Generate IPLD blocks table and related GQL API (#260)

* Add ipld-blocks entity generation

* Populate ipld-blocks table

* Rename ipld-block entity and update after each event

* Move ipld-hook to hooks.ts

* Change IPLD block structure

* Add cid field in blocks

* Fetch prev. IPLDBlock for a contract

* GQL API to query IPLDBlock by CID

* Save cid in blocks in existing watchers

* Update codegen docs

* GQL API for getting last derived state (#3)

* GQL API for getting last derived state

* Rename query to getState

* Change query names to getState and getStateByCid

* Save BigInt as string

* Move function to prepare IPLDBlock to indexer

* Refactor IPLDBlock hook

* Add genesis hook

* Call post-block hook after a block is marked as complete

* Add IPLDBlock checkpointing

* Use queryRunner instead of a new repo for queries

* Add a query to get block in ipld-eth-client

* Get latest checkpoints for all contracts for checkpointing.

* Call post-block hook in a queue

* Pass server config to Indexer in watch-contract cli

Co-authored-by: nikugogoi <nabarun@deepstacksoft.com>

packages/codegen/README.md

@@ -53,13 +53,13 @@
   yarn codegen --input-file ./test/examples/contracts/ERC721.sol --contract-name ERC721 --output-folder ../my-erc721-watcher --mode storage --kind lazy
   ```
 
-  Generate code for `ERC721` contract in both `eth_call` and `storage` mode, `active` kind:
+  Generate code for `ERC20` contract in both `eth_call` and `storage` mode, `active` kind:
 
   ```bash
-  yarn codegen --input-file ../../node_modules/@openzeppelin/contracts/token/ERC721/ERC721.sol --contract-name ERC721 --output-folder ../demo-erc721-watcher --mode all --kind active
+  yarn codegen --input-file ../../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol --contract-name ERC20 --output-folder ../demo-erc20-watcher --mode all --kind active
   ```
 
-  This will create a folder called `demo-erc721-watcher` containing the generated code at the specified path. Follow the steps in [Run Generated Watcher](#run-generated-watcher) to setup and run the generated watcher.
+  This will create a folder called `demo-erc20-watcher` containing the generated code at the specified path. Follow the steps in [Run Generated Watcher](#run-generated-watcher) to setup and run the generated watcher.
 
 ## Run Generated Watcher
 
@@ -79,7 +79,9 @@
 
   * Edit the custom hook function `handleEvent` (triggered on an event) in `src/hooks.ts` to perform corresponding indexing using the `Indexer` object.
 
-  * Refer to `src/hooks.example.ts` for an example hook function for events in an ERC20 contract.
+  * Edit the custom hook function `handleBlock` (triggered on a block) in `src/hooks.ts` to save `IPLDBlock`s using the `Indexer` object.
+
+  * The existing example hooks in `src/hooks.ts` are for an `ERC20` contract.
 
 ### Run
 
@@ -106,7 +108,7 @@
   * To watch a contract:
 
     ```bash
-    yarn watch:contract --address <contract-address> --kind ERC721 --starting-block [block-number]
+    yarn watch:contract --address <contract-address> --kind <contract-kind> --starting-block [block-number]
     ```
 
   * To fill a block range:

packages/codegen/package.json

@@ -21,6 +21,7 @@
   "dependencies": {
     "@poanet/solidity-flattener": "https://github.com/vulcanize/solidity-flattener.git",
     "@solidity-parser/parser": "^0.13.2",
+    "@vulcanize/util": "^0.1.0",
     "gql-generator": "https://github.com/vulcanize/gql-generator.git",
     "graphql": "^15.5.0",
     "graphql-compose": "^9.0.3",

packages/codegen/src/data/entities/BlockProgress.yaml

@@ -9,6 +9,10 @@ indexOn:
   - columns:
       - parentHash
 columns:
+  - name: cid
+    pgType: varchar
+    tsType: string
+    columnType: Column
   - name: blockHash
     pgType: varchar
     tsType: string

packages/codegen/src/data/entities/IPLDBlock.yaml

@@ -0,0 +1,41 @@
+className: IPLDBlock
+indexOn:
+  - columns:
+      - block
+      - contractAddress
+columns:
+  - name: block
+    tsType: BlockProgress
+    columnType: ManyToOne
+    lhs: ()
+    rhs: BlockProgress
+  - name: contractAddress
+    pgType: varchar
+    tsType: string
+    columnType: Column
+    columnOptions:
+      - option: length
+        value: 42
+  - name: cid
+    pgType: varchar
+    tsType: string
+    columnType: Column
+  - name: kind
+    pgType: varchar
+    tsType: string
+    columnType: Column
+  - name: data
+    pgType: text
+    tsType: string
+    columnType: Column
+imports:
+  - toImport:
+      - Entity
+      - PrimaryGeneratedColumn
+      - Column
+      - Index
+      - ManyToOne
+    from: typeorm
+  - toImport:
+      - BlockProgress
+    from: ./BlockProgress

packages/codegen/src/entity.ts

@@ -37,7 +37,6 @@ export class Entity {
     }
 
     const entityObject: any = {
-      // Capitalize the first letter of name.
       className: '',
       indexOn: [],
       columns: [],
@@ -188,6 +187,7 @@ export class Entity {
     this._addSyncStatusEntity();
     this._addContractEntity();
     this._addBlockProgressEntity();
+    this._addIPLDBlockEntity();
 
     const template = Handlebars.compile(this._templateString);
     this._entities.forEach(entityObj => {
@@ -218,4 +218,9 @@ export class Entity {
     const entity = yaml.load(fs.readFileSync(path.resolve(__dirname, TABLES_DIR, 'BlockProgress.yaml'), 'utf8'));
     this._entities.push(entity);
   }
+
+  _addIPLDBlockEntity (): void {
+    const entity = yaml.load(fs.readFileSync(path.resolve(__dirname, TABLES_DIR, 'IPLDBlock.yaml'), 'utf8'));
+    this._entities.push(entity);
+  }
 }

packages/codegen/src/generate-code.ts

@@ -7,8 +7,8 @@ import fetch from 'node-fetch';
 import path from 'path';
 import yargs from 'yargs';
 import { hideBin } from 'yargs/helpers';
-import { flatten } from '@poanet/solidity-flattener';
 
+import { flatten } from '@poanet/solidity-flattener';
 import { parse, visit } from '@solidity-parser/parser';
 import { KIND_ACTIVE, KIND_LAZY } from '@vulcanize/util';
 
@@ -209,15 +209,12 @@ function generateWatcher (data: string, visitor: Visitor, argv: any) {
   exportWatchContract(outStream);
 
   let hooksOutStream;
-  let exampleOutStream;
   if (outputDir) {
     hooksOutStream = fs.createWriteStream(path.join(outputDir, 'src/hooks.ts'));
-    exampleOutStream = fs.createWriteStream(path.join(outputDir, 'src/hooks.example.ts'));
   } else {
     hooksOutStream = process.stdout;
-    exampleOutStream = process.stdout;
   }
-  exportHooks(hooksOutStream, exampleOutStream);
+  exportHooks(hooksOutStream);
 
   outStream = outputDir
     ? fs.createWriteStream(path.join(outputDir, 'src/fill.ts'))

packages/codegen/src/hooks.ts

@@ -8,23 +8,14 @@ import Handlebars from 'handlebars';
 import { Writable } from 'stream';
 
 const HOOKS_TEMPLATE_FILE = './templates/hooks-template.handlebars';
-const EXAMPLE_TEMPLATE_FILE = './templates/hooks-example-template.handlebars';
 
 /**
- * Writes the hooks and hooks.example files generated from templates to a stream.
+ * Writes the hooks file generated from template to a stream.
  * @param outStream A writable output stream to write the hooks file to.
- * @param exampleOutStream A writable output stream to write the hooks.example file to.
  */
-export function exportHooks (hooksOutStream: Writable, exampleOutStream: Writable): void {
+export function exportHooks (hooksOutStream: Writable): void {
   const hooksTemplateString = fs.readFileSync(path.resolve(__dirname, HOOKS_TEMPLATE_FILE)).toString();
-  const exampleTemplateString = fs.readFileSync(path.resolve(__dirname, EXAMPLE_TEMPLATE_FILE)).toString();
-
   const hooksTemplate = Handlebars.compile(hooksTemplateString);
-  const exampleTemplate = Handlebars.compile(exampleTemplateString);
-
   const hooks = hooksTemplate({});
-  const example = exampleTemplate({});
-
   hooksOutStream.write(hooks);
-  exampleOutStream.write(example);
 }

packages/codegen/src/schema.ts

@@ -97,6 +97,9 @@ export class Schema {
     // Add a mutation for watching a contract.
     this._addWatchContractMutation();
 
+    this._addIPLDType();
+    this._addIPLDQuery();
+
     return this._composer.buildSchema();
   }
 
@@ -173,6 +176,7 @@ export class Schema {
     this._composer.createObjectTC({
       name: blockName,
       fields: {
+        cid: 'String!',
         hash: 'String!',
         number: 'Int!',
         timestamp: 'Int!',
@@ -234,6 +238,40 @@ export class Schema {
     });
   }
 
+  _addIPLDType (): void {
+    this._composer.createObjectTC({
+      name: 'ResultIPLDBlock',
+      fields: {
+        block: () => this._composer.getOTC('Block').NonNull,
+        contractAddress: 'String!',
+        cid: 'String!',
+        kind: 'String!',
+        data: 'String!'
+      }
