[英]How to randomize two String collections in the same fashion in distributed system?
我有幾個 collections 字符串(約 100k 個元素)。 它們從相同的網絡源初始化:
List<String> source = Arrays.asList("cat Tom", "dog Woof", "bird Carry", "fish Silent", "mice Dr Black");
List<String> list1 = new ArrayList<>(source);
List<String> list2 = new ArrayList<>(source);
List<String> list3 = new ArrayList<>(source);
在他們的一生中,他們可以獨立修改:
list1.add("raccoon George");
list2.set(2, "bird Frank"); // Different bird
list3.remove(2); // No birds!
這些 collections 存在於不同的 JVM 中,但具有相同(共享)的種子:
String seed = UUID.randomUUID().toString();
我需要一些排序/洗牌方法(或Comparator )來隨機化這些 collections:
magicSort(list1, seed); // JVM #1
magicSort(list2, seed); // JVM #2
magicSort(list3, seed); // JVM #3
要像這樣接收一致/可重復的 output:
[mice Dr Black, bird Carry, raccoon George, cat Tom, dog Woof, fish Silent]
[mice Dr Black, bird Frank, cat Tom, dog Woof, fish Silent]
[mice Dr Black, cat Tom, dog Woof, fish Silent]
這不起作用:
Map<String, UUID>
中保持隨機順序 - 因為 (a) 集合的動態性質和 (b) 分布式設置。任何幫助將不勝感激
編輯#1
這不起作用:
sha1
, md5
和類似的 hash 算法 - 因為它們不為具有相同前綴的項目提供親和力 - bird Carry
和bird Frank
可以放置在遠離彼此的位置。編輯#2
附加條件:具有相同前綴的項目應該組合在一起(親和),例如所有的鳥都放在老鼠和浣熊之間。
非常感謝評論中的散列提示!
我最終通過偽隨機散列(類似於 Fisher-Yates shuffle)重新映射字符順序。 rest 代碼是從String.compareTo
復制粘貼的:
private void magicSort(List<String> list, String seed) {
list.sort(new ShuffleComparator(seed));
}
public class ShuffleComparator implements Comparator<String> {
private static final long MAGIC = 0x5DEECE66DL;
private final String seed;
public ShuffleComparator(String seed) {
this.seed = seed;
}
@Override
public int compare(String s1, String s2) {
int len1 = s1.length();
int len2 = s2.length();
int lim = Math.min(len1, len2);
int seedLen = seed.length();
long random = seed.hashCode();
for (int k = 0; k < lim; k++) {
random = random * MAGIC + seed.charAt(k % seedLen);
char c1 = s1.charAt(k);
char c2 = s2.charAt(k);
if (c1 != c2) {
return ((random % (c1 + 0xFFFF)) & 0xFFFF) -
((random % (c2 + 0xFFFF)) & 0xFFFF) > 0 ? 1 : -1;
}
}
return (random > 0 ? 1 : -1) * (len1 - len2);
}
}
結果:
例子:
seed: b85a9119-3a98-4491-b503-fc2cfdc344f3
[raccoon George, bird Carry, mice Dr Black, fish Silent, cat Tom, dog Woof]
[bird Frank, mice Dr Black, fish Silent, cat Tom, dog Woof]
[mice Dr Black, fish Silent, cat Tom, dog Woof]
seed: d5378421-d0ea-4b17-80e9-1de6a163bf38
[bird Carry, dog Woof, fish Silent, raccoon George, mice Dr Black, cat Tom]
[bird Frank, dog Woof, fish Silent, mice Dr Black, cat Tom]
[dog Woof, fish Silent, mice Dr Black, cat Tom]
seed: a5f94f60-1207-4f83-9723-bbab5e3b8075
[cat Tom, raccoon George, mice Dr Black, bird Carry, dog Woof, fish Silent]
[cat Tom, mice Dr Black, bird Frank, dog Woof, fish Silent]
[cat Tom, mice Dr Black, dog Woof, fish Silent]
seed: 4b77a61f-c639-42fc-96b2-e1add9f359e9
[bird Carry, raccoon George, cat Tom, mice Dr Black, dog Woof, fish Silent]
[bird Frank, cat Tom, mice Dr Black, dog Woof, fish Silent]
[cat Tom, mice Dr Black, dog Woof, fish Silent]
seed: 2dd78e21-d4ad-4e8a-b139-5d35fe2b0481
[dog Woof, fish Silent, raccoon George, mice Dr Black, bird Carry, cat Tom]
[dog Woof, fish Silent, mice Dr Black, bird Frank, cat Tom]
[dog Woof, fish Silent, mice Dr Black, cat Tom]
編輯#1
對於測試,我還實現了基於哈希的比較器,因此將在此處發布。 以防萬一您不需要親和力(例如我的情況),但需要純洗牌:
private void magicSort(List<String> list, String seed) {
list.sort(new HashComparator(seed, "SHA-1"));
}
public class HashComparator implements Comparator<String> {
private static final long MAGIC = 0x5DEECE66DL;
private final ThreadLocal<MessageDigest> messageDigest;
private final byte[] seed;
private final int seedHash;
public HashComparator(String seed, String algorithm) {
this.seed = seed.getBytes(ISO_8859_1);
this.seedHash = seed.hashCode();
this.messageDigest = ThreadLocal.withInitial(() -> {
try {
return MessageDigest.getInstance(algorithm);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e.getMessage(), e);
}
});
}
@Override
public int compare(String s1, String s2) {
if (s1.equals(s2)) {
return 0;
}
int diff = getSignature(s1).compareTo(getSignature(s2));
if (diff != 0) {
return diff;
}
long random = seedHash;
random = random * MAGIC + s1.hashCode();
random = random * MAGIC + s2.hashCode();
return ((random & 1) == 0 ? 1 : -1) * s1.compareTo(s2);
}
private ByteBuffer getSignature(String s) {
MessageDigest digest = messageDigest.get();
digest.reset();
digest.update(seed);
for (int i = 0, size = s.length(); i < size; i++) {
char c = s.charAt(i);
digest.update((byte) (c >> 8));
digest.update((byte) c);
}
return ByteBuffer.wrap(digest.digest());
}
}
結果:
例子:
8d465fde-9310-4b6c-9709-5cc395deb45e
[raccoon George, mice Dr Black, dog Woof, fish Silent, cat Tom, bird Carry]
[bird Frank, mice Dr Black, dog Woof, fish Silent, cat Tom]
[mice Dr Black, dog Woof, fish Silent, cat Tom]
6daa90dd-f7e7-4615-a45c-fefb0de10c20
[bird Carry, mice Dr Black, fish Silent, cat Tom, dog Woof, raccoon George]
[mice Dr Black, bird Frank, fish Silent, cat Tom, dog Woof]
[mice Dr Black, fish Silent, cat Tom, dog Woof]
9f30b259-c8d1-41f5-8221-40b17cb04260
[cat Tom, mice Dr Black, raccoon George, dog Woof, fish Silent, bird Carry]
[bird Frank, cat Tom, mice Dr Black, dog Woof, fish Silent]
[cat Tom, mice Dr Black, dog Woof, fish Silent]
94b6710f-3232-453d-8009-6d81658b2cca
[dog Woof, fish Silent, bird Carry, cat Tom, mice Dr Black, raccoon George]
[dog Woof, fish Silent, cat Tom, mice Dr Black, bird Frank]
[dog Woof, fish Silent, cat Tom, mice Dr Black]
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.