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GeezerVison is showing github.com — lmdbjava/src/test/java/org/lmdbjava/TutorialTest.java at master · lmdbjava/lmdbjava Expand file tree/ Copy pathTutorialTest.javaMore file actions 621 lines (523 loc) · 22.8 KB / Copy pathTutorialTest.javaFile metadata and controls621 lines (523 loc) · 22.8 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 /* * Copyright © 2016-2025 The LmdbJava Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.lmdbjava; import static java.nio.charset.StandardCharsets.UTF_8; import static java.util.concurrent.TimeUnit.SECONDS; import static org.assertj.core.api.Assertions.assertThat; import static org.lmdbjava.ByteBufferProxy.PROXY_OPTIMAL; import static org.lmdbjava.DbiFlags.MDB_CREATE; import static org.lmdbjava.DbiFlags.MDB_DUPSORT; import static org.lmdbjava.DbiFlags.MDB_INTEGERKEY; import static org.lmdbjava.DbiFlags.MDB_REVERSEKEY; import static org.lmdbjava.DirectBufferProxy.PROXY_DB; import static org.lmdbjava.GetOp.MDB_SET; import static org.lmdbjava.SeekOp.MDB_FIRST; import static org.lmdbjava.SeekOp.MDB_LAST; import static org.lmdbjava.SeekOp.MDB_PREV; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.file.Path; import java.util.ArrayList; import java.util.List; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import org.agrona.DirectBuffer; import org.agrona.MutableDirectBuffer; import org.agrona.concurrent.UnsafeBuffer; import org.junit.jupiter.api.AfterEach; import org.junit.jupiter.api.BeforeEach; import org.junit.jupiter.api.Test; import org.lmdbjava.CursorIterable.KeyVal; /** * Welcome to LmdbJava! * * <p>This short tutorial will walk you through using LmdbJava step-by-step. * * <p>If you are using a 64-bit Windows, Linux or OS X machine, you can simply run this tutorial by * adding the LmdbJava JAR to your classpath. It includes the required system libraries. If you are * using another 64-bit platform, you'll need to install the LMDB system library yourself. 32-bit * platforms are not supported. * * <p>Start the JVM with arguments <code>--add-opens java.base/java.nio=ALL-UNNAMED * --add-opens java.base/sun.nio.ch=ALL-UNNAMED</code> to suppress JVM warnings. */ public final class TutorialTest { private static final String DB_NAME = "my DB"; private TempDir tempDir; @BeforeEach void beforeEach() { tempDir = new TempDir(); } @AfterEach void afterEach() { tempDir.cleanup(); } /** In this first tutorial we will use LmdbJava with some basic defaults. */ @Test void tutorial1() { // We need a storage directory first. // The path cannot be on a remote file system. final Path dir = tempDir.createTempDir(); // We always need an Env. An Env owns a physical on-disk storage file. One // Env can store many different databases (ie sorted maps). final Env<ByteBuffer> env = Env.create() // LMDB also needs to know how large our DB might be. Over-estimating is OK. .setMapSize(10_485_760) // LMDB also needs to know how many DBs (Dbi) we want to store in this Env. .setMaxDbs(1) // Now let's open the Env. The same path can be concurrently opened and // used in different processes, but do not open the same path twice in // the same process at the same time. .open(dir); // We need a Dbi for each DB. A Dbi roughly equates to a sorted map. The // MDB_CREATE flag causes the DB to be created if it doesn't already exist. final Dbi<ByteBuffer> db = env.createDbi().setDbName(DB_NAME).withDefaultComparator().setDbiFlags(MDB_CREATE).open(); // We want to store some data, so we will need a direct ByteBuffer. // Note that LMDB keys cannot exceed maxKeySize bytes (511 bytes by default). // Values can be larger. final ByteBuffer key = ByteBuffer.allocateDirect(env.getMaxKeySize()); final ByteBuffer val = ByteBuffer.allocateDirect(700); key.put("greeting".getBytes(UTF_8)).flip(); val.put("Hello world".getBytes(UTF_8)).flip(); final int valSize = val.remaining(); // Now store it. Dbi.put() internally begins and commits a transaction (Txn). db.put(key, val); // To fetch any data from LMDB we need a Txn. A Txn is very important in // LmdbJava because it offers