Merge #11031: [rpc] deprecate estimatefee

048e0c3e2 [rpc] [tests] Add deprecated RPC test (Cristian Mircea Messel)
d4cdbd6fb [rpc] Deprecate estimatefee RPC (John Newbery)

Pull request description:

  Deprecates estimatefee in v0.16, for final removal in v0.17.

  This commit introduces a phased removal of RPC methods. RPC method is
  disabled by default in version x, but can be enabled by using the
  `-deprecatedrpc=<methodname>` argument. RPC method is removed entirely in version
  (x+1).

  This gives users fair warning that an RPC is to be removed, and time to change client software if necessary. Deprecation warnings in RPC return values or release notes are easily ignored.

  This is a more generic version of the approach I tried to use in #10841, which too late to make it into v0.15.

Tree-SHA512: 9695a600e84b812974387333e4a6805d18972da30befb754e9e4da77cd9815d00c5cc2ee0b0350bdbbdb5fdc6ba47789f8b2c6f5b15c8cd5a1deefcc4832da30

5 files changed, 17 insertions, 0 deletions

diff --git a/src/init.cpp b/src/init.cpp
index e80170b24d..55670c7dc6 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -430,6 +430,7 @@ std::string HelpMessage(HelpMessageMode mode)
         strUsage += HelpMessageOpt("-checkmempool=<n>", strprintf("Run checks every <n> transactions (default: %u)", defaultChainParams->DefaultConsistencyChecks()));
         strUsage += HelpMessageOpt("-checkpoints", strprintf("Disable expensive verification for known chain history (default: %u)", DEFAULT_CHECKPOINTS_ENABLED));
         strUsage += HelpMessageOpt("-disablesafemode", strprintf("Disable safemode, override a real safe mode event (default: %u)", DEFAULT_DISABLE_SAFEMODE));
+        strUsage += HelpMessageOpt("-deprecatedrpc=<method>", "Allows deprecated RPC method(s) to be used");
         strUsage += HelpMessageOpt("-testsafemode", strprintf("Force safe mode (default: %u)", DEFAULT_TESTSAFEMODE));
         strUsage += HelpMessageOpt("-dropmessagestest=<n>", "Randomly drop 1 of every <n> network messages");
         strUsage += HelpMessageOpt("-fuzzmessagestest=<n>", "Randomly fuzz 1 of every <n> network messages");
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index f0ffa07e12..5ac32dc974 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -789,6 +789,12 @@ UniValue estimatefee(const JSONRPCRequest& request)
             + HelpExampleCli("estimatefee", "6")
             );
 
+    if (!IsDeprecatedRPCEnabled("estimatefee")) {
+        throw JSONRPCError(RPC_METHOD_DEPRECATED, "estimatefee is deprecated and will be fully removed in v0.17. "
+            "To use estimatefee in v0.16, restart bitcoind with -deprecatedrpc=estimatefee.\n"
+            "Projects should transition to using estimatesmartfee before upgrading to v0.17");
+    }
+
     RPCTypeCheck(request.params, {UniValue::VNUM});
 
     int nBlocks = request.params[0].get_int();
diff --git a/src/rpc/protocol.h b/src/rpc/protocol.h
index 5c9c64f67d..056f93e7db 100644
--- a/src/rpc/protocol.h
+++ b/src/rpc/protocol.h
@@ -57,6 +57,7 @@ enum RPCErrorCode
     RPC_VERIFY_REJECTED             = -26, //!< Transaction or block was rejected by network rules
     RPC_VERIFY_ALREADY_IN_CHAIN     = -27, //!< Transaction already in chain
     RPC_IN_WARMUP                   = -28, //!< Client still warming up
+    RPC_METHOD_DEPRECATED           = -32, //!< RPC method is deprecated
 
     //! Aliases for backward compatibility
     RPC_TRANSACTION_ERROR           = RPC_VERIFY_ERROR,
diff --git a/src/rpc/server.cpp b/src/rpc/server.cpp
index 428ab3b9b0..a73b697e01 100644
--- a/src/rpc/server.cpp
+++ b/src/rpc/server.cpp
@@ -382,6 +382,13 @@ void JSONRPCRequest::parse(const UniValue& valRequest)
         throw JSONRPCError(RPC_INVALID_REQUEST, "Params must be an array or object");
 }
 
+bool IsDeprecatedRPCEnabled(const std::string& method)
+{
+    const std::vector<std::string> enabled_methods = gArgs.GetArgs("-deprecatedrpc");
+
+    return find(enabled_methods.begin(), enabled_methods.end(), method) != enabled_methods.end();
+}
+
 static UniValue JSONRPCExecOne(const UniValue& req)
 {
     UniValue rpc_result(UniValue::VOBJ);
diff --git a/src/rpc/server.h b/src/rpc/server.h
index 777acbcb94..31d6304271 100644
--- a/src/rpc/server.h
+++ b/src/rpc/server.h
@@ -171,6 +171,8 @@ public:
     bool appendCommand(const std::string& name, const CRPCCommand* pcmd);
 };
 
+bool IsDeprecatedRPCEnabled(const std::string& method);
+
 extern CRPCTable tableRPC;
 
 /**