lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 1 | package com.google.net.stubby; |
| 2 | |
ejona | 8c76c8a | 2014-10-09 09:53:41 -0700 | [diff] [blame] | 3 | import static com.google.common.base.Charsets.US_ASCII; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 4 | |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 5 | import com.google.common.base.Function; |
| 6 | import com.google.common.base.Preconditions; |
| 7 | import com.google.common.collect.Iterables; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 8 | import com.google.common.collect.LinkedListMultimap; |
| 9 | import com.google.common.collect.ListMultimap; |
| 10 | import com.google.common.collect.Lists; |
| 11 | |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 12 | import java.util.Iterator; |
| 13 | import java.util.List; |
| 14 | import java.util.Map; |
| 15 | import java.util.Set; |
| 16 | |
| 17 | import javax.annotation.concurrent.NotThreadSafe; |
| 18 | |
| 19 | /** |
| 20 | * Provides access to read and write metadata values to be exchanged during a call. |
| 21 | * <p> |
| 22 | * This class is not thread safe, implementations should ensure that header reads and writes |
| 23 | * do not occur in multiple threads concurrently. |
| 24 | * </p> |
| 25 | */ |
| 26 | @NotThreadSafe |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 27 | public abstract class Metadata { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 28 | |
| 29 | /** |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 30 | * All binary headers should have this suffix in their names. Vice versa. |
| 31 | */ |
| 32 | public static final String BINARY_HEADER_SUFFIX = "-bin"; |
| 33 | |
| 34 | /** |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 35 | * Interleave keys and values into a single iterator. |
| 36 | */ |
| 37 | private static Iterator<String> fromMapEntries(Iterable<Map.Entry<String, String>> entries) { |
| 38 | final Iterator<Map.Entry<String, String>> iterator = entries.iterator(); |
| 39 | return new Iterator<String>() { |
| 40 | Map.Entry<String, String> last; |
| 41 | @Override |
| 42 | public boolean hasNext() { |
| 43 | return last != null || iterator.hasNext(); |
| 44 | } |
| 45 | |
| 46 | @Override |
| 47 | public String next() { |
| 48 | if (last == null) { |
| 49 | last = iterator.next(); |
| 50 | return last.getKey(); |
| 51 | } else { |
| 52 | String val = last.getValue(); |
| 53 | last = null; |
| 54 | return val; |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | @Override |
| 59 | public void remove() { |
| 60 | throw new UnsupportedOperationException(); |
| 61 | } |
| 62 | }; |
| 63 | } |
| 64 | |
| 65 | /** |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 66 | * Simple metadata marshaller that encodes strings as is. |
| 67 | * |
| 68 | * <p>This should be used with ASCII strings that only contain printable characters and space. |
| 69 | * Otherwise the output may be considered invalid and discarded by the transport. |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 70 | */ |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 71 | public static final AsciiMarshaller<String> ASCII_STRING_MARSHALLER = |
| 72 | new AsciiMarshaller<String>() { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 73 | |
| 74 | @Override |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 75 | public String toAsciiString(String value) { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 76 | return value; |
| 77 | } |
| 78 | |
| 79 | @Override |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 80 | public String parseAsciiString(String serialized) { |
| 81 | return serialized; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 82 | } |
| 83 | }; |
| 84 | |
ejona | 9d50299 | 2014-09-22 12:23:19 -0700 | [diff] [blame] | 85 | /** |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 86 | * Simple metadata marshaller that encodes an integer as a signed decimal string. |
ejona | 9d50299 | 2014-09-22 12:23:19 -0700 | [diff] [blame] | 87 | */ |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 88 | public static final AsciiMarshaller<Integer> INTEGER_MARSHALLER = new AsciiMarshaller<Integer>() { |
ejona | 9d50299 | 2014-09-22 12:23:19 -0700 | [diff] [blame] | 89 | |
| 90 | @Override |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 91 | public String toAsciiString(Integer value) { |
ejona | 9d50299 | 2014-09-22 12:23:19 -0700 | [diff] [blame] | 92 | return value.toString(); |
| 93 | } |
| 94 | |
| 95 | @Override |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 96 | public Integer parseAsciiString(String serialized) { |
| 97 | return Integer.parseInt(serialized); |
ejona | 9d50299 | 2014-09-22 12:23:19 -0700 | [diff] [blame] | 98 | } |
| 99 | }; |