+    });
+  }
+
+  _addIPLDQuery (): void {
+    this._composer.Query.addFields({
+      getStateByCID: {
+        type: this._composer.getOTC('ResultIPLDBlock'),
+        args: {
+          cid: 'String!'
+        }
+      }
+    });
+
+    this._composer.Query.addFields({
+      getState: {
+        type: this._composer.getOTC('ResultIPLDBlock'),
+        args: {
+          blockHash: 'String!',
+          contractAddress: 'String!'
+        }
+      }
+    });
+  }
+
   /**
    * Adds an event subscription to the schema.
    */
@@ -254,6 +292,7 @@ export class Schema {
         type: 'Boolean!',
         args: {
           contractAddress: 'String!',
+          kind: 'String!',
           startingBlock: 'Int'
         }
       }

packages/codegen/src/templates/client-template.handlebars

@@ -3,7 +3,6 @@
 //
 
 import { gql } from '@apollo/client/core';
-
 import { GraphQLClient, GraphQLConfig } from '@vulcanize/ipld-eth-client';
 
 import { queries, mutations, subscriptions } from './gql';

packages/codegen/src/templates/config-template.handlebars

@@ -3,6 +3,12 @@
   port = 3008
   kind = "{{watcherKind}}"
 
+  # Checkpointing derived state.
+  checkpointing = true
+
+  # Checkpoint interval in number of blocks.
+  checkpointInterval = 2000
+
 [database]
   type = "postgres"
   host = "localhost"

packages/codegen/src/templates/database-template.handlebars

@@ -3,15 +3,16 @@
 //
 
 import assert from 'assert';
-import { Connection, ConnectionOptions, DeepPartial, FindConditions, QueryRunner, FindManyOptions } from 'typeorm';
+import { Connection, ConnectionOptions, DeepPartial, FindConditions, QueryRunner, FindManyOptions, In, Between } from 'typeorm';
 import path from 'path';
 
-import { Database as BaseDatabase, QueryOptions, Where } from '@vulcanize/util';
+import { Database as BaseDatabase, QueryOptions, Where, MAX_REORG_DEPTH } from '@vulcanize/util';
 
 import { Contract } from './entity/Contract';
 import { Event } from './entity/Event';
 import { SyncStatus } from './entity/SyncStatus';
 import { BlockProgress } from './entity/BlockProgress';
+import { IPLDBlock } from './entity/IPLDBlock';
 
 {{#each queries as | query |}}
 import { {{query.entityName}} } from './entity/{{query.entityName}}';
@@ -78,6 +79,159 @@ export class Database {
   }
 
   {{/each}}
+  async getIPLDBlocks (where: FindConditions<IPLDBlock>): Promise<IPLDBlock[]> {
+    const repo = this._conn.getRepository(IPLDBlock);
+    return repo.find({ where, relations: ['block'] });
+  }
+
+  async getLatestCheckpoints (queryRunner: QueryRunner): Promise<IPLDBlock[]> {
+    // Get the latest checkpoints for all the contracts.
+    const result = await queryRunner.manager.createQueryBuilder(IPLDBlock, 'ipld_block')
+      .distinctOn(['contract_address'])
+      .orderBy('contract_address')
+      .innerJoinAndSelect(Contract, 'contract', 'contract_address = contract.address')
+      .leftJoinAndSelect('ipld_block.block', 'block')
+      .where('block.is_pruned = false')
+      .andWhere('ipld_block.kind = :kind', { kind: 'checkpoint' })
+      .addOrderBy('ipld_block.block_id', 'DESC')
+      .getMany();
+
+    return result;
+  }
+
+  async getPrevIPLDBlock (queryRunner: QueryRunner, blockHash: string, contractAddress: string): Promise<IPLDBlock | undefined> {
+    const heirerchicalQuery = `
+      WITH RECURSIVE cte_query AS
+      (
+        SELECT
+          b.block_hash,
+          b.block_number,
+          b.parent_hash,
+          1 as depth,
+          i.id
+        FROM
+          block_progress b
+          LEFT JOIN
+            ipld_block i ON i.block_id = b.id
+        WHERE
+          b.block_hash = $1
+        UNION ALL
+          SELECT
+            b.block_hash,
+            b.block_number,
+            b.parent_hash,
+            c.depth + 1,
+            i.id
+          FROM
+            block_progress b
+            LEFT JOIN
+              ipld_block i
+              ON i.block_id = b.id
+              AND i.contract_address = $2
+            INNER JOIN
+              cte_query c ON c.parent_hash = b.block_hash
+            WHERE
+              c.id IS NULL AND c.depth < $3
+      )
+      SELECT
+        block_number, id
+      FROM
+        cte_query
+      ORDER BY block_number ASC
+      LIMIT 1;
+    `;
+
+    // Fetching block and id for previous IPLDBlock in frothy region.
+    const [{ block_number: blockNumber, id }] = await queryRunner.query(heirerchicalQuery, [blockHash, contractAddress, MAX_REORG_DEPTH]);
+
+    let result: IPLDBlock | undefined;
+    if (id) {
+      result = await queryRunner.manager.findOne(IPLDBlock, { id }, { relations: ['block'] });
+    } else {
+      // If IPLDBlock not found in frothy region get latest IPLDBlock in the pruned region.
+      // Filter out IPLDBlocks from pruned blocks.
+      const canonicalBlockNumber = blockNumber + 1;
+
+      result = await queryRunner.manager.createQueryBuilder(IPLDBlock, 'ipld_block')
+        .leftJoinAndSelect('ipld_block.block', 'block')
+        .where('block.is_pruned = false')
+        .andWhere('ipld_block.contract_address = :contractAddress', { contractAddress })
+        .andWhere('block.block_number <= :canonicalBlockNumber', { canonicalBlockNumber })
+        .orderBy('block.block_number', 'DESC')
+        .limit(1)
+        .getOne();
+    }
+
+    return result;
+  }
+
+  async getPrevIPLDBlocksAfterCheckpoint (queryRunner: QueryRunner, blockHash: string, checkpointBlockNumber: number, contractAddress: string): Promise<IPLDBlock[]> {
+    const heirerchicalQuery = `
+      WITH RECURSIVE cte_query AS
+      (
+        SELECT
+          b.block_hash,
+          b.block_number,
+          b.parent_hash,
+          1 as depth,
+          i.id
+        FROM
+          block_progress b
+          LEFT JOIN
+            ipld_block i ON i.block_id = b.id
+        WHERE
+          b.block_hash = $1
+        UNION ALL
+          SELECT
+            b.block_hash,
+            b.block_number,
+            b.parent_hash,
+            c.depth + 1,
+            i.id
+          FROM
+            block_progress b
+            LEFT JOIN
+              ipld_block i
+              ON i.block_id = b.id
+              AND i.contract_address = $2
+            INNER JOIN
+              cte_query c ON c.parent_hash = b.block_hash
+            WHERE
+              c.depth < $3
+      )
+      SELECT
+        block_number, id
+      FROM
+        cte_query
+      ORDER BY block_number ASC
+    `;
+
+    // Fetching ids for previous IPLDBlocks in the frothy region.
+    const queryResult = await queryRunner.query(heirerchicalQuery, [blockHash, contractAddress, MAX_REORG_DEPTH]);
+
+    let frothyIds = queryResult.map((obj: any) => obj.id);
+    frothyIds = frothyIds.filter((id: any) => id !== null);
+
+    const frothyBlockNumber = queryResult[0].block_number;
+
+    // Fetching all diff blocks after checkpoint till current blockNumber.
+    const ipldBlocks = await queryRunner.manager.find(IPLDBlock, {
+      relations: ['block'],
+      where: [
+        { contractAddress, block: { isPruned: false, blockNumber: Between(checkpointBlockNumber + 1, frothyBlockNumber - 1) } },
+        { id: In(frothyIds) }
+      ],
+      order: { block: 'ASC' }
+    });
+
+    return ipldBlocks;
+  }
+
+  async saveOrUpdateIPLDBlock (ipldBlock: IPLDBlock): Promise<IPLDBlock> {
+    const repo = this._conn.getRepository(IPLDBlock);
+    return repo.save(ipldBlock);
+  }
+
   async getContract (address: string): Promise<Contract | undefined> {
     const repo = this._conn.getRepository(Contract);
 
@@ -180,6 +334,11 @@ export class Database {
     return this._baseDatabase.getBlockProgressEntities(repo, where, options);
   }
 
+  async getLatestBlockProgress (): Promise<BlockProgress | undefined> {
+    const repo = this._conn.getRepository(BlockProgress);
+    return repo.findOne({ order: { blockNumber: 'DESC' } });
+  }
+
   async updateBlockProgress (queryRunner: QueryRunner, blockHash: string, lastProcessedEventIndex: number): Promise<void> {
     const repo = queryRunner.manager.getRepository(BlockProgress);
 

packages/codegen/src/templates/events-template.handlebars

@@ -12,6 +12,8 @@ import {
   EventWatcher as BaseEventWatcher,
   QUEUE_BLOCK_PROCESSING,
   QUEUE_EVENT_PROCESSING,
+  QUEUE_BLOCK_CHECKPOINT,
+  QUEUE_HOOKS,
   UNKNOWN_EVENT_NAME,
   UpstreamConfig
 } from '@vulcanize/util';
@@ -85,6 +87,23 @@ export class EventWatcher {
       }
 
       const dbEvents = await this._baseEventWatcher.eventProcessingCompleteHandler(job);
+
+      if (dbEvents.length > 0) {
+        const dbEvent = dbEvents[0];
+
+        // If the block is marked as complete:
+        // a. Push a post-block hook job.
