Let old/new backends co-exist

Now both the old and the new backends are compiled in, the user can
choose which one to use with a command line switch.

Lower the barrier for testing.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

.circleci/config.yml

@@ -43,57 +43,46 @@ jobs:
     <<: *defaults
     steps:
       - build:
-          build-config: -Dbuild_docs=true -Dnew_backends=true
+          build-config: -Dbuild_docs=true
   minimal:
     <<: *defaults
     steps:
       - build:
-          build-config: -Dopengl=false -Ddbus=false -Dregex=false -Dconfig_file=false -Dnew_backends=true
+          build-config: -Dopengl=false -Ddbus=false -Dregex=false -Dconfig_file=false
   nogl:
     <<: *defaults
     steps:
       - build:
-          build-config: -Dopengl=false -Dnew_backends=true
+          build-config: -Dopengl=false
   noregex:
     <<: *defaults
     steps:
       - build:
-          build-config: -Dregex=false -Dnew_backends=true
+          build-config: -Dregex=false
   clang_basic:
     <<: *defaults
     steps:
       - build:
           cc: clang-6.0
-          build-config: -Dnew_backends=true
+          build-config:
   clang_minimal:
     <<: *defaults
     steps:
       - build:
           cc: clang-6.0
-          build-config: -Dopengl=false -Ddbus=false -Dregex=false -Dconfig_file=false -Dnew_backends=true
+          build-config: -Dopengl=false -Ddbus=false -Dregex=false -Dconfig_file=false
   clang_nogl:
     <<: *defaults
     steps:
       - build:
           cc: clang-6.0
-          build-config: -Dopengl=false -Dnew_backends=true
+          build-config: -Dopengl=false
   clang_noregex:
     <<: *defaults
     steps:
       - build:
           cc: clang-6.0
-          build-config: -Dregex=false -Dnew_backends=true
-  clang_basic_nonew:
-    <<: *defaults
-    steps:
-      - build:
-          cc: clang-6.0
-          build-config:
-  basic_nonew:
-    <<: *defaults
-    steps:
-      - build:
-          build-config:
+          build-config: -Dregex=false
 
 workflows:
   all_builds:
@@ -104,8 +93,6 @@ workflows:
       - clang_minimal
       - nogl
       - clang_nogl
-      - clang_basic_nonew
-      - basic_nonew
 #     - test-xvfb
 
 # vim: set sw=2 ts=8 et:

man/compton.1.asciidoc

@@ -76,6 +76,9 @@ OPTIONS
 *--log-file*::
 	Set the log file. If *--log-file* is never specified, logs will be written to stderr. Otherwise, logs will to writeen to the given file, though some of the early logs might still be written to the stderr. When setting this option from the config file, it is recommended to use an absolute path.
 
+*--experimental-backends*::
+	Use the new, reimplemented version of the backends. The new backends are HIGHLY UNSTABLE at this point, you have been warned. This option is not available in the config file.
+
 *--show-all-xerrors*::
 	Show all X errors (for debugging).
 

meson_options.txt

@@ -11,6 +11,4 @@ option('xrescheck', type: 'boolean', value: false, description: 'Enable X resour
 
 option('build_docs', type: 'boolean', value: false, description: 'Build documentation and man pages')
 
-option('new_backends', type: 'boolean', value: false, description: 'Does not really do anything right now')
-
 option('modularize', type: 'boolean', value: false, description: 'Build with clang\'s module system')

src/backend/backend.h

@@ -115,7 +115,7 @@ typedef struct backend_info {
 	void *(*prepare_win)(void *backend_data, session_t *ps, win *w)
 	    __attribute__((nonnull(1, 2, 3)));
 
