qt: allow `walletpassphrase` in debug console without -server

Currently it is only possible to use `walletpassphrase` to unlock the
wallet when bitcoin is started in server mode.

Almost everything that manipulates the wallet in the RPC console
needs the wallet to be unlocked and is thus unusable without -server.

This is pretty unintuitive to me, and I'm sure it's even more confusing
to users.

Solve this with a very minimal change: by making the GUI start a
dummy RPC thread just to handle timeouts.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/rpcserver.cpp b/src/rpcserver.cpp
index 9d34a900ff..0d9e95402b 100644
--- a/src/rpcserver.cpp
+++ b/src/rpcserver.cpp
@@ -38,6 +38,7 @@ static asio::io_service* rpc_io_service = NULL;
 static map<string, boost::shared_ptr<deadline_timer> > deadlineTimers;
 static ssl::context* rpc_ssl_context = NULL;
 static boost::thread_group* rpc_worker_group = NULL;
+static boost::asio::io_service::work *rpc_dummy_work = NULL;
 
 void RPCTypeCheck(const Array& params,
                   const list<Value_type>& typesExpected,
@@ -607,6 +608,19 @@ void StartRPCThreads()
         rpc_worker_group->create_thread(boost::bind(&asio::io_service::run, rpc_io_service));
 }
 
+void StartDummyRPCThread()
+{
+    if(rpc_io_service == NULL)
+    {
+        rpc_io_service = new asio::io_service();
+        /* Create dummy "work" to keep the thread from exiting when no timeouts active,
+         * see http://www.boost.org/doc/libs/1_51_0/doc/html/boost_asio/reference/io_service.html#boost_asio.reference.io_service.stopping_the_io_service_from_running_out_of_work */
+        rpc_dummy_work = new asio::io_service::work(*rpc_io_service);
+        rpc_worker_group = new boost::thread_group();
+        rpc_worker_group->create_thread(boost::bind(&asio::io_service::run, rpc_io_service));
+    }
+}
+
 void StopRPCThreads()
 {
     if (rpc_io_service == NULL) return;
@@ -615,6 +629,7 @@ void StopRPCThreads()
     rpc_io_service->stop();
     if (rpc_worker_group != NULL)
         rpc_worker_group->join_all();
+    delete rpc_dummy_work; rpc_dummy_work = NULL;
     delete rpc_worker_group; rpc_worker_group = NULL;
     delete rpc_ssl_context; rpc_ssl_context = NULL;
     delete rpc_io_service; rpc_io_service = NULL;