rpc: add next to getdifficulty and gettarget

Obtain the difficulty / target for the next block without having to call getblocktemplate.
Sjors · Dec 31, 2024 · 7696188 · 7696188
1 parent da1eb29
commit 7696188
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Showing 3 changed files with 50 additions and 4 deletions.
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
@@ -29,6 +29,7 @@
 #include <net_processing.h>
 #include <node/blockstorage.h>
 #include <node/context.h>
+#include <node/miner.h>
 #include <node/transaction.h>
 #include <node/utxo_snapshot.h>
 #include <node/warnings.h>
@@ -68,6 +69,7 @@ using interfaces::Mining;
 using node::BlockManager;
 using node::NodeContext;
 using node::SnapshotMetadata;
+using node::UpdateTime;
 using util::MakeUnorderedList;
 
 std::tuple<std::unique_ptr<CCoinsViewCursor>, CCoinsStats, const CBlockIndex*>
@@ -431,7 +433,9 @@ static RPCHelpMan getdifficulty()
 {
     return RPCHelpMan{"getdifficulty",
                 "\nReturns the proof-of-work difficulty as a multiple of the minimum difficulty.\n",
-                {},
+                {
+                    {"next", RPCArg::Type::BOOL, RPCArg::Default{false}, "difficulty for the next block, if found now"},
+                },
                 RPCResult{
                     RPCResult::Type::NUM, "", "the proof-of-work difficulty as a multiple of the minimum difficulty."},
                 RPCExamples{
@@ -442,7 +446,26 @@ static RPCHelpMan getdifficulty()
 {
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
     LOCK(cs_main);
-    return GetDifficulty(*CHECK_NONFATAL(chainman.ActiveChain().Tip()));
+    CBlockIndex* tip{CHECK_NONFATAL(chainman.ActiveChain().Tip())};
+
+    bool next{false};
+    if (!request.params[0].isNull()) {
+        next = request.params[0].get_bool();
+    }
+
+    if (next) {
+        CBlock block{};
+        auto consensusParams{chainman.GetParams().GetConsensus()};
+        // This also updates nBits
+        UpdateTime(&block, consensusParams, tip);
+        CBlockIndex index(block);
+        index.pprev = tip;
+        index.nHeight = tip->nHeight + 1;
+        return GetDifficulty(index);
+    } else {
+        return GetDifficulty(*tip);
+    }
+
 },
     };
 }
@@ -451,7 +474,9 @@ static RPCHelpMan gettarget()
 {
     return RPCHelpMan{"gettarget",
                 "\nReturns the proof-of-work target.\n",
-                {},
+                {
+                    {"next", RPCArg::Type::BOOL, RPCArg::Default{false}, "target for the next block, if found now"},
+                },
                 RPCResult{
                     RPCResult::Type::STR_HEX, "", "the proof-of-work target."},
                 RPCExamples{
@@ -463,7 +488,24 @@ static RPCHelpMan gettarget()
     ChainstateManager& chainman = EnsureAnyChainman(request.context);
     LOCK(cs_main);
     CBlockIndex* tip{CHECK_NONFATAL(chainman.ActiveChain().Tip())};
-    return GetTarget(*tip, chainman.GetParams().GetConsensus().powLimit).GetHex();
+    auto consensusParams{chainman.GetParams().GetConsensus()};
+
+    bool next{false};
+    if (!request.params[0].isNull()) {
+        next = request.params[0].get_bool();
+    }
+
+    if (next) {
+        CBlock block{};
+        // This also updates nBits
+        UpdateTime(&block, consensusParams, tip);
+        CBlockIndex index(block);
+        index.pprev = tip;
+        index.nHeight = tip->nHeight + 1;
+        return GetTarget(index, consensusParams.powLimit).GetHex();
+    } else {
+        return GetTarget(*tip, consensusParams.powLimit).GetHex();
+    }
 },
     };
 }

diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
@@ -114,6 +114,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "getblock", 1, "verbose" },
     { "getblockheader", 1, "verbose" },
     { "getchaintxstats", 0, "nblocks" },
+    { "getdifficulty", 0, "next" },
+    { "gettarget", 0, "next" },
     { "gettransaction", 1, "include_watchonly" },
     { "gettransaction", 2, "verbose" },
     { "getrawtransaction", 1, "verbosity" },

diff --git a/test/functional/rpc_blockchain.py b/test/functional/rpc_blockchain.py
@@ -441,11 +441,13 @@ def _test_getdifficulty(self):
         # 1 hash in 2 should be valid, so difficulty should be 1/2**31
         # binary => decimal => binary math is why we do this check
         assert abs(difficulty * 2**31 - 1) < 0.0001
+        assert_equal(self.nodes[0].getdifficulty(next=True), difficulty)
 
     def _test_gettarget(self):
         self.log.info("Test gettarget")
         target = self.nodes[0].gettarget()
         assert_equal(target, REGTEST_TARGET_STR)
+        assert_equal(self.nodes[0].gettarget(next=True), REGTEST_TARGET_STR)
 
     def _test_getnetworkhashps(self):
         self.log.info("Test getnetworkhashps")