[Qemu-devel] [RFC 0/5] ui/cocoa: Use OSX's main loop

[Qemu-devel] [RFC 0/5] ui/cocoa: Use OSX's main loop

[Peter Maydell]

This set of patches rearranges how we handle events on
the OSX Cocoa UI so that we use the main thread to run
the OSX event loop, and we don't do a long blocking
operation from the applicationDidFinishLaunching callback.
Instead we create a second thread which runs qemu_main()
and becomes the QEMU main-loop thread. The callbacks from
QEMU into the cocoa code asynchronously dispatch their
work to the main thread, and the main thread takes the
iothread lock before calling into QEMU code.

This code all works (though I have only smoke-tested it),
but it is marked RFC because it seems to be unclear whether
the current code in git master is really problematic for
Mojave. If it's not actually solving a problem then it's
a bit tricky to justify this rework, though it does mean
we're doing a less "weird" set of things and behaving a bit
more like how OSX expects apps to behave, so it might in
theory mean less chance of future breakage.

NB: the code to asynchronously run code blocks on the
main thread uses dispatch_get_main_queue(), which is a
10.10-or-later function. If we're going to go with this
refactoring I think the benefit in clarity-of-code is a
worthwhile gain for dropping support for ancient OSX versions.

Patchset structure:
 * patch 1 does the "make sure we have the iothread lock for
   calls into QEMU" (which is effectively a no-op initially
   since we'll already be holding that lock when our refresh
   etc callbacks are called)
 * patch 2 makes switchSurface directly take the pixman image
   (which is refcounted) rather than the DisplaySurface (which
   is not), so we can make the calls to it asynchronous later
 * patches 3 and 4 are just trivial code motion
 * patch 5 does the bulk of the work (and can't really be split
   further without the UI being broken at the intermediate point)

thanks
-- PMM

Peter Maydell (5):
  ui/cocoa: Ensure we have the iothread lock when calling into QEMU
  ui/cocoa: Use the pixman image directly in switchSurface
  ui/cocoa: Factor out initial menu creation
  ui/cocoa: Move console/device menu creation code up in file
  ui/cocoa: Perform UI operations only on the main thread

 ui/cocoa.m | 441 +++++++++++++++++++++++++++++++----------------------
 1 file changed, 258 insertions(+), 183 deletions(-)

-- 
2.19.2

[Qemu-devel] [RFC 1/5] ui/cocoa: Ensure we have the iothread lock when calling into QEMU

[Peter Maydell]

The Cocoa UI should run on the main thread; this is enforced
in OSX Mojave. In order to be able to run on the main thread,
we need to make sure we hold the iothread lock whenever we
call into various QEMU UI midlayer functions.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 ui/cocoa.m | 83 ++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 59 insertions(+), 24 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index ecf12bfc2e4..9148ecdeb4c 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -117,6 +117,21 @@ bool stretch_video;
 NSTextField *pauseLabel;
 NSArray * supportedImageFileTypes;
 
+// Utility function to run specified code block with iothread lock held
+typedef void (^CodeBlock)(void);
+
+static void with_iothread_lock(CodeBlock block)
+{
+    bool locked = qemu_mutex_iothread_locked();
+    if (!locked) {
+        qemu_mutex_lock_iothread();
+    }
+    block();
+    if (!locked) {
+        qemu_mutex_unlock_iothread();
+    }
+}
+
 // Mac to QKeyCode conversion
 const int mac_to_qkeycode_map[] = {
     [kVK_ANSI_A] = Q_KEY_CODE_A,
@@ -294,6 +309,7 @@ static void handleAnyDeviceErrors(Error * err)
 - (void) toggleFullScreen:(id)sender;
 - (void) handleMonitorInput:(NSEvent *)event;
 - (void) handleEvent:(NSEvent *)event;
+- (void) handleEventLocked:(NSEvent *)event;
 - (void) setAbsoluteEnabled:(BOOL)tIsAbsoluteEnabled;
 /* The state surrounding mouse grabbing is potentially confusing.
  * isAbsoluteEnabled tracks qemu_input_is_absolute() [ie "is the emulated
@@ -632,8 +648,14 @@ QemuCocoaView *cocoaView;
 
 - (void) handleEvent:(NSEvent *)event
 {
-    COCOA_DEBUG("QemuCocoaView: handleEvent\n");
+    with_iothread_lock(^{
+        [self handleEventLocked:event];
+    });
+}
 
+- (void) handleEventLocked:(NSEvent *)event
+{
+    COCOA_DEBUG("QemuCocoaView: handleEvent\n");
     int buttons = 0;
     int keycode = 0;
     bool mouse_event = false;
@@ -928,15 +950,18 @@ QemuCocoaView *cocoaView;
  */
 - (void) raiseAllKeys
 {
-    int index;
     const int max_index = ARRAY_SIZE(modifiers_state);
 
