EOS多节点同步代码分析

不念不忘少年蓝@ 2022-05-20 06:09 219阅读 0赞

EOS version: 1.0.7

一. 配置文件的修改

EOS的节点同步流程是通过p2p来完成，在nodeos的配置文件config.ini中填写，其默认路径为~/.local/share/eosio/nodeos/config目录下,配置项及其格式如下：

p2p-peer-address = 10.186.11.223:9876
    121 p2p-peer-address = 10.186.11.220:9876
    122 p2p-peer-address = 10.186.11.141:9876

可以填写多个p2p站点地址。

二.节点同步的chain\_id

每一个节点都唯一分配一个chain\_id,如果两个节点的chian\_id不相等的话，是无法进行同步的,代码中处理如下：

![复制代码][copycode.gif]

void net_plugin_impl::handle_message( connection_ptr c, const handshake_message &msg) {
             ...
    
    if( msg.chain_id != chain_id) {
                elog( "Peer on a different chain. Closing connection");
                c->enqueue( go_away_message(go_away_reason::wrong_chain) );
                return;
             }
    
             ...
    }

![复制代码][copycode.gif]

那么这个chain\_id是如何开成的？

chain\_id在chain\_plugin中定义，在net\_plugin中使用，在chain\_plugin中如下定义

//controller.cpp

![复制代码][copycode.gif]

chain_id( cfg.genesis.compute_chain_id() )
    
    
    //genesis_state.cpp
    
    chain::chain_id_type genesis_state::compute_chain_id() const {

digest\_type::encoder enc;  
fc::raw::pack( enc, \*this );  
return chain\_id\_type\{enc.result()\};  
\}

![复制代码][copycode.gif]

这里相当于把整个genesis的数据做了一个类似hash的操作，默认情况下genesis的数据在代码中填写：

![复制代码][copycode.gif]

chain_config   initial_configuration = {
          .max_block_net_usage                  = config::default_max_block_net_usage,
          .target_block_net_usage_pct           = config::default_target_block_net_usage_pct,
          .max_transaction_net_usage            = config::default_max_transaction_net_usage,
          .base_per_transaction_net_usage       = config::default_base_per_transaction_net_usage,
          .net_usage_leeway                     = config::default_net_usage_leeway,
          .context_free_discount_net_usage_num  = config::default_context_free_discount_net_usage_num,
          .context_free_discount_net_usage_den  = config::default_context_free_discount_net_usage_den,
    
          .max_block_cpu_usage                  = config::default_max_block_cpu_usage,
          .target_block_cpu_usage_pct           = config::default_target_block_cpu_usage_pct,
          .max_transaction_cpu_usage            = config::default_max_transaction_cpu_usage,
          .min_transaction_cpu_usage            = config::default_min_transaction_cpu_usage,
    
          .max_transaction_lifetime             = config::default_max_trx_lifetime,
          .deferred_trx_expiration_window       = config::default_deferred_trx_expiration_window,
          .max_transaction_delay                = config::default_max_trx_delay,
          .max_inline_action_size               = config::default_max_inline_action_size,
          .max_inline_action_depth              = config::default_max_inline_action_depth,
          .max_authority_depth                  = config::default_max_auth_depth,
       };

![复制代码][copycode.gif]

还可以通过nodeos命令行参数--genesis-json加载一个指定的配置文件genesis.json,其内容一般如下格式：

![复制代码][copycode.gif]

{
      "initial_timestamp": "2018-03-02T12:00:00.000",
      "initial_key": "EOS8Znrtgwt8TfpmbVpTKvA2oB8Nqey625CLN8bCN3TEbgx86Dsvr",
      "initial_configuration": {
        "max_block_net_usage": 1048576,
        "target_block_net_usage_pct": 1000,
        "max_transaction_net_usage": 524288,
        "base_per_transaction_net_usage": 12,
        "net_usage_leeway": 500,
        "context_free_discount_net_usage_num": 20,
        "context_free_discount_net_usage_den": 100,
        "max_block_cpu_usage": 100000,
        "target_block_cpu_usage_pct": 500,
        "max_transaction_cpu_usage": 50000,
        "min_transaction_cpu_usage": 100,
        "max_transaction_lifetime": 3600,
        "deferred_trx_expiration_window": 600,
        "max_transaction_delay": 3888000,
        "max_inline_action_size": 4096,
        "max_inline_action_depth": 4,
        "max_authority_depth": 6,
        "max_generated_transaction_count": 16
      },
      "initial_chain_id": "0000000000000000000000000000000000000000000000000000000000000000"
    }

![复制代码][copycode.gif]

所以，节点之间能同步的条件是参数配置需要完全相当的。

四.区块同步数据流

数据同步涉及几个消息：

handshake\_message,　　//hello握手信息，  
　　chain\_size\_message,　　//暂未看到使用  
　　go\_away\_message　//停止同步消息  
　　time\_message,　　// 时间戳相关  
　　notice\_message,　　//区块和事务状态同步  
　　request\_message,　　//请求发送区块同步，带有区块的num数据  
　　sync\_request\_message,　　//在request\_message基础上加了一个定时器做超时处理  
　　signed\_block,　　　　　　// 具体的区块数据  
　　packed\_transaction　　　　//事务同步处理

现在假设有一个节点M,它的p2p-peer-address对就有三个地址a、b、c,现在数据同步的流程基本上有下面几个步骤.

