perf: backport stability and performance fixes from upstream

WebDriverAgentLib/Categories/XCUIElement+FBUtilities.m

@@ -139,18 +139,21 @@ - (void)fb_waitUntilStableWithTimeout:(NSTimeInterval)timeout
     return;
   }
 
-  NSTimeInterval previousTimeout = FBConfiguration.waitForIdleTimeout;
-  BOOL previousQuiescence = self.application.fb_shouldWaitForQuiescence;
-  FBConfiguration.waitForIdleTimeout = timeout;
-  if (!previousQuiescence) {
-    self.application.fb_shouldWaitForQuiescence = YES;
-  }
-  [[[self.application applicationImpl] currentProcess]
-   fb_waitForQuiescenceIncludingAnimationsIdle:YES];
-  if (previousQuiescence != self.application.fb_shouldWaitForQuiescence) {
-    self.application.fb_shouldWaitForQuiescence = previousQuiescence;
+  XCUIApplication *application = self.application;
+  // Recursive synchronization also covers nested stability checks on this thread.
+  @synchronized (FBConfiguration.class) {
+    NSTimeInterval previousTimeout = FBConfiguration.waitForIdleTimeout;
+    BOOL previousQuiescence = application.fb_shouldWaitForQuiescence;
+    @try {
+      FBConfiguration.waitForIdleTimeout = timeout;
+      application.fb_shouldWaitForQuiescence = YES;
+      [[[application applicationImpl] currentProcess]
+        fb_waitForQuiescenceIncludingAnimationsIdle:YES];
+    } @finally {
+      application.fb_shouldWaitForQuiescence = previousQuiescence;
+      FBConfiguration.waitForIdleTimeout = previousTimeout;
+    }
   }
-  FBConfiguration.waitForIdleTimeout = previousTimeout;
 }
 
 - (void)fb_raiseStaleElementExceptionWithError:(NSError *)error __attribute__((noreturn))

WebDriverAgentLib/Commands/FBElementCommands.m

@@ -346,15 +346,15 @@ + (NSArray *)routes
 
 + (id<FBResponsePayload>)handlePressAndDragCoordinateWithVelocity:(FBRouteRequest *)request
 {
-  FBSession *session = request.session;
+  XCUIApplication *application = request.session.activeApplication;
   CGVector startOffset = CGVectorMake((CGFloat)[request.arguments[@"fromX"] doubleValue],
                                      (CGFloat)[request.arguments[@"fromY"] doubleValue]);
   XCUICoordinate *startCoordinate = [self.class gestureCoordinateWithOffset:startOffset
-                                                                    element:session.activeApplication];
+                                                                    element:application];
   CGVector endOffset = CGVectorMake((CGFloat)[request.arguments[@"toX"] doubleValue],
                                     (CGFloat)[request.arguments[@"toY"] doubleValue]);
   XCUICoordinate *endCoordinate = [self.class gestureCoordinateWithOffset:endOffset
-                                                                  element:session.activeApplication];
+                                                                  element:application];
   [startCoordinate pressForDuration:[request.arguments[@"pressDuration"] doubleValue]
                thenDragToCoordinate:endCoordinate
                        withVelocity:[request.arguments[@"velocity"] doubleValue]

WebDriverAgentLib/Utilities/FBImageProcessor.m

@@ -120,7 +120,9 @@ + (nullable NSData *)fixedImageDataWithImageData:(NSData *)imageData
     }
 
     UIGraphicsImageRendererFormat *format = [[UIGraphicsImageRendererFormat alloc] init];
-    format.scale = scalingFactor;
+    // scaledSize already applies the requested factor in points. Preserve the
+    // image's pixels-per-point scale instead of applying that factor twice.
+    format.scale = image.scale;
     UIGraphicsImageRenderer *renderer = [[UIGraphicsImageRenderer alloc] initWithSize:scaledSize
                                                                                format:format];
     UIImageOrientation desiredOrientation = orientation == nil

WebDriverAgentLib/Utilities/FBXCAXClientProxy.m

@@ -20,6 +20,7 @@
 @interface FBXCAXClientProxy ()
 
 @property (nonatomic) NSMutableDictionary<NSNumber *, XCUIApplication *> *appsCache;
+@property (nonatomic, nullable) id<FBXCAccessibilityElement> cachedSystemApplication;
 
 @end
 
@@ -67,7 +68,16 @@ - (BOOL)setAXTimeout:(NSTimeInterval)timeout error:(NSError **)error
 