-   for (index = 0; index < max_index; index++) {
-       if (modifiers_state[index]) {
-           modifiers_state[index] = 0;
-           qemu_input_event_send_key_qcode(dcl->con, index, false);
-       }
-   }
+    with_iothread_lock(^{
+        int index;
+
+        for (index = 0; index < max_index; index++) {
+            if (modifiers_state[index]) {
+                modifiers_state[index] = 0;
+                qemu_input_event_send_key_qcode(dcl->con, index, false);
+            }
+        }
+    });
 }
 @end
 
@@ -1198,13 +1223,17 @@ QemuCocoaView *cocoaView;
 /* Restarts QEMU */
 - (void)restartQEMU:(id)sender
 {
-    qmp_system_reset(NULL);
+    with_iothread_lock(^{
+        qmp_system_reset(NULL);
+    });
 }
 
 /* Powers down QEMU */
 - (void)powerDownQEMU:(id)sender
 {
-    qmp_system_powerdown(NULL);
+    with_iothread_lock(^{
+        qmp_system_powerdown(NULL);
+    });
 }
 
 /* Ejects the media.
@@ -1220,9 +1249,11 @@ QemuCocoaView *cocoaView;
         return;
     }
 
-    Error *err = NULL;
-    qmp_eject(true, [drive cStringUsingEncoding: NSASCIIStringEncoding],
-              false, NULL, false, false, &err);
+    __block Error *err = NULL;
+    with_iothread_lock(^{
+        qmp_eject(true, [drive cStringUsingEncoding: NSASCIIStringEncoding],
+                  false, NULL, false, false, &err);
+    });
     handleAnyDeviceErrors(err);
 }
 
@@ -1254,16 +1285,18 @@ QemuCocoaView *cocoaView;
             return;
         }
 
-        Error *err = NULL;
-        qmp_blockdev_change_medium(true,
-                                   [drive cStringUsingEncoding:
-                                          NSASCIIStringEncoding],
-                                   false, NULL,
-                                   [file cStringUsingEncoding:
-                                         NSASCIIStringEncoding],
-                                   true, "raw",
-                                   false, 0,
-                                   &err);
+        __block Error *err = NULL;
+        with_iothread_lock(^{
+            qmp_blockdev_change_medium(true,
+                                       [drive cStringUsingEncoding:
+                                                  NSASCIIStringEncoding],
+                                       false, NULL,
+                                       [file cStringUsingEncoding:
+                                                 NSASCIIStringEncoding],
+                                       true, "raw",
+                                       false, 0,
+                                       &err);
+        });
         handleAnyDeviceErrors(err);
     }
 }
@@ -1402,7 +1435,9 @@ QemuCocoaView *cocoaView;
     // get the throttle percentage
     throttle_pct = [sender tag];
 
-    cpu_throttle_set(throttle_pct);
+    with_iothread_lock(^{
+        cpu_throttle_set(throttle_pct);
+    });
     COCOA_DEBUG("cpu throttling at %d%c\n", cpu_throttle_get_percentage(), '%');
 }
 
-- 
2.19.2

[Qemu-devel] [RFC 2/5] ui/cocoa: Use the pixman image directly in switchSurface

[Peter Maydell]

Currently the switchSurface method takes a DisplaySurface. We want
to change our DisplayChangeListener's dpy_gfx_switch callback
to do this work asynchronously on a different thread. The caller
of the switch callback will free the old DisplaySurface
immediately the callback returns, so to ensure that the
other thread doesn't access freed data we need to switch
to using the underlying pixman image instead. The pixman
image is reference counted, so we will be able to take
a reference to it to avoid it vanishing too early.

In this commit we only change the switchSurface method
to take a pixman image, and keep the flow of control
synchronous for now.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 ui/cocoa.m | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index 9148ecdeb4c..997b0199c6c 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -303,7 +303,7 @@ static void handleAnyDeviceErrors(Error * err)
     BOOL isAbsoluteEnabled;
     BOOL isMouseDeassociated;
 }
-- (void) switchSurface:(DisplaySurface *)surface;
+- (void) switchSurface:(pixman_image_t *)image;
 - (void) grabMouse;
 - (void) ungrabMouse;
 - (void) toggleFullScreen:(id)sender;
@@ -478,12 +478,13 @@ QemuCocoaView *cocoaView;
     }
 }
 
-- (void) switchSurface:(DisplaySurface *)surface
+- (void) switchSurface:(pixman_image_t *)image
 {
     COCOA_DEBUG("QemuCocoaView: switchSurface\n");
 