1.handshake\_message处理流程

首先，M结点会向a、b、c循环发起连接并发送一条握手信息，这条信息是一个名为struct handshake\_message，定义如下：

![复制代码][copycode.gif]

struct handshake_message {
          uint16_t                   network_version = 0; //net version, require  M == a == b == c      chain_id_type              chain_id; // M == a == b == c      fc::sha256                 node_id; ///< used to identify peers and prevent self-connect
          chain::public_key_type     key; ///< authentication key; may be a producer or peer key, or empty
          tstamp                     time;
          fc::sha256                 token; ///< digest of time to prove we own the private key of the key above
          chain::signature_type      sig; ///< signature for the digest
          string                     p2p_address;
          uint32_t                   last_irreversible_block_num = 0;
          block_id_type              last_irreversible_block_id;
          uint32_t                   head_num = 0;
          block_id_type              head_id;
          string                     os;
          string                     agent;
          int16_t                    generation;
       };

![复制代码][copycode.gif]

包括了对通信的基本要求的参数,该消息初始化后会将其放入名为write\_queue的消息队列中，最后消息是使用asio::async\_write进行发送，发送消息的成功与否是通过回调来处理的。

![复制代码][copycode.gif]

void connection::do_queue_write() {
    
    ...
    while (write_queue.size() > 0) {
             auto& m = write_queue.front();
             bufs.push_back(boost::asio::buffer(*m.buff));
             out_queue.push_back(m);
             write_queue.pop_front();
          }
          boost::asio::async_write(*socket, bufs, [c](boost::system::error_code ec, std::size_t w) {
     try {
            for (auto& m: conn->out_queue) {
                      m.callback(ec, w);
                   }
    
    while (conn->out_queue.size() > 0) {
                      conn->out_queue.pop_front();
                   }
                   conn->enqueue_sync_block();
                   conn->do_queue_write();
    
        }
    ...
    }

![复制代码][copycode.gif]

对端收到handshake\_message的消息后处理如下代码：

![复制代码][copycode.gif]

void sync_manager::recv_handshake (connection_ptr c, const handshake_message &msg) {
        controller& cc = chain_plug->chain();
          uint32_t lib_num = cc.last_irreversible_block_num( );
          uint32_t peer_lib = msg.last_irreversible_block_num;
          reset_lib_num(c);
          c->syncing = false;
    
          //--------------------------------
          // sync need checks; (lib == last irreversible block)
          //
          // 0. my head block id == peer head id means we are all caugnt up block wise
          // 1. my head block num < peer lib - start sync locally
          // 2. my lib > peer head num - send an last_irr_catch_up notice if not the first generation
          //
          // 3  my head block num <= peer head block num - update sync state and send a catchup request
          // 4  my head block num > peer block num ssend a notice catchup if this is not the first generation
          //
          //-----------------------------
    
          uint32_t head = cc.head_block_num( );
          block_id_type head_id = cc.head_block_id();
          if (head_id == msg.head_id) {
          ...  
        }
            
        ...
    }

![复制代码][copycode.gif]

梳理流程：

*  两个节点历史区块id相等，不进行同步；
 *  A节点区块的head\_block\_num小于B节点不可逆区块的head\_block\_num，则B给A发送消息notice\_message，消息中包含A节点所需要同步的区块范围，每次同步块数为sync\_req\_span，此参数在genesis.json中设置或者是程度初始的；
 *  A节点不可逆区块的head\_block\_num大于B节点区块的head\_block\_num，则A给B发送消息notice\_message，消息中包含可逆与不可逆区块的block\_num；
 *  A节点区块的head\_block\_num小于B节点的head\_block\_num，A节点会产生一个request\_message消息发送给B;

2.go\_away\_message

一般在某些异常情况下节点A会断开与其它节点的同步，会发送一个go\_away\_message，会带有一个错误码：

![复制代码][copycode.gif]

enum go_away_reason {
        no_reason, ///< no reason to go away
        self, ///< the connection is to itself
        duplicate, ///< the connection is redundant
        wrong_chain, ///< the peer's chain id doesn't match
        wrong_version, ///< the peer's network version doesn't match
        forked, ///< the peer's irreversible blocks are different
        unlinkable, ///< the peer sent a block we couldn't use
        bad_transaction, ///< the peer sent a transaction that failed verification
        validation, ///< the peer sent a block that failed validation
        benign_other, ///< reasons such as a timeout. not fatal but warrant resetting
        fatal_other, ///< a catch-all for errors we don't have discriminated
        authentication ///< peer failed authenicatio
      };

