added files via upload

Tweaks/FLEX/GlobalStateExplorers/SystemLog/FLEXASLLogController.m

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+//
+//  FLEXASLLogController.m
+//  FLEX
+//
+//  Created by Tanner on 3/14/19.
+//  Copyright © 2020 FLEX Team. All rights reserved.
+//
+
+#import "FLEXASLLogController.h"
+#import <asl.h>
+
+// Querying the ASL is much slower in the simulator. We need a longer polling interval to keep things responsive.
+#if TARGET_IPHONE_SIMULATOR
+    #define updateInterval 5.0
+#else
+    #define updateInterval 0.5
+#endif
+
+@interface FLEXASLLogController ()
+
+@property (nonatomic, readonly) void (^updateHandler)(NSArray<FLEXSystemLogMessage *> *);
+
+@property (nonatomic) NSTimer *logUpdateTimer;
+@property (nonatomic, readonly) NSMutableIndexSet *logMessageIdentifiers;
+
+// ASL stuff
+
+@property (nonatomic) NSUInteger heapSize;
+@property (nonatomic) dispatch_queue_t logQueue;
+@property (nonatomic) dispatch_io_t io;
+@property (nonatomic) NSString *remaining;
+@property (nonatomic) int stderror;
+@property (nonatomic) NSString *lastTimestamp;
+
+@end
+
+@implementation FLEXASLLogController
+
++ (instancetype)withUpdateHandler:(void(^)(NSArray<FLEXSystemLogMessage *> *newMessages))newMessagesHandler {
+    return [[self alloc] initWithUpdateHandler:newMessagesHandler];
+}
+
+- (id)initWithUpdateHandler:(void(^)(NSArray<FLEXSystemLogMessage *> *newMessages))newMessagesHandler {
+    NSParameterAssert(newMessagesHandler);
+
+    self = [super init];
+    if (self) {
+        _updateHandler = newMessagesHandler;
+        _logMessageIdentifiers = [NSMutableIndexSet new];
+        self.logUpdateTimer = [NSTimer scheduledTimerWithTimeInterval:updateInterval
+                                                               target:self
+                                                             selector:@selector(updateLogMessages)
+                                                             userInfo:nil
+                                                              repeats:YES];
+    }
+
+    return self;
+}
+
+- (void)dealloc {
+    [self.logUpdateTimer invalidate];
+}
+
+- (BOOL)startMonitoring {
+    [self.logUpdateTimer fire];
+    return YES;
+}
+
+- (void)updateLogMessages {
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+        NSArray<FLEXSystemLogMessage *> *newMessages;
+        @synchronized (self) {
+            newMessages = [self newLogMessagesForCurrentProcess];
+            if (!newMessages.count) {
+                return;
+            }
+
+            for (FLEXSystemLogMessage *message in newMessages) {
+                [self.logMessageIdentifiers addIndex:(NSUInteger)message.messageID];
+            }
+
+            self.lastTimestamp = @(asl_get(newMessages.lastObject.aslMessage, ASL_KEY_TIME) ?: "null");
+        }
+
+        dispatch_async(dispatch_get_main_queue(), ^{
+            self.updateHandler(newMessages);
+        });
+    });
+}
+
+#pragma mark - Log Message Fetching
+
+- (NSArray<FLEXSystemLogMessage *> *)newLogMessagesForCurrentProcess {
+    if (!self.logMessageIdentifiers.count) {
+        return [self allLogMessagesForCurrentProcess];
+    }
+
+    aslresponse response = [self ASLMessageListForCurrentProcess];
+    aslmsg aslMessage = NULL;
+
+    NSMutableArray<FLEXSystemLogMessage *> *newMessages = [NSMutableArray new];
+
+    while ((aslMessage = asl_next(response))) {
+        NSUInteger messageID = (NSUInteger)atoll(asl_get(aslMessage, ASL_KEY_MSG_ID));
+        if (![self.logMessageIdentifiers containsIndex:messageID]) {
+            [newMessages addObject:[FLEXSystemLogMessage logMessageFromASLMessage:aslMessage]];
+        }
+    }
+
+    asl_release(response);
+    return newMessages;
+}
+
+- (aslresponse)ASLMessageListForCurrentProcess {
+    static NSString *pidString = nil;
+    if (!pidString) {
+        pidString = @([NSProcessInfo.processInfo processIdentifier]).stringValue;
+    }
+
+    // Create system log query object.
+    asl_object_t query = asl_new(ASL_TYPE_QUERY);
+
+    // Filter for messages from the current process.
+    // Note that this appears to happen by default on device, but is required in the simulator.
+    asl_set_query(query, ASL_KEY_PID, pidString.UTF8String, ASL_QUERY_OP_EQUAL);
+    // Filter for messages after the last retrieved message.
+    if (self.lastTimestamp) {
+        asl_set_query(query, ASL_KEY_TIME, self.lastTimestamp.UTF8String, ASL_QUERY_OP_GREATER);
+    }
+
+    return asl_search(NULL, query);
+}
+
+- (NSArray<FLEXSystemLogMessage *> *)allLogMessagesForCurrentProcess {
+    aslresponse response = [self ASLMessageListForCurrentProcess];
+    aslmsg aslMessage = NULL;
+
+    NSMutableArray<FLEXSystemLogMessage *> *logMessages = [NSMutableArray new];
+    while ((aslMessage = asl_next(response))) {
+        [logMessages addObject:[FLEXSystemLogMessage logMessageFromASLMessage:aslMessage]];
+    }
+    asl_release(response);
+
+    return logMessages;
+}
+
+@end