+        // b. Push a block checkpointing job.
+        if (dbEvent.block.isComplete) {
+          await this._jobQueue.pushJob(QUEUE_HOOKS, { blockHash: dbEvent.block.blockHash });
+
+          // Push checkpointing job if checkpointing is on.
+          if (this._indexer._serverConfig.checkpointing) {
+            await this._jobQueue.pushJob(QUEUE_BLOCK_CHECKPOINT, { blockHash: dbEvent.block.blockHash, blockNumber: dbEvent.block.blockNumber });
+          }
+        }
+      }
+
       const timeElapsedInSeconds = (Date.now() - Date.parse(createdOn)) / 1000;
 
       // Cannot publish individual event as they are processed together in a single job.

packages/codegen/src/templates/fill-template.handlebars

@@ -44,11 +44,11 @@ export const main = async (): Promise<any> => {
 
   const config = await getConfig(argv.configFile);
 
-  assert(config.server, 'Missing server config');
+  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: serverConfig } = config;
-
-  const { upstream, database: dbConfig, jobQueue: jobQueueConfig } = config;
 
+  assert(upstream, 'Missing upstream config');
   assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
 
   const db = new Database(dbConfig);
   await db.init();
@@ -75,7 +75,7 @@ export const main = async (): Promise<any> => {
   // Note: In-memory pubsub works fine for now, as each watcher is a single process anyway.
   // Later: https://www.apollographql.com/docs/apollo-server/data/subscriptions/#production-pubsub-libraries
   const pubsub = new PubSub();
-  const indexer = new Indexer(db, ethClient, postgraphileClient, ethProvider);
+  const indexer = new Indexer(serverConfig, db, ethClient, postgraphileClient, ethProvider);
 
   const { dbConnectionString, maxCompletionLagInSecs } = jobQueueConfig;
   assert(dbConnectionString, 'Missing job queue db connection string');

packages/codegen/src/templates/hooks-example-template.handlebars

@@ -1,51 +0,0 @@
-//
-// Copyright 2021 Vulcanize, Inc.
-//
-
-import assert from 'assert';
-
-import { Indexer, ResultEvent } from './indexer';
-
-/**
- * Event hook function.
- * @param indexer Indexer instance that contains methods to fetch and update the contract values in the database.
- * @param eventData ResultEvent object containing necessary information.
- */
-export async function handleEvent (indexer: Indexer, eventData: ResultEvent): Promise<void> {
-  assert(indexer);
-  assert(eventData);
-
-  // The following code is for ERC20 contract implementation.
-
-  // Perform indexing based on the type of event.
-  switch (eventData.event.__typename) {
-    // In case of ERC20 'Transfer' event.
-    case 'TransferEvent': {
-      // On a transfer, balances for both parties change.
-      // Therefore, trigger indexing for both sender and receiver.
-
-      // Get event fields from eventData.
-      // const { from, to } = eventData.event;
-
-      // Update balance entry for sender in the database.
-      // await indexer.balanceOf(eventData.block.hash, eventData.contract, from);
-
-      // Update balance entry for receiver in the database.
-      // await indexer.balanceOf(eventData.block.hash, eventData.contract, to);
-
-      break;
-    }
-    // In case of ERC20 'Approval' event.
-    case 'ApprovalEvent': {
-      // On an approval, allowance for (owner, spender) combination changes.
-
-      // Get event fields from eventData.
-      // const { owner, spender } = eventData.event;
-
-      // Update allowance entry for (owner, spender) combination in the database.
-      // await indexer.allowance(eventData.block.hash, eventData.contract, owner, spender);
-
-      break;
-    }
-  }
-}

packages/codegen/src/templates/hooks-template.handlebars

@@ -3,8 +3,103 @@
 //
 
 import assert from 'assert';
+import _ from 'lodash';
+
+import { UNKNOWN_EVENT_NAME } from '@vulcanize/util';
 
 import { Indexer, ResultEvent } from './indexer';
+import { BlockProgress } from './entity/BlockProgress';
+
+const ACCOUNTS = [
+  '0xDC7d7A8920C8Eecc098da5B7522a5F31509b5Bfc'
+];
+
+/**
+ * Genesis hook function.
+ * @param indexer Indexer instance.
+ * @param block Concerned block.
+ * @param contractAddress Address of the concerned contract.
+ */
+export async function genesisHook (indexer: Indexer, block: BlockProgress, contractAddress: string): Promise<void> {
+  // Store the genesis state values in an IPLDBlock.
+  const ipldBlockData: any = {};
+
+  // Setting the initial balances of accounts.
+  for (const account of ACCOUNTS) {
+    const balance = await indexer._balances(block.blockHash, contractAddress, account);
+    _.set(ipldBlockData, `state._balances[${account}]`, balance.value.toString());
+  }
+
+  const ipldBlock = await indexer.prepareIPLDBlock(block, contractAddress, ipldBlockData, 'checkpoint');
+  await indexer.saveOrUpdateIPLDBlock(ipldBlock);
+}
+
+/**
+ * Post-block hook function.
+ * @param indexer Indexer instance that contains methods to fetch the contract varaiable values.
+ * @param blockHash Block hash of the concerned block.
+ */
+export async function postBlockHook (indexer: Indexer, blockHash: string): Promise<void> {
+  // Get events for current block and make an entry of updated values in IPLDBlock.
+  const events = await indexer.getEventsByFilter(blockHash);
+
+  // No IPLDBlock entry if there are no events.
+  if (!events) {
+    return;
+  }
+
+  for (const event of events) {
+    if (event.eventName === UNKNOWN_EVENT_NAME) {
+      continue;
+    }
+
+    const block = event.block;
+    const contractAddress = event.contract;
+
+    const eventData = indexer.getResultEvent(event);
+
+    const ipldBlockData: any = {};
+
+    switch (event.eventName) {
+      case 'Transfer': {
+        const { from, to } = eventData.event;
+
+        const fromBalance = await indexer._balances(blockHash, contractAddress, from);
+        const toBalance = await indexer._balances(blockHash, contractAddress, to);
+
+        // {
+        //   "_balances": {
+        //      "0xCA6D29232D1435D8198E3E5302495417dD073d61": "100",
+        //      "0xDC7d7A8920C8Eecc098da5B7522a5F31509b5Bfc": "999999999999999999900"
+        //   }
+        // }
+        _.set(ipldBlockData, `state._balances[${from}]`, fromBalance.value.toString());
+        _.set(ipldBlockData, `state._balances[${to}]`, toBalance.value.toString());
+
+        break;
+      }
+
+      case 'Approval': {
+        const { owner, spender } = eventData.event;
+        const allowance = await indexer._allowances(blockHash, contractAddress, owner, spender);
+
+        // {
+        //   "_allowances": {
+        //      "0xDC7d7A8920C8Eecc098da5B7522a5F31509b5Bfc": {
+        //         "0xCA6D29232D1435D8198E3E5302495417dD073d61": "10"
+        //      }
+        //   }
+        // }
+        _.set(ipldBlockData, `state._allowances[${owner}][${spender}]`, allowance.value.toString());
+
+        break;
+      }
+    }
+
+    const ipldBlock = await indexer.prepareIPLDBlock(block, contractAddress, ipldBlockData);
+    await indexer.saveOrUpdateIPLDBlock(ipldBlock);
+  }
+}
 
 /**
  * Event hook function.
@@ -15,5 +110,37 @@ export async function handleEvent (indexer: Indexer, eventData: ResultEvent): Pr
   assert(indexer);
   assert(eventData);
 
+  // The following code is for ERC20 contract implementation.
+
   // Perform indexing based on the type of event.
+  switch (eventData.event.__typename) {
+    // In case of ERC20 'Transfer' event.
+    case 'TransferEvent': {
+      // On a transfer, balances for both parties change.
+      // Therefore, trigger indexing for both sender and receiver.
+
+      // Get event fields from eventData.
+      // const { from, to } = eventData.event;
+
+      // Update balance entry for sender in the database.
+      // await indexer.balanceOf(eventData.block.hash, eventData.contract, from);
+
+      // Update balance entry for receiver in the database.
+      // await indexer.balanceOf(eventData.block.hash, eventData.contract, to);
+
+      break;
+    }
+    // In case of ERC20 'Approval' event.
+    case 'ApprovalEvent': {
+      // On an approval, allowance for (owner, spender) combination changes.
+
+      // Get event fields from eventData.
+      // const { owner, spender } = eventData.event;
+
+      // Update allowance entry for (owner, spender) combination in the database.
+      // await indexer.allowance(eventData.block.hash, eventData.contract, owner, spender);
+
+      break;
+    }
+  }
 }

packages/codegen/src/templates/indexer-template.handlebars

@@ -4,23 +4,28 @@
 
 import assert from 'assert';
 import debug from 'debug';
-import { JsonFragment } from '@ethersproject/abi';
 import { DeepPartial, FindConditions } from 'typeorm';
 import JSONbig from 'json-bigint';
