fix: read free_memory when the event is captured, not only at SDK startup

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 - Properly sanitize the event context and SDK information (#1943)
 - Don't send error 429 as `network_error` (#1957)
+- Read free_memory when the event is captured, not only at SDK startup (#1962)
 - Sanitize Span data (#1963)
 - Deprecate not needed option `sdkInfo` (#1960)
 - Crash in profiling logger (#1964)

Sources/Sentry/SentryClient.m

@@ -4,6 +4,7 @@
 #import "SentryClient+Private.h"
 #import "SentryCrashDefaultMachineContextWrapper.h"
 #import "SentryCrashIntegration.h"
+#import "SentryCrashMonitor_System.h"
 #import "SentryCrashStackEntryMapper.h"
 #import "SentryDebugImageProvider.h"
 #import "SentryDefaultCurrentDateProvider.h"
@@ -487,10 +488,13 @@ - (SentryEvent *_Nullable)prepareEvent:(SentryEvent *)event
 
     event = [scope applyToEvent:event maxBreadcrumb:self.options.maxBreadcrumbs];
 
-    // Remove free_memory if OOM as free_memory stems from the current run and not of the time of
-    // the OOM.
     if ([self isOOM:event isCrashEvent:isCrashEvent]) {
+        // Remove free_memory if OOM as free_memory stems from the current run and not of
+        // the time of the OOM.
         [self removeFreeMemoryFromDeviceContext:event];
+    } else {
+        // Store the actual free memory at the time of this event
+        [self storeFreeMemoryToDeviceContext:event];
     }
 
     // With scope applied, before running callbacks run:
@@ -638,7 +642,24 @@ - (BOOL)isOOM:(SentryEvent *)event isCrashEvent:(BOOL)isCrashEvent
         [exception.mechanism.type isEqualToString:SentryOutOfMemoryMechanismType];
 }
 
+- (void)storeFreeMemoryToDeviceContext:(SentryEvent *)event
+{
+    [self modifyDeviceContext:event
+                        block:^(NSMutableDictionary *device) {
+                            device[SentryDeviceContextFreeMemoryKey] =
+                                @(sentrycrashcm_system_freememory());
+                        }];
+}
+
 - (void)removeFreeMemoryFromDeviceContext:(SentryEvent *)event
+{
+    [self modifyDeviceContext:event
+                        block:^(NSMutableDictionary *device) {
+                            [device removeObjectForKey:SentryDeviceContextFreeMemoryKey];
+                        }];
+}
+
+- (void)modifyDeviceContext:(SentryEvent *)event block:(void (^)(NSMutableDictionary *))block
 {
     if (nil == event.context || event.context.count == 0 || nil == event.context[@"device"]) {
         return;
@@ -647,9 +668,8 @@ - (void)removeFreeMemoryFromDeviceContext:(SentryEvent *)event
     NSMutableDictionary *context = [[NSMutableDictionary alloc] initWithDictionary:event.context];
     NSMutableDictionary *device =
         [[NSMutableDictionary alloc] initWithDictionary:context[@"device"]];
-    [device removeObjectForKey:SentryDeviceContextFreeMemoryKey];
+    block(device);
     context[@"device"] = device;
-
     event.context = context;
 }
 

Sources/SentryCrash/Recording/Monitors/SentryCrashMonitor_System.h

@@ -37,6 +37,8 @@ extern "C" {
  */
 SentryCrashMonitorAPI *sentrycrashcm_system_getAPI(void);
 
+uint64_t sentrycrashcm_system_freememory(void);
+
 #ifdef __cplusplus
 }
 #endif

Sources/SentryCrash/Recording/Monitors/SentryCrashMonitor_System.m

@@ -199,6 +199,12 @@
     return 0;
 }
 
+uint64_t
+sentrycrashcm_system_freememory(void)
+{
+    return freeMemory();
+}
+
 static uint64_t
 usableMemory(void)
 {