Fix a race condition by replacing mstats() with malloc_zone_statistics(). #15501

FirebasePerformance/Sources/FPRNanoPbUtils.m

@@ -363,9 +363,11 @@ firebase_perf_v1_GaugeMetric FPRGetGaugeMetric(NSArray *gaugeData, NSString *ses
       memoryReadings[memoryReadingsCount].used_app_heap_memory_kb =
           (int32_t)BYTES_TO_KB(gaugeData.heapUsed);
       memoryReadings[memoryReadingsCount].has_used_app_heap_memory_kb = true;
-      memoryReadings[memoryReadingsCount].free_app_heap_memory_kb =
-          (int32_t)BYTES_TO_KB(gaugeData.heapAvailable);
-      memoryReadings[memoryReadingsCount].has_free_app_heap_memory_kb = true;
+      if (gaugeData.heapAvailable > 0) {
+        memoryReadings[memoryReadingsCount].free_app_heap_memory_kb =
+            (int32_t)BYTES_TO_KB(gaugeData.heapAvailable);
+        memoryReadings[memoryReadingsCount].has_free_app_heap_memory_kb = true;
+      }
       memoryReadingsCount++;
     }
   }];

FirebasePerformance/Sources/Gauges/Memory/FPRMemoryGaugeCollector.m

@@ -19,7 +19,7 @@
 #import "FirebasePerformance/Sources/Configurations/FPRConfigurations.h"
 #import "FirebasePerformance/Sources/FPRConsoleLogger.h"
 
-#include <malloc/malloc.h>
+#include <mach/mach.h>
 
 @interface FPRMemoryGaugeCollector ()
 
@@ -37,10 +37,20 @@ @interface FPRMemoryGaugeCollector ()
 FPRMemoryGaugeData *fprCollectMemoryMetric(void) {
   NSDate *collectionTime = [NSDate date];
 
-  struct mstats ms = mstats();
+  // Reading task_info is safer to call from any thread, including during high throughput networking activity.
+  task_vm_info_data_t vmInfo;
+  mach_msg_type_number_t count = TASK_VM_INFO_COUNT;
+  u_long usedBytes = 0;
+  u_long freeBytes = 0;
+
+  kern_return_t kr = task_info(mach_task_self(), TASK_VM_INFO, (task_info_t)&vmInfo, &count);
+  if (kr == KERN_SUCCESS) {
+    // phys_footprint is the memory footprint used by Jetsam accounting.
+    usedBytes = (u_long)vmInfo.phys_footprint;
+  }
   FPRMemoryGaugeData *gaugeData = [[FPRMemoryGaugeData alloc] initWithCollectionTime:collectionTime
-                                                                            heapUsed:ms.bytes_used
-                                                                       heapAvailable:ms.bytes_free];
+                                                                            heapUsed:usedBytes
+                                                                       heapAvailable:freeBytes];
   return gaugeData;
 }