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
  47 - (instancetype)initWithName:(NSString*)name interval:(NSTimeInterval)interval block:(NSNumber* (^)(void))block clientClass:(Class)clientClass
  48 {
  49     if (self = [super init]) {
  50         if (![clientClass isSubclassOfClass:[SFAnalytics class]]) {
  51             secerror("SFAnalyticsSampler created without valid client class (%@)", clientClass);
  52             return nil;
  53         }
  54
  55         if (!name || (interval < 1.0f && interval != SFAnalyticsSamplerIntervalOncePerReport) || !block) {
  56             secerror("SFAnalyticsSampler created without proper data");
  57             return nil;
  58         }
  59
  60         _clientClass = clientClass;
  61         _block = block;
  62         _name = name;
  63         _samplingInterval = interval;
  64         [self newTimer];
  65     }
  66     return self;
  67 }
  68
  69 - (void)newTimer
  70 {
  71     if (_activeTimer) {
  72         [self pauseSampling];
  73     }
  74
  75     _oncePerReport = (_samplingInterval == SFAnalyticsSamplerIntervalOncePerReport);
  76     if (_oncePerReport) {
  77         [self setupOnceTimer];
  78     } else {
  79         [self setupPeriodicTimer];
  80     }
  81 }
  82
  83 - (void)setupOnceTimer
  84 {
  85     __weak __typeof(self) weakSelf = self;
  86     notify_register_dispatch(SFAnalyticsFireSamplersNotification, &_notificationToken, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(int token) {
  87         __strong __typeof(self) strongSelf = weakSelf;
  88         if (!strongSelf) {
  89             secnotice("SFAnalyticsSampler", "sampler went away before we could run its once-per-report block");
  90             notify_cancel(token);
  91             return;
  92         }
  93         [[strongSelf->_clientClass logger] logMetric:strongSelf->_block() withName:strongSelf->_name oncePerReport:strongSelf->_oncePerReport];
  94     });
  95     _activeTimer = YES;
  96 }
  97
  98 - (void)setupPeriodicTimer
  99 {
 100     _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0));
 101     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
 102
 103     __weak __typeof(self) weakSelf = self;
 104     dispatch_source_set_event_handler(_timer, ^{
 105         __strong __typeof(self) strongSelf = weakSelf;
 106         if (!strongSelf) {
 107             // TODO: can we cancel this thing from here?
 108             secnotice("SFAnalyticsSampler", "sampler went away before we could run its once-per-report block");
 109             return;
 110         }
 111         [[strongSelf->_clientClass logger] logMetric:strongSelf->_block() withName:strongSelf->_name oncePerReport:strongSelf->_oncePerReport];
 112     });
 113     dispatch_resume(_timer);
 114
 115     _activeTimer = YES;
 116 }
 117
 118 - (void)setSamplingInterval:(NSTimeInterval)interval
 119 {
 120     if (interval < 1.0f && !(interval == SFAnalyticsSamplerIntervalOncePerReport)) {
 121         secerror("SFAnalyticsSampler: interval %f is not supported", interval);
 122         return;
 123     }
 124
 125     _samplingInterval = interval;
 126     [self newTimer];
 127 }
 128
 129 - (NSTimeInterval)samplingInterval {
 130     return _samplingInterval;
 131 }
 132
 133 - (NSNumber*)sampleNow
 134 {
 135     NSNumber* result = _block();
 136     [[_clientClass logger] logMetric:result withName:_name oncePerReport:_oncePerReport];
 137     return result;
 138 }
 139
 140 - (void)pauseSampling
 141 {
 142     if (!_activeTimer) {
 143         return;
 144     }
 145
 146     if (_oncePerReport) {
 147         notify_cancel(_notificationToken);
 148         _notificationToken = 0;
 149     } else {
 150         dispatch_source_cancel(_timer);
 151     }
 152     _activeTimer = NO;
 153 }
 154
 155 - (void)resumeSampling
 156 {
 157     [self newTimer];
 158 }
 159
 160 - (void)dealloc
 161 {
 162     [self pauseSampling];
 163 }
 164
 165 @end
 166
 167 #endif