multiprocess: Add type conversion code for serializable types

Allow any C++ object that has Serialize and Unserialize methods and can be
serialized to a bitcoin CDataStream to be converted to a capnproto Data field
and passed as arguments or return values to capnproto methods using the Data
type.

Extend IPC unit test to cover this and verify the serialization happens
correctly.

3 files changed, 8 insertions, 1 deletions

diff --git a/src/test/ipc_test.capnp b/src/test/ipc_test.capnp
index f8473a4dec..7b970e2aff 100644
--- a/src/test/ipc_test.capnp
+++ b/src/test/ipc_test.capnp
@@ -9,7 +9,9 @@ $Cxx.namespace("gen");
 
 using Proxy = import "/mp/proxy.capnp";
 $Proxy.include("test/ipc_test.h");
+$Proxy.includeTypes("ipc/capnp/common-types.h");
 
 interface FooInterface $Proxy.wrap("FooImplementation") {
     add @0 (a :Int32, b :Int32) -> (result :Int32);
+    passOutPoint @1 (arg :Data) -> (result :Data);
 }
diff --git a/src/test/ipc_test.cpp b/src/test/ipc_test.cpp
index b84255f68b..f835859705 100644
--- a/src/test/ipc_test.cpp
+++ b/src/test/ipc_test.cpp
@@ -2,8 +2,8 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <mp/proxy-types.h>
 #include <logging.h>
+#include <mp/proxy-types.h>
 #include <test/ipc_test.capnp.h>
 #include <test/ipc_test.capnp.proxy.h>
 #include <test/ipc_test.h>
@@ -51,6 +51,10 @@ void IpcTest()
     // Test: make sure arguments were sent and return value is received
     BOOST_CHECK_EQUAL(foo->add(1, 2), 3);
 
+    COutPoint txout1{Txid::FromUint256(uint256{100}), 200};
+    COutPoint txout2{foo->passOutPoint(txout1)};
+    BOOST_CHECK(txout1 == txout2);
+
     // Test cleanup: disconnect pipe and join thread
     disconnect_client();
     thread.join();
diff --git a/src/test/ipc_test.h b/src/test/ipc_test.h
index 61c85b5a47..f100ae8c5d 100644
--- a/src/test/ipc_test.h
+++ b/src/test/ipc_test.h
@@ -11,6 +11,7 @@ class FooImplementation
 {
 public:
     int add(int a, int b) { return a + b; }
+    COutPoint passOutPoint(COutPoint o) { return o; }
 };
 
 void IpcTest();