 import { ethers } from 'ethers';
-import { BaseProvider } from '@ethersproject/providers';
+import { sha256 } from 'multiformats/hashes/sha2';
+import { CID } from 'multiformats/cid';
+import _ from 'lodash';
 
+import { JsonFragment } from '@ethersproject/abi';
+import { BaseProvider } from '@ethersproject/providers';
+import * as codec from '@ipld/dag-json';
 import { EthClient } from '@vulcanize/ipld-eth-client';
 import { StorageLayout } from '@vulcanize/solidity-mapper';
-import { EventInterface, Indexer as BaseIndexer, ValueResult, UNKNOWN_EVENT_NAME, Where, QueryOptions } from '@vulcanize/util';
+import { Indexer as BaseIndexer, ValueResult, UNKNOWN_EVENT_NAME, ServerConfig, Where, QueryOptions } from '@vulcanize/util';
 
 import { Database } from './database';
 import { Contract } from './entity/Contract';
 import { Event } from './entity/Event';
 import { SyncStatus } from './entity/SyncStatus';
 import { BlockProgress } from './entity/BlockProgress';
+import { IPLDBlock } from './entity/IPLDBlock';
 import artifacts from './artifacts/{{inputFileName}}.json';
-import { handleEvent } from './hooks';
+import { genesisHook, handleEvent, postBlockHook } from './hooks';
 
 const log = debug('vulcanize:indexer');
 
@@ -30,6 +35,7 @@ const {{capitalize event.name}}_EVENT = '{{event.name}}';
 
 export type ResultEvent = {
   block: {
+    cid: string;
     hash: string;
     number: number;
     timestamp: number;
@@ -48,7 +54,21 @@ export type ResultEvent = {
   event: any;
 
   proof: string;
-}
+};
+
+export type ResultIPLDBlock = {
+  block: {
+    cid: string;
+    hash: string;
+    number: number;
+    timestamp: number;
+    parentHash: string;
+  };
+  contractAddress: string;
+  cid: string;
+  kind: string;
+  data: string;
+};
 
 export class Indexer {
   _db: Database
@@ -56,12 +76,13 @@ export class Indexer {
   _ethProvider: BaseProvider
   _postgraphileClient: EthClient;
   _baseIndexer: BaseIndexer
+  _serverConfig: ServerConfig
 
   _abi: JsonFragment[]
   _storageLayout: StorageLayout
   _contract: ethers.utils.Interface
 
-  constructor (db: Database, ethClient: EthClient, postgraphileClient: EthClient, ethProvider: BaseProvider) {
+  constructor (serverConfig: ServerConfig, db: Database, ethClient: EthClient, postgraphileClient: EthClient, ethProvider: BaseProvider) {
     assert(db);
     assert(ethClient);
 
@@ -89,6 +110,7 @@ export class Indexer {
 
     return {
       block: {
+        cid: block.cid,
         hash: block.blockHash,
         number: block.blockNumber,
         timestamp: block.blockTimestamp,
@@ -115,6 +137,24 @@ export class Indexer {
     };
   }
 
+  getResultIPLDBlock (ipldBlock: IPLDBlock): ResultIPLDBlock {
+    const block = ipldBlock.block;
+
+    return {
+      block: {
+        cid: block.cid,
+        hash: block.blockHash,
+        number: block.blockNumber,
+        timestamp: block.blockTimestamp,
+        parentHash: block.parentHash
+      },
+      contractAddress: ipldBlock.contractAddress,
+      cid: ipldBlock.cid,
+      kind: ipldBlock.kind,
+      data: ipldBlock.data
+    };
+  }
+
   {{#each queries as | query |}}
   async {{query.name}} (blockHash: string, contractAddress: string
     {{~#each query.params}}, {{this.name~}}: {{this.type~}} {{/each}}): Promise<ValueResult> {
@@ -166,6 +206,175 @@ export class Indexer {
   }
 
   {{/each}}
+  async processBlock (job: any): Promise<void> {
+    const { data: { blockHash } } = job;
+
+    // Call custom post-block hook.
+    await postBlockHook(this, blockHash);
+  }
+
+  async processCheckpoint (job: any): Promise<void> {
+    // Create a checkpoint IPLDBlock for contracts that were checkpointed checkPointInterval blocks before.
+
+    // Return if checkpointInterval is <= 0.
+    const checkpointInterval = this._serverConfig.checkpointInterval;
+    if (checkpointInterval <= 0) return;
+
+    const { data: { blockNumber: currentBlockNumber, blockHash: currentBlockHash } } = job;
+
+    // Get latest checkpoints for all the contracts.
+    // Assuming checkPointInterval > MAX_REORG_DEPTH.
+    const latestCheckpointBlocks = await this.getLatestCheckpoints();
+
+    // For each contractAddress, merge the diff till now.
+    for (const checkpointBlock of latestCheckpointBlocks) {
+      // Check if it is time for a new checkpoint.
+      if (checkpointBlock.block.blockNumber > currentBlockNumber - checkpointInterval) {
+        continue;
+      }
+
+      const { contractAddress, block: { blockNumber: checkpointBlockNumber } } = checkpointBlock;
+
+      // Fetching all diff blocks after checkpoint.
+      const diffBlocks = await this.getPrevIPLDBlocksAfterCheckpoint(currentBlockHash, checkpointBlockNumber, contractAddress);
+
+      let checkPoint = codec.decode(Buffer.from(checkpointBlock.data)) as any;
+
+      for (const diffBlock of diffBlocks) {
+        const diff = codec.decode(Buffer.from(diffBlock.data));
+        checkPoint = _.merge(checkPoint, diff);
+      }
+
+      // Getting the current block.
+      const block = await this.getBlockProgress(currentBlockHash);
+      assert(block);
+
+      const ipldBlock = await this.prepareIPLDBlock(block, contractAddress, checkPoint, 'checkpoint');
+      await this.saveOrUpdateIPLDBlock(ipldBlock);
+    }
+  }
+
+  async getLatestCheckpoints (): Promise<IPLDBlock[]> {
+    // Get the latest checkpoints for all the contracts.
+    const dbTx = await this._db.createTransactionRunner();
+    let res;
+
+    try {
+      res = await this._db.getLatestCheckpoints(dbTx);
+      await dbTx.commitTransaction();
+    } catch (error) {
+      await dbTx.rollbackTransaction();
+      throw error;
+    } finally {
+      await dbTx.release();
+    }
+    return res;
+  }
+
+  async getIPLDBlock (block: BlockProgress, contractAddress: string): Promise<IPLDBlock | undefined> {
+    const ipldBlocks = await this._db.getIPLDBlocks({ block, contractAddress });
+
+    // There can be only one IPLDBlock for a { block, contractAddress } combination.
+    assert(ipldBlocks.length <= 1);
+
+    return ipldBlocks[0];
+  }
+
+  async getIPLDBlockByCid (cid: string): Promise<IPLDBlock | undefined> {
+    const ipldBlocks = await this._db.getIPLDBlocks({ cid });
+
+    // There can be only one IPLDBlock with a particular cid.
+    assert(ipldBlocks.length <= 1);
+
+    return ipldBlocks[0];
+  }
+
+  async getPrevIPLDBlock (blockHash: string, contractAddress: string): Promise<IPLDBlock | undefined> {
+    const dbTx = await this._db.createTransactionRunner();
+    let res;
+
+    try {
+      res = await this._db.getPrevIPLDBlock(dbTx, blockHash, contractAddress);
+      await dbTx.commitTransaction();
+    } catch (error) {
+      await dbTx.rollbackTransaction();
+      throw error;
+    } finally {
+      await dbTx.release();
+    }
+    return res;
+  }
+
+  async getPrevIPLDBlocksAfterCheckpoint (blockHash: string, checkpointBlockNumber: number, contractAddress: string): Promise<IPLDBlock[]> {
+    const dbTx = await this._db.createTransactionRunner();
+    let res;
+
+    try {
+      res = await this._db.getPrevIPLDBlocksAfterCheckpoint(dbTx, blockHash, checkpointBlockNumber, contractAddress);
+      await dbTx.commitTransaction();
+    } catch (error) {
+      await dbTx.rollbackTransaction();
+      throw error;
+    } finally {
+      await dbTx.release();
+    }
+
+    return res;
+  }
+
+  async saveOrUpdateIPLDBlock (ipldBlock: IPLDBlock): Promise<IPLDBlock> {
+    return this._db.saveOrUpdateIPLDBlock(ipldBlock);
+  }
+
+  async prepareIPLDBlock (block: BlockProgress, contractAddress: string, data: any, kind?: string):Promise<any> {
+    // Get an existing IPLDBlock for current block and contractAddress.
+    const currentIPLDBlock = await this.getIPLDBlock(block, contractAddress);
+
+    // If an IPLDBlock for { block, contractAddress } already exists, update the data field.
+    if (currentIPLDBlock) {
+      const oldData = codec.decode(Buffer.from(currentIPLDBlock.data));
+      data = _.merge(oldData, data);
+    } else {
+      // Fetch the parent IPLDBlock.
+      const parentIPLDBlock = await this.getPrevIPLDBlock(block.blockHash, contractAddress);
+
+      // Setting the meta-data for an IPLDBlock (done only once per block).
+      data.meta = {
+        id: contractAddress,
+        kind: kind || 'diff',
+        parent: {
+          '/': parentIPLDBlock ? parentIPLDBlock.cid : null
+        },
+        ethBlock: {
+          cid: {
+            '/': block.cid
+          },
+          num: block.blockNumber
+        }
+      };
+    }
+
+    // Encoding the data using dag-json codec.
+    const bytes = codec.encode(data);
+
+    // Calculating sha256 (multi)hash of the encoded data.