-    int w = surface_width(surface);
-    int h = surface_height(surface);
+    int w = pixman_image_get_width(image);
+    int h = pixman_image_get_height(image);
+    pixman_format_code_t image_format = pixman_image_get_format(image);
     /* cdx == 0 means this is our very first surface, in which case we need
      * to recalculate the content dimensions even if it happens to be the size
      * of the initial empty window.
@@ -505,10 +506,10 @@ QemuCocoaView *cocoaView;
         CGDataProviderRelease(dataProviderRef);
 
     //sync host window color space with guests
-    screen.bitsPerPixel = surface_bits_per_pixel(surface);
-    screen.bitsPerComponent = surface_bytes_per_pixel(surface) * 2;
+    screen.bitsPerPixel = PIXMAN_FORMAT_BPP(image_format);
+    screen.bitsPerComponent = DIV_ROUND_UP(screen.bitsPerPixel, 8) * 2;
 
-    dataProviderRef = CGDataProviderCreateWithData(NULL, surface_data(surface), w * 4 * h, NULL);
+    dataProviderRef = CGDataProviderCreateWithData(NULL, pixman_image_get_data(image), w * 4 * h, NULL);
 
     // update windows
     if (isFullscreen) {
@@ -1608,7 +1609,7 @@ static void cocoa_switch(DisplayChangeListener *dcl,
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
 
     COCOA_DEBUG("qemu_cocoa: cocoa_switch\n");
-    [cocoaView switchSurface:surface];
+    [cocoaView switchSurface:surface->image];
     [pool release];
 }
 
-- 
2.19.2

[Qemu-devel] [RFC 3/5] ui/cocoa: Factor out initial menu creation

[Peter Maydell]

Factor out the long code sequence in main() which creates
the initial set of menus. This will make later patches
which move initialization code around a bit clearer.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 ui/cocoa.m | 78 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 41 insertions(+), 37 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index 997b0199c6c..da511bfb4fa 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -1444,43 +1444,8 @@ QemuCocoaView *cocoaView;
 
 @end
 
-
-int main (int argc, const char * argv[]) {
-
-    gArgc = argc;
-    gArgv = (char **)argv;
-    int i;
-
-    /* In case we don't need to display a window, let's not do that */
-    for (i = 1; i < argc; i++) {
-        const char *opt = argv[i];
-
-        if (opt[0] == '-') {
-            /* Treat --foo the same as -foo.  */
-            if (opt[1] == '-') {
-                opt++;
-            }
-            if (!strcmp(opt, "-h") || !strcmp(opt, "-help") ||
-                !strcmp(opt, "-vnc") ||
-                !strcmp(opt, "-nographic") ||
-                !strcmp(opt, "-version") ||
-                !strcmp(opt, "-curses") ||
-                !strcmp(opt, "-display") ||
-                !strcmp(opt, "-qtest")) {
-                return qemu_main(gArgc, gArgv, *_NSGetEnviron());
-            }
-        }
-    }
-
-    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
-
-    // Pull this console process up to being a fully-fledged graphical
-    // app with a menubar and Dock icon
-    ProcessSerialNumber psn = { 0, kCurrentProcess };
-    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
-
-    [NSApplication sharedApplication];
-
+static void create_initial_menus(void)
+{
     // Add menus
     NSMenu      *menu;
     NSMenuItem  *menuItem;
@@ -1564,6 +1529,45 @@ int main (int argc, const char * argv[]) {
     menuItem = [[[NSMenuItem alloc] initWithTitle:@"Window" action:nil keyEquivalent:@""] autorelease];
     [menuItem setSubmenu:menu];
     [[NSApp mainMenu] addItem:menuItem];
+}
+
+int main (int argc, const char * argv[]) {
+
+    gArgc = argc;
+    gArgv = (char **)argv;
+    int i;
+
+    /* In case we don't need to display a window, let's not do that */
+    for (i = 1; i < argc; i++) {
+        const char *opt = argv[i];
+
+        if (opt[0] == '-') {
+            /* Treat --foo the same as -foo.  */
+            if (opt[1] == '-') {
+                opt++;
+            }
+            if (!strcmp(opt, "-h") || !strcmp(opt, "-help") ||
+                !strcmp(opt, "-vnc") ||
+                !strcmp(opt, "-nographic") ||
+                !strcmp(opt, "-version") ||
+                !strcmp(opt, "-curses") ||
+                !strcmp(opt, "-display") ||
+                !strcmp(opt, "-qtest")) {
+                return qemu_main(gArgc, gArgv, *_NSGetEnviron());
+            }
+        }
+    }
+
+    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
+
+    // Pull this console process up to being a fully-fledged graphical
+    // app with a menubar and Dock icon
+    ProcessSerialNumber psn = { 0, kCurrentProcess };
+    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
+
+    [NSApplication sharedApplication];
+
+    create_initial_menus();
 
     // Create an Application controller
     QemuCocoaAppController *appController = [[QemuCocoaAppController alloc] init];
-- 
2.19.2

[Qemu-devel] [RFC 4/5] ui/cocoa: Move console/device menu creation code up in file

[Peter Maydell]

Move the console/device menu creation code functions
further up in the source file, next to the code which
creates the initial menus. We're going to want to
change the location we call these functions from in
the next patch.

