refactor: Move src/interfaces/*.cpp files to libbitcoin_common.a

These belong in libbitcoin_common.a, not libbitcoin_util.a, because they aren't
general-purpose utilities, they just contain common code that is used by both
the node and the wallet. Another reason to reason to not include these in
libbitcoin_util.a is to prevent them from being used by the kernel library.

Author: ryanofsky

src/Makefile.am

@@ -633,6 +633,7 @@ libbitcoin_common_a_SOURCES = \
   chainparams.cpp \
   coins.cpp \
   common/bloom.cpp \
+  common/interfaces.cpp \
   common/run_command.cpp \
   compressor.cpp \
   core_read.cpp \
@@ -678,9 +679,6 @@ libbitcoin_util_a_SOURCES = \
   chainparamsbase.cpp \
   clientversion.cpp \
   fs.cpp \
-  interfaces/echo.cpp \
-  interfaces/handler.cpp \
-  interfaces/init.cpp \
   logging.cpp \
   random.cpp \
   randomenv.cpp \

src/interfaces/handler.cpp renamed to src/common/interfaces.cpp

@@ -1,17 +1,26 @@
-// Copyright (c) 2018-2021 The Bitcoin Core developers
+// Copyright (c) 2021 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include <interfaces/echo.h>
 #include <interfaces/handler.h>
 
-
 #include <boost/signals2/connection.hpp>
+#include <memory>
 #include <utility>
 
-namespace interfaces {
+namespace common {
 namespace {
+class CleanupHandler : public interfaces::Handler
+{
+public:
+    explicit CleanupHandler(std::function<void()> cleanup) : m_cleanup(std::move(cleanup)) {}
+    ~CleanupHandler() override { if (!m_cleanup) return; m_cleanup(); m_cleanup = nullptr; }
+    void disconnect() override { if (!m_cleanup) return; m_cleanup(); m_cleanup = nullptr; }
+    std::function<void()> m_cleanup;
+};
 
-class HandlerImpl : public Handler
+class HandlerImpl : public interfaces::Handler
 {
 public:
     explicit HandlerImpl(boost::signals2::connection connection) : m_connection(std::move(connection)) {}
@@ -21,25 +30,24 @@ class HandlerImpl : public Handler
     boost::signals2::scoped_connection m_connection;
 };
 
-class CleanupHandler : public Handler
+class EchoImpl : public interfaces::Echo
 {
 public:
-    explicit CleanupHandler(std::function<void()> cleanup) : m_cleanup(std::move(cleanup)) {}
-    ~CleanupHandler() override { if (!m_cleanup) return; m_cleanup(); m_cleanup = nullptr; }
-    void disconnect() override { if (!m_cleanup) return; m_cleanup(); m_cleanup = nullptr; }
-    std::function<void()> m_cleanup;
+    std::string echo(const std::string& echo) override { return echo; }
 };
-
 } // namespace
+} // namespace common
 
-std::unique_ptr<Handler> MakeHandler(boost::signals2::connection connection)
+namespace interfaces {
+std::unique_ptr<Handler> MakeHandler(std::function<void()> cleanup)
 {
-    return std::make_unique<HandlerImpl>(std::move(connection));
+    return std::make_unique<common::CleanupHandler>(std::move(cleanup));
 }
 
-std::unique_ptr<Handler> MakeHandler(std::function<void()> cleanup)
+std::unique_ptr<Handler> MakeHandler(boost::signals2::connection connection)
 {
-    return std::make_unique<CleanupHandler>(std::move(cleanup));
+    return std::make_unique<common::HandlerImpl>(std::move(connection));
 }
 
+std::unique_ptr<Echo> MakeEcho() { return std::make_unique<common::EchoImpl>(); }
 } // namespace interfaces

src/interfaces/echo.cpp

@@ -5,18 +5,19 @@
 #ifndef BITCOIN_INTERFACES_INIT_H
 #define BITCOIN_INTERFACES_INIT_H
 
+#include <interfaces/chain.h>
+#include <interfaces/echo.h>
+#include <interfaces/node.h>
+#include <interfaces/wallet.h>
+
 #include <memory>
 
 namespace node {
 struct NodeContext;
 } // namespace node
 
 namespace interfaces {
-class Chain;
-class Echo;
 class Ipc;
-class Node;
-class WalletLoader;
 
 //! Initial interface created when a process is first started, and used to give
 //! and get access to other interfaces (Node, Chain, Wallet, etc).
@@ -29,11 +30,11 @@ class Init
 {
 public:
     virtual ~Init() = default;
-    virtual std::unique_ptr<Node> makeNode();
-    virtual std::unique_ptr<Chain> makeChain();
-    virtual std::unique_ptr<WalletLoader> makeWalletLoader(Chain& chain);
-    virtual std::unique_ptr<Echo> makeEcho();
-    virtual Ipc* ipc();
+    virtual std::unique_ptr<Node> makeNode() { return nullptr; }
+    virtual std::unique_ptr<Chain> makeChain() { return nullptr; }
+    virtual std::unique_ptr<WalletLoader> makeWalletLoader(Chain& chain) { return nullptr; }
+    virtual std::unique_ptr<Echo> makeEcho() { return nullptr; }
+    virtual Ipc* ipc() { return nullptr; }
 };
 
 //! Return implementation of Init interface for the node process. If the argv