cmcfarlen commented on PR #13189:
URL: https://github.com/apache/trafficserver/pull/13189#issuecomment-4512896481
# Trial Revert v2 — Notes
Companion log for `revert-incompat-plan-v2.md`. Each section captures one
revert step on branch `revert-incompat-trial-v2`.
## Setup
- **Source branch**: `upstream/master`
- **Source HEAD**: `09c4f8a125` (Enable code review settings in .asf.yaml,
#13183)
- **Trial branch**: `revert-incompat-trial-v2`
- **Plan**: 11 reverts, dependency-aware order, pre-emptive LogAccess
fix-up after 11-Dev revert.
## Reverts
### Step 1–4: Config-reload + TLS-cert-compression dependents
| Step | PR | Commit | Result |
|---|---|---|---|
| 1 | #13090 | `4645b7dcb3` | clean, 43 files / +227 -903 |
| 2 | #13110 | `34790b0a9d` | clean, 10 files / +11 -657 |
| 3 | #13117 | `4f1d3594dd` | clean, 4 files / -27 |
| 4 | #13088 | `b98d8d0b31` | clean (large; deletes TLS cert compression
infra) |
### Step 5: #13070 plugin.yaml migration
| | |
|---|---|
| Commit | `49d109470b` |
| Result | **clean** (was 6 conflicts in v1; the dependent reverts cleared
the path) |
### Step 6–7: Storage migration chain
| Step | PR | Commit | Result |
|---|---|---|---|
| 6 | #13048 | `9828150402` | clean, 3 files |
| 7 | #13031 | `6d32974095` | **clean** (was 5 conflicts in v1; #13048 +
#13070 reverts already removed) |
### Step 8: #12998 Parallel SSL cert load
| | |
|---|---|
| Commit | `e5136dde5b` |
| Result | clean, 8 files (auto-merged records.yaml docs, RecordsConfig.cc,
SSLConfig.cc) |
### Step 9: #12988 + #12997 — surface conflict on ReverseProxy.cc
Initially attempted `git revert #12997` directly. Hit:
- 1 content conflict in ReverseProxy.cc
- 10 modify/delete conflicts on `tests/gold_tests/remap_yaml/*.yaml` files
(added by #12997, modified by #13003 "Proxy Verifier: use concise stack
protocol")
Aborted, added **#12988** ("Publish remap table after initial load") to the
revert list. #12988 is *not* incompatible — it's a compat improvement —
but it touched the same `init_reverse_proxy()` block as #12997, creating a
surface-level conflict.
Revert order: #12988 → #12997. Both clean after that.
| Step | PR | Commit |
|---|---|---|
| 9a | #12988 | `f0b3be46b7` |
| 9b | #12997 | `8ef420635d` |
### Step 10: 11-Dev merge (#12983)
| | |
|---|---|
| Commit | `30a01d6e41` |
| Result | **9 conflicts** (down from 17 in v1 — dependent reverts cleared
most surfaces) |
Conflict resolution:
- Manual: `Filenames.h`, `hostdb/CMakeLists.txt` (kept #13115
`add_subdirectory(unit_tests)`), `records/CMakeLists.txt` (kept only
`test_RecDumpRecords.cc`), `P_SSLConfig.h` (restored session-cache fields).
- `--theirs`: `SSLUtils.cc` (tightly coupled to ssl_multicert.yaml), 4× gold
tests.
- `git rm`: 1 UD file (`negative-caching-malformed-cc.replay.yaml`).
### Step 11: #12913 master-side version bump
| | |
|---|---|
| Commit | `f0f4f16149` |
| Result | clean, 1 line |
### Step 12 (added during execution): #12404 cqssrt log field
After 11-Dev revert, the restored `marshal_client_ssl_resumption_type`
function referenced `m_http_sm`, which #13123 (kept on master, in 10.2.x as
#13124) renamed to `m_data`. v1 fixed this with a fixup commit; v2 instead
reverts the original PR (#12404) for cleanliness.
| | |
|---|---|
| Commit | `26cafc24d2` |
| Result | clean, 5 files / +3 -49 |
#12404 is in **both** master and 10.2.x (pre-divergence). Reverting it on
the trial branch is safe; reverting it in production would require also
removing the `cqssrt` log field from 10.2.x (out of scope for the trial).
### Step 13 (incidental): cmake-format.sh fix
Format hook hung because `git ls-tree -r HEAD` listed
`src/config/CMakeLists.txt` (which had been deleted by an earlier revert)
and `cmake-format` raised `FileNotFoundError`. Patched the script to
filter out files staged for deletion via
`git diff --cached --name-only --diff-filter=D`.
| | |
|---|---|
| Commit | `3a8d37117b` |
| Status | useful for upstream — not a revert |
## Build verification
```
$ cmake --build build-mydev
[265/266] Linking CXX executable src/traffic_server/traffic_server
$ echo $?
0
```
**`traffic_server` binary built cleanly** (18 MB). Some `ld: warning:
ignoring
duplicate libraries` are present but cosmetic, not errors.
## Final state vs upstream/10.2.x
- 261 commits on trial-v2 not on 10.2.x (master-additive PRs that survived)
- 98 commits on 10.2.x not on trial-v2 (10.2.x branch-specific work)
- 507 files changed, +15,778 / -3,869 lines
## v2 verdict: how painful, with lessons applied?
**Mechanical effort once dependencies were known:** ~90 minutes total.
13 reverts including the two discovered during execution (#12988, #12404).
**Cost categories that v1 surfaced and v2 confirmed:**
1. **Direct conflicts — small.** #13031 had 0 conflicts in v2 vs 5 in v1
once the dependent reverts (#13070, #13048) ran first. The 11-Dev
merge had 9 conflicts vs 17 in v1.
2. **Dependency-chain reverts — predictable but additive.** The plan
identified 7 dependents up front. One more (#12988) surfaced as a
surface conflict during execution.
3. **Silent post-merge dependencies — eliminated** by reverting #13088,
#12998, #12997 *before* the 11-Dev merge. The build went clean on
first attempt afterward.
4. **#12404-style "old PR uses now-renamed member" — predicted, found.**
Pre-emptive fix-up was in the plan; user preferred clean revert
instead of fix-up.
**Revised effort estimate for production:**
- v1 estimate was 3–5 days optimistic / 1–2 weeks realistic.
- v2 result: with dependency map in hand, the mechanical work is
tractable in a single afternoon. **1–2 days realistic** for someone
who can review the plan and resolve conflicts confidently.
- The remaining cost is **social, not mechanical**: 13 reverts means 13
contributor conversations about dropped/deferred features. Several of
the reverted PRs (#12892, #13070, #12997, #13088, #12998) are
significant work that authors will want re-landed once 10.2.0 ships.
## Trial branch state at completion
- Branch: `revert-incompat-trial-v2`
- HEAD: `3a8d37117b` (cmake-format.sh fix)
- Build: **clean** ✓
- Notes file and plan are uncommitted (intentional; trial artifacts)
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