| 100 | |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 101 | private final ListMultimap<String, MetadataEntry> store; |
| 102 | private final boolean serializable; |
| 103 | |
| 104 | /** |
| 105 | * Constructor called by the transport layer when it receives binary metadata. |
| 106 | */ |
| 107 | // TODO(user): Convert to use ByteString so we can cache transformations |
| 108 | private Metadata(byte[]... binaryValues) { |
| 109 | store = LinkedListMultimap.create(); |
| 110 | for (int i = 0; i < binaryValues.length; i++) { |
ejona | 8c76c8a | 2014-10-09 09:53:41 -0700 | [diff] [blame] | 111 | String name = new String(binaryValues[i], US_ASCII); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 112 | store.put(name, new MetadataEntry(binaryValues[++i])); |
| 113 | } |
| 114 | this.serializable = false; |
| 115 | } |
| 116 | |
| 117 | /** |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 118 | * Constructor called by the application layer when it wants to send metadata. |
| 119 | */ |
| 120 | private Metadata() { |
| 121 | store = LinkedListMultimap.create(); |
| 122 | this.serializable = true; |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Returns true if a value is defined for the given key. |
| 127 | */ |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 128 | public boolean containsKey(Key<?> key) { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 129 | return store.containsKey(key.name); |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * Returns the last metadata entry added with the name 'name' parsed as T. |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 134 | * @return the parsed metadata entry or null if there are none. |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 135 | */ |
| 136 | public <T> T get(Key<T> key) { |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 137 | if (containsKey(key)) { |
| 138 | MetadataEntry metadataEntry = Iterables.getLast(store.get(key.name())); |
| 139 | return metadataEntry.getParsed(key); |
| 140 | } |
| 141 | return null; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 142 | } |
| 143 | |
| 144 | /** |
| 145 | * Returns all the metadata entries named 'name', in the order they were received, |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 146 | * parsed as T or null if there are none. |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 147 | */ |
| 148 | public <T> Iterable<T> getAll(final Key<T> key) { |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 149 | if (containsKey(key)) { |
| 150 | return Iterables.transform( |
| 151 | store.get(key.name()), |
| 152 | new Function<MetadataEntry, T>() { |
| 153 | @Override |
| 154 | public T apply(MetadataEntry entry) { |
| 155 | return entry.getParsed(key); |
| 156 | } |
| 157 | }); |
| 158 | } |
| 159 | return null; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 160 | } |
| 161 | |
| 162 | public <T> void put(Key<T> key, T value) { |
| 163 | store.put(key.name(), new MetadataEntry(key, value)); |
| 164 | } |
| 165 | |
| 166 | /** |
| 167 | * Remove a specific value. |
| 168 | */ |
| 169 | public <T> boolean remove(Key<T> key, T value) { |
| 170 | return store.remove(key.name(), value); |
| 171 | } |
| 172 | |
| 173 | /** |
| 174 | * Remove all values for the given key. |
| 175 | */ |
| 176 | public <T> List<T> removeAll(final Key<T> key) { |
| 177 | return Lists.transform(store.removeAll(key.name()), new Function<MetadataEntry, T>() { |
| 178 | @Override |
| 179 | public T apply(MetadataEntry metadataEntry) { |
| 180 | return metadataEntry.getParsed(key); |
| 181 | } |
| 182 | }); |
| 183 | } |
| 184 | |
| 185 | /** |
| 186 | * Can this metadata be serialized. Metadata constructed from raw binary or ascii values |
| 187 | * cannot be serialized without merging it into a serializable instance using |
| 188 | * {@link #merge(Metadata, java.util.Set)} |
| 189 | */ |
| 190 | public boolean isSerializable() { |
| 191 | return serializable; |
| 192 | } |
| 193 | |
| 194 | /** |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 195 | * Serialize all the metadata entries. |
| 196 | * |
| 197 | * <p>It produces serialized names and values interleaved. result[i*2] are names, while |
| 198 | * result[i*2+1] are values. |
| 199 | * |
| 200 | * <p>Names are ASCII string bytes. If the name ends with "-bin", the value can be raw binary. |
| 201 | * Otherwise, the value must be printable ASCII characters or space. |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 202 | */ |
| 203 | public byte[][] serialize() { |
| 204 | Preconditions.checkState(serializable, "Can't serialize raw metadata"); |
| 205 | byte[][] serialized = new byte[store.size() * 2][]; |
| 206 | int i = 0; |
