以太坊源碼分析-同步之Syncing接口

在節點同步的過程當中，咱們常常須要執行eth.syncing來查看當前的同步狀況，本篇博客帶領你們看一下syncing api的源代碼實現。

1

Syncing方法源代碼

// Syncing returns false in case the node is currently not syncing with the network. It can be up to date or has not`

// yet received the latest block headers from its pears. In case it is synchronizing:`

// - startingBlock: block number this node started to synchronise from`

// - currentBlock:  block number this node is currently importing`

// - highestBlock:  block number of the highest block header this node has received from peers`

// - pulledStates:  number of state entries processed until now`

// - knownStates:   number of known state entries that still need to be pulled`

func (s *PublicEthereumAPI)  Syncing()  (interface{}, error)  {`

progress := s.b.Downloader().Progress()`

// Return not syncing if the synchronisation already completed`

if progress.CurrentBlock  >= progress.HighestBlock  {`

return  false,  nil`

}`

// Otherwise gather the block sync stats`

return map[string]interface{}{`

"startingBlock": hexutil.Uint64(progress.StartingBlock),`

"currentBlock": hexutil.Uint64(progress.CurrentBlock),`

"highestBlock": hexutil.Uint64(progress.HighestBlock),`

"pulledStates": hexutil.Uint64(progress.PulledStates),`

"knownStates": hexutil.Uint64(progress.KnownStates),`

},  nil`

}`

</pre>

Syncing方法的源代碼很簡單，註釋說明也已經很清楚了。經過這段源代碼咱們能夠得知一下信息：

• 固然CurrentBlock大於等於HighestBlock時返回false，這也正是一般所說的同步完成以後，再執行eth.syncing()函數會返回false的緣由。

• startingBlock：開始同步的起始區塊編號；

• currentBlock：當前正在導入的區塊編號；

• highestBlock：經過所連接的節點得到的當前最高的區塊高度；

• pulledStates：當前已經拉取的狀態條目數；

• knownStates：當前已知的待拉取的總狀態條目數。

2

對應的結構體代碼

下面是同步信息對應的結構體的代碼及註釋。

1.  `// SyncProgress gives progress indications when the node is synchronising with`

2.  `// the Ethereum network.`

3.  `type SyncProgress  struct  {`

4.  `StartingBlock uint64 // Block number where sync began`

5.  `CurrentBlock uint64 // Current block number where sync is at`

6.  `HighestBlock uint64 // Highest alleged block number in the chain`

7.  `PulledStates uint64 // Number of state trie entries already downloaded`

8.  `KnownStates uint64 // Total number of state trie entries known about`

9.  `}`

</pre>

3

結構體信息計算

上面看到當執行eth.syncing返回結果信息的代碼，再延伸一下看看這些數據從哪裏來。進入下面Progress方法的內部實現：

progress := s.b.Downloader().Progress()

</pre>

能夠看到以下代碼：

1.  `// Progress retrieves the synchronisation boundaries, specifically the origin`

2.  `// block where synchronisation started at (may have failed/suspended); the block`

3.  `// or header sync is currently at; and the latest known block which the sync targets.`

4.  `//`

5.  `// In addition, during the state download phase of fast synchronisation the number`

6.  `// of processed and the total number of known states are also returned. Otherwise`

7.  `// these are zero.`

8.  `func (d *Downloader)  Progress() ethereum.SyncProgress  {`

9.  `// Lock the current stats and return the progress`

10.  `d.syncStatsLock.RLock()`

11.  `defer d.syncStatsLock.RUnlock()`

13.  `current := uint64(0)`

14.  `switch d.mode {`

15.  `case  FullSync:`

16.  `current = d.blockchain.CurrentBlock().NumberU64()`

17.  `case  FastSync:`

18.  `current = d.blockchain.CurrentFastBlock().NumberU64()`

19.  `case  LightSync:`

20.  `current = d.lightchain.CurrentHeader().Number.Uint64()`

21.  `}`

22.  `return ethereum.SyncProgress{`

23.  `StartingBlock: d.syncStatsChainOrigin,`

24.  `CurrentBlock: current,`

25.  `HighestBlock: d.syncStatsChainHeight,`

26.  `PulledStates: d.syncStatsState.processed,`

27.  `KnownStates: d.syncStatsState.processed + d.syncStatsState.pending,`

28.  `}`

29.  `}`

</pre>

從這端代碼咱們能夠分析得出，curren

• full模式：返回當前區塊的高度；

• fast模式：返回fast區塊的高度；

• light模式：返回當前的header編號；

• 而KnownStates又是由PulledStates的值加上當前處於pending裝的值得到。

4

總  結

經過上面源代碼分析，咱們已經能夠明瞭的看到當咱們執行eth.sycing時返回不一樣的結果信息所表明的含義。歡迎你們關注微信公衆號，獲取最新的相關技術分享。

內容來源：程序新視界

做者：二師兄

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