This commit is a pure code move with no other changes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 ui/cocoa.m | 184 ++++++++++++++++++++++++++---------------------------
 1 file changed, 92 insertions(+), 92 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index da511bfb4fa..2f533c77c47 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -1531,6 +1531,98 @@ static void create_initial_menus(void)
     [[NSApp mainMenu] addItem:menuItem];
 }
 
+/* Returns a name for a given console */
+static NSString * getConsoleName(QemuConsole * console)
+{
+    return [NSString stringWithFormat: @"%s", qemu_console_get_label(console)];
+}
+
+/* Add an entry to the View menu for each console */
+static void add_console_menu_entries(void)
+{
+    NSMenu *menu;
+    NSMenuItem *menuItem;
+    int index = 0;
+
+    menu = [[[NSApp mainMenu] itemWithTitle:@"View"] submenu];
+
+    [menu addItem:[NSMenuItem separatorItem]];
+
+    while (qemu_console_lookup_by_index(index) != NULL) {
+        menuItem = [[[NSMenuItem alloc] initWithTitle: getConsoleName(qemu_console_lookup_by_index(index))
+                                               action: @selector(displayConsole:) keyEquivalent: @""] autorelease];
+        [menuItem setTag: index];
+        [menu addItem: menuItem];
+        index++;
+    }
+}
+
+/* Make menu items for all removable devices.
+ * Each device is given an 'Eject' and 'Change' menu item.
+ */
+static void addRemovableDevicesMenuItems(void)
+{
+    NSMenu *menu;
+    NSMenuItem *menuItem;
+    BlockInfoList *currentDevice, *pointerToFree;
+    NSString *deviceName;
+
+    currentDevice = qmp_query_block(NULL);
+    pointerToFree = currentDevice;
+    if(currentDevice == NULL) {
+        NSBeep();
+        QEMU_Alert(@"Failed to query for block devices!");
+        return;
+    }
+
+    menu = [[[NSApp mainMenu] itemWithTitle:@"Machine"] submenu];
+
+    // Add a separator between related groups of menu items
+    [menu addItem:[NSMenuItem separatorItem]];
+
+    // Set the attributes to the "Removable Media" menu item
+    NSString *titleString = @"Removable Media";
+    NSMutableAttributedString *attString=[[NSMutableAttributedString alloc] initWithString:titleString];
+    NSColor *newColor = [NSColor blackColor];
+    NSFontManager *fontManager = [NSFontManager sharedFontManager];
+    NSFont *font = [fontManager fontWithFamily:@"Helvetica"
+                                          traits:NSBoldFontMask|NSItalicFontMask
+                                          weight:0
+                                            size:14];
+    [attString addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, [titleString length])];
+    [attString addAttribute:NSForegroundColorAttributeName value:newColor range:NSMakeRange(0, [titleString length])];
+    [attString addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInt: 1] range:NSMakeRange(0, [titleString length])];
+
+    // Add the "Removable Media" menu item
+    menuItem = [NSMenuItem new];
+    [menuItem setAttributedTitle: attString];
+    [menuItem setEnabled: NO];
+    [menu addItem: menuItem];
+
+    /* Loop through all the block devices in the emulator */
+    while (currentDevice) {
+        deviceName = [[NSString stringWithFormat: @"%s", currentDevice->value->device] retain];
+
+        if(currentDevice->value->removable) {
+            menuItem = [[NSMenuItem alloc] initWithTitle: [NSString stringWithFormat: @"Change %s...", currentDevice->value->device]
+                                                  action: @selector(changeDeviceMedia:)
+                                           keyEquivalent: @""];
+            [menu addItem: menuItem];
+            [menuItem setRepresentedObject: deviceName];
+            [menuItem autorelease];
+
+            menuItem = [[NSMenuItem alloc] initWithTitle: [NSString stringWithFormat: @"Eject %s", currentDevice->value->device]
+                                                  action: @selector(ejectDeviceMedia:)
+                                           keyEquivalent: @""];
+            [menu addItem: menuItem];
+            [menuItem setRepresentedObject: deviceName];
+            [menuItem autorelease];
+        }
+        currentDevice = currentDevice->next;
+    }
+    qapi_free_BlockInfoList(pointerToFree);
+}
+
 int main (int argc, const char * argv[]) {
 
     gArgc = argc;
@@ -1659,98 +1751,6 @@ static const DisplayChangeListenerOps dcl_ops = {
     .dpy_refresh = cocoa_refresh,
 };
 