| 207 | for (Map.Entry<String, MetadataEntry> entry : store.entries()) { |
| 208 | serialized[i++] = entry.getValue().key.asciiName(); |
| 209 | serialized[i++] = entry.getValue().getSerialized(); |
| 210 | } |
| 211 | return serialized; |
| 212 | } |
| 213 | |
| 214 | /** |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 215 | * Perform a simple merge of two sets of metadata. |
| 216 | * <p> |
| 217 | * Note that we can't merge non-serializable metadata into serializable. |
| 218 | * </p> |
| 219 | */ |
| 220 | public void merge(Metadata other) { |
| 221 | Preconditions.checkNotNull(other); |
| 222 | if (this.serializable) { |
| 223 | if (!other.serializable) { |
| 224 | throw new IllegalArgumentException( |
| 225 | "Cannot merge non-serializable metadata into serializable metadata without keys"); |
| 226 | } |
| 227 | } |
| 228 | store.putAll(other.store); |
| 229 | } |
| 230 | |
| 231 | /** |
| 232 | * Merge values for the given set of keys into this set of metadata. |
| 233 | */ |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 234 | @SuppressWarnings({"rawtypes", "unchecked"}) |
| 235 | public void merge(Metadata other, Set<Key<?>> keys) { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 236 | Preconditions.checkNotNull(other); |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 237 | for (Key<?> key : keys) { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 238 | if (other.containsKey(key)) { |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 239 | Iterable<?> values = other.getAll(key); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 240 | for (Object value : values) { |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 241 | put((Key) key, value); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 242 | } |
| 243 | } |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * Concrete instance for metadata attached to the start of a call. |
| 249 | */ |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 250 | public static class Headers extends Metadata { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 251 | private String path; |
| 252 | private String authority; |
| 253 | |
| 254 | /** |
| 255 | * Called by the transport layer to create headers from their binary serialized values. |
| 256 | */ |
| 257 | public Headers(byte[]... headers) { |
| 258 | super(headers); |
| 259 | } |
| 260 | |
| 261 | /** |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 262 | * Called by the application layer to construct headers prior to passing them to the |
| 263 | * transport for serialization. |
| 264 | */ |
| 265 | public Headers() { |
| 266 | } |
| 267 | |
| 268 | /** |
| 269 | * The path for the operation. |
| 270 | */ |
| 271 | public String getPath() { |
| 272 | return path; |
| 273 | } |
| 274 | |
| 275 | public void setPath(String path) { |
| 276 | this.path = path; |
| 277 | } |
| 278 | |
| 279 | /** |
| 280 | * The serving authority for the operation. |
| 281 | */ |
| 282 | public String getAuthority() { |
| 283 | return authority; |
| 284 | } |
| 285 | |
| 286 | public void setAuthority(String authority) { |
| 287 | this.authority = authority; |
| 288 | } |
nathanmittler | 23fbc7c | 2014-09-11 12:50:16 -0700 | [diff] [blame] | 289 | |
| 290 | @Override |
| 291 | public void merge(Metadata other) { |
| 292 | super.merge(other); |
| 293 | mergePathAndAuthority(other); |
| 294 | } |
| 295 | |
| 296 | @Override |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 297 | public void merge(Metadata other, Set<Key<?>> keys) { |
nathanmittler | 23fbc7c | 2014-09-11 12:50:16 -0700 | [diff] [blame] | 298 | super.merge(other, keys); |
| 299 | mergePathAndAuthority(other); |
| 300 | } |
| 301 | |
| 302 | private void mergePathAndAuthority(Metadata other) { |
| 303 | if (other instanceof Headers) { |
| 304 | Headers otherHeaders = (Headers) other; |
| 305 | path = otherHeaders.path != null ? otherHeaders.path : path; |
| 306 | authority = otherHeaders.authority != null ? otherHeaders.authority : authority; |
| 307 | } |
| 308 | } |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 309 | } |
| 310 | |
| 311 | /** |
| 312 | * Concrete instance for metadata attached to the end of the call. Only provided by |
| 313 | * servers. |
| 314 | */ |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 315 | public static class Trailers extends Metadata { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 316 | /** |
| 317 | * Called by the transport layer to create trailers from their binary serialized values. |
| 318 | */ |
| 319 | public Trailers(byte[]... headers) { |
| 320 | super(headers); |
| 321 | } |
| 322 | |
| 323 | /** |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 324 | * Called by the application layer to construct trailers prior to passing them to the |