+    const hash = await sha256.digest(bytes);
+
+    // Calculating the CID: v1, code: dag-json, hash.
+    const cid = CID.create(1, codec.code, hash);
+
+    let ipldBlock = currentIPLDBlock || new IPLDBlock();
+    ipldBlock = Object.assign(ipldBlock, {
+      block,
+      contractAddress,
+      cid: cid.toString(),
+      kind: data.meta.kind,
+      data: bytes
+    });
+
+    return ipldBlock;
+  }
+
   async triggerIndexingOnEvent (event: Event): Promise<void> {
     const resultEvent = this.getResultEvent(event);
 
@@ -209,14 +418,21 @@ export class Indexer {
     return { eventName, eventInfo };
   }
 
-  async watchContract (address: string, startingBlock: number): Promise<boolean> {
+  async watchContract (address: string, kind: string, startingBlock: number): Promise<boolean> {
     // Always use the checksum address (https://docs.ethers.io/v5/api/utils/address/#utils-getAddress).
-    await this._db.saveContract(ethers.utils.getAddress(address), '{{contractName}}', startingBlock);
+    await this._db.saveContract(ethers.utils.getAddress(address), kind, startingBlock);
+
+    // Getting the current block.
+    const currentBlock = await this._db.getLatestBlockProgress();
+    assert(currentBlock);
+
+    // Call custom genesis hook.
+    await genesisHook(this, currentBlock, address);
 
     return true;
   }
 
-  async getEventsByFilter (blockHash: string, contract: string, name: string | null): Promise<Array<Event>> {
+  async getEventsByFilter (blockHash: string, contract?: string, name?: string): Promise<Array<Event>> {
     return this._baseIndexer.getEventsByFilter(blockHash, contract, name);
   }
 
@@ -292,7 +508,7 @@ export class Indexer {
     return this._baseIndexer.getAncestorAtDepth(blockHash, depth);
   }
 
-  async _fetchAndSaveEvents ({ blockHash }: DeepPartial<BlockProgress>): Promise<BlockProgress> {
+  async _fetchAndSaveEvents ({ cid: blockCid, blockHash }: DeepPartial<BlockProgress>): Promise<BlockProgress> {
     assert(blockHash);
     let { block, logs } = await this._ethClient.getLogs({ blockHash });
 
@@ -375,6 +591,7 @@ export class Indexer {
 
     try {
       block = {
+        cid: blockCid,
         blockHash,
         blockNumber: block.number,
         blockTimestamp: block.timestamp,

packages/codegen/src/templates/job-runner-template.handlebars

@@ -16,6 +16,8 @@ import {
   JobRunner as BaseJobRunner,
   QUEUE_BLOCK_PROCESSING,
   QUEUE_EVENT_PROCESSING,
+  QUEUE_BLOCK_CHECKPOINT,
+  QUEUE_HOOKS,
   JobQueueConfig,
   DEFAULT_CONFIG_PATH,
   getCustomProvider
@@ -42,10 +44,14 @@ export class JobRunner {
   async start (): Promise<void> {
     await this.subscribeBlockProcessingQueue();
     await this.subscribeEventProcessingQueue();
+    await this.subscribeBlockCheckpointQueue();
+    await this.subscribeHooksQueue();
   }
 
   async subscribeBlockProcessingQueue (): Promise<void> {
     await this._jobQueue.subscribe(QUEUE_BLOCK_PROCESSING, async (job) => {
+      // TODO Call pre-block hook here (Directly or indirectly (Like done through indexer.processEvent for events)).
+
       await this._baseJobRunner.processBlock(job);
 
       await this._jobQueue.markComplete(job);
@@ -65,6 +71,23 @@ export class JobRunner {
       await this._jobQueue.markComplete(job);
     });
   }
+
+  async subscribeBlockCheckpointQueue (): Promise<void> {
+    await this._jobQueue.subscribe(QUEUE_BLOCK_CHECKPOINT, async (job) => {
+      await this._indexer.processCheckpoint(job);
+
+      await this._jobQueue.markComplete(job);
+    });
+  }
+
+  // TODO: Make sure the hooks run in order.
+  async subscribeHooksQueue (): Promise<void> {
+    await this._jobQueue.subscribe(QUEUE_HOOKS, async (job) => {
+      await this._indexer.processBlock(job);
+
+      await this._jobQueue.markComplete(job);
+    });
+  }
 }
 
 export const main = async (): Promise<any> => {
@@ -80,16 +103,15 @@ export const main = async (): Promise<any> => {
 
   const config = await getConfig(argv.f);
 
-  assert(config.server, 'Missing server config');
+  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: serverConfig } = config;
-
-  const { upstream, database: dbConfig, jobQueue: jobQueueConfig } = config;
 
+  assert(upstream, 'Missing upstream config');
   assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
 
   const db = new Database(dbConfig);
   await db.init();
 
-  assert(upstream, 'Missing upstream config');
   const { ethServer: { gqlApiEndpoint, gqlPostgraphileEndpoint, rpcProviderEndpoint }, cache: cacheConfig } = upstream;
   assert(gqlApiEndpoint, 'Missing upstream ethServer.gqlApiEndpoint');
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
@@ -118,7 +140,7 @@ export const main = async (): Promise<any> => {
   const jobQueue = new JobQueue({ dbConnectionString, maxCompletionLag: maxCompletionLagInSecs });
   await jobQueue.start();
 
-  const jobRunner = new JobRunner(jobQueueConfig, indexer, jobQueue);
+  const jobRunner = new JobRunner(jobQueueConfig, serverConfig, indexer, jobQueue);
   await jobRunner.start();
 };
 

packages/codegen/src/templates/package-template.handlebars

@@ -23,7 +23,9 @@
   },
   "homepage": "https://github.com/vulcanize/watcher-ts#readme",
   "dependencies": {
+    "@apollo/client": "^3.3.19",
     "@ethersproject/providers": "5.3.0",
+    "@ipld/dag-json": "^8.0.1",
     "@vulcanize/cache": "^0.1.0",
     "@vulcanize/ipld-eth-client": "^0.1.0",
     "@vulcanize/solidity-mapper": "^0.1.0",
@@ -36,6 +38,8 @@
     "graphql": "^15.5.0",
     "graphql-import-node": "^0.0.4",
     "json-bigint": "^1.0.0",
+    "lodash": "^4.17.21",
+    "multiformats": "^9.4.8",
     "reflect-metadata": "^0.1.13",
     "typeorm": "^0.2.32",
     "yargs": "^17.0.1"

packages/codegen/src/templates/readme-template.handlebars

@@ -45,7 +45,9 @@
 
   * Edit the custom hook function `handleEvent` (triggered on an event) in [hooks.ts](./src/hooks.ts) to perform corresponding indexing using the `Indexer` object.
 
-  * Refer to [hooks.example.ts](./src/hooks.example.ts) for an example hook function for events in an ERC20 contract.
+  * Edit the custom hook function `handleBlock` (triggered on a block) in [hooks.ts](./src/hooks.ts) to save `IPLDBlock`s using the `Indexer` object.
+
+  * The existing example hooks in [hooks.ts](./src/hooks.ts) are for an `ERC20` contract.
 
 ## Run
 

packages/codegen/src/templates/resolvers-template.handlebars

@@ -34,9 +34,9 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
     },
 
     Mutation: {
-      watchContract: (_: any, { contractAddress, startingBlock = 1 }: { contractAddress: string, startingBlock: number }): Promise<boolean> => {
+      watchContract: (_: any, { contractAddress, kind, startingBlock = 1 }: { contractAddress: string, kind: string, startingBlock: number }): Promise<boolean> => {
-        log('watchContract', contractAddress, startingBlock);
+        log('watchContract', contractAddress, kind, startingBlock);
-        return indexer.watchContract(contractAddress, startingBlock);
+        return indexer.watchContract(contractAddress, kind, startingBlock);
       }
     },
 
@@ -52,8 +52,8 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
       },
 
       {{/each}}
-      events: async (_: any, { blockHash, contractAddress, name }: { blockHash: string, contractAddress: string, name: string }) => {
+      events: async (_: any, { blockHash, contractAddress, name }: { blockHash: string, contractAddress: string, name?: string }) => {
-        log('events', blockHash, contractAddress, name || '');
+        log('events', blockHash, contractAddress, name);
 
         const block = await indexer.getBlockProgress(blockHash);
         if (!block || !block.isComplete) {
@@ -74,6 +74,22 @@ export const createResolvers = async (indexer: Indexer, eventWatcher: EventWatch
 
         const events = await indexer.getEventsInRange(fromBlockNumber, toBlockNumber);
         return events.map(event => indexer.getResultEvent(event));
+      },
+
+      getStateByCID: async (_: any, { cid }: { cid: string }) => {
+        log('getStateByCID', cid);
+
+        const ipldBlock = await indexer.getIPLDBlockByCid(cid);
+
+        return ipldBlock && ipldBlock.block.isComplete ? indexer.getResultIPLDBlock(ipldBlock) : undefined;
+      },
+
+      getState: async (_: any, { blockHash, contractAddress }: { blockHash: string, contractAddress: string }) => {
+        log('getState', blockHash, contractAddress);
+
+        const ipldBlock = await indexer.getPrevIPLDBlock(blockHash, contractAddress);
+
+        return ipldBlock && ipldBlock.block.isComplete ? indexer.getResultIPLDBlock(ipldBlock) : undefined;
       }
     }
   };

packages/codegen/src/templates/server-template.handlebars

