feat(logservice): add LogService and its Crdt

src/doc/LogCrdt.ts

@@ -0,0 +1,39 @@
+import { State, StateVector } from '../sync'
+import { StateVectorOrder } from '../sync/StateVector'
+import { LogState } from './LogsService'
+
+export class LogCrdt {
+  private id: number
+  private state: StateVector
+  private share: boolean
+
+  constructor(id: number, state: LogState) {
+    this.id = id
+    this.share = state.share
+    this.state = new StateVector(state.vector)
+  }
+
+  merge(other: LogCrdt) {
+    const res = this.state.compareTo(other.state)
+    if (res === StateVectorOrder.INFERIOR) {
+      this.share = other.share
+      this.state = other.state
+    } else if (res === StateVectorOrder.CONCURRENT) {
+      this.share = this.share && other.share
+      this.state.maxPairwise(other.state)
+    }
+  }
+
+  setShare(newShare: boolean) {
+    this.share = newShare
+    if (this.state.get(this.id)) {
+      this.state.set(this.id, this.state.get(this.id) + 1)
+    } else {
+      this.state.set(this.id, 0)
+    }
+  }
+
+  get isShared(): boolean {
+    return this.share
+  }
+}

src/doc/LogsService.ts

@@ -0,0 +1,22 @@
+import { LogCrdt } from './LogCrdt'
+
+export interface LogState {
+  share: boolean
+  vector?: Map<number, number>
+}
+
+export class LogsService {
+  private crdt: LogCrdt
+
+  constructor(id: number, state: LogState) {
+    this.crdt = new LogCrdt(id, state)
+  }
+
+  public handleLocalLogState(share: boolean): void {
+    this.crdt.setShare(share)
+  }
+
+  public handleRemoteLogState(otherCrdt: LogCrdt): void {
+    this.crdt.merge(otherCrdt)
+  }
+}