redo_cache_lookup: move to examples; fix fallback lifetime - #13209
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bneradt merged 1 commit intoJun 23, 2026
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The redo_cache_lookup plugin kept the fallback URL as a pointer into the plugin.config argv storage. That storage can be released after plugin initialization, leaving cache-lookup-complete callbacks to dereference stale memory. This copies the parsed fallback URL into plugin-owned storage and passes its owned bytes to TSHttpTxnRedoCacheLookup. Also, while investigating this, it looks like this plugin was made simply to demonstrate the use of TSHttpTxnRedoCacheLookup rather than being a production-useful plugin. The initial commit says as much and there is no customer-facing documentation for this plugin. As such, I'm moving this to the examples plugin.
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Pull request overview
This PR fixes a lifetime bug in the redo_cache_lookup plugin by moving fallback URL storage into plugin-owned memory (avoiding pointers into plugin.config argv storage), and rehomes the plugin from plugins/experimental/ to example/plugins/c-api/ as an example of using TSHttpTxnRedoCacheLookup.
Changes:
- Moved
redo_cache_lookupfrom experimental plugins to the C-API examples and removed the experimental build option. - Copied the configured
--fallbackURL into owned storage and used it when callingTSHttpTxnRedoCacheLookup. - Added Catch2 unit tests for configuration parsing to ensure the fallback URL is copied.
Reviewed changes
Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| plugins/experimental/redo_cache_lookup/redo_cache_lookup.cc | Removed the experimental plugin implementation (now moved to examples). |
| plugins/experimental/redo_cache_lookup/README.md | Removed experimental plugin README (superseded by example readme). |
| plugins/experimental/redo_cache_lookup/CMakeLists.txt | Removed experimental plugin build definition. |
| plugins/experimental/CMakeLists.txt | Stopped including the removed experimental plugin directory. |
| cmake/ExperimentalPlugins.cmake | Removed BUILD_REDO_CACHE_LOOKUP option. |
| example/plugins/c-api/redo_cache_lookup/redo_cache_lookup.cc | New example plugin using C API and plugin-owned fallback storage. |
| example/plugins/c-api/redo_cache_lookup/redo_cache_lookup_config.h | Added config parsing helper for --fallback / -f. |
| example/plugins/c-api/redo_cache_lookup/readme.txt | Added example usage documentation. |
| example/plugins/c-api/redo_cache_lookup/unit_tests/test_redo_cache_lookup_config.cc | Added unit tests verifying fallback URL parsing/copy semantics. |
| example/plugins/c-api/CMakeLists.txt | Builds the new example plugin and its unit test under BUILD_TESTING. |
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| if (TSHttpTxnCacheLookupStatusGet(txnp, &status) != TS_SUCCESS || status == TS_CACHE_LOOKUP_MISS || | ||
| status == TS_CACHE_LOOKUP_SKIPPED) { | ||
| Dbg(dbg_ctl, "rewinding to check for fallback url: %s", config->fallback.c_str()); | ||
| TSHttpTxnRedoCacheLookup(txnp, config->fallback.c_str(), static_cast<int>(config->fallback.size())); | ||
| } |
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| TSCont contp = TSContCreate(handle_cache_lookup_complete, nullptr); | ||
| TSContDataSet(contp, new RedoCacheLookupConfig(*fallback)); |
zwoop
self-requested a review
May 29, 2026 17:12
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[approve ci autest] |
cmcfarlen
approved these changes
Jun 9, 2026
cmcfarlen
pushed a commit
to cmcfarlen/trafficserver
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Jul 29, 2026
…13209) The redo_cache_lookup plugin kept the fallback URL as a pointer into the plugin.config argv storage. That storage can be released after plugin initialization, leaving cache-lookup-complete callbacks to dereference stale memory. This copies the parsed fallback URL into plugin-owned storage and passes its owned bytes to TSHttpTxnRedoCacheLookup. Also, while investigating this, it looks like this plugin was made simply to demonstrate the use of TSHttpTxnRedoCacheLookup rather than being a production-useful plugin. The initial commit says as much and there is no customer-facing documentation for this plugin. As such, I'm moving this to the examples plugin.
cmcfarlen
pushed a commit
to cmcfarlen/trafficserver
that referenced
this pull request
Jul 29, 2026
…13209) The redo_cache_lookup plugin kept the fallback URL as a pointer into the plugin.config argv storage. That storage can be released after plugin initialization, leaving cache-lookup-complete callbacks to dereference stale memory. This copies the parsed fallback URL into plugin-owned storage and passes its owned bytes to TSHttpTxnRedoCacheLookup. Also, while investigating this, it looks like this plugin was made simply to demonstrate the use of TSHttpTxnRedoCacheLookup rather than being a production-useful plugin. The initial commit says as much and there is no customer-facing documentation for this plugin. As such, I'm moving this to the examples plugin. (cherry picked from commit 468e764)
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The redo_cache_lookup plugin kept the fallback URL as a pointer into the plugin.config argv storage. That storage can be released after plugin initialization, leaving cache-lookup-complete callbacks to dereference stale memory.
This copies the parsed fallback URL into plugin-owned storage and passes its owned bytes to TSHttpTxnRedoCacheLookup.
Also, while investigating this, it looks like this plugin was made simply to demonstrate the use of TSHttpTxnRedoCacheLookup rather than being a production-useful plugin. The initial commit says as much and there is no customer-facing documentation for this plugin. As such, I'm moving this to the examples plugin.