@@ -38,18 +38,17 @@ export const main = async (): Promise<any> => {
 
   const config = await getConfig(argv.f);
 
-  assert(config.server, 'Missing server config');
+  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: serverConfig } = config;
-
-  const { host, port, kind: watcherKind } = config.server;
-
-  const { upstream, database: dbConfig, jobQueue: jobQueueConfig } = config;
 
+  assert(upstream, 'Missing upstream config');
   assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
+
+  const { host, port, kind: watcherKind } = serverConfig;
 
   const db = new Database(dbConfig);
   await db.init();
 
-  assert(upstream, 'Missing upstream config');
   const { ethServer: { gqlApiEndpoint, gqlPostgraphileEndpoint, rpcProviderEndpoint }, cache: cacheConfig } = upstream;
   assert(gqlApiEndpoint, 'Missing upstream ethServer.gqlApiEndpoint');
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
@@ -69,7 +68,7 @@ export const main = async (): Promise<any> => {
 
   const ethProvider = getCustomProvider(rpcProviderEndpoint);
 
-  const indexer = new Indexer(db, ethClient, postgraphileClient, ethProvider);
+  const indexer = new Indexer(serverConfig, db, ethClient, postgraphileClient, ethProvider);
 
   // Note: In-memory pubsub works fine for now, as each watcher is a single process anyway.
   // Later: https://www.apollographql.com/docs/apollo-server/data/subscriptions/#production-pubsub-libraries

packages/codegen/src/templates/watch-contract-template.handlebars

@@ -5,10 +5,14 @@
 import assert from 'assert';
 import yargs from 'yargs';
 import 'reflect-metadata';
+import { getDefaultProvider } from 'ethers';
 
 import { Config, DEFAULT_CONFIG_PATH, getConfig } from '@vulcanize/util';
+import { getCache } from '@vulcanize/cache';
+import { EthClient } from '@vulcanize/ipld-eth-client';
 
 import { Database } from '../database';
+import { Indexer } from '../indexer';
 
 (async () => {
   const argv = await yargs.parserConfiguration({
@@ -42,14 +46,37 @@ import { Database } from '../database';
   }).argv;
 
   const config: Config = await getConfig(argv.configFile);
-  const { database: dbConfig } = config;
 
-  assert(dbConfig);
+  const { upstream, database: dbConfig, server: serverConfig } = config;
+
+  assert(upstream, 'Missing upstream config');
+  assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
 
   const db = new Database(dbConfig);
   await db.init();
 
-  await db.saveContract(argv.address, argv.kind, argv.startingBlock);
+  const { ethServer: { gqlApiEndpoint, gqlPostgraphileEndpoint, rpcProviderEndpoint }, cache: cacheConfig } = upstream;
+  assert(gqlApiEndpoint, 'Missing upstream ethServer.gqlApiEndpoint');
+  assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
+
+  const cache = await getCache(cacheConfig);
+
+  const ethClient = new EthClient({
+    gqlEndpoint: gqlApiEndpoint,
+    gqlSubscriptionEndpoint: gqlPostgraphileEndpoint,
+    cache
+  });
+
+  const postgraphileClient = new EthClient({
+    gqlEndpoint: gqlPostgraphileEndpoint,
+    cache
+  });
+
+  const ethProvider = getDefaultProvider(rpcProviderEndpoint);
+
+  const indexer = new Indexer(serverConfig, db, ethClient, postgraphileClient, ethProvider);
+  await indexer.watchContract(argv.address, argv.kind, argv.startingBlock);
 
   await db.close();
 })();

packages/erc20-watcher/src/entity/BlockProgress.ts

@@ -14,6 +14,9 @@ export class BlockProgress implements BlockProgressInterface {
   @PrimaryGeneratedColumn()
   id!: number;
 
+  @Column('varchar')
+  cid!: string;
+
   @Column('varchar', { length: 66 })
   blockHash!: string;
 

packages/erc20-watcher/src/fill.ts

@@ -71,6 +71,7 @@ export const main = async (): Promise<any> => {
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
 
   const cache = await getCache(cacheConfig);
+
   const ethClient = new EthClient({
     gqlEndpoint: gqlApiEndpoint,
     gqlSubscriptionEndpoint: gqlPostgraphileEndpoint,

packages/erc20-watcher/src/indexer.ts

@@ -12,7 +12,7 @@ import { BaseProvider } from '@ethersproject/providers';
 
 import { EthClient } from '@vulcanize/ipld-eth-client';
 import { StorageLayout } from '@vulcanize/solidity-mapper';
-import { Indexer as BaseIndexer, ValueResult, UNKNOWN_EVENT_NAME, JobQueue, Where, QueryOptions } from '@vulcanize/util';
+import { IndexerInterface, Indexer as BaseIndexer, ValueResult, UNKNOWN_EVENT_NAME, JobQueue, Where, QueryOptions } from '@vulcanize/util';
 
 import { Database } from './database';
 import { Event } from './entity/Event';
@@ -43,7 +43,7 @@ interface EventResult {
   proof?: string;
 }
 
-export class Indexer {
+export class Indexer implements IndexerInterface {
   _db: Database
   _ethClient: EthClient
   _postgraphileClient: EthClient
@@ -257,6 +257,11 @@ export class Indexer {
     await this.triggerIndexingOnEvent(event);
   }
 
+  async processBlock (blockHash: string): Promise<void> {
+    // Empty post-block method.
+    assert(blockHash);
+  }
+
   parseEventNameAndArgs (kind: string, logObj: any): any {
     let eventName = UNKNOWN_EVENT_NAME;
     let eventInfo = {};
@@ -292,7 +297,7 @@ export class Indexer {
     return { eventName, eventInfo };
   }
 
-  async getEventsByFilter (blockHash: string, contract: string, name: string | null): Promise<Array<Event>> {
+  async getEventsByFilter (blockHash: string, contract: string, name?: string): Promise<Array<Event>> {
     return this._baseIndexer.getEventsByFilter(blockHash, contract, name);
   }
 
@@ -376,7 +381,7 @@ export class Indexer {
     return this._baseIndexer.getAncestorAtDepth(blockHash, depth);
   }
 
-  async _fetchAndSaveEvents ({ blockHash }: DeepPartial<BlockProgress>): Promise<BlockProgress> {
+  async _fetchAndSaveEvents ({ cid: blockCid, blockHash }: DeepPartial<BlockProgress>): Promise<BlockProgress> {
     assert(blockHash);
     let { block, logs } = await this._ethClient.getLogs({ blockHash });
 
@@ -441,6 +446,7 @@ export class Indexer {
 
     try {
       block = {
+        cid: blockCid,
         blockHash,
         blockNumber: block.number,
         blockTimestamp: block.timestamp,

packages/erc20-watcher/src/job-runner.ts

@@ -16,9 +16,11 @@ import {
   JobRunner as BaseJobRunner,
   QUEUE_BLOCK_PROCESSING,
   QUEUE_EVENT_PROCESSING,
+  QUEUE_HOOKS,
   JobQueueConfig,
   DEFAULT_CONFIG_PATH,
-  getCustomProvider
+  getCustomProvider,
+  ServerConfig
 } from '@vulcanize/util';
 
 import { Indexer } from './indexer';
@@ -31,12 +33,14 @@ export class JobRunner {
   _jobQueue: JobQueue
   _baseJobRunner: BaseJobRunner
   _jobQueueConfig: JobQueueConfig
+  _serverConfig: ServerConfig
 
-  constructor (jobQueueConfig: JobQueueConfig, indexer: Indexer, jobQueue: JobQueue) {
+  constructor (jobQueueConfig: JobQueueConfig, serverConfig: ServerConfig, indexer: Indexer, jobQueue: JobQueue) {
     this._jobQueueConfig = jobQueueConfig;
     this._indexer = indexer;
     this._jobQueue = jobQueue;
-    this._baseJobRunner = new BaseJobRunner(this._jobQueueConfig, this._indexer, this._jobQueue);
+    this._serverConfig = serverConfig;
+    this._baseJobRunner = new BaseJobRunner(this._jobQueueConfig, this._serverConfig, this._indexer, this._jobQueue);
   }
 
   async start (): Promise<void> {
@@ -55,6 +59,14 @@ export class JobRunner {
       await this._baseJobRunner.processEvent(job);
     });
   }
+
+  async subscribeHooksQueue (): Promise<void> {
+    await this._jobQueue.subscribe(QUEUE_HOOKS, async (job) => {
+      await this._indexer.processBlock(job);
+
+      await this._jobQueue.markComplete(job);
+    });
+  }
 }
 
 export const main = async (): Promise<any> => {
@@ -70,21 +82,21 @@ export const main = async (): Promise<any> => {
 
   const config = await getConfig(argv.f);
 
-  assert(config.server, 'Missing server config');
+  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: serverConfig } = config;
-
-  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: { mode } } = config;
 
+  assert(upstream, 'Missing upstream config');
   assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
 
   const db = new Database(dbConfig);
   await db.init();
 
-  assert(upstream, 'Missing upstream config');
   const { ethServer: { gqlApiEndpoint, gqlPostgraphileEndpoint, rpcProviderEndpoint }, cache: cacheConfig } = upstream;
   assert(gqlApiEndpoint, 'Missing upstream ethServer.gqlApiEndpoint');
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
 
   const cache = await getCache(cacheConfig);
+
   const ethClient = new EthClient({
     gqlEndpoint: gqlApiEndpoint,
     gqlSubscriptionEndpoint: gqlPostgraphileEndpoint,
@@ -106,9 +118,9 @@ export const main = async (): Promise<any> => {
   const jobQueue = new JobQueue({ dbConnectionString, maxCompletionLag: maxCompletionLagInSecs });