 - (id<FBXCAccessibilityElement>)systemApplication
 {
-  return [FBAXClient systemApplication];
+  @synchronized (self) {
+    id<FBXCAccessibilityElement> systemApplication = self.cachedSystemApplication;
+    if (nil == systemApplication) {
+      // The system application's identity cannot change without it being killed,
+      // which takes WDA down with it, so it is safe to cache it forever.
+      systemApplication = [FBAXClient systemApplication];
+      self.cachedSystemApplication = systemApplication;
+    }
+    return systemApplication;
+  }
 }
 
 - (NSDictionary *)defaultParameters

WebDriverAgentLib/Utilities/FBXCodeCompatibility.m

@@ -8,15 +8,20 @@
 
 #import "FBXCodeCompatibility.h"
 
+#import <stdatomic.h>
+
 #import "FBXCAXClientProxy.h"
 #import "FBConfiguration.h"
 #import "FBErrorBuilder.h"
 #import "FBLogger.h"
+#import "FBRunLoopSpinner.h"
 #import "XCUIApplication+FBHelpers.h"
 #import "XCUIElementQuery.h"
 #import "FBXCTestDaemonsProxy.h"
 #import "XCTestManager_ManagerInterface-Protocol.h"
 
+static const NSTimeInterval TESTMANAGERD_VERSION_TIMEOUT_SEC = 20.;
+
 @implementation XCUIElementQuery (FBCompatibility)
 
 - (id<FBXCElementSnapshot>)fb_uniqueSnapshotWithError:(NSError **)error
@@ -85,12 +90,25 @@ NSInteger FBTestmanagerdVersion(void)
   dispatch_once(&getTestmanagerdVersion, ^{
     id<XCTestManager_ManagerInterface> proxy = [FBXCTestDaemonsProxy testRunnerProxy];
     if ([(NSObject *)proxy respondsToSelector:@selector(_XCT_exchangeProtocolVersion:reply:)]) {
-      [FBRunLoopSpinner spinUntilCompletion:^(void(^completion)(void)){
-        [proxy _XCT_exchangeProtocolVersion:testmanagerdVersion reply:^(unsigned long long code) {
-          testmanagerdVersion = (NSInteger) code;
-          completion();
-        }];
+      __block atomic_bool didReply = false;
+      __block NSInteger receivedVersion = 0;
+      [proxy _XCT_exchangeProtocolVersion:testmanagerdVersion reply:^(unsigned long long code) {
+        receivedVersion = (NSInteger) code;
+        atomic_store(&didReply, true);
+      }];
+      // Commands are served from the main thread, so a daemon that never replies
+      // must not block it forever. The run loop keeps spinning to deliver the reply
+      BOOL isReplied = [[[FBRunLoopSpinner new]
+                         timeout:TESTMANAGERD_VERSION_TIMEOUT_SEC]
+                        spinUntilTrue:^BOOL{
+        return atomic_load(&didReply);
       }];
+      if (isReplied) {
+        testmanagerdVersion = receivedVersion;
+      } else {
+        [FBLogger logFmt:@"Did not receive a testmanagerd protocol version reply within %.0f seconds; assuming the newest/full-featured protocol", TESTMANAGERD_VERSION_TIMEOUT_SEC];
+        testmanagerdVersion = 0xFFFF;
+      }
     } else {
       testmanagerdVersion = 0xFFFF;
     }

