From 4beeeff531620774ce72d0df05a617b6d347898f Mon Sep 17 00:00:00 2001
From: Andrew McKnight <andrew.mcknight@sentry.io>
Date: Wed, 16 Aug 2023 10:19:22 -0800
Subject: [PATCH] feat: measure cpu energy usage estimates (#3217)

---
 CHANGELOG.md                                  |  5 +++
 Sources/Sentry/SentryMetricProfiler.mm        | 36 +++++++++++++++++++
 Sources/Sentry/SentrySystemWrapper.mm         | 18 ++++++++++
 Sources/Sentry/include/SentryMetricProfiler.h |  1 +
 Sources/Sentry/include/SentrySystemWrapper.h  |  6 ++++
 5 files changed, 66 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61b7f79cc1d..d5ce568ccef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+### Features
+
+- Record energy usage estimates for profiling (#3217)
 
 ## 8.9.4
 
diff --git a/Sources/Sentry/SentryMetricProfiler.mm b/Sources/Sentry/SentryMetricProfiler.mm
index 879776afe46..7f8d9eb35ad 100644
--- a/Sources/Sentry/SentryMetricProfiler.mm
+++ b/Sources/Sentry/SentryMetricProfiler.mm
@@ -29,6 +29,7 @@ @implementation SentryMetricReading
 
 NSString *const kSentryMetricProfilerSerializationKeyMemoryFootprint = @"memory_footprint";
 NSString *const kSentryMetricProfilerSerializationKeyCPUUsageFormat = @"cpu_usage_%d";
+NSString *const kSentryMetricProfilerSerializationKeyCPUEnergyUsage = @"cpu_energy_usage";
 
 NSString *const kSentryMetricProfilerSerializationUnitBytes = @"byte";
 NSString *const kSentryMetricProfilerSerializationUnitPercentage = @"percent";
@@ -82,6 +83,9 @@ @implementation SentryMetricProfiler {
     NSMutableDictionary<NSNumber *, NSMutableArray<SentryMetricReading *> *> *_cpuUsage;
 
     NSMutableArray<SentryMetricReading *> *_memoryFootprint;
+
+    NSNumber *previousEnergyReading;
+    NSMutableArray<SentryMetricReading *> *_cpuEnergyUsage;
 }
 
 - (instancetype)init
@@ -98,6 +102,7 @@ - (instancetype)init
         }
 
         _memoryFootprint = [NSMutableArray<SentryMetricReading *> array];
+        _cpuEnergyUsage = [NSMutableArray<SentryMetricReading *> array];
     }
     return self;
 }
@@ -123,8 +128,10 @@ - (void)stop
                                                       and:(uint64_t)endSystemTime;
 {
     NSArray<SentryMetricReading *> *memoryFootprint;
+    NSArray<SentryMetricReading *> *cpuEnergyUsage;
     NSDictionary<NSNumber *, NSArray<SentryMetricReading *> *> *cpuUsage;
     @synchronized(self) {
+        cpuEnergyUsage = [NSArray<SentryMetricReading *> arrayWithArray:_cpuEnergyUsage];
         memoryFootprint = [NSArray<SentryMetricReading *> arrayWithArray:_memoryFootprint];
         cpuUsage = [NSDictionary<NSNumber *, NSArray<SentryMetricReading *> *>
             dictionaryWithDictionary:_cpuUsage];
@@ -136,6 +143,11 @@ - (void)stop
             = serializeValuesWithNormalizedTime(memoryFootprint,
                 kSentryMetricProfilerSerializationUnitBytes, startSystemTime, endSystemTime);
     }
+    if (cpuEnergyUsage.count > 0) {
+        dict[kSentryMetricProfilerSerializationKeyCPUEnergyUsage]
+            = serializeValuesWithNormalizedTime(cpuEnergyUsage,
+                kSentryMetricProfilerSerializationUnitBytes, startSystemTime, endSystemTime);
+    }
 
     [cpuUsage enumerateKeysAndObjectsUsingBlock:^(NSNumber *_Nonnull core,
         NSArray<SentryMetricReading *> *_Nonnull readings, BOOL *_Nonnull stop) {
@@ -167,6 +179,7 @@ - (void)registerSampler
               eventHandler:^{
                   [weakSelf recordCPUPercentagePerCore];
                   [weakSelf recordMemoryFootprint];
+                  [weakSelf recordEnergyUsageEstimate];
               }];
 }
 
