b43f254813
### Background The issue is that when saving an RDB with module AUX data, the module AUX metadata (moduleid, when, ...) is saved to the RDB even though the module did not saved any actual data. This prevent loading the RDB in the absence of the module (although there is no actual data in the RDB that requires the module to be loaded). ### Solution The solution suggested in this PR is that module AUX will be saved on the RDB only if the module actually saved something during `aux_save` function. To support backward compatibility, we introduce `aux_save2` callback that acts the same as `aux_save` with the tiny change of avoid saving the aux field if no data was actually saved by the module. Modules can use the new API to make sure that if they have no data to save, then it will be possible to load the created RDB even without the module. ### Concerns A module may register for the aux load and save hooks just in order to be notified when saving or loading starts or completed (there are better ways to do that, but it still possible that someone used it). However, if a module didn't save a single field in the save callback, it means it's not allowed to read in the read callback, since it has no way to distinguish between empty and non-empty payloads. furthermore, it means that if the module did that, it must never change it, since it'll break compatibility with it's old RDB files, so this is really not a valid use case. Since some modules (ones who currently save one field indicating an empty payload), need to know if saving an empty payload is valid, and if Redis is gonna ignore an empty payload or store it, we opted to add a new API (rather than change behavior of an existing API and expect modules to check the redis version) ### Technical Details To avoid saving AUX data on RDB, we change the code to first save the AUX metadata (moduleid, when, ...) into a temporary buffer. The buffer is then flushed to the rio at the first time the module makes a write operation inside the `aux_save` function. If the module saves nothing (and `aux_save2` was used), the entire temporary buffer is simply dropped and no data about this AUX field is saved to the RDB. This make it possible to load the RDB even in the absence of the module. Test was added to verify the fix.
Redis Test Suite
The normal execution mode of the test suite involves starting and manipulating
local redis-server instances, inspecting process state, log files, etc.
The test suite also supports execution against an external server, which is
enabled using the --host and --port parameters. When executing against an
external server, tests tagged external:skip are skipped.
There are additional runtime options that can further adjust the test suite to match different external server configurations:
| Option | Impact |
|---|---|
--singledb |
Only use database 0, don't assume others are supported. |
--ignore-encoding |
Skip all checks for specific encoding. |
--ignore-digest |
Skip key value digest validations. |
--cluster-mode |
Run in strict Redis Cluster compatibility mode. |
--large-memory |
Enables tests that consume more than 100mb |
Tags
Tags are applied to tests to classify them according to the subsystem they test, but also to indicate compatibility with different run modes and required capabilities.
Tags can be applied in different context levels:
start_servercontexttagscontext that bundles several tests together- A single test context.
The following compatibility and capability tags are currently used:
| Tag | Indicates |
|---|---|
external:skip |
Not compatible with external servers. |
cluster:skip |
Not compatible with --cluster-mode. |
large-memory |
Test that requires more than 100mb |
tls:skip |
Not compatible with --tls. |
needs:repl |
Uses replication and needs to be able to SYNC from server. |
needs:debug |
Uses the DEBUG command or other debugging focused commands (like OBJECT). |
needs:pfdebug |
Uses the PFDEBUG command. |
needs:config-maxmemory |
Uses CONFIG SET to manipulate memory limit, eviction policies, etc. |
needs:config-resetstat |
Uses CONFIG RESETSTAT to reset statistics. |
needs:reset |
Uses RESET to reset client connections. |
needs:save |
Uses SAVE to create an RDB file. |
When using an external server (--host and --port), filtering using the
external:skip tags is done automatically.
When using --cluster-mode, filtering using the cluster:skip tag is done
automatically.
When not using --large-memory, filtering using the largemem:skip tag is done
automatically.
In addition, it is possible to specify additional configuration. For example, to
run tests on a server that does not permit SYNC use:
./runtest --host <host> --port <port> --tags -needs:repl