Pw/block download fix (#27)

* Fixed the block download calculation

* Comment fix

* More fixes

yarn-project/sdk/src/core_sdk/block_downloader.ts

@@ -11,10 +11,17 @@ export class BlockDownloader {
  private interruptableSleep = new InterruptableSleep();
  private semaphore: Semaphore;
  private queue = new MemoryFifo<Block[]>();
+ private genesisTake;
  private debug = createDebugLogger('bb:block_downloader');
 
- constructor(private rollupProvider: RollupProvider, maxQueueSize: number, private initialTreeSize: number) {
+ constructor(private rollupProvider: RollupProvider, maxQueueSize: number, initialTreeSize: number) {
  this.semaphore = new Semaphore(maxQueueSize);
+ // Choosing 55 as an initial chunk to insert if starting from 0, is an aztec-connect optimisation.
+ // The aztec-connect genesis data consists of 73 rollups.
+ // Initially inserting 55 brings us to 128, after which we work with chunks of 128 rollups.
+ // If not synching from zero, the chunk size is whatever takes us up to the next 128 alignment.
+ // This allows for optimal subtree insertions in the client side merkle tree for better sync performance.
+ this.genesisTake = 128 - (initialTreeSize % 128);
  }
 
  public start(from = 0) {
@@ -31,13 +38,12 @@ export class BlockDownloader {
  const fn = async () => {
  while (this.running) {
  try {
- // Choosing 55 as an initial chunk to insert if starting from 0, is an aztec-connect optimisation.
- // The aztec-connect genesis data consists of 73 rollups.
- // Initially inserting 55 brings us to 128, after which we work with chunks of 128 rollups.
- // If not synching from zero, the chunk size is whatever takes us up to the next 128 alignment.
- // This allows for optimal subtree insertions in the client side merkle tree for better sync performance.
- const initialTake = 128 - ((this.from === 0 ? this.initialTreeSize : this.from) % 128);
- const blocks = await this.rollupProvider.getBlocks(this.from, this.from === from ? initialTake : 128);
+ // If requesting from block 0, then take the fixed number of blocks to take us to 128 (genesisTake)
+ // Otherwise, take blocks as required to get us to a 128 aligned boundary starting from block (128 - initialTreeSize).
+ // e.g. we are trying to get to blocks 183, 311, 439 etc....
+ const takeValue =
+ this.from < this.genesisTake ? this.genesisTake - this.from : 128 - ((this.from - this.genesisTake) % 128);
+ const blocks = await this.rollupProvider.getBlocks(this.from, takeValue);
 
  if (!blocks.length) {
  await this.interruptableSleep.sleep(10000);