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

FirebasePerformance/Sources/FPRNanoPbUtils.m

@@ -363,9 +363,6 @@ 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;
       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 +37,22 @@ @interface FPRMemoryGaugeCollector ()
 FPRMemoryGaugeData *fprCollectMemoryMetric(void) {
   NSDate *collectionTime = [NSDate date];
 
-  struct mstats ms = mstats();
+  // Using task_info(TASK_VM_INFO) avoids allocator-introspection (mstats/malloc_zone_statistics),
+  // which could crash under heavy allocation contention. it's safe to call from any thread.
+  task_vm_info_data_t vmInfo;
+  mach_msg_type_number_t count = TASK_VM_INFO_COUNT;
+  u_long usedBytes = 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;
+  } else {
+    FPRLogDebug(kFPRMemoryCollection, @"task_info() failed with error: %d", kr);
+  }
   FPRMemoryGaugeData *gaugeData = [[FPRMemoryGaugeData alloc] initWithCollectionTime:collectionTime
-                                                                            heapUsed:ms.bytes_used
-                                                                       heapAvailable:ms.bytes_free];
+                                                                            heapUsed:usedBytes
+                                                                       heapAvailable:0];
   return gaugeData;
 }
 

FirebasePerformance/Sources/Gauges/Memory/FPRMemoryGaugeData.h

@@ -24,10 +24,12 @@ NS_ASSUME_NONNULL_BEGIN
 /** @brief Time at which memory data was measured. */
 @property(nonatomic, readonly) NSDate *collectionTime;
 
-/** @brief Heap memory that is used. */
+/** @brief Physical memory footprint of the application, measured via task_info phys_footprint.
+ *  Note: This represents the total memory used by the process (as reported by Jetsam accounting),
+ *  not just heap allocations. It includes heap, stack, memory-mapped files, and other resources. */
 @property(nonatomic, readonly) u_long heapUsed;
 
-/** @brief Heap memory that is available. */
+/** @brief Heap memory that is available. Always 0 as this metric is not available via task_info. */
 @property(nonatomic, readonly) u_long heapAvailable;
 
 - (instancetype)init NS_UNAVAILABLE;
@@ -36,8 +38,8 @@ NS_ASSUME_NONNULL_BEGIN
  * Creates an instance of memory gauge data with the provided information.
  *
  * @param collectionTime Time at which the gauge data was collected.
- * @param heapUsed Heap memory that is used.
- * @param heapAvailable Heap memory that is available.
+ * @param heapUsed Physical memory footprint of the application (measured via task_info phys_footprint).
+ * @param heapAvailable Heap memory that is available. Always 0 as this metric is not available.
  * @return Instance of memory gauge data.
  */
 - (instancetype)initWithCollectionTime:(NSDate *)collectionTime