| 325 | * transport for serialization. |
| 326 | */ |
| 327 | public Trailers() { |
| 328 | } |
| 329 | } |
| 330 | |
| 331 | |
| 332 | /** |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 333 | * Marshaller for metadata values that are serialized into raw binary. |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 334 | */ |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 335 | public static interface BinaryMarshaller<T> { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 336 | /** |
| 337 | * Serialize a metadata value to bytes. |
| 338 | * @param value to serialize |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 339 | * @return serialized version of value |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 340 | */ |
| 341 | public byte[] toBytes(T value); |
| 342 | |
| 343 | /** |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 344 | * Parse a serialized metadata value from bytes. |
| 345 | * @param serialized value of metadata to parse |
| 346 | * @return a parsed instance of type T |
| 347 | */ |
| 348 | public T parseBytes(byte[] serialized); |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 349 | } |
| 350 | |
| 351 | /** |
| 352 | * Marshaller for metadata values that are serialized into ASCII strings that contain only |
| 353 | * printable characters and space. |
| 354 | */ |
| 355 | public static interface AsciiMarshaller<T> { |
| 356 | /** |
| 357 | * Serialize a metadata value to a ASCII string that contains only printable characters and |
| 358 | * space. |
| 359 | * |
| 360 | * @param value to serialize |
| 361 | * @return serialized version of value, or null if value cannot be transmitted. |
| 362 | */ |
| 363 | public String toAsciiString(T value); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 364 | |
| 365 | /** |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 366 | * Parse a serialized metadata value from an ASCII string. |
| 367 | * @param serialized value of metadata to parse |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 368 | * @return a parsed instance of type T |
| 369 | */ |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 370 | public T parseAsciiString(String serialized); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 371 | } |
| 372 | |
| 373 | /** |
| 374 | * Key for metadata entries. Allows for parsing and serialization of metadata. |
| 375 | */ |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 376 | public abstract static class Key<T> { |
| 377 | |
| 378 | /** |
| 379 | * Creates a key for a binary header. |
| 380 | * |
| 381 | * @param name must end with {@link BINARY_HEADER_SUFFIX} |
| 382 | */ |
| 383 | public static <T> Key<T> of(String name, BinaryMarshaller<T> marshaller) { |
| 384 | return new BinaryKey<T>(name, marshaller); |
| 385 | } |
| 386 | |
| 387 | /** |
| 388 | * Creates a key for a ASCII header. |
| 389 | * |
| 390 | * @param name must not end with {@link BINARY_HEADER_SUFFIX} |
| 391 | */ |
| 392 | public static <T> Key<T> of(String name, AsciiMarshaller<T> marshaller) { |
| 393 | return new AsciiKey<T>(name, marshaller); |
ejona | 9d50299 | 2014-09-22 12:23:19 -0700 | [diff] [blame] | 394 | } |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 395 | |
| 396 | private final String name; |
| 397 | private final byte[] asciiName; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 398 | |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 399 | private Key(String name) { |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 400 | this.name = Preconditions.checkNotNull(name, "name").toLowerCase().intern(); |
lryan | 28497e3 | 2014-10-17 16:14:38 -0700 | [diff] [blame] | 401 | this.asciiName = this.name.getBytes(US_ASCII); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 402 | } |
| 403 | |
| 404 | public String name() { |
| 405 | return name; |
| 406 | } |
| 407 | |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 408 | // TODO (lryan): Migrate to ByteString |
| 409 | public byte[] asciiName() { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 410 | return asciiName; |
| 411 | } |
| 412 | |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 413 | @Override |
| 414 | public boolean equals(Object o) { |
| 415 | if (this == o) return true; |
| 416 | if (o == null || getClass() != o.getClass()) return false; |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 417 | Key<?> key = (Key<?>) o; |
lryan | 1369ea1 | 2014-09-23 10:36:55 -0700 | [diff] [blame] | 418 | return !(name != null ? !name.equals(key.name) : key.name != null); |
| 419 | } |
| 420 | |
| 421 | @Override |
| 422 | public int hashCode() { |
| 423 | return name != null ? name.hashCode() : 0; |
| 424 | } |
| 425 | |
| 426 | @Override |