-/* Returns a name for a given console */
-static NSString * getConsoleName(QemuConsole * console)
-{
-    return [NSString stringWithFormat: @"%s", qemu_console_get_label(console)];
-}
-
-/* Add an entry to the View menu for each console */
-static void add_console_menu_entries(void)
-{
-    NSMenu *menu;
-    NSMenuItem *menuItem;
-    int index = 0;
-
-    menu = [[[NSApp mainMenu] itemWithTitle:@"View"] submenu];
-
-    [menu addItem:[NSMenuItem separatorItem]];
-
-    while (qemu_console_lookup_by_index(index) != NULL) {
-        menuItem = [[[NSMenuItem alloc] initWithTitle: getConsoleName(qemu_console_lookup_by_index(index))
-                                               action: @selector(displayConsole:) keyEquivalent: @""] autorelease];
-        [menuItem setTag: index];
-        [menu addItem: menuItem];
-        index++;
-    }
-}
-
-/* Make menu items for all removable devices.
- * Each device is given an 'Eject' and 'Change' menu item.
- */
-static void addRemovableDevicesMenuItems(void)
-{
-    NSMenu *menu;
-    NSMenuItem *menuItem;
-    BlockInfoList *currentDevice, *pointerToFree;
-    NSString *deviceName;
-
-    currentDevice = qmp_query_block(NULL);
-    pointerToFree = currentDevice;
-    if(currentDevice == NULL) {
-        NSBeep();
-        QEMU_Alert(@"Failed to query for block devices!");
-        return;
-    }
-
-    menu = [[[NSApp mainMenu] itemWithTitle:@"Machine"] submenu];
-
-    // Add a separator between related groups of menu items
-    [menu addItem:[NSMenuItem separatorItem]];
-
-    // Set the attributes to the "Removable Media" menu item
-    NSString *titleString = @"Removable Media";
-    NSMutableAttributedString *attString=[[NSMutableAttributedString alloc] initWithString:titleString];
-    NSColor *newColor = [NSColor blackColor];
-    NSFontManager *fontManager = [NSFontManager sharedFontManager];
-    NSFont *font = [fontManager fontWithFamily:@"Helvetica"
-                                          traits:NSBoldFontMask|NSItalicFontMask
-                                          weight:0
-                                            size:14];
-    [attString addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, [titleString length])];
-    [attString addAttribute:NSForegroundColorAttributeName value:newColor range:NSMakeRange(0, [titleString length])];
-    [attString addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInt: 1] range:NSMakeRange(0, [titleString length])];
-
-    // Add the "Removable Media" menu item
-    menuItem = [NSMenuItem new];
-    [menuItem setAttributedTitle: attString];
-    [menuItem setEnabled: NO];
-    [menu addItem: menuItem];
-
-    /* Loop through all the block devices in the emulator */
-    while (currentDevice) {
-        deviceName = [[NSString stringWithFormat: @"%s", currentDevice->value->device] retain];
-
-        if(currentDevice->value->removable) {
-            menuItem = [[NSMenuItem alloc] initWithTitle: [NSString stringWithFormat: @"Change %s...", currentDevice->value->device]
-                                                  action: @selector(changeDeviceMedia:)
-                                           keyEquivalent: @""];
-            [menu addItem: menuItem];
-            [menuItem setRepresentedObject: deviceName];
-            [menuItem autorelease];
-
-            menuItem = [[NSMenuItem alloc] initWithTitle: [NSString stringWithFormat: @"Eject %s", currentDevice->value->device]
-                                                  action: @selector(ejectDeviceMedia:)
-                                           keyEquivalent: @""];
-            [menu addItem: menuItem];
-            [menuItem setRepresentedObject: deviceName];
-            [menuItem autorelease];
-        }
-        currentDevice = currentDevice->next;
-    }
-    qapi_free_BlockInfoList(pointerToFree);
-}
-
 static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
 {
     COCOA_DEBUG("qemu_cocoa: cocoa_display_init\n");
-- 
2.19.2

[Qemu-devel] [RFC 5/5] ui/cocoa: Perform UI operations only on the main thread

[Peter Maydell]

The OSX Mojave release is more picky about enforcing the Cocoa API
restriction that only the main thread may perform UI calls. To
accommodate this we need to restructure the Cocoa code:
 * the special OSX main() creates a second thread and uses
   that to call the vl.c qemu_main(); the original main
   thread goes into the OSX event loop
 * the refresh, switch and update callbacks asynchronously
   tell the main thread to do the necessary work
 * the refresh callback no longer does the "get events from the
   UI event queue and handle them" loop, since we now use
   the stock OSX event loop

All these things have to be changed in one commit, to avoid
breaking bisection.

