[RPC] Add interface to access mempool stats

src/Makefile.am

@@ -461,6 +461,7 @@ libbitcoin_node_a_SOURCES = \
   rpc/txoutproof.cpp \
   script/sigcache.cpp \
   signet.cpp \
+  stats/rpc_stats.cpp \
   stats/stats.cpp \
   timedata.cpp \
   torcontrol.cpp \

src/rpc/register.h

@@ -24,6 +24,7 @@ void RegisterRawTransactionRPCCommands(CRPCTable &tableRPC);
 void RegisterSignMessageRPCCommands(CRPCTable&);
 void RegisterSignerRPCCommands(CRPCTable &tableRPC);
 void RegisterTxoutProofRPCCommands(CRPCTable&);
+void RegisterStatsRPCCommands(CRPCTable&);
 
 static inline void RegisterAllCoreRPCCommands(CRPCTable &t)
 {
@@ -40,6 +41,7 @@ static inline void RegisterAllCoreRPCCommands(CRPCTable &t)
     RegisterSignerRPCCommands(t);
 #endif // ENABLE_EXTERNAL_SIGNER
     RegisterTxoutProofRPCCommands(t);
+    RegisterStatsRPCCommands(t);
 }
 
 #endif // BITCOIN_RPC_REGISTER_H

src/stats/rpc_stats.cpp

@@ -0,0 +1,79 @@
+// Copyright (c) 2016 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <rpc/server.h>
+#include <rpc/util.h>
+#include <stats/stats.h>
+#include <util/strencodings.h>
+
+#include <stdint.h>
+
+#include <univalue.h>
+
+static RPCHelpMan getmempoolstats()
+{
+    return RPCHelpMan{"getmempoolstats",
+                "\nReturns the collected mempool statistics (non-linear non-interpolated samples).\n",
+                {},
+                RPCResult{
+                    RPCResult::Type::OBJ, "", "",
+                    {
+                        {RPCResult::Type::NUM_TIME, "time_from", "Timestamp, first sample"},
+                        {RPCResult::Type::NUM_TIME, "time_to", "Timestamp, last sample"},
+                        {RPCResult::Type::ARR, "samples", "",
+                        {
+                            {RPCResult::Type::ARR_FIXED, "", "",
+                            {
+                                {RPCResult::Type::NUM, "", "Sample time in seconds (relative to other sample times only)"},
+                                {RPCResult::Type::NUM, "", "Number of transactions in the memory pool"},
+                                {RPCResult::Type::NUM, "", "Memory usage by memory pool"},
+                                {RPCResult::Type::NUM, "", "Minimum fee per kB"},
+                            }},
+                        }},
+                    }},
+                RPCExamples{
+                    HelpExampleCli("getmempoolstats", "")
+            + HelpExampleRpc("getmempoolstats", "")
+                },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+    // get stats from the core stats model
+    uint64_t timeFrom = 0;
+    uint64_t timeTo = 0;
+    mempoolSamples_t samples = CStats::DefaultStats()->mempoolGetValuesInRange(timeFrom, timeTo);
+
+    // use "flat" json encoding for performance reasons
+    UniValue samplesObj(UniValue::VARR);
+    for (struct CStatsMempoolSample& sample : samples) {
+        UniValue singleSample(UniValue::VARR);
+        singleSample.push_back(UniValue((uint64_t)sample.m_time_delta));
+        singleSample.push_back(UniValue(sample.m_tx_count));
+        singleSample.push_back(UniValue(sample.m_dyn_mem_usage));
+        singleSample.push_back(UniValue(sample.m_min_fee_per_k));
+        samplesObj.push_back(singleSample);
+    }
+
+    UniValue result(UniValue::VOBJ);
+    result.pushKV("time_from", timeFrom);
+    result.pushKV("time_to", timeTo);
+    result.pushKV("samples", samplesObj);
+
+    return result;
+},
+    };
+}
+
+void RegisterStatsRPCCommands(CRPCTable& t)
+{
+// clang-format off
+static const CRPCCommand commands[] =
+{ //  category              actor (function)
+  //  --------------------- ------------------------
+    { "stats",              &getmempoolstats,                    },
+};
+// clang-format on
+    for (const auto& c : commands) {
+        t.appendCommand(c.name, &c);
+    }
+}

test/functional/rpc_help.py

@@ -103,7 +103,7 @@ class HelpRpcTest(BitcoinTestFramework):
         # command titles
         titles = [line[3:-3] for line in node.help().splitlines() if line.startswith('==')]
 
-        components = ['Blockchain', 'Control', 'Mining', 'Network', 'Rawtransactions', 'Util']
+        components = ['Blockchain', 'Control', 'Mining', 'Network', 'Rawtransactions', 'Stats', 'Util']
 
         if self.is_wallet_compiled():
             components.append('Wallet')