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FlutterBackBufferCache Class Reference

`#import <FlutterSurfaceManager.h>`

Inheritance diagram for FlutterBackBufferCache:

## Instance Methods
(nullable FlutterSurface *) | - removeSurfaceForSize:
(void) | - returnSurfaces:
(NSUInteger) | - count

## Detailed Description

Cache of back buffers to prevent unnecessary IOSurface allocations.

Definition at line 83 of file FlutterSurfaceManager.h.

## Method Documentation

## ◆ count

- (NSUInteger) count |  |  |

Returns number of surfaces currently in cache. Used for tests.

Definition at line 271 of file FlutterSurfaceManager.mm.

346 {
347 @synchronized(self) {
348 return _surfaces.count;
349 }
350 }

Referenced by flutter::testing::TEST().

## ◆ removeSurfaceForSize:

- (nullable FlutterSurface *) removeSurfaceForSize: |  | (CGSize) | size |

Removes surface with given size from cache (if available) and returns it.

Definition at line 271 of file FlutterSurfaceManager.mm.

295 :(CGSize)size {
296 @synchronized(self) {
297 // Purge all cached surfaces if the size has changed.
298 if (_surfaces.firstObject != nil && !CGSizeEqualToSize(_surfaces.firstObject.size, size)) {
299 [_surfaces removeAllObjects];
300 }
301
302 FlutterSurface* res;
303
304 // Returns youngest surface that is not in use. Returning youngest surface ensures
305 // that the cache doesn't keep more surfaces than it needs to, as the unused surfaces
306 // kept in cache will have their age kept increasing until purged (inside [returnSurfaces:]).
307 for (FlutterSurface* surface in _surfaces) {
308 if (!surface.isInUse &&
309 (res == nil || [self ageForSurface:res] > [self ageForSurface:surface])) {
310 res = surface;
311 }
312 }
313 if (res != nil) {
314 [_surfaces removeObject:res];
315 }
316 return res;
317 }
318 }
FlutterSurface
Definition: FlutterSurface.h:17

## ◆ returnSurfaces:

- (void) returnSurfaces: |  | (nonnull NSArray<FlutterSurface*>*) | surfaces |

Removes all cached surfaces replacing them with new ones.

Definition at line 271 of file FlutterSurfaceManager.mm.

320 :(nonnull NSArray<FlutterSurface*>*)returnedSurfaces {
321 @synchronized(self) {
322 for (FlutterSurface* surface in returnedSurfaces) {
323 [self setAge:0 forSurface:surface];
324 }
325 for (FlutterSurface* surface in _surfaces) {
326 [self setAge:[self ageForSurface:surface] + 1 forSurface:surface];
327 }
328
329 [_surfaces addObjectsFromArray:returnedSurfaces];
330
331 // Purge all surface with age = kSurfaceEvictionAge. Reaching this age can mean two things:
332 // - Surface is still in use and we can't return it. This can happen in some edge
333 // cases where the compositor holds on to the surface for much longer than expected.
334 // - Surface is not in use but it hasn't been requested from the cache for a while.
335 // This means there are too many surfaces in the cache.
336 [_surfaces filterUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(FlutterSurface* surface,
337 NSDictionary* bindings) {
338 return [self ageForSurface:surface] < kSurfaceEvictionAge;
339 }]];
340 }
341
342 // performSelector:withObject:afterDelay needs to be performed on RunLoop thread
343 [self performSelectorOnMainThread:@selector(reschedule) withObject:nil waitUntilDone:NO];
344 }

The documentation for this class was generated from the following files:

- shell/platform/darwin/macos/framework/Source/FlutterSurfaceManager.h
- shell/platform/darwin/macos/framework/Source/FlutterSurfaceManager.mm