   await jobQueue.start();
 
-  const indexer = new Indexer(db, ethClient, postgraphileClient, ethProvider, jobQueue, mode);
+  const indexer = new Indexer(db, ethClient, postgraphileClient, ethProvider, jobQueue, serverConfig.mode);
 
-  const jobRunner = new JobRunner(jobQueueConfig, indexer, jobQueue);
+  const jobRunner = new JobRunner(jobQueueConfig, serverConfig, indexer, jobQueue);
   await jobRunner.start();
 };
 

packages/erc20-watcher/src/server.ts

@@ -56,6 +56,7 @@ export const main = async (): Promise<any> => {
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
 
   const cache = await getCache(cacheConfig);
+
   const ethClient = new EthClient({
     gqlEndpoint: gqlApiEndpoint,
     gqlSubscriptionEndpoint: gqlPostgraphileEndpoint,

packages/ipld-eth-client/src/eth-queries.ts

@@ -100,6 +100,7 @@ subscription {
   listen(topic: "header_cids") {
     relatedNode {
       ... on EthHeaderCid {
+        cid
         blockHash
         blockNumber
         parentHash

packages/uni-info-watcher/src/entity/BlockProgress.ts

@@ -14,6 +14,9 @@ export class BlockProgress implements BlockProgressInterface {
   @PrimaryGeneratedColumn()
   id!: number;
 
+  @Column('varchar')
+  cid!: string;
+
   @Column('varchar', { length: 66 })
   blockHash!: string;
 

packages/uni-info-watcher/src/events.ts

@@ -92,6 +92,7 @@ export interface TransferEvent {
 }
 
 export interface Block {
+  cid: string;
   number: number;
   hash: string;
   timestamp: number;

packages/uni-info-watcher/src/indexer.ts

@@ -70,6 +70,7 @@ export class Indexer implements IndexerInterface {
 
     return {
       block: {
+        cid: block.cid,
         hash: block.blockHash,
         number: block.blockNumber,
         timestamp: block.blockTimestamp,
@@ -152,6 +153,11 @@ export class Indexer implements IndexerInterface {
     console.timeEnd('time:indexer#processEvent-mapping_code');
   }
 
+  async processBlock (blockHash: string): Promise<void> {
+    // Empty post-block method.
+    assert(blockHash);
+  }
+
   async getBlockEntities (where: { [key: string]: any } = {}, queryOptions: QueryOptions): Promise<any> {
     if (where.timestamp_gt) {
       where.blockTimestamp_gt = where.timestamp_gt;

packages/uni-info-watcher/src/job-runner.ts

@@ -17,10 +17,12 @@ import {
   JobQueue,
   QUEUE_BLOCK_PROCESSING,
   QUEUE_EVENT_PROCESSING,
+  QUEUE_HOOKS,
   JobRunner as BaseJobRunner,
   JobQueueConfig,
   DEFAULT_CONFIG_PATH,
-  getCustomProvider
+  getCustomProvider,
+  ServerConfig
 } from '@vulcanize/util';
 
 import { Indexer } from './indexer';
@@ -33,12 +35,14 @@ export class JobRunner {
   _jobQueue: JobQueue
   _baseJobRunner: BaseJobRunner
   _jobQueueConfig: JobQueueConfig
+  _serverConfig: ServerConfig
 
-  constructor (jobQueueConfig: JobQueueConfig, indexer: Indexer, jobQueue: JobQueue) {
+  constructor (jobQueueConfig: JobQueueConfig, serverConfig: ServerConfig, indexer: Indexer, jobQueue: JobQueue) {
     this._jobQueueConfig = jobQueueConfig;
     this._indexer = indexer;
     this._jobQueue = jobQueue;
-    this._baseJobRunner = new BaseJobRunner(this._jobQueueConfig, this._indexer, this._jobQueue);
+    this._serverConfig = serverConfig;
+    this._baseJobRunner = new BaseJobRunner(this._jobQueueConfig, this._serverConfig, this._indexer, this._jobQueue);
   }
 
   async start (): Promise<void> {
@@ -57,6 +61,14 @@ export class JobRunner {
       await this._baseJobRunner.processEvent(job);
     });
   }
+
+  async subscribeHooksQueue (): Promise<void> {
+    await this._jobQueue.subscribe(QUEUE_HOOKS, async (job) => {
+      await this._indexer.processBlock(job);
+
+      await this._jobQueue.markComplete(job);
+    });
+  }
 }
 
 export const main = async (): Promise<any> => {
@@ -72,11 +84,11 @@ export const main = async (): Promise<any> => {
 
   const config = await getConfig(argv.f);
 
-  assert(config.server, 'Missing server config');
+  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: serverConfig } = config;
-
-  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: { mode } } = config;
 
+  assert(upstream, 'Missing upstream config');
   assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
 
   const db = new Database(dbConfig);
   await db.init();
@@ -130,9 +142,9 @@ export const main = async (): Promise<any> => {
   const jobQueue = new JobQueue({ dbConnectionString, maxCompletionLag: maxCompletionLagInSecs });
   await jobQueue.start();
 
-  const indexer = new Indexer(db, uniClient, erc20Client, ethClient, postgraphileClient, ethProvider, jobQueue, mode);
+  const indexer = new Indexer(db, uniClient, erc20Client, ethClient, postgraphileClient, ethProvider, jobQueue, serverConfig.mode);
 
-  const jobRunner = new JobRunner(jobQueueConfig, indexer, jobQueue);
+  const jobRunner = new JobRunner(jobQueueConfig, serverConfig, indexer, jobQueue);
   await jobRunner.start();
 };
 

packages/uni-info-watcher/src/server.ts

@@ -68,6 +68,7 @@ export const main = async (): Promise<any> => {
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
 
   const cache = await getCache(cacheConfig);
+
   const ethClient = new EthClient({
     gqlEndpoint: gqlApiEndpoint,
     gqlSubscriptionEndpoint: gqlPostgraphileEndpoint,

packages/uni-watcher/src/entity/BlockProgress.ts

@@ -14,6 +14,9 @@ export class BlockProgress implements BlockProgressInterface {
   @PrimaryGeneratedColumn()
   id!: number;
 
+  @Column('varchar')
+  cid!: string;
+
   @Column('varchar', { length: 66 })
   blockHash!: string;
 

packages/uni-watcher/src/indexer.ts

@@ -69,6 +69,7 @@ export class Indexer implements IndexerInterface {
 
     return {
       block: {
+        cid: block.cid,
         hash: block.blockHash,
         number: block.blockNumber,
         timestamp: block.blockTimestamp,
@@ -121,6 +122,11 @@ export class Indexer implements IndexerInterface {
     }
   }
 
+  async processBlock (blockHash: string): Promise<void> {
+    // Empty post-block method.
+    assert(blockHash);
+  }
+
   parseEventNameAndArgs (kind: string, logObj: any): any {
     let eventName = UNKNOWN_EVENT_NAME;
     let eventInfo = {};
@@ -339,7 +345,7 @@ export class Indexer implements IndexerInterface {
     return contract;
   }
 
-  async getEventsByFilter (blockHash: string, contract: string, name: string | null): Promise<Array<Event>> {
+  async getEventsByFilter (blockHash: string, contract: string, name?: string): Promise<Array<Event>> {
     return this._baseIndexer.getEventsByFilter(blockHash, contract, name);
   }
 
@@ -428,7 +434,7 @@ export class Indexer implements IndexerInterface {
     return this._baseIndexer.getAncestorAtDepth(blockHash, depth);
   }
 
-  async _fetchAndSaveEvents ({ blockHash }: DeepPartial<BlockProgress>): Promise<BlockProgress> {
+  async _fetchAndSaveEvents ({ cid: blockCid, blockHash }: DeepPartial<BlockProgress>): Promise<BlockProgress> {
     assert(blockHash);
 
     const logsPromise = this._ethClient.getLogs({ blockHash });
@@ -516,6 +522,7 @@ export class Indexer implements IndexerInterface {
 
     try {
       block = {
+        cid: blockCid,
         blockHash,
         blockNumber: block.number,
         blockTimestamp: block.timestamp,

packages/uni-watcher/src/job-runner.ts

@@ -16,9 +16,11 @@ import {
   JobRunner as BaseJobRunner,
   QUEUE_BLOCK_PROCESSING,
   QUEUE_EVENT_PROCESSING,
+  QUEUE_HOOKS,
   JobQueueConfig,
   DEFAULT_CONFIG_PATH,
-  getCustomProvider
+  getCustomProvider,
+  ServerConfig
 } from '@vulcanize/util';
 
 import { Indexer } from './indexer';
@@ -31,12 +33,14 @@ export class JobRunner {
   _jobQueue: JobQueue
   _baseJobRunner: BaseJobRunner
   _jobQueueConfig: JobQueueConfig
+  _serverConfig: ServerConfig
 
-  constructor (jobQueueConfig: JobQueueConfig, indexer: Indexer, jobQueue: JobQueue) {
+  constructor (jobQueueConfig: JobQueueConfig, serverConfig: ServerConfig, indexer: Indexer, jobQueue: JobQueue) {
     this._jobQueueConfig = jobQueueConfig;
     this._indexer = indexer;
     this._jobQueue = jobQueue;
-    this._baseJobRunner = new BaseJobRunner(this._jobQueueConfig, this._indexer, this._jobQueue);
+    this._serverConfig = serverConfig;
+    this._baseJobRunner = new BaseJobRunner(this._jobQueueConfig, this._serverConfig, this._indexer, this._jobQueue);
   }
 
   async start (): Promise<void> {
@@ -55,6 +59,14 @@ export class JobRunner {
       await this._baseJobRunner.processEvent(job);
     });
   }
+
+  async subscribeHooksQueue (): Promise<void> {
+    await this._jobQueue.subscribe(QUEUE_HOOKS, async (job) => {
+      await this._indexer.processBlock(job);
+
+      await this._jobQueue.markComplete(job);
+    });
+  }
 }
 
 export const main = async (): Promise<any> => {