| 427 | public String toString() { |
| 428 | return "Key{name='" + name + "'}"; |
| 429 | } |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 430 | |
| 431 | /** |
| 432 | * Serialize a metadata value to bytes. |
| 433 | * @param value to serialize |
| 434 | * @return serialized version of value |
| 435 | */ |
| 436 | abstract byte[] toBytes(T value); |
| 437 | |
| 438 | /** |
| 439 | * Parse a serialized metadata value from bytes. |
| 440 | * @param serialized value of metadata to parse |
| 441 | * @return a parsed instance of type T |
| 442 | */ |
| 443 | abstract T parseBytes(byte[] serialized); |
| 444 | } |
| 445 | |
| 446 | private static class BinaryKey<T> extends Key<T> { |
| 447 | private final BinaryMarshaller<T> marshaller; |
| 448 | |
| 449 | /** |
| 450 | * Keys have a name and a binary marshaller used for serialization. |
| 451 | */ |
| 452 | private BinaryKey(String name, BinaryMarshaller<T> marshaller) { |
| 453 | super(name); |
| 454 | Preconditions.checkArgument(name.endsWith(BINARY_HEADER_SUFFIX), |
| 455 | "Binary header is named " + name + ". It must end with " + BINARY_HEADER_SUFFIX); |
| 456 | this.marshaller = Preconditions.checkNotNull(marshaller); |
| 457 | } |
| 458 | |
| 459 | @Override |
| 460 | byte[] toBytes(T value) { |
| 461 | return marshaller.toBytes(value); |
| 462 | } |
| 463 | |
| 464 | @Override |
| 465 | T parseBytes(byte[] serialized) { |
| 466 | return marshaller.parseBytes(serialized); |
| 467 | } |
| 468 | } |
| 469 | |
| 470 | private static class AsciiKey<T> extends Key<T> { |
| 471 | private final AsciiMarshaller<T> marshaller; |
| 472 | |
| 473 | /** |
| 474 | * Keys have a name and an ASCII marshaller used for serialization. |
| 475 | */ |
| 476 | private AsciiKey(String name, AsciiMarshaller<T> marshaller) { |
| 477 | super(name); |
| 478 | Preconditions.checkArgument(!name.endsWith(BINARY_HEADER_SUFFIX), |
| 479 | "ASCII header is named " + name + ". It must not end with " + BINARY_HEADER_SUFFIX); |
| 480 | this.marshaller = Preconditions.checkNotNull(marshaller); |
| 481 | } |
| 482 | |
| 483 | @Override |
| 484 | byte[] toBytes(T value) { |
| 485 | return marshaller.toAsciiString(value).getBytes(US_ASCII); |
| 486 | } |
| 487 | |
| 488 | @Override |
| 489 | T parseBytes(byte[] serialized) { |
| 490 | return marshaller.parseAsciiString(new String(serialized, US_ASCII)); |
| 491 | } |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 492 | } |
| 493 | |
| 494 | private static class MetadataEntry { |
| 495 | Object parsed; |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 496 | |
| 497 | @SuppressWarnings("rawtypes") |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 498 | Key key; |
| 499 | byte[] serializedBinary; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 500 | |
| 501 | /** |
| 502 | * Constructor used when application layer adds a parsed value. |
| 503 | */ |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 504 | private MetadataEntry(Key<?> key, Object parsed) { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 505 | this.parsed = Preconditions.checkNotNull(parsed); |
| 506 | this.key = Preconditions.checkNotNull(key); |
| 507 | } |
| 508 | |
| 509 | /** |
| 510 | * Constructor used when reading a value from the transport. |
| 511 | */ |
| 512 | private MetadataEntry(byte[] serialized) { |
| 513 | Preconditions.checkNotNull(serialized); |
| 514 | this.serializedBinary = serialized; |
| 515 | } |
| 516 | |
nathanmittler | 0304b3d | 2014-10-24 13:39:13 -0700 | [diff] [blame] | 517 | @SuppressWarnings("unchecked") |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 518 | public <T> T getParsed(Key<T> key) { |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 519 | T value = (T) parsed; |
| 520 | if (value != null) { |
| 521 | if (this.key != key) { |
| 522 | // Keys don't match so serialize using the old key |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 523 | serializedBinary = this.key.toBytes(value); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 524 | } else { |
| 525 | return value; |
| 526 | } |
| 527 | } |
| 528 | this.key = key; |
| 529 | if (serializedBinary != null) { |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 530 | value = key.parseBytes(serializedBinary); |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 531 | } |
| 532 | parsed = value; |
| 533 | return value; |
| 534 | } |
| 535 | |
| 536 | @SuppressWarnings("unchecked") |
| 537 | public byte[] getSerialized() { |
| 538 | return serializedBinary = |
| 539 | serializedBinary == null |
zhangkun | 2b116ef | 2014-12-03 20:28:00 -0800 | [diff] [blame^] | 540 | ? key.toBytes(parsed) : serializedBinary; |
lryan | e4bd1c7 | 2014-09-08 14:03:35 -0700 | [diff] [blame] | 541 | } |
| 542 | } |
| 543 | } |