From dd7902906ea6996550c344a985bf18de8cf7ccc0 Mon Sep 17 00:00:00 2001
From: Junxiao Shi <git@mail1.yoursunny.com>
Date: Sun, 10 Mar 2024 02:58:58 +0000
Subject: [PATCH] svs: decouple Component from StateVector codec

---
 pkg/svs/src/state-vector.ts | 28 ++++++++++++++++++----
 pkg/svs/src/sync.ts         | 46 ++++++++++++++++++-------------------
 2 files changed, 46 insertions(+), 28 deletions(-)

diff --git a/pkg/svs/src/state-vector.ts b/pkg/svs/src/state-vector.ts
index 74de5450..8bdb4343 100644
--- a/pkg/svs/src/state-vector.ts
+++ b/pkg/svs/src/state-vector.ts
@@ -83,7 +83,7 @@ export class StateVector {
     return o;
   }
 
-  /** Encode TLV-VALUE of name component. */
+  /** Encode TLV-VALUE only. */
   public encodeTo(encoder: Encoder): void {
     const list = Array.from(this);
     list.sort(([a], [b]) => -a.compare(b));
@@ -95,12 +95,15 @@ export class StateVector {
     }
   }
 
-  /** Encode to name component. */
+  /**
+   * Encode to name component.
+   * @deprecated No longer supported.
+   */
   public toComponent(): Component {
     return new Component(TT.StateVector, Encoder.encode(this));
   }
 
-  /** Decode TLV-VALUE of name component. */
+  /** Decode TLV-VALUE only. */
   public static decodeFrom(decoder: Decoder): StateVector {
     const vv = new StateVector();
     while (!decoder.eof) {
@@ -115,7 +118,10 @@ export class StateVector {
     return vv;
   }
 
-  /** Decode from name component. */
+  /**
+   * Decode from name component.
+   * @deprecated No longer supported.
+   */
   public static fromComponent(comp: Component): StateVector {
     if (comp.type !== TT.StateVector) {
       throw new Error("unexpected NameComponent TLV-TYPE");
@@ -125,7 +131,19 @@ export class StateVector {
 }
 
 export namespace StateVector {
-  /** TLV-TYPE of name component. */
+  /**
+   * StateVector TLV-TYPE.
+   *
+   * @remarks
+   * SVS v1 encodes StateVector as a name component of this type.
+   * SVS v2 encodes StateVector as a sub-element of this type within AppParameters.
+   */
+  export const Type = TT.StateVector;
+
+  /**
+   * TLV-TYPE of name component.
+   * @deprecated Use {@link Type}.
+   */
   export const NameComponentType = TT.StateVector;
 
   export interface DiffEntry {
diff --git a/pkg/svs/src/sync.ts b/pkg/svs/src/sync.ts
index e72931ab..b18477de 100644
--- a/pkg/svs/src/sync.ts
+++ b/pkg/svs/src/sync.ts
@@ -1,8 +1,9 @@
 import { consume, type ConsumerOptions, type Endpoint, produce, type Producer, type ProducerHandler } from "@ndn/endpoint";
 import { Forwarder } from "@ndn/fw";
-import { Interest, Name, type NameLike, nullSigner, type Signer, type Verifier } from "@ndn/packet";
+import { Component, Interest, Name, type NameLike, nullSigner, type Signer, type Verifier } from "@ndn/packet";
 import { type SyncNode, type SyncProtocol, SyncUpdate } from "@ndn/sync-api";
-import { CustomEvent, randomJitter, trackEventListener } from "@ndn/util";
+import { Decoder, Encoder } from "@ndn/tlv";
+import { assert, CustomEvent, randomJitter, trackEventListener } from "@ndn/util";
 import type { Promisable } from "type-fest";
 import { TypedEventTarget } from "typescript-event-target";
 
