FLEX/Classes/GlobalStateExplorers/FLEXLiveObjectsController.m

//
//  FLEXLiveObjectsController.m
//  Flipboard
//
//  Created by Ryan Olson on 5/28/14.
//  Copyright (c) 2020 FLEX Team. All rights reserved.
//

#import "FLEXLiveObjectsController.h"
#import "FLEXHeapEnumerator.h"
#import "FLEXObjectListViewController.h"
#import "FLEXUtility.h"
#import "FLEXScopeCarousel.h"
#import "FLEXTableView.h"
#import <objc/runtime.h>

static const NSInteger kFLEXLiveObjectsSortAlphabeticallyIndex = 0;
static const NSInteger kFLEXLiveObjectsSortByCountIndex = 1;
static const NSInteger kFLEXLiveObjectsSortBySizeIndex = 2;

@interface FLEXLiveObjectsController ()

@property (nonatomic) NSDictionary<NSString *, NSNumber *> *instanceCountsForClassNames;
@property (nonatomic) NSDictionary<NSString *, NSNumber *> *instanceSizesForClassNames;
@property (nonatomic, readonly) NSArray<NSString *> *allClassNames;
@property (nonatomic) NSArray<NSString *> *filteredClassNames;
@property (nonatomic) NSString *headerTitle;

@end

@implementation FLEXLiveObjectsController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.showsSearchBar = YES;
    self.showSearchBarInitially = YES;
    self.searchBarDebounceInterval = kFLEXDebounceInstant;
    self.showsCarousel = YES;
    self.carousel.items = @[@"A→Z", @"Count", @"Size"];
    
    self.refreshControl = [UIRefreshControl new];
    [self.refreshControl addTarget:self action:@selector(refreshControlDidRefresh:) forControlEvents:UIControlEventValueChanged];
    
    [self reloadTableData];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    
    dispatch_async(dispatch_get_main_queue(), ^{
        // This doesn't work unless it's wrapped in this dispatch_async call
        [self.searchController.searchBar becomeFirstResponder];
    });
}

- (NSArray<NSString *> *)allClassNames {
    return self.instanceCountsForClassNames.allKeys;
}

- (void)reloadTableData {
    // Set up a CFMutableDictionary with class pointer keys and NSUInteger values.
    // We abuse CFMutableDictionary a little to have primitive keys through judicious casting, but it gets the job done.
    // The dictionary is intialized with a 0 count for each class so that it doesn't have to expand during enumeration.
    // While it might be a little cleaner to populate an NSMutableDictionary with class name string keys to NSNumber counts,
    // we choose the CF/primitives approach because it lets us enumerate the objects in the heap without allocating any memory during enumeration.
    // The alternative of creating one NSString/NSNumber per object on the heap ends up polluting the count of live objects quite a bit.
    unsigned int classCount = 0;
    Class *classes = objc_copyClassList(&classCount);
    CFMutableDictionaryRef mutableCountsForClasses = CFDictionaryCreateMutable(NULL, classCount, NULL, NULL);
    for (unsigned int i = 0; i < classCount; i++) {
        CFDictionarySetValue(mutableCountsForClasses, (__bridge const void *)classes[i], (const void *)0);
    }
    
    // Enumerate all objects on the heap to build the counts of instances for each class.
    [FLEXHeapEnumerator enumerateLiveObjectsUsingBlock:^(__unsafe_unretained id object, __unsafe_unretained Class actualClass) {
        NSUInteger instanceCount = (NSUInteger)CFDictionaryGetValue(mutableCountsForClasses, (__bridge const void *)actualClass);
        instanceCount++;
        CFDictionarySetValue(mutableCountsForClasses, (__bridge const void *)actualClass, (const void *)instanceCount);
    }];
    
    // Convert our CF primitive dictionary into a nicer mapping of class name strings to counts that we will use as the table's model.
    NSMutableDictionary<NSString *, NSNumber *> *mutableCountsForClassNames = [NSMutableDictionary new];
    NSMutableDictionary<NSString *, NSNumber *> *mutableSizesForClassNames = [NSMutableDictionary new];
    for (unsigned int i = 0; i < classCount; i++) {
        Class class = classes[i];
        NSUInteger instanceCount = (NSUInteger)CFDictionaryGetValue(mutableCountsForClasses, (__bridge const void *)(class));
        NSString *className = @(class_getName(class));
        if (instanceCount > 0) {
            [mutableCountsForClassNames setObject:@(instanceCount) forKey:className];
        }
        [mutableSizesForClassNames setObject:@(class_getInstanceSize(class)) forKey:className];
    }
    free(classes);
    
    self.instanceCountsForClassNames = mutableCountsForClassNames;
    self.instanceSizesForClassNames = mutableSizesForClassNames;
    
    [self updateSearchResults:nil];
}

- (void)refreshControlDidRefresh:(id)sender {
    [self reloadTableData];
    [self.refreshControl endRefreshing];
}