@@ -205,6 +218,29 @@ - (void)recordCPUPercentagePerCore
     }
 }
 
+- (void)recordEnergyUsageEstimate
+{
+    NSError *error;
+    const auto reading =
+        [SentryDependencyContainer.sharedInstance.systemWrapper cpuEnergyUsageWithError:&error];
+    if (error) {
+        SENTRY_LOG_ERROR(@"Failed to read CPU energy usage: %@", error);
+        return;
+    }
+
+    if (previousEnergyReading == nil) {
+        previousEnergyReading = reading;
+        return;
+    }
+
+    const auto value = reading.unsignedIntegerValue - previousEnergyReading.unsignedIntegerValue;
+    previousEnergyReading = reading;
+
+    @synchronized(self) {
+        [_cpuEnergyUsage addObject:[self metricReadingForValue:@(value)]];
+    }
+}
+
 - (SentryMetricReading *)metricReadingForValue:(NSNumber *)value
 {
     const auto reading = [[SentryMetricReading alloc] init];
diff --git a/Sources/Sentry/SentrySystemWrapper.mm b/Sources/Sentry/SentrySystemWrapper.mm
index 6e626700e8e..47264a7afdc 100644
--- a/Sources/Sentry/SentrySystemWrapper.mm
+++ b/Sources/Sentry/SentrySystemWrapper.mm
@@ -59,4 +59,22 @@ - (SentryRAMBytes)memoryFootprintBytes:(NSError *__autoreleasing _Nullable *)err
     return result;
 }
 
+- (NSNumber *)cpuEnergyUsageWithError:(NSError **)error
+{
+    struct task_power_info_v2 powerInfo;
+
+    mach_msg_type_number_t size = TASK_POWER_INFO_V2_COUNT;
+
+    task_t task = mach_task_self();
+    kern_return_t kr = task_info(task, TASK_POWER_INFO_V2, (task_info_t)&powerInfo, &size);
+    if (kr != KERN_SUCCESS) {
+        if (error) {
+            *error = NSErrorFromSentryErrorWithKernelError(
+                kSentryErrorKernel, @"Error with task_info(…TASK_POWER_INFO_V2…).", kr);
+            ;
+        }
+    }
+    return @(powerInfo.cpu_energy.total_system + powerInfo.cpu_energy.total_user);
+}
+
 @end
diff --git a/Sources/Sentry/include/SentryMetricProfiler.h b/Sources/Sentry/include/SentryMetricProfiler.h
index cdeedec7ea1..0182ddccd26 100644
--- a/Sources/Sentry/include/SentryMetricProfiler.h
+++ b/Sources/Sentry/include/SentryMetricProfiler.h
@@ -10,6 +10,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 SENTRY_EXTERN NSString *const kSentryMetricProfilerSerializationKeyMemoryFootprint;
 SENTRY_EXTERN NSString *const kSentryMetricProfilerSerializationKeyCPUUsageFormat;
+SENTRY_EXTERN NSString *const kSentryMetricProfilerSerializationKeyCPUEnergyUsage;
 
 SENTRY_EXTERN NSString *const kSentryMetricProfilerSerializationUnitBytes;
 SENTRY_EXTERN NSString *const kSentryMetricProfilerSerializationUnitPercentage;
diff --git a/Sources/Sentry/include/SentrySystemWrapper.h b/Sources/Sentry/include/SentrySystemWrapper.h
index 09d01a67d14..c98a26f30ae 100644
--- a/Sources/Sentry/include/SentrySystemWrapper.h
+++ b/Sources/Sentry/include/SentrySystemWrapper.h
@@ -26,6 +26,12 @@ typedef mach_vm_size_t SentryRAMBytes;
  */
 - (nullable NSArray<NSNumber *> *)cpuUsagePerCore:(NSError **)error;
 
+/**
+ * @return The cumulative amount of nanojoules expended by the CPU for this task since process
+ * start.
+ */
+- (nullable NSNumber *)cpuEnergyUsageWithError:(NSError **)error;
+
 @end
 
 NS_ASSUME_NONNULL_END