以太坊交易池(txpool)的管理

在使用节点的过程中txpool是不可不了解的知识点，交易从发出到被打包都经历了哪些过程？txpool在这个过程中又起到什么作用？今天这篇文章就带大家简单了解一下。

昨天的文章《以太坊如何清除已发出未打包的交易》已经聊到txpool中未被清除的交易如何清除，今天就系统的再聊一聊txpool。

txpool对应的启动参数

我们先来了解一下，针对txpool有哪些参数项可以设置，然后着重分析。

--txpool.nolocals            为本地提交交易禁用价格豁免
--txpool.journal value       本地交易的磁盘日志：用于节点重启 (默认: "transactions.rlp")
--txpool.rejournal value     重新生成本地交易日志的时间间隔 (默认: 1小时)
--txpool.pricelimit value    加入交易池的最小的gas价格限制(默认: 1)
--txpool.pricebump value     价格波动百分比（相对之前已有交易） (默认: 10)
--txpool.accountslots value  每个帐户保证可执行的最少交易槽数量  (默认: 16)
--txpool.globalslots value   所有帐户可执行的最大交易槽数量 (默认: 4096)
--txpool.accountqueue value  每个帐户允许的最多非可执行交易槽数量 (默认: 64)
--txpool.globalqueue value   所有帐户非可执行交易最大槽数量  (默认: 1024)
--txpool.lifetime value      非可执行交易最大入队时间(默认: 3小时)

txpool内容的查看

> txpool.content
{
  pending: {},
  queued: {}
}

很显然，txpool中由两部分构成pending和queued组成。那么他们两者有什么分别呢。最明显的是一个为待打包状态，一个为队列中。这里我们发起了两笔不同的交易：

> eth.sendTransaction({from:"0xdae19174969a7404e222c24b6726e4d089c12768",to:"0x5929a871f57a1C5F7E4eA304CAe92DACD1C1556b",value:web3.toWei(0.01,"ether"),gasPrice:21000000000,nonce:2});
"0x7db7883bb23a31deb9f01b5e6fb28363b1aee1b9b6797ea8b5706be170a1187c"

> eth.sendTransaction({from:"0xdae19174969a7404e222c24b6726e4d089c12768",to:"0x5929a871f57a1C5F7E4eA304CAe92DACD1C1556b",value:web3.toWei(0.01,"ether")});
"0x2784a79a8c454c72700e7be3b31c1c98ceaea232ca4992a6830b0fc999ebb653"

很显然，第一笔交易指定了nonce为2，第二笔交易未指定nonce值，因为此地址没有发起过交易那么nonce值默认为0。这时我们再看一下txpool中的内容：

> txpool.content
{
  pending: {
    0xdAE19174969A7404e222c24B6726E4D089c12768: {
      0: {
        blockHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
        blockNumber: null,
        from: "0xdae19174969a7404e222c24b6726e4d089c12768",
        gas: "0x15f90",
        gasPrice: "0x1",
        hash: "0x2784a79a8c454c72700e7be3b31c1c98ceaea232ca4992a6830b0fc999ebb653",
        input: "0x",
        nonce: "0x0",
        r: "0xdabcd46d8d0b61e468d9f10119d544437f89cd094c35a89e5cbed298faf52c4a",
        s: "0x3670f23ecfb0a12e982a60438640fe042eefc50646a077de0244a8d67a84af9e",
        to: "0x5929a871f57a1c5f7e4ea304cae92dacd1c1556b",
        transactionIndex: "0x0",
        v: "0xa95",
        value: "0x2386f26fc10000"
      }
    }
  },
  queued: {
    0xdAE19174969A7404e222c24B6726E4D089c12768: {
      2: {
        blockHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
        blockNumber: null,
        from: "0xdae19174969a7404e222c24b6726e4d089c12768",
        gas: "0x15f90",
        gasPrice: "0x4e3b29200",
        hash: "0x7db7883bb23a31deb9f01b5e6fb28363b1aee1b9b6797ea8b5706be170a1187c",
        input: "0x",
        nonce: "0x2",
        r: "0xa8953a87c326c02da9d7a712d6c7ac0cd415cbc71ea0c24423f9e01b1fec65bd",
        s: "0x3faefc3a0db585a67f02996a7167890e41ff5fd8fd4be6efff3bea7a797fad29",
        to: "0x5929a871f57a1c5f7e4ea304cae92dacd1c1556b",
        transactionIndex: "0x0",
        v: "0xa96",
        value: "0x2386f26fc10000"
      }
    }
  }
}