ACID characteristics and internally holds a // read-only key buffer and read-only value buffer. These read-only buffers // are always the same two Java objects, but point to different LMDB-managed // memory as we use Dbi (and Cursor) methods. These read-only buffers remain // valid only until the Txn is released or the next Dbi or Cursor call. If // you need data afterwards, you should copy the bytes to your own buffer. try (Txn<ByteBuffer> txn = env.txnRead()) { final ByteBuffer found = db.get(txn, key); assertThat(found).isNotNull(); // The fetchedVal is read-only and points to LMDB memory final ByteBuffer fetchedVal = txn.val(); assertThat(fetchedVal.remaining()).isEqualTo(valSize); // Let's double-check the fetched value is correct assertThat(UTF_8.decode(fetchedVal).toString()).isEqualTo("Hello world"); } // We can also delete. The simplest way is to let Dbi allocate a new Txn... db.delete(key); // Now if we try to fetch the deleted row, it won't be present try (Txn<ByteBuffer> txn = env.txnRead()) { assertThat(db.get(txn, key)).isNull(); } env.close(); } /** In this second tutorial we'll learn more about LMDB's ACID Txns. */ @Test void tutorial2() { final Path dir = tempDir.createTempDir(); try { final Env<ByteBuffer> env = createSimpleEnv(dir); final Dbi<ByteBuffer> db = env.createDbi().setDbName(DB_NAME).withDefaultComparator().setDbiFlags(MDB_CREATE).open(); final ByteBuffer key = ByteBuffer.allocateDirect(env.getMaxKeySize()); final ByteBuffer val = ByteBuffer.allocateDirect(700); // Let's write and commit "key1" via a Txn. A Txn can include multiple Dbis. // Note write Txns block other write Txns, due to writes being serialized. // It's therefore important to avoid unnecessarily long-lived write Txns. try (Txn<ByteBuffer> txn = env.txnWrite()) { key.put("key1".getBytes(UTF_8)).flip(); val.put("lmdb".getBytes(UTF_8)).flip(); db.put(txn, key, val); // We can read data too, even though this is a write Txn. final ByteBuffer found = db.get(txn, key); assertThat(found).isNotNull(); // An explicit commit is required, otherwise Txn.close() rolls it back. txn.commit(); } // Open a read-only Txn. It only sees data that existed at Txn creation time. final Txn<ByteBuffer> rtx = env.txnRead(); // Our read Txn can fetch key1 without problem, as it existed at Txn creation. ByteBuffer found = db.get(rtx, key); assertThat(found).isNotNull(); // Note that our main test thread holds the Txn. Only one Txn per thread is // typically permitted (the exception is a read-only Env with MDB_NOTLS). // // Let's write out a "key2" via a new write Txn in a different thread. final ExecutorService es = Executors.newCachedThreadPool(); es.execute( () -> { try (Txn<ByteBuffer> txn = env.txnWrite()) { key.clear(); key.put("key2".getBytes(UTF_8)).flip(); db.put(txn, key, val); txn.commit(); } }); es.shutdown(); es.awaitTermination(10, SECONDS); // Even though key2 has been committed, our read Txn still can't see it. found = db.get(rtx, key); assertThat(found).isNull(); // To see key2, we could create a new Txn. But a reset/renew is much faster. // Reset/renew is also important to avoid long-lived read Txns, as these // prevent the re-use of free pages by write Txns (ie the DB will grow). rtx.reset(); // ... potentially long operation here ... rtx.renew(); found = db.get(rtx, key); assertThat(found).isNotNull(); // Don't forget to close the read Txn now we're completely finished. We could // have avoided this if we used a try-with-resources block, but we wanted to // play around with multiple concurrent Txns to demonstrate the "I" in ACID. rtx.close(); env.close(); } catch (final InterruptedException e) { throw new RuntimeException(e); } } /** * In this third tutorial we'll have a look at the Cursor. Up until now we've just used Dbi, which * is good enough for simple cases but unsuitable if you don't know the key to fetch, or want to * iterate over all the data etc. */ @Test void tutorial3() { final Path dir = tempDir.createTempDir(); final Env<ByteBuffer> env = createSimpleEnv(dir); final Dbi<ByteBuffer> db = env.createDbi().setDbName(DB_NAME).withDefaultComparator().setDbiFlags(MDB_CREATE).open(); final ByteBuffer key = ByteBuffer.allocateDirect(env.getMaxKeySize()); final ByteBuffer val = ByteBuffer.allocateDirect(700); try (Txn<ByteBuffer> txn = env.txnWrite()) { // A cursor always belongs to a particular Dbi. final Cursor<ByteBuffer> c = db.openCursor(txn); // We can put via a Cursor. Note we're adding keys in a strange order, // as we want to show you that LMDB returns them in sorted order. key.put("zzz".getBytes(UTF_8)).flip(); val.put("lmdb".getBytes(UTF_8)).flip(); c.put(key, val); key.clear(); key.put("aaa".getBytes(UTF_8)).flip(); c.put(key, val); key.clear(); key.put("ccc".getBytes(UTF_8)).flip(); c.put(key, val); // We can read from the Cursor by key. c.get(key, MDB_SET); assertThat(UTF_8.decode(c.key()).toString()).isEqualTo("ccc"); // Let's see that LMDB provides the keys in appropriate order.... c.seek(MDB_FIRST); assertThat(UTF_8.decode(c.key()).toString()).isEqualTo("aaa"); c.seek(MDB_LAST); assertThat(UTF_8.decode(c.key()).toString()).isEqualTo("zzz"); c.seek(MDB_PREV); assertThat(UTF_8.decode(c.key()).toString()).isEqualTo("ccc"); // Cursors can also delete the current key. c.delete(); c.close(); txn.commit(); } // A read-only Cursor can survive its original Txn being closed. This is // useful if you want to close the original Txn (eg maybe you created the // Cursor during the constructor of a singleton with a throw-away Txn). Of // course, you cannot use the Cursor if its Txn is closed or currently reset. final Txn<ByteBuffer> tx1 = env.txnRead(); final Cursor<ByteBuffer> c = db.openCursor(tx1); tx1.close(); // The Cursor becomes usable again by "renewing" it with an active read Txn. final Txn<ByteBuffer> tx2 = env.txnRead(); c.renew(tx2); c.seek(MDB_FIRST); // As usual with read Txns, we can reset and renew them. The Cursor does // not need any special handling if we do this. tx2.reset(); // ... potentially long operation here ... tx2.renew(); c.seek(MDB_LAST); tx2.close(); env.close(); } /** * In this fourth tutorial we'll take a quick look at the iterators. These are a more Java * idiomatic form of using the Cursors we looked at in tutorial 3. */ @Test void tutorial4() { final Path dir = tempDir.createTempDir(); final Env<ByteBuffer> env = createSimpleEnv(dir); final Dbi<ByteBuffer> db = env.createDbi().setDbName(DB_NAME).withDefaultComparator().setDbiFlags(MDB_CREATE).open(); try (Txn<ByteBuffer> txn = env.txnWrite()) { final ByteBuffer key = ByteBuffer.allocateDirect(env.getMaxKeySize()); final ByteBuffer val = ByteBuffer.allocateDirect(700); // Insert some data. Note that ByteBuffer order defaults to Big Endian. // LMDB does not persist the byte order, but it's critical to sort keys. // If your numeric keys don't sort as expected, review buffer byte order. val.putInt(100); key.putInt(1); db.put(txn, key, val); key.clear(); key.putInt(2); db.put(txn, key, val); key.clear(); // Each iterable uses a cursor and must be closed when finished. Iterate // forward in terms of key ordering starting with the first key. try (CursorIterable<ByteBuffer> ci = db.iterate(txn, KeyRange.all())) { for (final KeyVal<ByteBuffer> kv : ci) { assertThat(kv.key()).isNotNull(); assertThat(kv.val()).isNotNull(); } } // Iterate backward in terms of key ordering starting with the last key. try (CursorIterable<ByteBuffer> ci = db.iterate(txn, KeyRange.allBackward())) { for (final KeyVal<ByteBuffer> kv : ci) { assertThat(kv.key()).isNotNull(); assertThat(kv.val()).isNotNull(); } } // There are many ways to control the desired key range via KeyRange, such // as arbitrary start and stop values, direction etc. We've adopted Guava's // terminology for our range classes (see KeyRangeType for further details). key.putInt(1); final KeyRange<ByteBuffer> range = KeyRange.atLeastBackward(key); try (CursorIterable<ByteBuffer> ci = db.iterate(txn, range)) { for (final KeyVal<ByteBuffer> kv : ci) { assertThat(kv.key()).isNotNull(); assertThat(kv.val()).isNotNull(); } } } env.close(); } /** In this fifth tutorial we'll explore multiple values sharing a single key. */ @Test void