WebDriverAgentLib/Utilities/FBXPath.m

@@ -463,6 +463,19 @@ + (int)recordElementAttributes:(xmlTextWriterPtr)writer
                      indexPath:(nullable NSString *)indexPath
             includedAttributes:(nullable NSSet<Class> *)includedAttributes
 {
+  return [self recordElementAttributes:writer forElement:element indexPath:indexPath
+                    includedAttributes:includedAttributes siblingIndex:nil];
+}
+
++ (int)recordElementAttributes:(xmlTextWriterPtr)writer
+                    forElement:(id<FBXCElementSnapshot>)element
+                     indexPath:(nullable NSString *)indexPath
+            includedAttributes:(nullable NSSet<Class> *)includedAttributes
+                  siblingIndex:(nullable NSNumber *)siblingIndex
+{
+  FBXCElementSnapshotWrapper *wrapped = [FBXCElementSnapshotWrapper ensureWrapped:element];
+  // Calculated once for all dimension attributes
+  NSDictionary *rect = nil;
   for (Class attributeCls in FBElementAttribute.supportedAttributes) {
     // include all supported attributes by default unless enumerated explicitly
     if (includedAttributes && ![includedAttributes containsObject:attributeCls]) {
@@ -478,8 +491,16 @@ + (int)recordElementAttributes:(xmlTextWriterPtr)writer
         !FBDoesElementSupportMinMaxValue(element.elementType)) {
       continue;
     }
-    int rc = [attributeCls recordWithWriter:writer
-                                 forElement:[FBXCElementSnapshotWrapper ensureWrapped:element]];
+    int rc;
+    if (attributeCls == FBIndexAttribute.class && nil != siblingIndex) {
+      // The caller already knows the position, so do not scan the siblings to find it
+      rc = [attributeCls recordWithWriter:writer forValue:siblingIndex.stringValue];
+    } else if ([attributeCls isSubclassOfClass:FBDimensionAttribute.class]) {
+      rect = rect ?: wrapped.wdRect;
+      rc = [attributeCls recordWithWriter:writer forValue:[rect[[attributeCls name]] description]];
+    } else {
+      rc = [attributeCls recordWithWriter:writer forElement:wrapped];
+    }
     if (rc < 0) {
       return rc;
     }
@@ -518,6 +539,17 @@ + (int)writeXmlWithRootElement:(id<FBXCElementSnapshot>)root
                   elementStore:(nullable NSMutableDictionary *)elementStore
             includedAttributes:(nullable NSSet<Class> *)includedAttributes
                         writer:(xmlTextWriterPtr)writer
+{
+  return [self writeXmlWithRootElement:root indexPath:indexPath elementStore:elementStore
+                    includedAttributes:includedAttributes writer:writer siblingIndex:nil];
+}
+
++ (int)writeXmlWithRootElement:(id<FBXCElementSnapshot>)root
+                     indexPath:(nullable NSString *)indexPath
+                  elementStore:(nullable NSMutableDictionary *)elementStore
+            includedAttributes:(nullable NSSet<Class> *)includedAttributes
+                        writer:(xmlTextWriterPtr)writer
+                  siblingIndex:(nullable NSNumber *)siblingIndex
 {
   NSAssert((indexPath == nil && elementStore == nil) || (indexPath != nil && elementStore != nil), @"Either both or none of indexPath and elementStore arguments should be equal to nil", nil);
 
@@ -537,7 +569,8 @@ + (int)writeXmlWithRootElement:(id<FBXCElementSnapshot>)root
   rc = [self recordElementAttributes:writer
                           forElement:root
                            indexPath:indexPath
-                  includedAttributes:includedAttributes];
+                  includedAttributes:includedAttributes
+                        siblingIndex:siblingIndex];
   if (rc < 0) {
     return rc;
   }
@@ -553,7 +586,8 @@ + (int)writeXmlWithRootElement:(id<FBXCElementSnapshot>)root
                                indexPath:newIndexPath
                             elementStore:elementStore
                       includedAttributes:includedAttributes
-                                  writer:writer];
+                                  writer:writer
+                            siblingIndex:@(i)];
       if (rc < 0) {
         return rc;
       }

WebDriverAgentLib/Utilities/LRUCache/LRUCache.m

@@ -80,7 +80,7 @@ - (nullable LRUCacheNode *)moveNodeToHead:(nullable LRUCacheNode *)node
   }
   LRUCacheNode *nextNode = node.next;
   if (nil != nextNode) {
-    nextNode.prev = node.prev;
+    nextNode.prev = previousNode;
   }
   if (node == self.tailNode) {
     self.tailNode = previousNode;
@@ -94,19 +94,22 @@ - (void)removeNode:(nullable LRUCacheNode *)node
     return;
   }
 
+  LRUCacheNode *previousNode = node.prev;
   if (nil != node.next) {
-    node.next.prev = node.prev;
+    node.next.prev = previousNode;
   }
   if (node == self.headNode) {
     self.headNode = node.next;
   }
-  if (nil != node.prev) {
-    node.prev.next = node.next;
+  if (nil != previousNode) {
+    previousNode.next = node.next;
   }
   if (node == self.tailNode) {
-    self.tailNode = node.prev;
+    self.tailNode = previousNode;
   }
   [self.store removeObjectForKey:(id)node.key];
+  node.next = nil;
+  node.prev = nil;
 }
 
 - (nullable LRUCacheNode *)addNodeToHead:(nullable LRUCacheNode *)node

WebDriverAgentLib/Utilities/LRUCache/LRUCacheNode.h

@@ -26,8 +26,8 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, readonly) id<NSCopying> key;
 /*! Pointer to the next node */
 @property (nonatomic, nullable) LRUCacheNode *next;
-/*! Pointer to the previous node */
-@property (nonatomic, nullable) LRUCacheNode *prev;
+/*! Pointer to the previous node. Weak to avoid retain cycles between neighbour nodes */
+@property (nonatomic, weak, nullable) LRUCacheNode *prev;
 
