Merge #18740: Remove g_rpc_node global

b3f7f375efb9a9ca9a7a4f2caf41fe3df2262520 refactor: Remove g_rpc_node global (Russell Yanofsky)
ccb5059ee89f6e8dc31ba5b82830b384890bb65e scripted-diff: Remove g_rpc_node references (Russell Yanofsky)
6fca33b2edc09ed62dab2323c780b31585de1750 refactor: Pass NodeContext to RPC and REST methods through util::Ref (Russell Yanofsky)
691c817b340d10e806dc3b1834d2a8fcc5e681fd Add util::Ref class as temporary alternative for c++17 std::any (Russell Yanofsky)

Pull request description:

  This PR removes the `g_rpc_node` global, to get same benefits we see removing other globals and make RPC code more testable, modular, and reusable.

  This uses a hybrid of the approaches suggested in #17548. Instead of using `std::any`, which isn't available in c++11, or `void*`, which isn't type safe, it uses a small new `util::Ref` helper class, which acts like a simplified `std::any` that only holds references, not values.

  Motivation for writing this was to provide an simpler alternative to #18647 by Harris Brakmić (brakmic) which avoids some shortcomings of that PR (https://github.com/bitcoin/bitcoin/pull/18647#issuecomment-617878826)

ACKs for top commit:
  MarcoFalke:
    re-ACK b3f7f375ef, only change is adding back const and more tests 🚾
  ajtowns:
    ACK b3f7f375efb9a9ca9a7a4f2caf41fe3df2262520

Tree-SHA512: 56292268a001bdbe34d641db1180c215351503966ff451e55cc96c9137f1d262225d7d7733de9c9da7ce7d7a4b34213a98c2476266b58c89dbbb0f3cb5aa5d70

1 files changed, 9 insertions, 8 deletions

diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 59ab80bcd5..bcaed1ef88 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -227,7 +227,7 @@ static UniValue generatetodescriptor(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, error);
     }
 
-    const CTxMemPool& mempool = EnsureMemPool();
+    const CTxMemPool& mempool = EnsureMemPool(request.context);
 
     return generateBlocks(mempool, coinbase_script, num_blocks, max_tries);
 }
@@ -265,7 +265,7 @@ static UniValue generatetoaddress(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Error: Invalid address");
     }
 
-    const CTxMemPool& mempool = EnsureMemPool();
+    const CTxMemPool& mempool = EnsureMemPool(request.context);
 
     CScript coinbase_script = GetScriptForDestination(destination);
 
@@ -311,7 +311,7 @@ static UniValue generateblock(const JSONRPCRequest& request)
         coinbase_script = GetScriptForDestination(destination);
     }
 
-    const CTxMemPool& mempool = EnsureMemPool();
+    const CTxMemPool& mempool = EnsureMemPool(request.context);
 
     std::vector<CTransactionRef> txs;
     const auto raw_txs_or_txids = request.params[1].get_array();
@@ -403,7 +403,7 @@ static UniValue getmininginfo(const JSONRPCRequest& request)
             }.Check(request);
 
     LOCK(cs_main);
-    const CTxMemPool& mempool = EnsureMemPool();
+    const CTxMemPool& mempool = EnsureMemPool(request.context);
 
     UniValue obj(UniValue::VOBJ);
     obj.pushKV("blocks",           (int)::ChainActive().Height());
@@ -449,7 +449,7 @@ static UniValue prioritisetransaction(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Priority is no longer supported, dummy argument to prioritisetransaction must be 0.");
     }
 
-    EnsureMemPool().PrioritiseTransaction(hash, nAmount);
+    EnsureMemPool(request.context).PrioritiseTransaction(hash, nAmount);
     return true;
 }
 
@@ -635,17 +635,18 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
     if (strMode != "template")
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");
 
-    if(!g_rpc_node->connman)
+    NodeContext& node = EnsureNodeContext(request.context);
+    if(!node.connman)
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
 
-    if (g_rpc_node->connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
+    if (node.connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
         throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, PACKAGE_NAME " is not connected!");
 
     if (::ChainstateActive().IsInitialBlockDownload())
         throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
 
     static unsigned int nTransactionsUpdatedLast;
-    const CTxMemPool& mempool = EnsureMemPool();
+    const CTxMemPool& mempool = EnsureMemPool(request.context);
 
     if (!lpval.isNull())
     {