From 7a5fa7fa2de26b7aa5de76ae2e830dcbac6e11e4 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Thu, 10 Oct 2019 16:02:10 +1100
Subject: [PATCH] log: allow setting the default_sink

---
 log/level.hpp |  4 ++++
 log/log.cpp   | 24 ++++++++++++++++++++++--
 log/log.hpp   | 10 ++++------
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/log/level.hpp b/log/level.hpp
index e97a4593..59989969 100644
--- a/log/level.hpp
+++ b/log/level.hpp
@@ -12,6 +12,10 @@
 
 #include <string>
 
+// Windows.h or one of its friends defines a macro 'ERROR'. Screw Microsoft.
+#ifdef ERROR
+#undef ERROR
+#endif
 
 namespace cruft::log {
     ///////////////////////////////////////////////////////////////////////////
diff --git a/log/log.cpp b/log/log.cpp
index 3d926b8a..4b79151f 100644
--- a/log/log.cpp
+++ b/log/log.cpp
@@ -14,6 +14,7 @@
 
 #include "sink/console.hpp"
 
+#include <mutex>
 #include <map>
 #include <string>
 
@@ -42,11 +43,30 @@ cruft::log::needs_break (level_t level)
 
 
 ///////////////////////////////////////////////////////////////////////////////
+static std::once_flag s_sink_init;
+static std::unique_ptr<cruft::log::sink::base> s_default_sink;
+
+
+//-----------------------------------------------------------------------------
+cruft::log::sink::base&
+cruft::log::default_sink (std::unique_ptr<sink::base> value)
+{
+    s_default_sink = std::move (value);
+    return *s_default_sink;
+}
+
+
+//-----------------------------------------------------------------------------
 cruft::log::sink::base&
 cruft::log::default_sink ()
 {
-    static sink::console s_default_sink (PACKAGE_NAME);
-    return s_default_sink;
+    std::call_once (s_sink_init, [&] () {
+        default_sink (
+            std::make_unique<sink::console> (PACKAGE_NAME)
+        );
+    });
+
+    return *s_default_sink;
 }
 
 
diff --git a/log/log.hpp b/log/log.hpp
index d974bd87..58a9f710 100644
--- a/log/log.hpp
+++ b/log/log.hpp
@@ -13,19 +13,17 @@
 #include "sink/base.hpp"
 #include "../format.hpp"
 
-
-#include <iosfwd>
+#include <memory>
 #include <string>
 
-// Windows.h or one of its friends defines a macro 'ERROR'. Screw Microsoft.
-#ifdef ERROR
-#undef ERROR
-#endif
 
 namespace cruft::log {
     ///////////////////////////////////////////////////////////////////////////
     sink::base& default_sink (void);
+    sink::base& default_sink (std::unique_ptr<sink::base>);
 
+
+    //-------------------------------------------------------------------------
     void write (level_t, std::string const &msg);
     void write (level_t, char const *msg);
     void write (level_t, std::string_view msg);