chore: make random sequence resolver more random (#80)

Author: godruoyi

README.md

@@ -28,7 +28,7 @@ Snowflake & Sonyflake algorithm PHP implementation [中文文档](https://github
 
 ![file](https://images.godruoyi.com/logos/201908/13/_1565672621_LPW65Pi8cG.png)
 
-Snowflake is a network service that generates unique ID numbers at high scale with simple guarantees.
+Snowflake is a network service that generates unique ID numbers at a high scale with simple guarantees.
 
 1. The first bit is an unused sign bit.
 2. The second part consists of a 41-bit timestamp (in milliseconds) representing the offset of the current time relative to a certain reference time.
@@ -84,7 +84,7 @@ $snowflake = new \Godruoyi\Snowflake\Snowflake($datacenterId, $workerId);
 $snowflake->id();
 ```
 
-3. Specify start time.
+3. Specify the start time.
 
 ```php
 $snowflake = new \Godruoyi\Snowflake\Snowflake;
@@ -95,7 +95,16 @@ $snowflake->id();
 
 > The maximum value of a 41-bit timestamp (in milliseconds) can represent up to 69 years, so the Snowflake algorithm can run safely for 69 years. In order to make the most of it, we recommend setting a start time.
 
-4. Use Sonyflake
+4. Using different sequence number resolvers (optional).
+
+```php
+$snowflake = new \Godruoyi\Snowflake\Snowflake;
+$snowflake->setSequenceResolver(new \Godruoyi\Snowflake\RandomSequenceResolver);
+
+$snowflake->id();
+```
+
+5. Use Sonyflake
 
 ```php
 $sonyflake = new \Godruoyi\Snowflake\Sonyflake;

src/RandomSequenceResolver.php

@@ -43,7 +43,7 @@ public function sequence(int $currentTime): int
             return $this->sequence;
         }
 
-        $this->sequence = random_int(0, $this->maxSequence);
+        $this->sequence = crc32(uniqid((string) random_int(0, PHP_INT_MAX), true)) % $this->maxSequence;
         $this->lastTimeStamp = $currentTime;
 
         return $this->sequence;

src/Snowflake.php

@@ -60,8 +60,8 @@ public function __construct(int $datacenter = 0, int $workerId = 0)
         $maxWorkId = -1 ^ (-1 << self::MAX_WORKID_LENGTH);
 
         // If not set datacenter or workid, we will set a default value to use.
-        $this->datacenter = $datacenter > $maxDataCenter || $datacenter < 0 ? random_int(0, 31) : $datacenter;
-        $this->workerId = $workerId > $maxWorkId || $workerId < 0 ? random_int(0, 31) : $workerId;
+        $this->datacenter = $datacenter > $maxDataCenter || $datacenter <= 0 ? random_int(0, 31) : $datacenter;
+        $this->workerId = $workerId > $maxWorkId || $workerId <= 0 ? random_int(0, 31) : $workerId;
     }
 
     /**

tests/FileLockResolverTest.php

@@ -18,14 +18,15 @@
 class FileLockResolverTest extends TestCase
 {
     private static string $mainLockFileDirPath;
+
     private static string $unWriteableFileDirPath;
 
     private FileLockResolver $fileLocker;
 
     public static function setUpBeforeClass(): void
     {
-        self::$mainLockFileDirPath = dirname(__DIR__) . '/.locks';
-        self::$unWriteableFileDirPath = __DIR__ . '/.locks';
+        self::$mainLockFileDirPath = dirname(__DIR__).'/.locks';
+        self::$unWriteableFileDirPath = __DIR__.'/.locks';
     }
 
     protected function setUp(): void
@@ -375,7 +376,7 @@ private function touch(string $content = ''): string
 
     private function cleanUpLockFileDirs(): void
     {
-        $glob = self::$mainLockFileDirPath . '/*';
+        $glob = self::$mainLockFileDirPath.'/*';
         $files = glob($glob);
         foreach ($files as $file) {
             if (is_file($file)) {

tests/PredisSequenceResolverTest.php

@@ -19,7 +19,7 @@
 
 class PredisSequenceResolverTest extends TestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         if (! class_exists('Predis\\Client')) {
             $this->markTestSkipped('Predis extension is not installed');

tests/RandomSequenceResolverTest.php

@@ -29,7 +29,7 @@ public function test_basic(): void
         $this->assertCount(Snowflake::MAX_SEQUENCE_SIZE, $seqs);
     }
 
-    public function test_can_generate_unique_id_by_snowflake(): void
+    public function test_can_generate_unique_id_using_same_instance(): void
     {
         $snowflake = new Snowflake(1, 1);
         $seqs = [];
@@ -40,4 +40,19 @@ public function test_can_generate_unique_id_by_snowflake(): void
 
         $this->assertCount(Snowflake::MAX_SEQUENCE_SIZE, $seqs);
     }
+
+    public function test_can_generate_unique_id_by_different_instance(): void
+    {
+        for ($i = 0; $i < 1000; $i++) {
+            $ids = [];
+
+            for ($i = 0; $i < 100_000; $i++) {
+                $snowflake = new Snowflake();
+                $ids[$snowflake->id()] = true;
+            }
+
+            // We expect to have at least 100_000 - 10 unique ids if using random sequence resolver
+            $this->assertGreaterThanOrEqual(100_000 - 10, count($ids));
+        }
+    }
 }

tests/RedisSequenceResolverTest.php

@@ -17,7 +17,7 @@
 
 class RedisSequenceResolverTest extends TestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         if (! extension_loaded('redis')) {
             $this->markTestSkipped('Redis extension is not installed');

tests/SwooleSequenceResolverTest.php

@@ -16,7 +16,7 @@
 
 class SwooleSequenceResolverTest extends TestCase
 {
-    public function setUp(): void
+    protected function setUp(): void
     {
         if (version_compare(PHP_VERSION, '8.4') >= 0) {
             $this->markTestSkipped('Swoole does not yet support PHP 8.4');