Merge #19399: refactor: Replace RecursiveMutex with Mutex in rpc/server.cpp

6fdfeeb refactor: Replace RecursiveMutex with Mutex in rpc/server.cpp (Hennadii Stepanov)

Pull request description:

  The functions that could lock this mutex, i.e., `SetRPCWarmupStatus()`, `SetRPCWarmupFinished()`, `RPCIsInWarmup()`, `CRPCTable::execute()`, do not call itself recursively, and do not call each other either directly or indirectly. Therefore, the `g_rpc_warmup_mutex` could be a non-recursive mutex.

  Related to #19303.

ACKs for top commit:
  laanwj:
    ACK 6fdfeeb
  MarcoFalke:
    ACK 6fdfeeb

Tree-SHA512: 05a8ac58c0cd6a3c9afad9e06ad78059642e3e97715e129f379c0bf6dccdb58e70d05d965f23e7432fd3f02d7f97967a778ffb8e424837891d9d785a9e98964c

Author: laanwj

src/rpc/server.cpp

@@ -20,10 +20,10 @@
 #include <mutex>
 #include <unordered_map>
 
-static RecursiveMutex cs_rpcWarmup;
+static Mutex g_rpc_warmup_mutex;
 static std::atomic<bool> g_rpc_running{false};
-static bool fRPCInWarmup GUARDED_BY(cs_rpcWarmup) = true;
-static std::string rpcWarmupStatus GUARDED_BY(cs_rpcWarmup) = "RPC server started";
+static bool fRPCInWarmup GUARDED_BY(g_rpc_warmup_mutex) = true;
+static std::string rpcWarmupStatus GUARDED_BY(g_rpc_warmup_mutex) = "RPC server started";
 /* Timer-creating functions */
 static RPCTimerInterface* timerInterface = nullptr;
 /* Map of name to timer. */
@@ -327,20 +327,20 @@ void RpcInterruptionPoint()
 
 void SetRPCWarmupStatus(const std::string& newStatus)
 {
-    LOCK(cs_rpcWarmup);
+    LOCK(g_rpc_warmup_mutex);
     rpcWarmupStatus = newStatus;
 }
 
 void SetRPCWarmupFinished()
 {
-    LOCK(cs_rpcWarmup);
+    LOCK(g_rpc_warmup_mutex);
     assert(fRPCInWarmup);
     fRPCInWarmup = false;
 }
 
 bool RPCIsInWarmup(std::string *outStatus)
 {
-    LOCK(cs_rpcWarmup);
+    LOCK(g_rpc_warmup_mutex);
     if (outStatus)
         *outStatus = rpcWarmupStatus;
     return fRPCInWarmup;
@@ -439,7 +439,7 @@ UniValue CRPCTable::execute(const JSONRPCRequest &request) const
 {
     // Return immediately if in warmup
     {
-        LOCK(cs_rpcWarmup);
+        LOCK(g_rpc_warmup_mutex);
         if (fRPCInWarmup)
             throw JSONRPCError(RPC_IN_WARMUP, rpcWarmupStatus);
     }