Persistent mode

[xlc]

• Save chain/blocks to sqlite db
• Load chain from db
• Config to specify max number of blocks to be stored in memory. If db is enabled, save them to db before purge.

[qiweiii]

• Config to specify max number of blocks to be stored in memory. (Max memory block count #353)
  • background: problem is now all blocks are in memory, long-running testnet create too many blocks will break the program.
  • stage1: when exceed the max number of block, delete old blocks, so it won't break
    • add a config max-memory-block-count, default to a number, maybe 2000
    • in blockchain/index, blocksByHash object records all the blocks in memory, when #registerBlock, we can check the number of blocks, if exceed the max-memory-block-count, remove the earliest inserted block. Since we need insertion order, maybe change it to a JS Map() to make it a simple LRU data structure.
• If db is enabled, save chain/blocks to db before purge (Save blocks to db #359)
  • entities:

    •   @Entity()
        export class Block {
          @PrimaryColumn()
          blockHash: string;
        
          @Column()
          blockNumber: number;
        
          @Column({ type: 'json', nullable: true })
          header: object;
        
          @Column({ nullable: true })
          parentBlockHash: string;
        
          @Column('simple-array', { nullable: true })
          extrinsics: string[];
        }

  • when #registerBlock, if exceed max-memory-block-count, save block in db
  • when getBlock, get data from memory first, if not found, get from db
  • when stop, save all blocks in memory to db
• Load chain/blocks from db, and resume from where it stopped
  • user need to use the same config and the corresponding db file to ensure it works?
  • recreate the blockchain using the config
  • travel to latest block
• Multiple chain support using different db files

[xlc]

No need to change build block mode. We still want this with all the existing modes.

[qiweiii]

updated