Merge lp:~alan-griffiths/mir/add-mir-Server-add_pre_init_callback into lp:mir

[Alan Griffiths]

[mirserver] Add mir::Server::add_pre_init_callback() so that downstreams (e.g. lp:miral) can, for example, register DisplayConfigurationObservers before initialization starts (LP: #1645284)

[Mir CI Bot (mir-ci-bot)]

PASSED: Continuous integration, rev:3850
https://mir-jenkins.ubuntu.com/job/mir-ci/2276/
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review: Approve (continuous-integration)

[Andreas Pokorny (andreas-pokorny)]

sure

nice chaining..

review: Approve

[Cemil Azizoglu (cemil-azizoglu)]

No tests?

review: Needs Fixing

[Kevin DuBois (kdub)]

lgtm

review: Approve

[Daniel van Vugt (vanvugt)]

I don't mind (even without tests).

Not sure this chaining approach is better or worse than just using a list...

review: Approve

=== modified file 'include/server/mir/server.h'
--- include/server/mir/server.h	2016-10-04 06:35:05 +0000
+++ include/server/mir/server.h	2016-11-28 14:45:32 +0000
@@ -56,7 +56,7 @@
 namespace scene
 {
 class ApplicationNotRespondingDetector;
-class BufferStreamFactory; 
+class BufferStreamFactory;
 class PromptSessionListener;
 class PromptSessionManager;
 class SessionListener;
@@ -190,6 +190,11 @@
  *  These allow the user to insert logic into startup or error handling.
  *  For obvious reasons they should be called before run().
  *  @{ */
+    /// Add a callback to be invoked when the settings have been applied, but before
+    /// the server has been initialized. This allows client code to get access Mir objects.
+    /// If multiple callbacks are added they will be invoked in the sequence added.
+    void add_pre_init_callback(std::function<void()> const& pre_init_callback);
+
     /// Add a callback to be invoked when the server has been initialized,
     /// but before it starts. This allows client code to get access Mir objects.
     /// If multiple callbacks are added they will be invoked in the sequence added.

=== modified file 'src/server/server.cpp'
--- src/server/server.cpp	2016-11-02 05:07:18 +0000
+++ src/server/server.cpp	2016-11-28 14:45:32 +0000
@@ -148,6 +148,7 @@
     std::string config_file;
     std::shared_ptr<ServerConfiguration> server_config;
 
+    std::function<void()> pre_init_callback{[]{}};
     std::function<void()> init_callback{[]{}};
     std::function<void()> stop_callback{[]{}};
     int argc{0};
@@ -287,6 +288,19 @@
     self->argv = argv;
 }
 
+void mir::Server::add_pre_init_callback(std::function<void()> const& pre_init_callback)
+{
+    auto const& existing = self->pre_init_callback;
+
+    auto const updated = [=]
+        {
+            existing();
+            pre_init_callback();
+        };
+
+    self->pre_init_callback = updated;
+}
+
 void mir::Server::add_init_callback(std::function<void()> const& init_callback)
 {
     auto const& existing = self->init_callback;
@@ -387,6 +401,8 @@
         if (self->emergency_cleanup_handler)
             emergency_cleanup->add(self->emergency_cleanup_handler);
 
+        self->pre_init_callback();
+
         run_mir(
             *self->server_config,
             [&](DisplayServer&)

=== modified file 'src/server/symbols.map'
--- src/server/symbols.map	2016-11-15 23:48:01 +0000
+++ src/server/symbols.map	2016-11-28 14:45:32 +0000
@@ -8,7 +8,7 @@
     VTT?for?mir::shell::SystemCompositorWindowManager;
 
 # The following symbols come from running a script over the generated docs. Vis:
-# ../tools/process_doxygen_xml.py doc/xml/*.xml | grep "^mirserver public" | sed "s/mirserver public: /    /" | sort  
+# ../tools/process_doxygen_xml.py doc/xml/*.xml | grep "^mirserver public" | sed "s/mirserver public: /    /" | sort
     mir::check_for_termination_exception*;
     mir::clear_termination_exception*;
     mir::compositor::Compositor::Compositor*;
@@ -839,3 +839,10 @@
   };
  local: *;
 };
+
+MIR_SERVER_0.26 {
+ global:
+  extern "C++" {
+    mir::Server::add_pre_init_callback*;
+  };
+} MIR_SERVER_0.25;