- (void)updateHeaderTitle {
    NSUInteger totalCount = 0;
    NSUInteger totalSize = 0;
    for (NSString *className in self.allClassNames) {
        NSUInteger count = self.instanceCountsForClassNames[className].unsignedIntegerValue;
        totalCount += count;
        totalSize += count * self.instanceSizesForClassNames[className].unsignedIntegerValue;
    }

    NSUInteger filteredCount = 0;
    NSUInteger filteredSize = 0;
    for (NSString *className in self.filteredClassNames) {
        NSUInteger count = self.instanceCountsForClassNames[className].unsignedIntegerValue;
        filteredCount += count;
        filteredSize += count * self.instanceSizesForClassNames[className].unsignedIntegerValue;
    }
    
    if (filteredCount == totalCount) {
        // Unfiltered
        self.headerTitle = [NSString
            stringWithFormat:@"%@ objects, %@",
            @(totalCount), [NSByteCountFormatter
                stringFromByteCount:totalSize
                countStyle:NSByteCountFormatterCountStyleFile
            ]
        ];
    } else {
        self.headerTitle = [NSString
            stringWithFormat:@"%@ of %@ objects, %@",
            @(filteredCount), @(totalCount), [NSByteCountFormatter
                stringFromByteCount:filteredSize
                countStyle:NSByteCountFormatterCountStyleFile
            ]
        ];
    }
}


#pragma mark - FLEXGlobalsEntry

+ (NSString *)globalsEntryTitle:(FLEXGlobalsRow)row {
    return @"💩  Heap Objects";
}

+ (UIViewController *)globalsEntryViewController:(FLEXGlobalsRow)row {
    FLEXLiveObjectsController *liveObjectsViewController = [self new];
    liveObjectsViewController.title = [self globalsEntryTitle:row];

    return liveObjectsViewController;
}


#pragma mark - Search bar

- (void)updateSearchResults:(NSString *)filter {
    NSInteger selectedScope = self.selectedScope;
    
    if (filter.length) {
        NSPredicate *searchPredicate = [NSPredicate predicateWithFormat:@"SELF CONTAINS[cd] %@", filter];
        self.filteredClassNames = [self.allClassNames filteredArrayUsingPredicate:searchPredicate];
    } else {
        self.filteredClassNames = self.allClassNames;
    }
    
    if (selectedScope == kFLEXLiveObjectsSortAlphabeticallyIndex) {
        self.filteredClassNames = [self.filteredClassNames sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
    } else if (selectedScope == kFLEXLiveObjectsSortByCountIndex) {
        self.filteredClassNames = [self.filteredClassNames sortedArrayUsingComparator:^NSComparisonResult(NSString *className1, NSString *className2) {
            NSNumber *count1 = self.instanceCountsForClassNames[className1];
            NSNumber *count2 = self.instanceCountsForClassNames[className2];
            // Reversed for descending counts.
            return [count2 compare:count1];
        }];
    } else if (selectedScope == kFLEXLiveObjectsSortBySizeIndex) {
        self.filteredClassNames = [self.filteredClassNames sortedArrayUsingComparator:^NSComparisonResult(NSString *className1, NSString *className2) {
            NSNumber *count1 = self.instanceCountsForClassNames[className1];
            NSNumber *count2 = self.instanceCountsForClassNames[className2];
            NSNumber *size1 = self.instanceSizesForClassNames[className1];
            NSNumber *size2 = self.instanceSizesForClassNames[className2];
            // Reversed for descending sizes.
            return [@(count2.integerValue * size2.integerValue) compare:@(count1.integerValue * size1.integerValue)];
        }];
    }
    
    [self updateHeaderTitle];
    [self.tableView reloadData];
}


#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return self.filteredClassNames.count;
}

- (UITableViewCell *)tableView:(__kindof UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView
        dequeueReusableCellWithIdentifier:kFLEXDefaultCell
        forIndexPath:indexPath
    ];

    NSString *className = self.filteredClassNames[indexPath.row];
    NSNumber *count = self.instanceCountsForClassNames[className];
    NSNumber *size = self.instanceSizesForClassNames[className];
    unsigned long totalSize = count.unsignedIntegerValue * size.unsignedIntegerValue;
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    cell.textLabel.text = [NSString stringWithFormat:@"%@ (%ld, %@)",
        className, (long)[count integerValue],
        [NSByteCountFormatter
            stringFromByteCount:totalSize
            countStyle:NSByteCountFormatterCountStyleFile
        ]
    ];
    
    return cell;
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
    return self.headerTitle;
}


#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    NSString *className = self.filteredClassNames[indexPath.row];
    UIViewController *instances = [FLEXObjectListViewController instancesOfClassWithName:className];
    [self.navigationController pushViewController:instances animated:YES];
}

@end