From af82884ab7c485c8b4c5ac93c308127c39c196be Mon Sep 17 00:00:00 2001
From: Daniel Kraft <d@domob.eu>
Date: Wed, 29 Oct 2014 18:08:31 +0100
Subject: Add "warmup mode" for RPC server.

Start the RPC server before doing all the (expensive) startup
initialisations like loading the block index.  Until the node is ready,
return all calls immediately with a new error signalling "in warmup"
with an appropriate status message (similar to the init message).

This is useful for RPC clients to know that the server is there (e. g.,
they don't have to start it) but not yet available.  It is used in
Namecoin and Huntercoin already for some time, and there exists a UI
hooked onto the RPC interface that actively uses this to its advantage.
---
 src/rpcserver.cpp | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'src/rpcserver.cpp')

diff --git a/src/rpcserver.cpp b/src/rpcserver.cpp
index 08ed73f6d..cc80887ba 100644
--- a/src/rpcserver.cpp
+++ b/src/rpcserver.cpp
@@ -34,6 +34,10 @@ using namespace std;
 static std::string strRPCUserColonPass;
 
 static bool fRPCRunning = false;
+static bool fRPCInWarmup = true;
+static std::string rpcWarmupStatus("RPC server started");
+static CCriticalSection cs_rpcWarmup;
+
 //! These are created by StartRPCThreads, destroyed in StopRPCThreads
 static asio::io_service* rpc_io_service = NULL;
 static map<string, boost::shared_ptr<deadline_timer> > deadlineTimers;
@@ -744,6 +748,19 @@ bool IsRPCRunning()
     return fRPCRunning;
 }
 
+void SetRPCWarmupStatus(const std::string& newStatus)
+{
+    LOCK(cs_rpcWarmup);
+    rpcWarmupStatus = newStatus;
+}
+
+void SetRPCWarmupFinished()
+{
+    LOCK(cs_rpcWarmup);
+    assert(fRPCInWarmup);
+    fRPCInWarmup = false;
+}
+
 void RPCRunHandler(const boost::system::error_code& err, boost::function<void(void)> func)
 {
     if (!err)
@@ -870,6 +887,13 @@ static bool HTTPReq_JSONRPC(AcceptedConnection *conn,
         if (!read_string(strRequest, valRequest))
             throw JSONRPCError(RPC_PARSE_ERROR, "Parse error");
 
+        // Return immediately if in warmup
+        {
+            LOCK(cs_rpcWarmup);
+            if (fRPCInWarmup)
+                throw JSONRPCError(RPC_IN_WARMUP, rpcWarmupStatus);
+        }
+
         string strReply;
 
         // singleton request
-- 
cgit v1.2.3