-	/// Free resources allocated by prepare()
+	/// Free resources allocated by prepare_win()
 	void (*release_win)(void *backend_data, session_t *ps, win *w, void *win_data)
 	    __attribute__((nonnull(1, 2, 3)));
 

src/backend/meson.build

@@ -1,8 +1,5 @@
 # enable xrender
-srcs += [ files('backend_common.c') ]
-if get_option('new_backends')
-  srcs += [ files('xrender.c', 'backend.c') ]
-endif
+srcs += [ files('backend_common.c', 'xrender.c', 'backend.c') ]
 
 # enable opengl
 if get_option('opengl')

src/compton.c

@@ -46,6 +46,7 @@
 #include "types.h"
 #include "c2.h"
 #include "log.h"
+#include "backend/backend.h"
 #ifdef CONFIG_DBUS
 #include "dbus.h"
 #endif
@@ -738,6 +739,7 @@ repair_win(session_t *ps, win *w) {
   add_damage(ps, &parts);
   pixman_region32_fini(&parts);
 }
+
 static void
 restack_win(session_t *ps, win *w, xcb_window_t new_above) {
   xcb_window_t old_above;
@@ -802,8 +804,17 @@ restack_win(session_t *ps, win *w, xcb_window_t new_above) {
 void
 configure_win(session_t *ps, xcb_configure_notify_event_t *ce) {
   // On root window changes
+  auto root_change_fn = backend_list[ps->o.backend]->root_change;
   if (ce->window == ps->root) {
-    free_paint(ps, &ps->tgt_buffer);
+    if (ps->o.experimental_backends) {
+      if (!root_change_fn) {
+        // deinit/reinit backend if the backend cannot handle root change
+        backend_list[ps->o.backend]->deinit(ps->backend_data, ps);
+	ps->backend_data = NULL;
+      }
+    } else {
+      free_paint(ps, &ps->tgt_buffer);
+    }
 
     ps->root_width = ce->width;
     ps->root_height = ce->height;
@@ -838,7 +849,13 @@ configure_win(session_t *ps, xcb_configure_notify_event_t *ce) {
     if (BKEND_GLX == ps->o.backend)
       glx_on_root_change(ps);
 #endif
-
+    if (ps->o.experimental_backends) {
+      if (root_change_fn) {
+        root_change_fn(ps->backend_data, ps);
+      } else {
+        ps->backend_data = backend_list[ps->o.backend]->init(ps);
+      }
+    }
     force_repaint(ps);
 
     return;
@@ -1948,11 +1965,26 @@ redir_start(session_t *ps) {
 
     // Map overlay window. Done firstly according to this:
     // https://bugzilla.gnome.org/show_bug.cgi?id=597014
-    if (ps->overlay)
+    if (ps->overlay) {
       xcb_map_window(ps->c, ps->overlay);
+    }
 
     xcb_composite_redirect_subwindows(ps->c, ps->root, XCB_COMPOSITE_REDIRECT_MANUAL);
 
+    x_sync(ps->c);
+
+    if (ps->o.experimental_backends) {
+      // Reinitialize win_data
+      backend_info_t *bi = backend_list[ps->o.backend];
+      assert(bi);
+      ps->backend_data = bi->init(ps);
+      for (win *w = ps->list; w; w = w->next) {
+        if (w->a.map_state == XCB_MAP_STATE_VIEWABLE) {
+          w->win_data = bi->prepare_win(ps->backend_data, ps, w);
+        }
+      }
+    }
+
     /*
     // Unredirect GL context window as this may have an effect on VSync:
     // < http://dri.freedesktop.org/wiki/CompositeSwap >
@@ -1979,6 +2011,7 @@ static void
 redir_stop(session_t *ps) {
   if (ps->redirected) {
     log_debug("Screen unredirected.");
+    backend_info_t *bi = backend_list[ps->o.backend];
     // Destroy all Pictures as they expire once windows are unredirected
     // If we don't destroy them here, looks like the resources are just
     // kept inaccessible somehow
@@ -1992,7 +2025,18 @@ redir_stop(session_t *ps) {
       }
 