现在txpool中有两笔交易，其中nonce为0的在pending中，nonce为2的在queued中。为什么只有nonce不同的两笔交易，在txpool中的位置却不同呢？

txpool的处理流程

首先，如果不传入nonce值，那么geth节点会默认计算当前地址已经发起了的交易中最大的nonce值为多少，然后将其+1，然后将此交易放置在pending中，等待节点打包。

其次，如果传入的nonce值过大，在进入txpool中检查到它之前的nonce并没有使用过，那么此笔交易不会发送到pending中，而且放置在queued中。只有当前面的nonce补齐之后，才会进入到pending中。那么，我们再发一笔交易把nonce补齐看看：

> eth.sendTransaction({from:"0xdae19174969a7404e222c24b6726e4d089c12768",to:"0x5929a871f57a1C5F7E4eA304CAe92DACD1C1556b",value:web3.toWei(0.01,"ether")});
"0x7ee17d38405c01bab4eec4d9dc62a6bba98283e243a2d9132187706485878ef5"

> txpool.content
{
  pending: {
    0xdAE19174969A7404e222c24B6726E4D089c12768: {
      0: {
        blockHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
        blockNumber: null,
        from: "0xdae19174969a7404e222c24b6726e4d089c12768",
        gas: "0x15f90",
        gasPrice: "0x1",
        hash: "0x2784a79a8c454c72700e7be3b31c1c98ceaea232ca4992a6830b0fc999ebb653",
        input: "0x",
        nonce: "0x0",
        r: "0xdabcd46d8d0b61e468d9f10119d544437f89cd094c35a89e5cbed298faf52c4a",
        s: "0x3670f23ecfb0a12e982a60438640fe042eefc50646a077de0244a8d67a84af9e",
        to: "0x5929a871f57a1c5f7e4ea304cae92dacd1c1556b",
        transactionIndex: "0x0",
        v: "0xa95",
        value: "0x2386f26fc10000"
      },
      1: {
        blockHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
        blockNumber: null,
        from: "0xdae19174969a7404e222c24b6726e4d089c12768",
        gas: "0x15f90",
        gasPrice: "0x1",
        hash: "0x7ee17d38405c01bab4eec4d9dc62a6bba98283e243a2d9132187706485878ef5",
        input: "0x",
        nonce: "0x1",
        r: "0xe03fb4d94b0ff04107c855bfd88a84ecdefb03f4c9b0cea5341591aa69d4751e",
        s: "0x4d2f60f4045e5492cd4818145cec73c78b00e0cff57026c4528d91a82dee76e1",
        to: "0x5929a871f57a1c5f7e4ea304cae92dacd1c1556b",
        transactionIndex: "0x0",
        v: "0xa96",
        value: "0x2386f26fc10000"
      },
      2: {
        blockHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
        blockNumber: null,
        from: "0xdae19174969a7404e222c24b6726e4d089c12768",
        gas: "0x15f90",
        gasPrice: "0x4e3b29200",
        hash: "0x7db7883bb23a31deb9f01b5e6fb28363b1aee1b9b6797ea8b5706be170a1187c",
        input: "0x",
        nonce: "0x2",
        r: "0xa8953a87c326c02da9d7a712d6c7ac0cd415cbc71ea0c24423f9e01b1fec65bd",
        s: "0x3faefc3a0db585a67f02996a7167890e41ff5fd8fd4be6efff3bea7a797fad29",
        to: "0x5929a871f57a1c5f7e4ea304cae92dacd1c1556b",
        transactionIndex: "0x0",
        v: "0xa96",
        value: "0x2386f26fc10000"
      }
    }
  },
  queued: {}
}

很明显，当中间的nonce被补齐之后，原来处于queued当中的交易被放置到了pending中。