![复制代码][copycode.gif]

3.time\_message

这个消息应该是发送一个带有几个时间标志的keeplive消息包，目前设置的是每32秒发送一次。

4.notice\_message

这个消息定义如下：

struct notice_message {
        notice_message () : known_trx(), known_blocks() {}
        ordered_txn_ids known_trx;
        ordered_blk_ids known_blocks;
      };

它包含了区块的信息和交易信息，也即对可逆区块，可逆事务，不可逆区块，不可逆事务都可以通过这个消息处理。比如，节点A把本地节点最新区块和事务信息(block\_num)发送给节点B，节点B收到后会将本地的区块和事务信息(block\_num)进行比较，根据比较的结果决定谁给谁传输数据。

5.request\_message

A节点请求端分为四种，节点B做为接收端，分别给予的应答如下：

对于区块：

*  catch\_up：B节点把本地的所有可逆的区块打包发给节点A; 
 *  normal:根据A节点vector里面的区块id，在本地(B节点)不可逆的区块中进行查找，如果找到了就把该区块就发给A；

对于事务：

*  catch\_up：B节点把A节点所需要的可逆的transaction id 并且自己本地有的数据发送给A；
 *  normal:　　B节点把A节点所需要的不可逆的transaction id 并且自己本地有的数据发送给A；

6.sync\_request\_message

此消息是在request\_message实现基础上加了一个5S的定时器，同步消息在5S内没有得到应答会取消当前同步后再重新要求同步；

7.signed\_block

这里发送的是具体的区块数据，一般是收到request\_message或者 sync\_request\_message消息后把本节点的区块发给对方；

![复制代码][copycode.gif]

bool connection::enqueue_sync_block() {
          controller& cc = app().find_plugin<chain_plugin>()->chain();
          if (!peer_requested)
             return false;
          uint32_t num = ++peer_requested->last;
          bool trigger_send = num == peer_requested->start_block;
          if(num == peer_requested->end_block) {
             peer_requested.reset();
          }
          try {
        
    　　　　　　//从本地取出区块数据
             signed_block_ptr sb = cc.fetch_block_by_number(num);
             if(sb) {
        
    　　　　　　　//放入消息队列并异步发送
                enqueue( *sb, trigger_send);
                return true;
             }
          } catch ( ... ) {
             wlog( "write loop exception" );
          }
          return false;
       }

![复制代码][copycode.gif]

8.packed\_transaction

节点A把多个transacton放在一起进行打包发送，收到packed\_transaction消息的节点会对其进行各种校验，如果校验结果正确，会把数据缓存到本地，然后再对本端所有p2p-peer-address的地址进行广播。所以对于多个transaction的数据，在这里就实现了在多个地址之间相互快速传播的功能。

![复制代码][copycode.gif]

void net_plugin_impl::handle_message( connection_ptr c, const packed_transaction &msg) {
          fc_dlog(logger, "got a packed transaction, cancel wait");
          peer_ilog(c, "received packed_transaction");
          if( sync_master->is_active(c) ) {
             fc_dlog(logger, "got a txn during sync - dropping");
             return;
          }
          transaction_id_type tid = msg.id();
    
    　　　　//收到数据后取异步定时器
          c->cancel_wait();
          if(local_txns.get<by_id>().find(tid) != local_txns.end()) {
             fc_dlog(logger, "got a duplicate transaction - dropping");
             return;
          }
    　　　　//将数据保存到本地的缓存中
          dispatcher->recv_transaction(c, tid);
          uint64_t code = 0;
    
    　　　　//对数据进行校验，然后把结果传递给回调函数
          chain_plug->accept_transaction(msg, [=](const static_variant<fc::exception_ptr, transaction_trace_ptr>& result) {
             if (result.contains<fc::exception_ptr>()) {
                auto e_ptr = result.get<fc::exception_ptr>();
                if (e_ptr->code() != tx_duplicate::code_value && e_ptr->code() != expired_tx_exception::code_value)
                   elog("accept txn threw  ${m}",("m",result.get<fc::exception_ptr>()->to_detail_string()));
                   peer_elog(c, "bad packed_transaction : ${m}", ("m",result.get<fc::exception_ptr>()->what()));
             } else {
                auto trace = result.get<transaction_trace_ptr>();
    　　　　　　　　　if (!trace->except) {
                   fc_dlog(logger, "chain accepted transaction");
    　　　　　　　　
    　　　　　　　　　　//对其它p2p-peer-address进行广播，数据互传
                   dispatcher->bcast_transaction(msg);
                   return;
                }
    
                peer_elog(c, "bad packed_transaction : ${m}", ("m",trace->except->what()));
             }
    　　　　　　//数据校给失败，本地缓存数据回滚
             dispatcher->rejected_transaction(tid);
          });
       }

原文:https://www.cnblogs.com/hbright/p/9287669.html

[copycode.gif]: /images/20220520/99c689d0b7444086b0e0e72069160cf3.png