 /**
  Factory method to create a new cache node with the given value and key

WebDriverAgentTests/IntegrationTests/FBImageProcessorTests.m

@@ -9,6 +9,7 @@
 #import <XCTest/XCTest.h>
 
 #import "FBImageProcessor.h"
+@import UniformTypeIdentifiers;
 #import "FBIntegrationTestCase.h"
 
 
@@ -80,3 +81,36 @@ + (CGSize)sizeFromSize:(CGSize)size scalingFactor:(CGFloat)scalingFactor {
 
 @end
 
+
+// Synthetic images keep these renderer regressions independent of the app's screen.
+@interface FBImageRendererScalingTests : XCTestCase
+@end
+
+@implementation FBImageRendererScalingTests
+
+- (void)testOrientationFixDoesNotApplyScalingTwice
+{
+  for (NSNumber *sourceScale in @[@1, @2, @3]) {
+    UIGraphicsImageRendererFormat *format = [UIGraphicsImageRendererFormat new];
+    format.scale = sourceScale.doubleValue;
+    UIGraphicsImageRenderer *renderer = [[UIGraphicsImageRenderer alloc]
+      initWithSize:CGSizeMake(120, 80) format:format];
+    NSData *data = [renderer PNGDataWithActions:^(UIGraphicsImageRendererContext *context) {
+      [UIColor.redColor setFill];
+      [context fillRect:CGRectMake(0, 0, 120, 80)];
+    }];
+    FBImageProcessor *processor = [FBImageProcessor new];
+    NSData *scaled = [processor scaledImageWithData:data
+                                               uti:UTTypePNG
+                                     scalingFactor:0.5
+                                compressionQuality:1.0
+                                             error:nil];
+    UIImage *image = [UIImage imageWithData:scaled];
+    XCTAssertNotNil(image);
+    XCTAssertEqual(CGImageGetWidth(image.CGImage), (size_t)(60 * sourceScale.integerValue));
+    XCTAssertEqual(CGImageGetHeight(image.CGImage), (size_t)(40 * sourceScale.integerValue));
+  }
+}
+
+@end
+

WebDriverAgentTests/UnitTests/FBElementUtilitiesTests.m

@@ -12,12 +12,52 @@
 #import "FBElement.h"
 #import "XCUIElementDouble.h"
 #import "FBElementUtils.h"
+#import "FBConfiguration.h"
+#import "XCUIElement+FBUtilities.h"
+#import <objc/runtime.h>
+
+@interface FBQuiescenceApplicationDouble : NSObject
+@property (nonatomic) BOOL fb_shouldWaitForQuiescence;
+@property (nonatomic) NSTimeInterval observedTimeout;
+@end
+@implementation FBQuiescenceApplicationDouble
+- (id)applicationImpl { return self; }
+- (id)currentProcess { return self; }
+- (void)fb_waitForQuiescenceIncludingAnimationsIdle:(BOOL)includingAnimations
+{
+  self.observedTimeout = FBConfiguration.waitForIdleTimeout;
+  @throw [NSException exceptionWithName:@"QuiescenceFailure" reason:@"test" userInfo:nil];
+}
+@end
 
 @interface FBElementUtilitiesTests : XCTestCase
 @end
 
 @implementation FBElementUtilitiesTests
 
+- (void)testStabilityWaitRestoresSettingsAfterAnException
+{
+  NSTimeInterval originalTimeout = FBConfiguration.waitForIdleTimeout;
+  FBQuiescenceApplicationDouble *application = [FBQuiescenceApplicationDouble new];
+  XCUIElementDouble *element = [XCUIElementDouble new];
+  element.application = (id)application;
+  SEL selector = @selector(fb_waitUntilStableWithTimeout:);
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wcast-function-type-strict"
+  void (*wait)(id, SEL, NSTimeInterval) = (void (*)(id, SEL, NSTimeInterval))
+    class_getMethodImplementation(XCUIElement.class, selector);
+#pragma clang diagnostic pop
+  @try {
+    FBConfiguration.waitForIdleTimeout = 17;
+    XCTAssertThrowsSpecificNamed(wait(element, selector, 2), NSException, @"QuiescenceFailure");
+    XCTAssertEqual(application.observedTimeout, 2);
+    XCTAssertFalse(application.fb_shouldWaitForQuiescence);
+    XCTAssertEqual(FBConfiguration.waitForIdleTimeout, 17);
+  } @finally {
+    FBConfiguration.waitForIdleTimeout = originalTimeout;
+  }
+}
+
 - (void)testTypesFiltering {
   NSMutableArray *elements = [NSMutableArray new];
   XCUIElementDouble *el1 = [XCUIElementDouble new];