@@ -70,11 +82,11 @@ export const main = async (): Promise<any> => {
 
   const config = await getConfig(argv.f);
 
-  assert(config.server, 'Missing server config');
+  const { upstream, database: dbConfig, jobQueue: jobQueueConfig, server: serverConfig } = config;
-
-  const { upstream, database: dbConfig, jobQueue: jobQueueConfig } = config;
 
+  assert(upstream, 'Missing upstream config');
   assert(dbConfig, 'Missing database config');
+  assert(serverConfig, 'Missing server config');
 
   const db = new Database(dbConfig);
   await db.init();
@@ -109,7 +121,7 @@ export const main = async (): Promise<any> => {
   const indexer = new Indexer(db, ethClient, postgraphileClient, ethProvider, jobQueue);
   await indexer.init();
 
-  const jobRunner = new JobRunner(jobQueueConfig, indexer, jobQueue);
+  const jobRunner = new JobRunner(jobQueueConfig, serverConfig, indexer, jobQueue);
   await jobRunner.start();
 };
 

packages/uni-watcher/src/schema.ts

@@ -184,6 +184,7 @@ union Event = TransferEvent | PoolCreatedEvent | IncreaseLiquidityEvent | Decrea
 # Ethereum types
 
 type Block {
+  cid: String!
   hash: String!
   number: Int!
   timestamp: Int!

packages/util/src/config.ts

@@ -24,11 +24,13 @@ export interface JobQueueConfig {
   eventsInBatch: number;
 }
 
-interface ServerConfig {
+export interface ServerConfig {
   host: string;
   port: number;
   mode: string;
   kind: string;
+  checkpointing: boolean;
+  checkpointInterval: number;
 }
 
 export interface UpstreamConfig {

packages/util/src/constants.ts

@@ -7,6 +7,8 @@ export const MAX_REORG_DEPTH = 16;
 export const QUEUE_BLOCK_PROCESSING = 'block-processing';
 export const QUEUE_EVENT_PROCESSING = 'event-processing';
 export const QUEUE_CHAIN_PRUNING = 'chain-pruning';
+export const QUEUE_BLOCK_CHECKPOINT = 'block-checkpoint';
+export const QUEUE_HOOKS = 'hooks';
 
 export const JOB_KIND_INDEX = 'index';
 export const JOB_KIND_PRUNE = 'prune';

packages/util/src/database.ts

@@ -216,6 +216,7 @@ export class Database {
 
   async saveEvents (blockRepo: Repository<BlockProgressInterface>, eventRepo: Repository<EventInterface>, block: DeepPartial<BlockProgressInterface>, events: DeepPartial<EventInterface>[]): Promise<BlockProgressInterface> {
     const {
+      cid,
       blockHash,
       blockNumber,
       blockTimestamp,
@@ -234,6 +235,7 @@ export class Database {
     const numEvents = events.length;
 
     const entity = blockRepo.create({
+      cid,
       blockHash,
       parentHash,
       blockNumber,
@@ -473,6 +475,7 @@ export class Database {
       // If entity not found in frothy region get latest entity in the pruned region.
       // Filter out entities from pruned blocks.
       const canonicalBlockNumber = blockNumber + 1;
+
       const entityInPrunedRegion:any = await repo.createQueryBuilder('entity')
         .innerJoinAndSelect('block_progress', 'block', 'block.block_hash = entity.block_hash')
         .where('block.is_pruned = false')

packages/util/src/events.ts

@@ -124,11 +124,12 @@ export class EventWatcher {
   }
 
   async publishBlockProgressToSubscribers (blockProgress: BlockProgressInterface): Promise<void> {
-    const { blockHash, blockNumber, numEvents, numProcessedEvents, isComplete } = blockProgress;
+    const { cid, blockHash, blockNumber, numEvents, numProcessedEvents, isComplete } = blockProgress;
 
     // Publishing the event here will result in pushing the payload to GQL subscribers for `onAddressEvent(address)`.
     await this._pubsub.publish(BlockProgressEvent, {
       onBlockProgressEvent: {
+        cid,
         blockHash,
         blockNumber,
         numEvents,

packages/util/src/indexer.ts

@@ -208,7 +208,7 @@ export class Indexer {
     return this._db.getBlockEvents(blockHash, where, queryOptions);
   }
 
-  async getEventsByFilter (blockHash: string, contract: string, name: string | null): Promise<Array<EventInterface>> {
+  async getEventsByFilter (blockHash: string, contract?: string, name?: string): Promise<Array<EventInterface>> {
     if (contract) {
       const watchedContract = await this.isWatchedContract(contract);
       if (!watchedContract) {

packages/util/src/job-runner.ts

@@ -6,8 +6,19 @@ import assert from 'assert';
 import debug from 'debug';
 import { In } from 'typeorm';
 
-import { JobQueueConfig } from './config';
+import { JobQueueConfig, ServerConfig } from './config';
-import { JOB_KIND_INDEX, JOB_KIND_PRUNE, JOB_KIND_EVENTS, JOB_KIND_CONTRACT, MAX_REORG_DEPTH, QUEUE_BLOCK_PROCESSING, QUEUE_EVENT_PROCESSING, UNKNOWN_EVENT_NAME } from './constants';
+import {
+  JOB_KIND_INDEX,
+  JOB_KIND_PRUNE,
+  JOB_KIND_EVENTS,
+  JOB_KIND_CONTRACT,
+  MAX_REORG_DEPTH,
+  UNKNOWN_EVENT_NAME,
+  QUEUE_BLOCK_PROCESSING,
+  QUEUE_EVENT_PROCESSING,
+  QUEUE_BLOCK_CHECKPOINT,
+  QUEUE_HOOKS
+} from './constants';
 import { JobQueue } from './job-queue';
 import { EventInterface, IndexerInterface, SyncStatusInterface } from './types';
 import { wait } from './misc';
@@ -23,11 +34,13 @@ export class JobRunner {
   _jobQueue: JobQueue
   _jobQueueConfig: JobQueueConfig
   _blockProcessStartTime?: Date
+  _serverConfig: ServerConfig
 
-  constructor (jobQueueConfig: JobQueueConfig, indexer: IndexerInterface, jobQueue: JobQueue) {
+  constructor (jobQueueConfig: JobQueueConfig, serverConfig: ServerConfig, indexer: IndexerInterface, jobQueue: JobQueue) {
-    this._jobQueueConfig = jobQueueConfig;
     this._indexer = indexer;
     this._jobQueue = jobQueue;
+    this._jobQueueConfig = jobQueueConfig;
+    this._serverConfig = serverConfig;
   }
 
   async processBlock (job: any): Promise<void> {
@@ -117,7 +130,7 @@ export class JobRunner {
   }
 
   async _indexBlock (job: any, syncStatus: SyncStatusInterface): Promise<void> {
-    const { data: { blockHash, blockNumber, parentHash, priority, timestamp } } = job;
+    const { data: { cid, blockHash, blockNumber, parentHash, priority, timestamp } } = job;
 
     const indexBlockStartTime = new Date();
 
@@ -168,10 +181,11 @@ export class JobRunner {
           throw new Error(message);
         }
 
-        const [{ blockNumber: parentBlockNumber, parentHash: grandparentHash, timestamp: parentTimestamp }] = blocks;
+        const [{ cid: parentCid, blockNumber: parentBlockNumber, parentHash: grandparentHash, timestamp: parentTimestamp }] = blocks;
 
         await this._jobQueue.pushJob(QUEUE_BLOCK_PROCESSING, {
           kind: JOB_KIND_INDEX,
+          cid: parentCid,
           blockHash: parentHash,
           blockNumber: parentBlockNumber,
           parentHash: grandparentHash,
@@ -192,6 +206,7 @@ export class JobRunner {
 
         await this._jobQueue.pushJob(QUEUE_BLOCK_PROCESSING, {
           kind: JOB_KIND_INDEX,
+          cid: parentBlock.cid,
           blockHash: parentHash,
           blockNumber: parentBlock.blockNumber,
           parentHash: parentBlock.parentHash,
@@ -213,7 +228,7 @@ export class JobRunner {
 
       // Delay required to process block.
       await wait(jobDelayInMilliSecs);
-      blockProgress = await this._indexer.fetchBlockEvents({ blockHash, blockNumber, parentHash, blockTimestamp: timestamp });
+      blockProgress = await this._indexer.fetchBlockEvents({ cid, blockHash, blockNumber, parentHash, blockTimestamp: timestamp });
     }
 
     // Check if block has unprocessed events.
@@ -221,6 +236,17 @@ export class JobRunner {
       await this._jobQueue.pushJob(QUEUE_EVENT_PROCESSING, { kind: JOB_KIND_EVENTS, blockHash: blockProgress.blockHash, publish: true });
     }
 
+    if (!blockProgress.numEvents) {
+      // Push post-block hook and checkpointing jobs if there are no events as the block is already marked as complete.
+      await this._jobQueue.pushJob(QUEUE_HOOKS, { blockHash });
+
+      // Push checkpointing job only if checkpointing is on.
+      if (this._serverConfig.checkpointing) {
+        await this._jobQueue.pushJob(QUEUE_BLOCK_CHECKPOINT, { blockHash, blockNumber });
+      }
+    }
+
+
     const indexBlockDuration = new Date().getTime() - indexBlockStartTime.getTime();
     log(`time:job-runner#_indexBlock: ${indexBlockDuration}ms`);
   }

packages/util/src/types.ts

@@ -8,6 +8,7 @@ import { Where, QueryOptions } from './database';
 
 export interface BlockProgressInterface {
   id: number;
+  cid: string;
   blockHash: string;
   parentHash: string;
   blockNumber: number;
@@ -70,6 +71,7 @@ export interface IndexerInterface {
   parseEventNameAndArgs?: (kind: string, logObj: any) => any;
   isWatchedContract?: (address: string) => Promise<ContractInterface | undefined>;
   cacheContract?: (contract: ContractInterface) => void;
+  processBlock(blockHash: string): Promise<void>;
 }
 
 export interface EventWatcherInterface {