Note that since we use dispatch_get_main_queue(), this bumps
our minimum version requirement to OSX 10.10 Yosemite (released
in 2014, unsupported by Apple since 2017).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 ui/cocoa.m | 185 +++++++++++++++++++++++++++++++----------------------
 1 file changed, 110 insertions(+), 75 deletions(-)

diff --git a/ui/cocoa.m b/ui/cocoa.m
index 2f533c77c47..3897d2e370b 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -117,6 +117,9 @@ bool stretch_video;
 NSTextField *pauseLabel;
 NSArray * supportedImageFileTypes;
 
+QemuSemaphore display_init_sem;
+QemuSemaphore app_started_sem;
+
 // Utility function to run specified code block with iothread lock held
 typedef void (^CodeBlock)(void);
 
@@ -297,6 +300,7 @@ static void handleAnyDeviceErrors(Error * err)
     NSWindow *fullScreenWindow;
     float cx,cy,cw,ch,cdx,cdy;
     CGDataProviderRef dataProviderRef;
+    pixman_image_t *pixman_image;
     BOOL modifiers_state[256];
     BOOL isMouseGrabbed;
     BOOL isFullscreen;
@@ -502,13 +506,16 @@ QemuCocoaView *cocoaView;
     }
 
     // update screenBuffer
-    if (dataProviderRef)
+    if (dataProviderRef) {
         CGDataProviderRelease(dataProviderRef);
+        pixman_image_unref(pixman_image);
+    }
 
     //sync host window color space with guests
     screen.bitsPerPixel = PIXMAN_FORMAT_BPP(image_format);
     screen.bitsPerComponent = DIV_ROUND_UP(screen.bitsPerPixel, 8) * 2;
 
+    pixman_image = image;
     dataProviderRef = CGDataProviderCreateWithData(NULL, pixman_image_get_data(image), w * 4 * h, NULL);
 
     // update windows
@@ -979,7 +986,6 @@ QemuCocoaView *cocoaView;
 #endif
 {
 }
-- (void)startEmulationWithArgc:(int)argc argv:(char**)argv;
 - (void)doToggleFullScreen:(id)sender;
 - (void)toggleFullScreen:(id)sender;
 - (void)showQEMUDoc:(id)sender;
@@ -1067,8 +1073,8 @@ QemuCocoaView *cocoaView;
 - (void)applicationDidFinishLaunching: (NSNotification *) note
 {
     COCOA_DEBUG("QemuCocoaAppController: applicationDidFinishLaunching\n");
-    // launch QEMU, with the global args
-    [self startEmulationWithArgc:gArgc argv:(char **)gArgv];
+    /* Tell cocoa_display_init to proceed */
+    qemu_sem_post(&app_started_sem);
 }
 
 - (void)applicationWillTerminate:(NSNotification *)aNotification
@@ -1111,15 +1117,6 @@ QemuCocoaView *cocoaView;
     [cocoaView raiseAllKeys];
 }
 
-- (void)startEmulationWithArgc:(int)argc argv:(char**)argv
-{
-    COCOA_DEBUG("QemuCocoaAppController: startEmulationWithArgc\n");
-
-    int status;
-    status = qemu_main(argc, argv, *_NSGetEnviron());
-    exit(status);
-}
-
 /* We abstract the method called by the Enter Fullscreen menu item
  * because Mac OS 10.7 and higher disables it. This is because of the
  * menu item's old selector's name toggleFullScreen:
@@ -1623,32 +1620,59 @@ static void addRemovableDevicesMenuItems(void)
     qapi_free_BlockInfoList(pointerToFree);
 }
 
-int main (int argc, const char * argv[]) {
+/*
+ * The startup process for the OSX/Cocoa UI is complicated, because
+ * OSX insists that the UI runs on the initial main thread, and so we
+ * need to start a second thread which runs the vl.c qemu_main():
+ *
+ * Initial thread:                    2nd thread:
+ * in main():
+ *  create qemu-main thread
+ *  wait on display_init semaphore
+ *                                    call qemu_main()
+ *                                    ...
+ *                                    in cocoa_display_init():
+ *                                     post the display_init semaphore
+ *                                     wait on app_started semaphore
+ *  create application, menus, etc
+ *  enter OSX run loop
+ * in applicationDidFinishLaunching:
+ *  post app_started semaphore
+ *                                     tell main thread to fullscreen if needed
+ *                                    [...]
+ *                                    run qemu main-loop
+ *
+ * We do this in two stages so that we don't do the creation of the
+ * GUI application menus and so on for command line options like --help
+ * where we want to just print text to stdout and exit immediately.
+ */
 