@@ -25,25 +26,22 @@ type EventMap = SyncProtocol.EventMap<Name> & {
 /** StateVectorSync participant. */
 export class SvSync extends TypedEventTarget<EventMap> implements SyncProtocol<Name> {
   public static async create({
-    fw,
-    describe,
+    syncPrefix,
     endpoint, // eslint-disable-line etc/no-deprecated
+    fw = endpoint?.fw ?? Forwarder.getDefault(),
+    describe = `SvSync(${syncPrefix})`,
     initialStateVector = new StateVector(),
     initialize,
-    syncPrefix,
     syncInterestLifetime = 1000,
     steadyTimer = [30000, 0.1],
     suppressionTimer = [200, 0.5],
     signer = nullSigner,
     verifier,
   }: SvSync.Options): Promise<SvSync> {
-    fw ??= endpoint?.fw ?? Forwarder.getDefault();
-    describe ??= `SvSync(${syncPrefix})`;
-
     const sync = new SvSync(
+      syncPrefix,
       describe,
       initialStateVector,
-      syncPrefix,
       Interest.makeModifyFunc({
         canBePrefix: true,
         mustBeFresh: true,
@@ -57,18 +55,18 @@ export class SvSync extends TypedEventTarget<EventMap> implements SyncProtocol<N
     );
 
     await initialize?.(sync);
-    sync.producer = produce(sync.syncPrefix, sync.handleSyncInterest, {
+    sync.producer = produce(syncPrefix, sync.handleSyncInterest, {
       fw,
-      describe: `${sync.describe}[p]`,
+      describe: `${describe}[p]`,
       routeCapture: false,
     });
     return sync;
   }
 
   private constructor(
+      public readonly syncPrefix: Name,
       public readonly describe: string,
       private readonly own: StateVector,
-      public readonly syncPrefix: Name,
       private readonly modifyInterest: Interest.ModifyFunc,
       private readonly cOpts: ConsumerOptions,
       private readonly steadyTimer: () => number,
@@ -153,7 +151,9 @@ export class SvSync extends TypedEventTarget<EventMap> implements SyncProtocol<N
 
   private readonly handleSyncInterest: ProducerHandler = async (interest) => {
     await this.verifier?.verify(interest);
-    const recv = StateVector.fromComponent(interest.name.at(this.syncPrefix.length));
+    const vComp = interest.name.at(this.syncPrefix.length);
+    assert(vComp.type === StateVector.Type, "name component is not a StateVector");
+    const recv = new Decoder(vComp.value).decode(StateVector);
 
     const ourOlder = this.own.listOlderThan(recv);
     const ourNewer = recv.listOlderThan(this.own);
@@ -208,7 +208,7 @@ export class SvSync extends TypedEventTarget<EventMap> implements SyncProtocol<N
     this.debug("send");
 
     const interest = new Interest();
-    interest.name = this.syncPrefix.append(this.own.toComponent());
+    interest.name = this.syncPrefix.append(new Component(StateVector.Type, Encoder.encode(this.own)));
     this.modifyInterest(interest);
     await this.signer.sign(interest);
 
@@ -232,6 +232,15 @@ export namespace SvSync {
 
   /** {@link SvSync.create} options. */
   export interface Options {
+    /** Sync group prefix. */
+    syncPrefix: Name;
+
+    /**
+     * Endpoint for communication.
+     * @deprecated Specify `.fw`.
+     */
+    endpoint?: Endpoint;
+
     /**
      * Use the specified logical forwarder.
      * @defaultValue `Forwarder.getDefault()`
@@ -241,12 +250,6 @@ export namespace SvSync {
     /** Description for debugging purpose. */
     describe?: string;
 
-    /**
-     * Endpoint for communication.
-     * @deprecated Specify `.fw`.
-     */
-    endpoint?: Endpoint;
-
     /**
      * Initial state vector.
      * @defaultValue empty state vector
@@ -264,9 +267,6 @@ export namespace SvSync {
      */
     initialize?: (sync: SvSync) => Promisable<void>;
 
-    /** Sync group prefix. */
-    syncPrefix: Name;
-
     /**
      * Sync Interest lifetime in milliseconds.
      * @defaultValue 1000