {
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60 | throw new NotEnoughMemoryException(maxBytes);
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61 | }
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62 | }
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63 |
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64 | /**
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65 | * Check if that memory is available
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66 | * @param maxBytes The memory to check for
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67 | * @return <code>true</code> if that memory is available.
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68 | */
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69 | public synchronized boolean isAvailable(long maxBytes) {
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70 | if (maxBytes < 0) {
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71 | throw new IllegalArgumentException(MessageFormat.format("Cannot allocate negative number of bytes: {0}", maxBytes));
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72 | }
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73 | return getAvailableMemory() >= maxBytes;
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74 | }
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75 |
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76 | /**
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77 | * Gets the maximum amount of memory available for use in this manager.
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78 | * @return The maximum amount of memory.
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79 | */
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80 | public synchronized long getMaxMemory() {
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81 | return Runtime.getRuntime().maxMemory() - JOSM_CORE_FOOTPRINT;
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82 | }
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83 |
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84 | /**
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85 | * Gets the memory that is considered free.
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86 | * @return The memory that can be used for new allocations.
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87 | */
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88 | public synchronized long getAvailableMemory() {
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89 | return getMaxMemory() - activeHandles.stream().mapToLong(MemoryHandle::getSize).sum();
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90 | }
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91 |
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92 | /**
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93 | * Get the global memory manager instance.
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94 | * @return The memory manager.
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95 | */
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96 | public static MemoryManager getInstance() {
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97 | return INSTANCE;
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98 | }
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99 |
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100 | /**
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101 | * Reset the state of this manager to the default state.
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102 | * @return true if there were entries that have been reset.
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103 | */
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104 | protected synchronized List<MemoryHandle<?>> resetState() {
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105 | ArrayList<MemoryHandle<?>> toFree = new ArrayList<>(activeHandles);
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106 | toFree.forEach(MemoryHandle::free);
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107 | return toFree;
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108 | }
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109 |
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110 | /**
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111 | * A memory area managed by the {@link MemoryManager}.
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112 | * @author Michael Zangl
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113 | * @param <T> The content type.
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114 | */
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115 | public interface MemoryHandle<T> {
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116 |
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117 | /**
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118 | * Gets the content of this memory area.
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119 | * <p>
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120 | * This method should be the prefered access to the memory since it will do error checking when {@link #free()} was called.
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121 | * @return The memory area content.
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122 | */
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123 | T get();
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124 |
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125 | /**
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126 | * Get the size that was requested for this memory area.
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127 | * @return the size
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128 | */
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129 | long getSize();
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130 |
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131 | /**
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132 | * Manually release this memory area. There should be no memory consumed by this afterwards.
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133 | */
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134 | void free();
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135 | }
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136 |
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137 | private class ManualFreeMemoryHandle<T> implements MemoryHandle<T> {
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138 | private final String name;
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139 | private T content;
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140 | private final long size;
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141 |
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142 | ManualFreeMemoryHandle(String name, T content, long size) {
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143 | this.name = name;
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144 | this.content = content;
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145 | this.size = size;
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146 | }
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147 |
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148 | @Override
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149 | public T get() {
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150 | if (content == null) {
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151 | throw new IllegalStateException(MessageFormat.format("Memory area was accessed after free(): {0}", name));
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152 | }
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153 | return content;
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154 | }
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155 |
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156 | @Override
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157 | public long getSize() {
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158 | return size;
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159 | }
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160 |
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161 | @Override
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162 | public void free() {
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163 | if (content == null) {
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164 | throw new IllegalStateException(MessageFormat.format("Memory area was already marked as freed: {0}", name));
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165 | }
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166 | content = null;
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167 | synchronized (MemoryManager.this) {
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168 | activeHandles.remove(this);
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169 | }
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170 | }
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171 |
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172 | @Override
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173 | public String toString() {
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174 | return "MemoryHandle [name=" + name + ", size=" + size + ']';
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175 | }
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176 | }
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177 |
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178 | /**
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179 | * This exception is thrown if there is not enough memory for allocating the given object.
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180 | * @author Michael Zangl
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181 | */
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182 | public static class NotEnoughMemoryException extends Exception {
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183 | NotEnoughMemoryException(long memoryBytesRequired) {
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184 | super(tr("To add another layer you need to allocate at least {0,number,#}MB memory to JOSM using -Xmx{0,number,#}M "
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185 | + "option (see http://forum.openstreetmap.org/viewtopic.php?id=25677).\n"
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186 | + "Currently you have {1,number,#}MB memory allocated for JOSM",
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187 | memoryBytesRequired / 1024 / 1024, Runtime.getRuntime().maxMemory() / 1024 / 1024));
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188 | }
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189 | }
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190 | }
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