+static void *call_qemu_main(void *opaque)
+{
+    int status;
+
+    COCOA_DEBUG("Second thread: calling qemu_main()\n");
+    status = qemu_main(gArgc, gArgv, *_NSGetEnviron());
+    COCOA_DEBUG("Second thread: qemu_main() returned, exiting\n");
+    exit(status);
+}
+
+int main (int argc, const char * argv[]) {
+    QemuThread thread;
+
+    COCOA_DEBUG("Entered main()\n");
     gArgc = argc;
     gArgv = (char **)argv;
-    int i;
 
-    /* In case we don't need to display a window, let's not do that */
-    for (i = 1; i < argc; i++) {
-        const char *opt = argv[i];
+    qemu_sem_init(&display_init_sem, 0);
+    qemu_sem_init(&app_started_sem, 0);
 
-        if (opt[0] == '-') {
-            /* Treat --foo the same as -foo.  */
-            if (opt[1] == '-') {
-                opt++;
-            }
-            if (!strcmp(opt, "-h") || !strcmp(opt, "-help") ||
-                !strcmp(opt, "-vnc") ||
-                !strcmp(opt, "-nographic") ||
-                !strcmp(opt, "-version") ||
-                !strcmp(opt, "-curses") ||
-                !strcmp(opt, "-display") ||
-                !strcmp(opt, "-qtest")) {
-                return qemu_main(gArgc, gArgv, *_NSGetEnviron());
-            }
-        }
-    }
+    qemu_thread_create(&thread, "qemu_main", call_qemu_main,
+                       NULL, QEMU_THREAD_DETACHED);
+
+    COCOA_DEBUG("Main thread: waiting for display_init_sem\n");
+    qemu_sem_wait(&display_init_sem);
+    COCOA_DEBUG("Main thread: initializing app\n");
 
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
 
@@ -1661,12 +1685,24 @@ int main (int argc, const char * argv[]) {
 
     create_initial_menus();
 
+    /*
+     * Create the menu entries which depend on QEMU state (for consoles
+     * and removeable devices). These make calls back into QEMU functions,
+     * which is OK because at this point we know that the second thread
+     * holds the iothread lock and is synchronously waiting for us to
+     * finish.
+     */
+    add_console_menu_entries();
+    addRemovableDevicesMenuItems();
+
     // Create an Application controller
     QemuCocoaAppController *appController = [[QemuCocoaAppController alloc] init];
     [NSApp setDelegate:appController];
 
     // Start the main event loop
+    COCOA_DEBUG("Main thread: entering OSX run loop\n");
     [NSApp run];
+    COCOA_DEBUG("Main thread: left OSX run loop, exiting\n");
 
     [appController release];
     [pool release];
@@ -1684,17 +1720,19 @@ static void cocoa_update(DisplayChangeListener *dcl,
 
     COCOA_DEBUG("qemu_cocoa: cocoa_update\n");
 
-    NSRect rect;
-    if ([cocoaView cdx] == 1.0) {
-        rect = NSMakeRect(x, [cocoaView gscreen].height - y - h, w, h);
-    } else {
-        rect = NSMakeRect(
-            x * [cocoaView cdx],
-            ([cocoaView gscreen].height - y - h) * [cocoaView cdy],
-            w * [cocoaView cdx],
-            h * [cocoaView cdy]);
-    }
-    [cocoaView setNeedsDisplayInRect:rect];
+    dispatch_async(dispatch_get_main_queue(), ^{
+        NSRect rect;
+        if ([cocoaView cdx] == 1.0) {
+            rect = NSMakeRect(x, [cocoaView gscreen].height - y - h, w, h);
+        } else {
+            rect = NSMakeRect(
+                x * [cocoaView cdx],
+                ([cocoaView gscreen].height - y - h) * [cocoaView cdy],
+                w * [cocoaView cdx],
+                h * [cocoaView cdy]);
+        }
+        [cocoaView setNeedsDisplayInRect:rect];
+    });
 
     [pool release];
 }
@@ -1703,9 +1741,19 @@ static void cocoa_switch(DisplayChangeListener *dcl,
                          DisplaySurface *surface)
 {
     NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
+    pixman_image_t *image = surface->image;
 
     COCOA_DEBUG("qemu_cocoa: cocoa_switch\n");
-    [cocoaView switchSurface:surface->image];
+
+    // The DisplaySurface will be freed as soon as this callback returns.
+    // We take a reference to the underlying pixman image here so it does
+    // not disappear from under our feet; the switchSurface method will
+    // deref the old image when it is done with it.
+    pixman_image_ref(image);
+
+    dispatch_async(dispatch_get_main_queue(), ^{
+        [cocoaView switchSurface:image];
+    });
     [pool release];
 }
 