       // `w` might be freed by win_check_fade_finished
-      if (w) {
+      if (!w) {
+        continue;
+      }
+      if (ps->o.experimental_backends) {
+        assert(bi);
+        if (w->state == WSTATE_MAPPED) {
+          bi->release_win(ps->backend_data, ps, w, w->win_data);
+          w->win_data = NULL;
+        } else {
+          assert(!w->win_data);
+        }
+      } else {
         free_paint(ps, &w->paint);
       }
     }
@@ -2002,6 +2046,12 @@ redir_stop(session_t *ps) {
     if (ps->overlay)
       xcb_unmap_window(ps->c, ps->overlay);
 
+    if (ps->o.experimental_backends) {
+      // deinit backend
+      bi->deinit(ps->backend_data, ps);
+      ps->backend_data = NULL;
+    }
+
     // Must call XSync() here
     x_sync(ps->c);
 
@@ -2079,7 +2129,11 @@ _draw_callback(EV_P_ session_t *ps, int revents) {
   // If the screen is unredirected, free all_damage to stop painting
   if (ps->redirected && ps->o.stoppaint_force != ON) {
     static int paint = 0;
-    paint_all(ps, t, false);
+    if (ps->o.experimental_backends) {
+      paint_all_new(ps, t, false);
+    } else {
+      paint_all(ps, t, false);
+    }
 
     paint++;
     if (ps->o.benchmark && paint >= ps->o.benchmark)
@@ -2836,8 +2890,6 @@ session_destroy(session_t *ps) {
   free(ps->o.glx_fshader_win_str);
   free_xinerama_info(ps);
 
-  deinit_render(ps);
-
 #ifdef CONFIG_VSYNC_DRM
   // Close file opened for DRM VSync
   if (ps->drm_fd >= 0) {
@@ -2863,6 +2915,13 @@ session_destroy(session_t *ps) {
     ps->reg_win = XCB_NONE;
   }
 
+  if (ps->o.experimental_backends) {
+    // backend is deinitialized in redir_stop
+    assert(ps->backend_data == NULL);
+  } else {
+    deinit_render(ps);
+  }
+
   // Flush all events
   x_sync(ps->c);
   ev_io_stop(ps->loop, &ps->xiow);

src/compton.h

@@ -13,6 +13,7 @@
 
 #include <X11/Xutil.h>
 #include "common.h"
+#include "backend/backend.h"
 #include "win.h"
 #include "x.h"
 #include "c2.h"

src/config.h

@@ -79,6 +79,8 @@ typedef struct options_t {
 	bool monitor_repaint;
 	bool print_diagnostics;
 	// === General ===
+	/// Use the experimental new backends?
+	bool experimental_backends;
 	/// Path to write PID to.
 	char *write_pid_path;
 	/// The backend in use.
@@ -270,13 +272,14 @@ parse_config_libconfig(options_t *, const char *config_file, bool *shadow_enable
                        bool *fading_enable, bool *hasneg, win_option_mask_t *winopt_mask);
 #endif
 
-void set_default_winopts(options_t *, win_option_mask_t *, bool shadow_enable, bool fading_enable);
+void set_default_winopts(options_t *, win_option_mask_t *, bool shadow_enable,
+                         bool fading_enable);
 /// Parse a configuration file is that is enabled, also initialize the winopt_mask with
 /// default values
 /// Outputs and returns:
 ///   same as parse_config_libconfig
 char *parse_config(options_t *, const char *config_file, bool *shadow_enable,
-                  bool *fading_enable, bool *hasneg, win_option_mask_t *winopt_mask);
+                   bool *fading_enable, bool *hasneg, win_option_mask_t *winopt_mask);
 
 /**
  * Parse a backend option argument.

