Pre release

firestore/src/firestore_snippets/Counter.php

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+<?php
+/**
+ * Copyright 2019 Google Inc.
+ *
+ * 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.
+ */
+
+namespace Google\Cloud\Firestore;
+
+use Google\Cloud\Firestore\DocumentReference;
+
+// [START fs_counter_classes]
+/** Counter is a collection of documents (shards)
+ * to realize counter with high frequency
+ */
+class Counter
+{
+    /**
+     * @var int
+     */
+    private $numShards;
+
+    public function __construct(int $numShards)
+    {
+        $this->numShards = $numShards;
+    }
+
+    public function getNumShards()
+    {
+        return $this->numShards;
+    }
+}
+
+
+/** 
+ * Shard is a single counter, which is used in a group
+ * of other shards within Counter.
+ *  */
+class Shard
+{
+    /**
+     * @var int
+     */
+    private $count;
+
+    public function __construct(int $count)
+    {
+        $this->count = $count;
+    }
+
+    public function getCount()
+    {
+        return $this->count;
+    }
+}
+
+// [END fs_counter_classes]
+
+
+class SolutionCounters {
+    // [START fs_create_counter]
+    /**
+     * InitCounter creates a given number of shards as
+     * subcollection of specified document.
+     * 
+     * @param DocumentReference $ref Firestore document
+     * @param int $numShards The number of counter fragments. (default 10)
+     */
+    public static function initCounter(DocumentReference $ref, int $numShards = 10)
+    {
+        $counter = new Counter($numShards);
+        $colRef = $ref->collection('SHARDS');
+        for ($i = 0; $i < $counter->getNumShards(); $i++) {
+            $doc = $colRef->document($i);
+            $doc->set(['Cnt' => 0]);
+        }
+    }
+    // [END fs_create_counter]
+
+    // [START fs_increment_counter]
+    /**
+     * incrementCounter increments a randomly picked shard.
+     * 
+     * @param DocumentReference $ref Firestore document
+     * @param int $numShards The number of counter fragments. (default 10)
+     */
+    public static function incrementCounter(DocumentReference $ref, int $numShards = 10)
+    {
+        $colRef = $ref->collection('SHARDS');
+        $shardIdx = random_int(0, $numShards-1);
+        $doc = $colRef->document($shardIdx);
+        $doc->update([
+            ['path' => 'Cnt', 'value' => FieldValue::increment(1)]
+        ]);
+    }
+    // [END fs_increment_counter]
+
+    // [START fs_get_count]
+    /**
+     * getCount returns a total count across all shards.
+     * 
+     * @param DocumentReference $ref Firestore document
+     * @return int
+     */
+    public static function getCount(DocumentReference $ref)
+    {
+        $result = 0;
+        $docCollection = $ref->collection('SHARDS')->documents();
+        foreach ($docCollection as $doc) {
+            $result += $doc->data()['Cnt'];
+        }
+        return $result;
+    }
+    // [END fs_get_count]
+}

firestore/test/CounterTest.php

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+<?php
+/**
+ * Copyright 2019 Google Inc.
+ *
+ * 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.
+ */
+
+namespace Google\Cloud\Firestore;
+
+use Google\Cloud\Firestore\SolutionCounters;
+use Google\Cloud\Firestore\Counter;
+use Google\Cloud\Firestore\Shard;
+use Google\Cloud\TestUtils\TestTrait;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests for Firebase distributed counters
+ */
+class SolutionCountersTest extends TestCase 
+{
+    use TestTrait;
+
+    const COLLECTION_NAME='Shards_collection';
+    const SHARD_NAME='Distributed_counters';
+
+    private static $firestoreProjectId;
+
+    private static $ref;
+
+    public static function setUpBeforeClass()
+    {
+        require_once __DIR__."/../src/firestore_snippets/SolutionCounters.php";
+
+        self::$firestoreProjectId = self::requireEnv('FIRESTORE_PROJECT_ID');
+
+        $db = new FirestoreClient([
+            'projectId' => self::$firestoreProjectId
+        ]);
+
+        self::$ref=$db->collection(self::COLLECTION_NAME)->document(self::SHARD_NAME);
+    }
+
+    protected function setUp()
+    {
+        if (!extension_loaded('grpc')) {
+            self::markTestSkipped('Must enable grpc extension.');
+        }
+    }
+
+
+    /**
+     * @covers Google\Cloud\Firestore\Counter::getNumShards
+     */
+    public function testCounter()
+    {
+        $counter=new Counter(5);
+        $this->assertEquals(5, $counter->getNumShards());
+
+        $counter2=new Counter(1);
+        $this->assertEquals(1, $counter2->getNumShards());
+    }
+
+    /**
+     * @covers Google\Cloud\Firestore\Shard::getCount
+     */
+    public function testShard()
+    {
+        $shard = new Shard(7);
+        $this->assertEquals(7, $shard->getCount());
+
+        $shard2 = new Shard(2);
+        $this->assertEquals(2, $shard2->getCount());
+    }
+
+    /**
+     * @covers Google\Cloud\Firestore\SolutionCounters::initCounter
+     * @covers Google\Cloud\Firestore\SolutionCounters::incrementCounter
+     * @covers Google\Cloud\Firestore\SolutionCounters::getCount
+     */
+    public function testSolutionCounters()
+    {
+        $cnt=5;
+        SolutionCounters::initCounter(self::$ref, $cnt);
+
+        $collect = self::$ref->collection('SHARDS');
+        $docCollection = $collect->documents();
+        $docIdList=[];
+
+        foreach ($docCollection as $docSnap) {
+            $docIdList[] = $docSnap->id();
+        }
+        $this->assertEquals($cnt, count($docIdList));
+
+        $this->assertEquals(0, SolutionCounters::getCount(self::$ref));
+
+        SolutionCounters::incrementCounter(self::$ref, $cnt);
+        $this->assertEquals(1, SolutionCounters::getCount(self::$ref));
+
+        SolutionCounters::incrementCounter(self::$ref, $cnt);
+        $this->assertEquals(2, SolutionCounters::getCount(self::$ref));
+
+        SolutionCounters::incrementCounter(self::$ref, $cnt);
+        $this->assertEquals(3, SolutionCounters::getCount(self::$ref));
+
+        foreach ($docIdList as $docId){
+            $collect->document($docId)->delete();
+        }
+    }
+
+    /** Remove SHARD_NAME document
+     */
+    public static function tearDownAfterClass()
+    {
+        self::$ref->delete();
+    }
+}