@@ -1717,24 +1765,15 @@ static void cocoa_refresh(DisplayChangeListener *dcl)
     graphic_hw_update(NULL);
 
     if (qemu_input_is_absolute()) {
-        if (![cocoaView isAbsoluteEnabled]) {
-            if ([cocoaView isMouseGrabbed]) {
-                [cocoaView ungrabMouse];
+        dispatch_async(dispatch_get_main_queue(), ^{
+            if (![cocoaView isAbsoluteEnabled]) {
+                if ([cocoaView isMouseGrabbed]) {
+                    [cocoaView ungrabMouse];
+                }
             }
-        }
-        [cocoaView setAbsoluteEnabled:YES];
+            [cocoaView setAbsoluteEnabled:YES];
+        });
     }
-
-    NSDate *distantPast;
-    NSEvent *event;
-    distantPast = [NSDate distantPast];
-    do {
-        event = [NSApp nextEventMatchingMask:NSEventMaskAny untilDate:distantPast
-                        inMode: NSDefaultRunLoopMode dequeue:YES];
-        if (event != nil) {
-            [cocoaView handleEvent:event];
-        }
-    } while(event != nil);
     [pool release];
 }
 
@@ -1755,10 +1794,17 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
 {
     COCOA_DEBUG("qemu_cocoa: cocoa_display_init\n");
 
+    /* Tell main thread to go ahead and create the app and enter the run loop */
+    qemu_sem_post(&display_init_sem);
+    qemu_sem_wait(&app_started_sem);
+    COCOA_DEBUG("cocoa_display_init: app start completed\n");
+
     /* if fullscreen mode is to be used */
     if (opts->has_full_screen && opts->full_screen) {
-        [NSApp activateIgnoringOtherApps: YES];
-        [(QemuCocoaAppController *)[[NSApplication sharedApplication] delegate] toggleFullScreen: nil];
+        dispatch_async(dispatch_get_main_queue(), ^{
+            [NSApp activateIgnoringOtherApps: YES];
+            [(QemuCocoaAppController *)[[NSApplication sharedApplication] delegate] toggleFullScreen: nil];
+        });
     }
 
     dcl = g_malloc0(sizeof(DisplayChangeListener));
@@ -1769,17 +1815,6 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
 
     // register cleanup function
     atexit(cocoa_cleanup);
-
-    /* At this point QEMU has created all the consoles, so we can add View
-     * menu entries for them.
-     */
-    add_console_menu_entries();
-
-    /* Give all removable devices a menu item.
-     * Has to be called after QEMU has started to
-     * find out what removable devices it has.
-     */
-    addRemovableDevicesMenuItems();
 }
 
 static QemuDisplay qemu_display_cocoa = {
-- 
2.19.2

Re: [Qemu-devel] [RFC 0/5] ui/cocoa: Use OSX's main loop

[Richard Henderson]

On 12/1/18 6:30 AM, Peter Maydell wrote:
> Patchset structure:
>  * patch 1 does the "make sure we have the iothread lock for
>    calls into QEMU" (which is effectively a no-op initially
>    since we'll already be holding that lock when our refresh
>    etc callbacks are called)
>  * patch 2 makes switchSurface directly take the pixman image
>    (which is refcounted) rather than the DisplaySurface (which
>    is not), so we can make the calls to it asynchronous later
>  * patches 3 and 4 are just trivial code motion
>  * patch 5 does the bulk of the work (and can't really be split
>    further without the UI being broken at the intermediate point)

FWIW, this makes sense and is relatively easy to follow.
That said, I've never touched OSX at all, so can't even test.


r~

Re: [Qemu-devel] [RFC 0/5] ui/cocoa: Use OSX's main loop

[Gerd Hoffmann]

  Hi,

> NB: the code to asynchronously run code blocks on the
> main thread uses dispatch_get_main_queue(), which is a
> 10.10-or-later function. If we're going to go with this
> refactoring I think the benefit in clarity-of-code is a
> worthwhile gain for dropping support for ancient OSX versions.
> 
> Patchset structure:
>  * patch 1 does the "make sure we have the iothread lock for
>    calls into QEMU" (which is effectively a no-op initially
>    since we'll already be holding that lock when our refresh
>    etc callbacks are called)
>  * patch 2 makes switchSurface directly take the pixman image
>    (which is refcounted) rather than the DisplaySurface (which
>    is not), so we can make the calls to it asynchronous later
>  * patches 3 and 4 are just trivial code motion
>  * patch 5 does the bulk of the work (and can't really be split
>    further without the UI being broken at the intermediate point)

DisplaySurface / pixman changes look sane to me.
Can't really comment on the cocoa changes.

cheers,
  Gerd