src/options.c

@@ -440,6 +440,7 @@ static const struct option longopts[] = {
     {"log-file", required_argument, NULL, 322},
     {"reredir-on-root-change", no_argument, NULL, 731},
     {"glx-reinit-on-root-change", no_argument, NULL, 732},
+    {"experimental-backends", no_argument, NULL, 733},
     {"monitor-repaint", no_argument, NULL, 800},
     {"diagnostics", no_argument, NULL, 801},
     // Must terminate with a NULL entry
@@ -770,6 +771,7 @@ void get_cfg(options_t *opt, int argc, char *const *argv, bool shadow_enable,
 		P_CASEBOOL(319, no_x_selection);
 		P_CASEBOOL(731, reredir_on_root_change);
 		P_CASEBOOL(732, glx_reinit_on_root_change);
+		P_CASEBOOL(733, experimental_backends);
 		P_CASEBOOL(800, monitor_repaint);
 		case 801: opt->print_diagnostics = true; break;
 		default: usage(1); break;

src/win.c

@@ -24,6 +24,7 @@
 #include "log.h"
 #include "types.h"
 #include "region.h"
+#include "backend/backend.h"
 #include "render.h"
 
 #ifdef CONFIG_DBUS
@@ -609,7 +610,12 @@ void calc_win_size(session_t *ps, win *w) {
   calc_shadow_geometry(ps, w);
   w->flags |= WFLAG_SIZE_CHANGE;
   // Invalidate the shadow we built
-  free_paint(ps, &w->shadow_paint);
+  if (ps->o.experimental_backends) {
+    backend_list[ps->o.backend]->release_win(ps->backend_data, ps, w, w->win_data);
+    w->win_data = backend_list[ps->o.backend]->prepare_win(ps->backend_data, ps, w);
+  } else {
+    free_paint(ps, &w->shadow_paint);
+  }
 }
 
 /**
@@ -1228,9 +1234,21 @@ void win_update_bounding_shape(session_t *ps, win *w) {
     win_rounded_corners(ps, w);
 
   // Window shape changed, we should free old wpaint and shadow pict
-  free_paint(ps, &w->paint);
-  free_paint(ps, &w->shadow_paint);
-  //log_trace("free out dated pict");
+  if (ps->o.experimental_backends) {
+    //log_trace("free out dated pict");
+    // Window shape changed, we should free win_data
+    if (ps->redirected && w->state == WSTATE_MAPPED) {
+      // Note we only do this when screen is redirected, because
+      // otherwise win_data is not valid
+      backend_info_t *bi = backend_list[ps->o.backend];
+      bi->release_win(ps->backend_data, ps, w, w->win_data);
+      w->win_data = bi->prepare_win(ps->backend_data, ps, w);
+      //log_trace("free out dated pict");
+    }
+  } else {
+    free_paint(ps, &w->paint);
+    free_paint(ps, &w->shadow_paint);
+  }
 
   win_on_factor_change(ps, w);
 }
@@ -1321,8 +1339,17 @@ finish_unmap_win(session_t *ps, win **_w) {
   w->state = WSTATE_UNMAPPED;
   w->flags = 0;
 
-  free_paint(ps, &w->paint);
-  free_paint(ps, &w->shadow_paint);
+  if (ps->o.experimental_backends) {
+    // We are in unmap_win, we definitely was viewable
+    if (ps->redirected) {
+      assert(w->win_data);
+      backend_list[ps->o.backend]->release_win(ps->backend_data, ps, w, w->win_data);
+      w->win_data = NULL;
+    }
+  } else {
+    free_paint(ps, &w->paint);
+    free_paint(ps, &w->shadow_paint);
+  }
 }
 
 static void
@@ -1347,7 +1374,9 @@ finish_destroy_win(session_t *ps, win **_w) {
         ps->active_win = NULL;
       }
 
-      free_win_res(ps, w);
+      if (!ps->o.experimental_backends) {
+        free_win_res(ps, w);
+      }
 
       // Drop w from all prev_trans to avoid accessing freed memory in
       // repair_win()