refactor: Serialize envelope straight to a file

[itaybre]

:scroll: Description

Write files straight to a file on storeEnvelope instead of storing the data which may cause increased memory usage

:bulb: Motivation and Context

:green_heart: How did you test it?

:pencil: Checklist

You have to check all boxes before merging:

• [ ] I added tests to verify the changes.
• [ ] No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• [ ] I updated the docs if needed.
• [ ] I updated the wizard if needed.
• [ ] Review from the native team if needed.
• [ ] No breaking change or entry added to the changelog.
• [ ] No breaking change for hybrid SDKs or communicated to hybrid SDKs.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 84.42623% with 19 lines in your changes missing coverage. Please review.

Project coverage is 86.122%. Comparing base (5652830) to head (be55d4f).

Files with missing lines	Patch %	Lines
Sources/Sentry/SentrySerialization.m	84.166%	19 Missing :warning:

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #5360       +/-   ##
=============================================
- Coverage   86.179%   86.122%   -0.057%     
=============================================
  Files          399       399               
  Lines        34616     34712       +96     
  Branches     14972     15014       +42     
=============================================
+ Hits         29832     29895       +63     
- Misses        4739      4775       +36     
+ Partials        45        42        -3     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryFileManager.m	94.420% <100.000%> (-0.324%)	:arrow_down:
Sources/Sentry/SentrySerialization.m	93.823% <84.166%> (-5.340%)	:arrow_down:

... and 9 files with indirect coverage changes

---

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[github-actions[bot]]

Performance metrics :rocket:

	Plain	With Sentry	Diff
Startup time	1214.78 ms	1229.67 ms	14.89 ms
Size	23.75 KiB	849.02 KiB	825.27 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
077e94086236b0be69cb0982b64053b94f2c9ea4	1227.31 ms	1246.51 ms	19.20 ms
15b8c6111854bacf68624e765d99adcf93bfc987	1223.16 ms	1244.83 ms	21.67 ms
bc0c36e91c733f434511cb832b636fdc8ad90330	1220.41 ms	1239.45 ms	19.04 ms
455619dd977fcfe15f8d8294a8d217fcb0b90d15	1231.40 ms	1237.70 ms	6.30 ms
f8833c443d047f0c8dac5710e52b4c0624fc52ce	1236.45 ms	1252.82 ms	16.37 ms
728804f93e9f74d591108dd8a8d2df61a645c02b	1235.26 ms	1254.20 ms	18.94 ms
6e342acf0107a6421fa9221f9ecd93c5f3ef0b3b	1220.24 ms	1240.14 ms	19.90 ms
46f5eb8f90236e0b538f5ff1c237e290c12a25e6	1200.09 ms	1231.38 ms	31.29 ms
3912b16e2a203c2dd8155aa48aaf4c4dc10199e3	1230.54 ms	1249.65 ms	19.11 ms
061c982c8616fa6ca7f0762998f39a8f4d8d2fc2	1226.33 ms	1243.65 ms	17.33 ms

App size

Revision	Plain	With Sentry	Diff
077e94086236b0be69cb0982b64053b94f2c9ea4	21.58 KiB	706.97 KiB	685.39 KiB
15b8c6111854bacf68624e765d99adcf93bfc987	20.76 KiB	419.67 KiB	398.91 KiB
bc0c36e91c733f434511cb832b636fdc8ad90330	22.31 KiB	775.27 KiB	752.95 KiB
455619dd977fcfe15f8d8294a8d217fcb0b90d15	20.76 KiB	432.87 KiB	412.11 KiB
f8833c443d047f0c8dac5710e52b4c0624fc52ce	21.58 KiB	422.66 KiB	401.08 KiB
728804f93e9f74d591108dd8a8d2df61a645c02b	22.85 KiB	411.76 KiB	388.91 KiB
6e342acf0107a6421fa9221f9ecd93c5f3ef0b3b	20.76 KiB	436.66 KiB	415.90 KiB
46f5eb8f90236e0b538f5ff1c237e290c12a25e6	20.76 KiB	432.37 KiB	411.61 KiB
3912b16e2a203c2dd8155aa48aaf4c4dc10199e3	21.58 KiB	625.82 KiB	604.24 KiB
061c982c8616fa6ca7f0762998f39a8f4d8d2fc2	21.58 KiB	683.51 KiB	661.93 KiB

Previous results on branch: itay/cocoa-243-fix-nsmallocexception-when-writing-envelope-to-disk

Startup times

Revision	Plain	With Sentry	Diff
d3acd4be4f76c377e5fa4d42c5536ffa84130be9	1223.69 ms	1239.63 ms	15.94 ms
bf1998e1325b612d410fd79186b0762696470a24	1227.84 ms	1250.59 ms	22.76 ms
866822342e7c765c0b1289b5563be141d45fedf3	1212.33 ms	1232.67 ms	20.33 ms
9ac31f2b05a31afd8f74bc821670c62fe24648a6	1228.12 ms	1251.50 ms	23.38 ms

App size

Revision	Plain	With Sentry	Diff
d3acd4be4f76c377e5fa4d42c5536ffa84130be9	23.76 KiB	838.38 KiB	814.62 KiB
bf1998e1325b612d410fd79186b0762696470a24	23.75 KiB	848.95 KiB	825.20 KiB
866822342e7c765c0b1289b5563be141d45fedf3	23.76 KiB	838.63 KiB	814.87 KiB
9ac31f2b05a31afd8f74bc821670c62fe24648a6	23.76 KiB	838.99 KiB	815.23 KiB

[philipphofmann]

I don't have the bandwidth to review this PR today, and I'm on PTO the whole next week. FYI, I tried something similar with a NSFileHandle last year and we had a very nasty severe incident https://github.com/getsentry/sentry-cocoa/pull/4219 with corrupted envelopes. Check the changelog of 8.35.0 and the 8.35.1. Serializing envelopes is a core part of the SDK. When we do this we have to be 100% confident that everything is working correctly. With CI being so flaky right now, I highly doubt that we can be so confident.

While it's highly admirable that you're trying to improve this, I would rather focus on making the CI stable and postpone such refactorings for now, please.

[itaybre]

I don't have the bandwidth to review this PR today, and I'm on PTO the whole next week. FYI, I tried something similar with a NSFileHandle last year and we had a very nasty severe incident #4219 with corrupted envelopes. Check the changelog of 8.35.0 and the 8.35.1. Serializing envelopes is a core part of the SDK. When we do this we have to be 100% confident that everything is working correctly. With CI being so flaky right now, I highly doubt that we can be so confident.

While it's highly admirable that you're trying to improve this, I would rather focus on making the CI stable and postpone such refactorings for now, please.

I agree it is a risky change, and to be honest, I would like to refactor how we read envelopes too. It think the code can be improved and add some failsafes there.

Regarding the CI flakiness, we are improving there 💪

[github-actions[bot]]

🚨 Detected changes in high risk code 🚨

High-risk code can easily blow up and is hard to test. We had severe bugs in the past. Be extra careful when changing these files, and have an extra careful look at these:

• [ ] Sources/Sentry/SentryFileManager.m
• [ ] Sources/Sentry/SentrySerialization.m

[philprime]

Should this PR be marked as draft again?