Get Mining Candidate(GMC)
本文介绍GMC，面向未来的挖矿API。
什么是GMC
GMC 是一种为挖矿改进的 API，确保矿工在MVC网络中可以通过挖掘大区块来扩展，而不会因为区块大小的增长而受到 RPC 接口的限制。GMC
基于 Andrew Stone 和 Johan van der Hoeven 的工作，通过优化getblocktemplate接口，将其中的交易列表移除，只提供当前在内存池/区块候选中所有交易的Merkle
Proof证明来组装区块。
新增的 RPC 方法有 getminingcandidate 和 submitminingsolution。它们是传统的 getblocktemplate 和 submitblock
的平替接口。这些 RPC 调用不会将整个区块传递给矿池（在通过 RPC
接口传输时，整个区块的大小是实际区块大小的两倍多，这是因为RPC接口使用HEX编码格式，相对于二进制区块要大）。相反，它们传递候选区块头、预装配的
coinbase 交易和 coinbase 默克尔证明。这基本上与通过 Stratum
协议传递给哈希硬件的数据相同。也就是说，由于Merkle树的性质，挖矿所需要的数据量是对数O(logN)级别的。而并非线性O(N)
级别的，也就显著降低了挖矿所需要的带宽和负载。
矿池使用 getminingcandidate 接收前述的区块信息和一个跟踪标识符 (ID)。在找到一个新块后 30 秒内，MVC节点会默认清除未完成的
ID。矿工可以创建（或修改）新的coinbase 交易和区块头字段，以创建不同的候选项供哈希硬件使用。然后，通过 Stratum
将这些候选项转发给哈希硬件。当找到一个区块解（挖出新区块）时，矿池可以通过 submitminingsolution 将解决方案提交回节点。
使用 RPC getminingcandidate 和 RPC submitminingsolution 的一些好处包括：
- 大大减少带宽和延迟，特别是对于大区块。这种 RPC 需要 log2(区块大小) 的数据，这是由于默克尔分支的大小决定的。
- 更快的 JSON 解析和创建。
- 简洁的 JSON。
接口文档
详细的rpc接口以及参数说明可以参考mining command。
RPC getminingcandidate
Arguments: - [bool] provide_coinbase_tx (Optional - default is false)
返回值
| Variable | Description |
|---|---|
| [uuid] id | The assigned id from mvcd. This must be provided with submitting a potential solution |
| [hex string] prevHash | Big Endian hash of the previous block |
| [hex string] Coinbase (optional) | Suggested coinbase transaction is provided. Miner is free to supply their own or alter the supplied one. Altering will require parsing and splitting the coinbase in order to splice in/out data as required. Requires Wallet to be enabled. Only returned when provide_coinbase_tx argument is set to true. Returns error if Wallet is not enabled |
| [int32_t] version | The block version |
| [int64_t] coinbaseValue | Total funds available for the coinbase tx (in Satoshis) |
| [uint32_t] nBits | Compressed hexadecimal difficulty |
| [uint32_t] time | Current block time |
| [int] height | The candidate block height |
| [array] merkleProof | Merkle branch/path for the block, used to calculate the Merkle Root of the block candidate. This is a list of Little-Endian hex strings ordered from top to bottom |
返回值例
{
"id": "a5f1f38b-2a00-4913-833a-bbcbb39d5d2c",
"prevhash": "0000000020493e205694c9fcb42f7d4ce5d85e230d52fccc90a6354e13940396",
"coinbase": "02000000010000000000000000000000000000000000000000000000000000000000000000ffffffff0503878b1300ffffffff01c5a4a80400000000232103b8310da7c413106c6ce63814dbcd366c55e8ae39c8c43c1fdaeb76df56e4ff7dac00000000",
"version": 536870912,
"nBits": "1c4877e8",
"time": 1548132190,
"height": 1280903,
"merkleProof": [
"497d51f3a933dd6e933cd37a4a5799066086d4ff45dce23f0819c7a6c7174ccb",
"c2de445eda326b4afcec1291fc0dad3c526ddb551cbb01e2e10a10ebe79d2482",
"7f417e9de2e8c37566141e3057eec37747a924117413ee7c2b8f902dd81b095f",
"b25810a0b826ea8bf848d6e3f98f6c0bf4d097f0d1854d50c6e12988f29757d6"
]
}
RPC submitminingsolution
Arguments: A JSON String containing the below fields.
| Variable | Description |
|---|---|
| [uuid] id | The id supplied by getminingcandidate |
| [uint32_t] nonce | Miner generated nonce |
| [hex string] coinbase | The crafted or modified coinbase transaction (Optional) |
| [uint32_t] time | Block time (Optional - must fall within the mintime/maxtime consensus rules ) |
| [uint32_t] version | Block version (Optional) |
请求例
{
"id": a5f1f38b-2a00-4913-833a-bbcbb39d5d2c,
"nonce": 1804358173,
"coinbase": "...00ffffffff10028122000b2fc7237b322f414431322ffff...",
"time": 1528925410,
"version": 536870912
}
返回值例
Success: returns true
Failure: JSONRPCException or error reason comprising of but not limited to the following.
| Error | Description |
|---|---|
| Block candidate ID not found | Required ID was not found, ID is supplied by the corresponding getminingcandidate call |
| nonce not found | The nonce was not supplied or not recognized |
| coinbase decode failed | The supplied coinbase was unable to be parsed |
Other possible errors can result from the SubmitBlock (BIP22) method in which submitminingsolution ultimately calls upon.