Limit log batching to maximum 100 logs per batch

[denrase]

📜 Description

This took some digging. I was testing sending logs in a tight loop and got rejected by the backend.

[Sentry] [debug] [1763038665.309155] [SentryRequestOperation:36] Request status: 400
[Sentry] [debug] [1763038665.309175] [SentryRequestOperation:42] Request response: {"detail":"envelope exceeded size limits for type 'log' (https://develop.sentry.dev/sdk/envelopes/#size-limits)"}

So I checked replay code. The issue is that it has 1000 logs MAX item limit, which is not in any documentation we used when implementing the log batching. Its documented here (https://develop.sentry.dev/sdk/telemetry/logs/#buffering)

Another issue I saw during testing is that envelopes persisted with > 1000 log items are being re-tried, so this is something that clients out there may be experiencing.

💡 Motivation and Context

Log envelopes dropped by the backend.

💚 How did you test it?

Unit tests. Sample app.

📝 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.

Closes #6770

[denrase]

@philipphofmann @noahsmartin I'm thinking if we should also drop individual log item > 1MB or prune large attributes. WDYT?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.884%. Comparing base (402fe24) to head (422b652).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #6768       +/-   ##
=============================================
- Coverage   84.896%   84.884%   -0.013%     
=============================================
  Files          453       453               
  Lines        27597     27600        +3     
  Branches     12101     12104        +3     
=============================================
- Hits         23429     23428        -1     
- Misses        4123      4127        +4     
  Partials        45        45               

Files with missing lines	Coverage Δ
Sources/Swift/Tools/SentryLogBatcher.swift	98.461% <100.000%> (+0.036%)	⬆️

... and 5 files with indirect coverage changes

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[cleptric]

Let's please cap this at 100, as in https://develop.sentry.dev/sdk/telemetry/logs/#buffering.
We can always raise limits at a later date, but lowering them is hard.
Yes, Relay technically allows up to 1000 items, but we aligned on 100 across SDKs.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1214.40 ms	1264.69 ms	50.29 ms
Size	24.14 KiB	1.01 MiB	1014.72 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
4bf98bf	1219.13 ms	1244.50 ms	25.38 ms
5cbd333	1220.78 ms	1234.15 ms	13.36 ms
c174e5e	1209.65 ms	1238.73 ms	29.08 ms
5aa3ce5	1222.78 ms	1245.39 ms	22.61 ms
be882e4	1199.35 ms	1231.20 ms	31.86 ms
86eb6d5	1224.95 ms	1251.82 ms	26.87 ms
9c75c11	1228.42 ms	1262.81 ms	34.39 ms
d0f70ce	1226.54 ms	1247.04 ms	20.50 ms
9ccc0f5	1227.59 ms	1264.07 ms	36.47 ms
e36128b	1213.04 ms	1248.60 ms	35.56 ms

App size

Revision	Plain	With Sentry	Diff
4bf98bf	23.75 KiB	919.70 KiB	895.95 KiB
5cbd333	23.74 KiB	969.66 KiB	945.92 KiB
c174e5e	23.75 KiB	953.92 KiB	930.16 KiB
5aa3ce5	23.75 KiB	904.54 KiB	880.79 KiB
be882e4	23.75 KiB	946.69 KiB	922.94 KiB
86eb6d5	23.74 KiB	1.02 MiB	1016.53 KiB
9c75c11	23.74 KiB	1022.95 KiB	999.20 KiB
d0f70ce	23.75 KiB	913.09 KiB	889.34 KiB
9ccc0f5	24.14 KiB	1.01 MiB	1014.11 KiB
e36128b	23.75 KiB	963.19 KiB	939.44 KiB

Previous results on branch: fix/introduce-log-count-limit

Startup times

Revision	Plain	With Sentry	Diff
e29802f	1214.73 ms	1243.87 ms	29.14 ms

App size

Revision	Plain	With Sentry	Diff
e29802f	24.14 KiB	1.01 MiB	1014.03 KiB

[philipphofmann]

Thanks

[philipphofmann]

Let's please cap this at 100, as in https://develop.sentry.dev/sdk/telemetry/logs/#buffering. We can always raise limits at a later date, but lowering them is hard. Yes, Relay technically allows up to 1000 items, but we aligned on 100 across SDKs.

I also added this as recommendation to getsentry/sentry-docs#15513