tutorial5() { final Path dir = tempDir.createTempDir(); final Env<ByteBuffer> env = createSimpleEnv(dir); // This time we're going to tell the Dbi it can store > 1 value per key. // There are other flags available if we're storing integers etc. final Dbi<ByteBuffer> db = env.createDbi() .setDbName(DB_NAME) .withDefaultComparator() .setDbiFlags(MDB_CREATE, MDB_DUPSORT) .open(); // Duplicate support requires both keys and values to be <= max key size. final ByteBuffer key = ByteBuffer.allocateDirect(env.getMaxKeySize()); final ByteBuffer val = ByteBuffer.allocateDirect(env.getMaxKeySize()); try (Txn<ByteBuffer> txn = env.txnWrite()) { final Cursor<ByteBuffer> c = db.openCursor(txn); // Store one key, but many values, and in non-natural order. key.put("key".getBytes(UTF_8)).flip(); val.put("xxx".getBytes(UTF_8)).flip(); c.put(key, val); val.clear(); val.put("kkk".getBytes(UTF_8)).flip(); c.put(key, val); val.clear(); val.put("lll".getBytes(UTF_8)).flip(); c.put(key, val); // Cursor can tell us how many values the current key has. final long count = c.count(); assertThat(count).isEqualTo(3L); // Let's position the Cursor. Note sorting still works. c.seek(MDB_FIRST); assertThat(UTF_8.decode(c.val()).toString()).isEqualTo("kkk"); c.seek(MDB_LAST); assertThat(UTF_8.decode(c.val()).toString()).isEqualTo("xxx"); c.seek(MDB_PREV); assertThat(UTF_8.decode(c.val()).toString()).isEqualTo("lll"); c.close(); txn.commit(); } env.close(); } /** * Next up we'll show you how to easily check your platform (operating system and Java version) is * working properly with LmdbJava and the embedded LMDB native library. */ @Test void tutorial6() { final Path dir = tempDir.createTempDir(); // Note we need to specify the Verifier's DBI_COUNT for the Env. final Env<ByteBuffer> env = Env.create(PROXY_OPTIMAL) .setMapSize(10, ByteUnit.MEBIBYTES) .setMaxDbs(Verifier.DBI_COUNT) .open(dir); // Create a Verifier (it's a Callable<Long> for those needing full control). final Verifier v = new Verifier(env); // We now run the verifier for 3 seconds; it raises an exception on failure. // The method returns the number of entries it successfully verified. v.runFor(3, SECONDS); env.close(); } /** In this final tutorial we'll look at using Agrona's DirectBuffer. */ @Test void tutorial7() { final Path dir = tempDir.createTempDir(); // The critical difference is we pass the PROXY_DB field to Env.create(). // There's also a PROXY_SAFE if you want to stop ByteBuffer's Unsafe use. // Aside from that and a different type argument, it's the same as usual... final Env<DirectBuffer> env = Env.create(PROXY_DB).setMapSize(10, ByteUnit.MEBIBYTES).setMaxDbs(1).open(dir); final Dbi<DirectBuffer> db = env.createDbi().setDbName(DB_NAME).withDefaultComparator().setDbiFlags(MDB_CREATE).open(); final ByteBuffer keyBb = ByteBuffer.allocateDirect(env.getMaxKeySize()); final MutableDirectBuffer key = new UnsafeBuffer(keyBb); final MutableDirectBuffer val = new UnsafeBuffer(ByteBuffer.allocateDirect(700)); try (Txn<DirectBuffer> txn = env.txnWrite()) { try (Cursor<DirectBuffer> c = db.openCursor(txn)) { // Agrona is faster than ByteBuffer and its methods are nicer... val.putStringWithoutLengthUtf8(0, "The Value"); key.putStringWithoutLengthUtf8(0, "yyy"); c.put(key, val); key.putStringWithoutLengthUtf8(0, "ggg"); c.put(key, val); c.seek(MDB_FIRST); assertThat(c.key().getStringWithoutLengthUtf8(0, env.getMaxKeySize())).startsWith("ggg"); c.seek(MDB_LAST); assertThat(c.key().getStringWithoutLengthUtf8(0, env.getMaxKeySize())).startsWith("yyy"); // DirectBuffer has no position concept. Often you don't want to store // the unnecessary bytes of a varying-size buffer. Let's have a look... final int keyLen = key.putStringWithoutLengthUtf8(0, "12characters"); assertThat(keyLen).isEqualTo(12); assertThat(key.capacity()).isEqualTo(env.getMaxKeySize()); // To only store the 12 characters, we simply call wrap: key.wrap(key, 0, keyLen); assertThat(key.capacity()).isEqualTo(keyLen); c.put(key, val); c.seek(MDB_FIRST); assertThat(c.key().capacity()).isEqualTo(keyLen); assertThat(c.key().getStringWithoutLengthUtf8(0, c.key().capacity())) .isEqualTo("12characters"); // To