fix: additional profiling data races (#3035)

In #3018, there was a change to add locking where `processBacktrace` mutated data structures that could be accessed concurrently. It attempted to separate the code that did not access the shared data structures, and moved all mutating code to a section at the end of the function. However, it missed a few reads from those data structures that also needed to be synchronized (e.g. `frames.count` and `stacks.count`). Generally, separating the critical section from the rest of the logic in that function is not worth the pain because the taking the lock for the entire duration of the function is not expensive.

This refactor adds a new type, `SentryProfilingState`, that centralizes all logic for reading/writing the shared data structures. This has the additional benefit that you no longer need a `processBacktrace` function that takes many parameters where the lifetime of those parameters is unclear (this will be helpful for fixing the memory leaks in a subsequent PR).

---------

Co-authored-by: Sentry Github Bot <[email protected]>

CHANGELOG.md

@@ -4,7 +4,7 @@
 
 ### Fixed
 
-- Fix crashes in profiling serialization race condition (#3018)
+- Fix crashes in profiling serialization race condition (#3018, #3035)
 - Fix a crash for user interaction transactions (#3036)
 
 ## 8.7.1

Sentry.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		0354A22B2A134D9C003C3A04 /* SentryProfiler+Private.h in Headers */ = {isa = PBXBuildFile; fileRef = 0354A22A2A134D9C003C3A04 /* SentryProfiler+Private.h */; };
 		0356A570288B4612008BF593 /* SentryProfilesSampler.h in Headers */ = {isa = PBXBuildFile; fileRef = 0356A56E288B4612008BF593 /* SentryProfilesSampler.h */; };
 		0356A571288B4612008BF593 /* SentryProfilesSampler.m in Sources */ = {isa = PBXBuildFile; fileRef = 0356A56F288B4612008BF593 /* SentryProfilesSampler.m */; };
 		03BCC38A27E1BF49003232C7 /* SentryTime.h in Headers */ = {isa = PBXBuildFile; fileRef = 03BCC38927E1BF49003232C7 /* SentryTime.h */; };
@@ -861,6 +862,7 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		0354A22A2A134D9C003C3A04 /* SentryProfiler+Private.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = "SentryProfiler+Private.h"; path = "Sources/Sentry/include/SentryProfiler+Private.h"; sourceTree = SOURCE_ROOT; };
 		0356A56E288B4612008BF593 /* SentryProfilesSampler.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = SentryProfilesSampler.h; path = Sources/Sentry/include/SentryProfilesSampler.h; sourceTree = SOURCE_ROOT; };
 		0356A56F288B4612008BF593 /* SentryProfilesSampler.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; name = SentryProfilesSampler.m; path = Sources/Sentry/SentryProfilesSampler.m; sourceTree = SOURCE_ROOT; };
 		035E73C727D56757005EEB11 /* SentryBacktraceTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = SentryBacktraceTests.mm; sourceTree = "<group>"; };
@@ -3064,6 +3066,7 @@
 				03F84D1127DD414C008FE43F /* SentryProfiler.h */,
 				844EDD6B2949387000C86F34 /* SentryMetricProfiler.h */,
 				8454CF8B293EAF9A006AC140 /* SentryMetricProfiler.mm */,
+				0354A22A2A134D9C003C3A04 /* SentryProfiler+Private.h */,
 				84A888FC28D9B11700C51DFD /* SentryProfiler+Test.h */,
 				844EDC7B2942843400C86F34 /* SentryProfiler+SwiftTest.h */,
 				03F84D2B27DD4191008FE43F /* SentryProfiler.mm */,
@@ -3515,6 +3518,7 @@
 				7BC8522F24581096005A70F0 /* SentryFileContents.h in Headers */,
 				7B30B67C26527886006B2752 /* SentryDisplayLinkWrapper.h in Headers */,
 				7BD86ECF264A7C77005439DB /* SentryAppStartMeasurement.h in Headers */,
+				0354A22B2A134D9C003C3A04 /* SentryProfiler+Private.h in Headers */,
 				7DC8310A2398283C0043DD9A /* SentryCrashIntegration.h in Headers */,
 				63FE718320DA4C1100CDBAE8 /* SentryCrashReportFixer.h in Headers */,
 				03F84D2027DD414C008FE43F /* SentryStackBounds.hpp in Headers */,