feat/#76 implement roll back to

[danielvo11]

• allow user to config rollbackFunction in AloxideActionHandler
• reset index state to block number when rollback

Require lecle/demux-js#2 to be merged first

[codecov-io]

Codecov Report

Merging #130 (1b0086f) into master (e880000) will increase coverage by 0.04%.
The diff coverage is 97.36%.

@@            Coverage Diff             @@
##           master     #130      +/-   ##
==========================================
+ Coverage   95.64%   95.68%   +0.04%     
==========================================
  Files          72       72              
  Lines        1217     1252      +35     
  Branches      155      162       +7     
==========================================
+ Hits         1164     1198      +34     
- Misses         53       54       +1     

Impacted Files	Coverage Δ
packages/demux/src/AloxideActionHandler.ts	98.83% <97.36%> (-1.17%)	⬇️

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[manh-vv]

Let's implement this feature without introduce breaking change in the demux-js.

  protected async rollbackTo(blockNumber: number): Promise<void> {
    this.log.debug('-- roll back to block number:', blockNumber);
    // - [ ] TODO alter current index state
    // - [ ] TODO revert all change from blockNumber to current blockNumber
    // Aloxide Updater will create a snapshot of data when applying a last irreversible block
    // doing so we can quickly roll back to the last irreversible block state
    // This is only applied to Aloxide data
  }

  public async handleBlock(nextBlock: NextBlock, isReplay: boolean): Promise<number | null> {
    try {
      return super.handleBlock(nextBlock, isReplay);
    } catch (e) {
      if (e instanceof MismatchedBlockHashError) {
        // roll back to the last irreversible blocks
        // - [ ] TODO explain why it must be the last irreversible block
        // - [ ]  what hapen if the rollbackTo took too long to execute
        await this.rollbackTo(this.lastIrreversibleBlockNumber);
        return this.lastIrreversibleBlockNumber + 1;
      }

      throw e;
    }
  }

cc @danielalvess

[danielvo11]

@manh-vv please help me review again!.

[manh-vv]

Please have a direct talk if you have any questions about my comments.

[manh-vv]

LGTM