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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 81 of file FlutterSurfaceManager.h.

## Method Documentation

## ◆ count

- (NSUInteger) count |  |  |

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

Definition at line 352 of file FlutterSurfaceManager.mm.

352 {
353 @synchronized(self) {
354 return _surfaces.count;
355 }
356 }

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 301 of file FlutterSurfaceManager.mm.

301 :(CGSize)size {
302 @synchronized(self) {
303 // Purge all cached surfaces if the size has changed.
304 if (_surfaces.firstObject != nil && !CGSizeEqualToSize(_surfaces.firstObject.size, size)) {
305 [_surfaces removeAllObjects];
306 }
307
308 FlutterSurface* res;
309
310 // Returns youngest surface that is not in use. Returning youngest surface ensures
311 // that the cache doesn't keep more surfaces than it needs to, as the unused surfaces
312 // kept in cache will have their age kept increasing until purged (inside [returnSurfaces:]).
313 for (FlutterSurface* surface in _surfaces) {
314 if (!surface.isInUse &&
315 (res == nil || [self ageForSurface:res] > [self ageForSurface:surface])) {
316 res = surface;
317 }
318 }
319 if (res != nil) {
320 [_surfaces removeObject:res];
321 }
322 return res;
323 }
324 }

References FlutterSurface::isInUse.

## ◆ returnSurfaces:

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

Removes all cached surfaces replacing them with new ones.

Definition at line 326 of file FlutterSurfaceManager.mm.

326 :(nonnull NSArray<FlutterSurface*>*)returnedSurfaces {
327 @synchronized(self) {
328 for (FlutterSurface* surface in returnedSurfaces) {
329 [self setAge:0 forSurface:surface];
330 }
331 for (FlutterSurface* surface in _surfaces) {
332 [self setAge:[self ageForSurface:surface] + 1 forSurface:surface];
333 }
334
335 [_surfaces addObjectsFromArray:returnedSurfaces];
336
337 // Purge all surface with age = kSurfaceEvictionAge. Reaching this age can mean two things:
338 // - Surface is still in use and we can't return it. This can happen in some edge
339 // cases where the compositor holds on to the surface for much longer than expected.
340 // - Surface is not in use but it hasn't been requested from the cache for a while.
341 // This means there are too many surfaces in the cache.
342 [_surfaces filterUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(FlutterSurface* surface,
343 NSDictionary* bindings) {
344 return [self ageForSurface:surface] < kSurfaceEvictionAge;
345 }]];
346 }
347
348 // performSelector:withObject:afterDelay needs to be performed on RunLoop thread
349 [self performSelectorOnMainThread:@selector(reschedule) withObject:nil waitUntilDone:NO];
350 }

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

FlutterSurface
Definition: FlutterSurface.h:16