Merge pull request #930 from ethereumjs/blockchain-concurrency-and-sa…

…fety-improvements

Blockchain concurrency and safety improvements

packages/blockchain/CHANGELOG.md

@@ -6,6 +6,41 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 (modification: no type change headlines) and this project adheres to
 [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## 5.0.0-beta.2 - UNRELEASED
+
+This is the second beta release towards a final `v5.0.0` `Blockchain` library release, see [v5.0.0-beta.1 release notes](https://github.com/ethereumjs/ethereumjs-vm/releases/tag/%40ethereumjs%2Fblockchain%405.0.0-beta.1) for an overview on the full changes since the last publicly released version.
+
+This release introduces **new breaking changes**, so please carefully read the additional release note sections!
+
+**Safe Static Constructor**
+
+The library now has an additional safe static constructor `Blockchain.create()` which awaits the init method and throws if the init method throws:
+
+```typescript
+const common = new Common({ chain: 'ropsten' })
+const blockchain = await Blockchain.create({ common })
+```
+
+This is the new recommended way to instantiate a `Blockchain` object, see PR [#930](https://github.com/ethereumjs/ethereumjs-vm/pull/930).
+
+**Refactored Genesis Block Handling Mechanism**
+
+Genesis handling has been reworked to now be safer and reduce the risk of wiping a blockchain by setting a new genesis, see PR [#930](https://github.com/ethereumjs/ethereumjs-vm/pull/930).
+
+**Breaking**: The dedicated `setGenesisBlock()` methods and the optional `isGenesis` option on `Blockchain.putBlock()` have been removed. Instead the genesis block is created on initialization either from the `Common` library instance passed or a custom genesis block passed along with the `genesisBlock` option. If a custom genesis block is used, this custom block now always has to be passed along on `Blockchain` initialization, also when operating on an already existing DB. 
+
+**Changes and Refactoring**
+
+- Refactored `DBManager` with the introduction of an abstract DB operation handling mechanism, if you have modified `DBManager` in your code this will be a **potentially breaking** change for you, PR [#927](https://github.com/ethereumjs/ethereumjs-vm/pull/927)
+- Renaming of internal variables like `Blockchain._headBlock`, if you are using these variables in your code this will be a **potentially breaking** change for you, PR [#930](https://github.com/ethereumjs/ethereumjs-vm/pull/930)
+- Made internal `_` methods like `_saveHeads()` private, if you are using these functions in your code this will be a **potentially breaking** change for you, PR [#930](https://github.com/ethereumjs/ethereumjs-vm/pull/930)
+- Improved code documentation, PR [#930](https://github.com/ethereumjs/ethereumjs-vm/pull/930)
+- Fixed potential blockchain DB concurrency issues along PR [#930](https://github.com/ethereumjs/ethereumjs-vm/pull/930)
+
+**Testing and CI**
+
+- Dedicated `blockchain` reorg test setup and executable test, PR [#926](https://github.com/ethereumjs/ethereumjs-vm/pull/926)
+
 ## 5.0.0-beta.1 - 2020-10-22
 
 ### New Package Name

packages/blockchain/src/db/constants.ts

@@ -1,4 +1,4 @@
-import BN = require('bn.js')
+import { BN } from 'ethereumjs-util'
 
 // Geth compatible DB keys
 

packages/blockchain/src/db/helpers.ts

@@ -0,0 +1,78 @@
+import { DBOp, DBTarget } from './operation'
+import { BN, rlp } from 'ethereumjs-util'
+import { Block, BlockHeader } from '@ethereumjs/block'
+import { bufBE8 } from './constants'
+
+/*
+ * This extra helper file serves as an interface between the blockchain API functionality
+ * and the DB operations from `db/operation.ts` and also handles the right encoding of the keys
+ */
+
+function DBSetTD(TD: BN, blockNumber: BN, blockHash: Buffer): DBOp {
+  return DBOp.set(DBTarget.TotalDifficulty, rlp.encode(TD), {
+    blockNumber,
+    blockHash,
+  })
+}
+
+/*
+ * This method accepts either a BlockHeader or a Block and returns a list of DatabaseOperation instances
+ *
+ * - A "Set Header Operation" is always added
+ * - A "Set Body Operation" is only added if the body is not empty (it has transactions/uncles) or if the block is the genesis block
+ * (if there is a header but no block saved the DB will implicitly assume the block to be empty)
+ */
+function DBSetBlockOrHeader(blockBody: Block | BlockHeader): DBOp[] {
+  const header: BlockHeader = blockBody instanceof Block ? blockBody.header : blockBody
+  const dbOps = []
+
+  const blockNumber = header.number
+  const blockHash = header.hash()
+
+  const headerValue = header.serialize()
+  dbOps.push(
+    DBOp.set(DBTarget.Header, headerValue, {
+      blockNumber,
+      blockHash,
+    })
+  )
+
+  const isGenesis = header.number.eqn(0)
+
+  if (
+    isGenesis ||
+    (blockBody instanceof Block && (blockBody.transactions.length || blockBody.uncleHeaders.length))
+  ) {
+    const bodyValue = rlp.encode(blockBody.raw().slice(1))
+    dbOps.push(
+      DBOp.set(DBTarget.Body, bodyValue, {
+        blockNumber,
+        blockHash,
+      })
+    )
+  }
+
+  return dbOps
+}
+
+function DBSetHashToNumber(blockHash: Buffer, blockNumber: BN): DBOp {
+  const blockNumber8Byte = bufBE8(blockNumber)
+  return DBOp.set(DBTarget.HashToNumber, blockNumber8Byte, {
+    blockHash,
+  })
+}
+
+function DBSaveLookups(blockHash: Buffer, blockNumber: BN): DBOp[] {
+  const ops = []
+  ops.push(DBOp.set(DBTarget.NumberToHash, blockHash, { blockNumber }))
+
+  const blockNumber8Bytes = bufBE8(blockNumber)
+  ops.push(
+    DBOp.set(DBTarget.HashToNumber, blockNumber8Bytes, {
+      blockHash,
+    })
+  )
+  return ops
+}
+
+export { DBOp, DBSetTD, DBSetBlockOrHeader, DBSetHashToNumber, DBSaveLookups }

packages/blockchain/src/db/manager.ts

@@ -32,9 +32,9 @@ export type CacheMap = { [key: string]: Cache<Buffer> }
  * @hidden
  */
 export class DBManager {
-  _cache: CacheMap
-  _common: Common
-  _db: LevelUp
+  private _cache: CacheMap
+  private _common: Common
+  private _db: LevelUp
 
   constructor(db: LevelUp, common: Common) {
     this._db = db