BAEL-1155 crdt (#2659)

* BAEL-1155 crdt * BAEL-1155 fix pom
2017-10-06 10:36:50 +02:00
parent 6818505bea
commit c521aa66af
2 changed files with 163 additions and 4 deletions
@@ -0,0 +1,153 @@
+package com.baeldung.crdt;
+
+import com.netopyr.wurmloch.crdt.GCounter;
+import com.netopyr.wurmloch.crdt.GSet;
+import com.netopyr.wurmloch.crdt.LWWRegister;
+import com.netopyr.wurmloch.crdt.PNCounter;
+import com.netopyr.wurmloch.store.LocalCrdtStore;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class CRDTTest {
+
+    @Test
+    public void givenGrowOnlySet_whenTwoReplicasDiverge_thenShouldMergeItWithoutAConflict() {
+        //given
+        final LocalCrdtStore crdtStore1 = new LocalCrdtStore();
+        final LocalCrdtStore crdtStore2 = new LocalCrdtStore();
+        crdtStore1.connect(crdtStore2);
+
+        final GSet<String> replica1 = crdtStore1.createGSet("ID_1");
+        final GSet<String> replica2 = crdtStore2.<String>findGSet("ID_1").get();
+
+        //when
+        replica1.add("apple");
+        replica2.add("banana");
+
+        //then
+        assertThat(replica1).contains("apple", "banana");
+        assertThat(replica2).contains("apple", "banana");
+
+        //when
+        crdtStore1.disconnect(crdtStore2);
+
+        replica1.add("strawberry");
+        replica2.add("pear");
+
+
+        assertThat(replica1).contains("apple", "banana", "strawberry");
+        assertThat(replica2).contains("apple", "banana", "pear");
+
+        crdtStore1.connect(crdtStore2);
+
+        //then
+        assertThat(replica1).contains("apple", "banana", "strawberry", "pear");
+        assertThat(replica2).contains("apple", "banana", "strawberry", "pear");
+    }
+
+    @Test
+    public void givenIncrementOnlyCounter_whenTwoReplicasDiverge_thenShouldMergeIt() {
+        //given
+        final LocalCrdtStore crdtStore1 = new LocalCrdtStore();
+        final LocalCrdtStore crdtStore2 = new LocalCrdtStore();
+        crdtStore1.connect(crdtStore2);
+
+        final GCounter replica1 = crdtStore1.createGCounter("ID_1");
+        final GCounter replica2 = crdtStore2.findGCounter("ID_1").get();
+
+        //when
+        replica1.increment();
+        replica2.increment(2L);
+
+        //then
+        assertThat(replica1.get()).isEqualTo(3L);
+        assertThat(replica2.get()).isEqualTo(3L);
+
+        //when
+        crdtStore1.disconnect(crdtStore2);
+
+        replica1.increment(3L);
+        replica2.increment(5L);
+
+
+        assertThat(replica1.get()).isEqualTo(6L);
+        assertThat(replica2.get()).isEqualTo(8L);
+
+        crdtStore1.connect(crdtStore2);
+
+        // then
+        assertThat(replica1.get()).isEqualTo(11L);
+        assertThat(replica2.get()).isEqualTo(11L);
+    }
+
+    @Test
+    public void givenPNCounter_whenReplicasDiverge_thenShouldMergeWithoutAConflict() {
+        // given
+        final LocalCrdtStore crdtStore1 = new LocalCrdtStore();
+        final LocalCrdtStore crdtStore2 = new LocalCrdtStore();
+        crdtStore1.connect(crdtStore2);
+
+        final PNCounter replica1 = crdtStore1.createPNCounter("ID_1");
+        final PNCounter replica2 = crdtStore2.findPNCounter("ID_1").get();
+
+        //when
+        replica1.increment();
+        replica2.decrement(2L);
+
+        //then
+        assertThat(replica1.get()).isEqualTo(-1L);
+        assertThat(replica2.get()).isEqualTo(-1L);
+
+        //when
+        crdtStore1.disconnect(crdtStore2);
+
+        replica1.decrement(3L);
+        replica2.increment(5L);
+
+        assertThat(replica1.get()).isEqualTo(-4L);
+        assertThat(replica2.get()).isEqualTo(4L);
+
+        crdtStore1.connect(crdtStore2);
+
+        //then
+        assertThat(replica1.get()).isEqualTo(1L);
+        assertThat(replica2.get()).isEqualTo(1L);
+    }
+
+    @Test
+    public void givenLastWriteWinsStrategy_whenReplicasDiverge_thenAfterMergeShouldKeepOnlyLastValue() {
+        //given
+        final LocalCrdtStore crdtStore1 = new LocalCrdtStore("N_1");
+        final LocalCrdtStore crdtStore2 = new LocalCrdtStore("N_2");
+        crdtStore1.connect(crdtStore2);
+
+        final LWWRegister<String> replica1 = crdtStore1.createLWWRegister("ID_1");
+        final LWWRegister<String> replica2 = crdtStore2.<String>findLWWRegister("ID_1").get();
+
+        //when
+        replica1.set("apple");
+        replica2.set("banana");
+
+        // then
+        assertThat(replica1.get()).isEqualTo("banana");
+        assertThat(replica2.get()).isEqualTo("banana");
+
+
+        // when
+        crdtStore1.disconnect(crdtStore2);
+
+        replica1.set("strawberry");
+        replica2.set("pear");
+
+
+        assertThat(replica1.get()).isEqualTo("strawberry");
+        assertThat(replica2.get()).isEqualTo("pear");
+
+        crdtStore1.connect(crdtStore2);
+
+        //then
+        assertThat(replica1.get()).isEqualTo("pear");
+        assertThat(replica2.get()).isEqualTo("pear");
+    }
+}