Analytics/SFAnalyticsSampler.m

   1 /*
   2  * Copyright (c) 2017 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #if __OBJC2__
  25
  26 #import "SFAnalyticsSampler+Internal.h"
  27 #import "SFAnalytics+Internal.h"
  28 #import "SFAnalyticsDefines.h"
  29 #import "utilities/debugging.h"
  30 #include <notify.h>
  31 #include <dispatch/dispatch.h>
  32
  33 @implementation SFAnalyticsSampler {
  34     NSTimeInterval _samplingInterval;
  35     dispatch_source_t _timer;
  36     NSString* _name;
  37     NSNumber* (^_block)(void);
  38     int _notificationToken;
  39     Class _clientClass;
  40     BOOL _oncePerReport;
  41     BOOL _activeTimer;
  42 }
  43
  44 @synthesize name = _name;
  45 @synthesize samplingInterval = _samplingInterval;
  46 @synthesize oncePerReport = _oncePerReport;
  47
  48
  49 - (instancetype)initWithName:(NSString*)name interval:(NSTimeInterval)interval block:(NSNumber* (^)(void))block clientClass:(Class)clientClass
  50 {
  51     if (self = [super init]) {
  52         if (![clientClass isSubclassOfClass:[SFAnalytics class]]) {
  53             secerror("SFAnalyticsSampler created without valid client class (%@)", clientClass);
  54             return nil;
  55         }
  56
  57         if (!name || (interval < 1.0f && interval != SFAnalyticsSamplerIntervalOncePerReport) || !block) {
  58             secerror("SFAnalyticsSampler created without proper data");
  59             return nil;
  60         }
  61
  62         _clientClass = clientClass;
  63         _block = block;
  64         _name = name;
  65         _samplingInterval = interval;
  66         [self newTimer];
  67     }
  68     return self;
  69 }
  70
  71 - (void)newTimer
  72 {
  73     if (_activeTimer) {
  74         [self pauseSampling];
  75     }
  76
  77     _oncePerReport = (_samplingInterval == SFAnalyticsSamplerIntervalOncePerReport);
  78     if (_oncePerReport) {
  79         [self setupOnceTimer];
  80     } else {
  81         [self setupPeriodicTimer];
  82     }
  83 }
  84
  85 - (void)setupOnceTimer
  86 {
  87     __weak __typeof(self) weakSelf = self;
  88     notify_register_dispatch(SFAnalyticsFireSamplersNotification, &_notificationToken, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(int token) {
  89         __strong __typeof(self) strongSelf = weakSelf;
  90         if (!strongSelf) {
  91             secnotice("SFAnalyticsSampler", "sampler went away before we could run its once-per-report block");
  92             notify_cancel(token);
  93             return;
  94         }
  95         [[strongSelf->_clientClass logger] logMetric:strongSelf->_block() withName:strongSelf->_name oncePerReport:strongSelf->_oncePerReport];
  96     });
  97     _activeTimer = YES;
  98 }
  99
 100 - (void)setupPeriodicTimer
 101 {
 102     _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0));
 103     dispatch_source_set_timer(_timer, dispatch_walltime(0, _samplingInterval * NSEC_PER_SEC), _samplingInterval * NSEC_PER_SEC, _samplingInterval * NSEC_PER_SEC / 50.0);    // give 2% leeway on timer
 104
 105     __weak __typeof(self) weakSelf = self;
 106     dispatch_source_set_event_handler(_timer, ^{
 107         __strong __typeof(self) strongSelf = weakSelf;
 108         if (!strongSelf) {
 109             // TODO: can we cancel this thing from here?
 110             secnotice("SFAnalyticsSampler", "sampler went away before we could run its once-per-report block");
 111             return;
 112         }
 113         [[strongSelf->_clientClass logger] logMetric:strongSelf->_block() withName:strongSelf->_name oncePerReport:strongSelf->_oncePerReport];
 114     });
 115     dispatch_resume(_timer);
 116
 117     _activeTimer = YES;
 118 }
 119
 120 - (void)setSamplingInterval:(NSTimeInterval)interval
 121 {
 122     if (interval < 1.0f && !(interval == SFAnalyticsSamplerIntervalOncePerReport)) {
 123         secerror("SFAnalyticsSampler: interval %f is not supported", interval);
 124         return;
 125     }
 126
 127     _samplingInterval = interval;
 128     [self newTimer];
 129 }
 130
 131 - (NSTimeInterval)samplingInterval {
 132     return _samplingInterval;
 133 }
 134
 135 - (NSNumber*)sampleNow
 136 {
 137     NSNumber* result = _block();
 138     [[_clientClass logger] logMetric:result withName:_name oncePerReport:_oncePerReport];
 139     return result;
 140 }
 141
 142 - (void)pauseSampling
 143 {
 144     if (!_activeTimer) {
 145         return;
 146     }
 147
 148     if (_oncePerReport) {
 149         notify_cancel(_notificationToken);
 150         _notificationToken = 0;
 151     } else {
 152         dispatch_source_cancel(_timer);
 153     }
 154     _activeTimer = NO;
 155 }
 156
 157 - (void)resumeSampling
 158 {
 159     [self newTimer];
 160 }
 161
 162 - (void)dealloc
 163 {
 164     [self pauseSampling];
 165 }
 166
 167 @end
 168
 169 #endif