store bigger values again, just wrap the original buffer. key.wrap(keyBb); assertThat(key.capacity()).isEqualTo(env.getMaxKeySize()); } txn.commit(); } env.close(); } /** * In this tutorial we'll look at using keys that are longs. The same approach applies would apply * to int keys. */ @Test void tutorial8() { final Path dir = tempDir.createTempDir(); final Env<ByteBuffer> env = createSimpleEnv(dir); // This time we're going to tell the Dbi that all the keys are integers. // MDB_INTEGERKEY applies to both int and long keys. // LMDB can make optimisations for better performance. final Dbi<ByteBuffer> db = env.createDbi() .setDbName(DB_NAME) .withDefaultComparator() .setDbiFlags(MDB_CREATE, MDB_INTEGERKEY) .open(); // MDB_INTEGERKEY requires that the keys are written/read in native order final ByteBuffer key = ByteBuffer.allocateDirect(Long.BYTES).order(ByteOrder.nativeOrder()); final ByteBuffer val = ByteBuffer.allocateDirect(100); try (Txn<ByteBuffer> txn = env.txnWrite()) { // Store one key, but many values, and in non-natural order. key.putLong(42L).flip(); val.put("val-42".getBytes(UTF_8)).flip(); db.put(txn, key, val); key.clear(); val.clear(); key.putLong(1L).flip(); val.put("val-1".getBytes(UTF_8)).flip(); db.put(txn, key, val); key.clear(); val.clear(); key.putLong(Long.MAX_VALUE).flip(); val.put(("val-" + Long.MAX_VALUE).getBytes(UTF_8)).flip(); db.put(txn, key, val); key.clear(); val.clear(); key.putLong(1_000L).flip(); val.put("val-1".getBytes(UTF_8)).flip(); db.put(txn, key, val); // Get all the keys final List<Long> keys = new ArrayList<>(); try (CursorIterable<ByteBuffer> ci = db.iterate(txn, KeyRange.all())) { for (final KeyVal<ByteBuffer> kv : ci) { assertThat(kv.key()).isNotNull(); assertThat(kv.val()).isNotNull(); keys.add(kv.key().order(ByteOrder.nativeOrder()).getLong()); } } assertThat(keys).containsExactly(1L, 42L, 1_000L, Long.MAX_VALUE); txn.commit(); } env.close(); } /** In this tutorial we'll look storing the data in reverse order */ @Test void tutorial9() { final Path dir = tempDir.createTempDir(); final Env<ByteBuffer> env = createSimpleEnv(dir); final Dbi<ByteBuffer> db = env.createDbi() .setDbName(DB_NAME) .withDefaultComparator() .setDbiFlags(MDB_CREATE, MDB_REVERSEKEY) .open(); final ByteBuffer key = ByteBuffer.allocateDirect(100); final ByteBuffer val = ByteBuffer.allocateDirect(100); try (Txn<ByteBuffer> txn = env.txnWrite()) { // Store one key, but many values, and in non-natural order. key.put("tac".getBytes(UTF_8)).flip(); val.put("CAT".getBytes(UTF_8)).flip(); db.put(txn, key, val); key.clear(); val.clear(); key.put("god".getBytes(UTF_8)).flip(); val.put("DOG".getBytes(UTF_8)).flip(); db.put(txn, key, val); key.clear(); val.clear(); key.put("esroh".getBytes(UTF_8)).flip(); val.put("HORSE".getBytes(UTF_8)).flip(); db.put(txn, key, val); key.clear(); val.clear(); key.put("tnahpele".getBytes(UTF_8)).flip(); val.put("ELEPHANT".getBytes(UTF_8)).flip(); db.put(txn, key, val); // Get all the keys final List<String> keys = new ArrayList<>(); final List<String> values = new ArrayList<>(); try (CursorIterable<ByteBuffer> ci = db.iterate(txn, KeyRange.all())) { for (final KeyVal<ByteBuffer> kv : ci) { assertThat(kv.key()).isNotNull(); assertThat(kv.val()).isNotNull(); keys.add(UTF_8.decode(kv.key()).toString()); values.add(UTF_8.decode(kv.val()).toString()); } } assertThat(keys).containsExactly("tac", "god", "tnahpele", "esroh"); assertThat(values).containsExactly("CAT", "DOG", "ELEPHANT", "HORSE"); txn.commit(); } env.close(); } // You've finished! There are lots of other neat things we could show you (eg // how to speed up inserts by appending them in key order, using integer // or reverse ordered keys, using Env.DISABLE_CHECKS_PROP etc), but you now // know enough to tackle the JavaDocs with confidence. Have fun! private Env<ByteBuffer> createSimpleEnv(final Path path) { return Env.create().setMapSize(10, ByteUnit.MEBIBYTES).setMaxDbs(1).setMaxReaders(1).open(path); } } |
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