redict/tests
Eduardo Semprebon 91d0c758e5
Replica keep serving data during repl-diskless-load=swapdb for better availability (#9323)
For diskless replication in swapdb mode, considering we already spend replica memory
having a backup of current db to restore in case of failure, we can have the following benefits
by instead swapping database only in case we succeeded in transferring db from master:

- Avoid `LOADING` response during failed and successful synchronization for cases where the
  replica is already up and running with data.
- Faster total time of diskless replication, because now we're moving from Transfer + Flush + Load
  time to Transfer + Load only. Flushing the tempDb is done asynchronously after swapping.
- This could be implemented also for disk replication with similar benefits if consumers are willing
  to spend the extra memory usage.

General notes:
- The concept of `backupDb` becomes `tempDb` for clarity.
- Async loading mode will only kick in if the replica is syncing from a master that has the same
  repl-id the one it had before. i.e. the data it's getting belongs to a different time of the same timeline. 
- New property in INFO: `async_loading` to differentiate from the blocking loading
- Slot to Key mapping is now a field of `redisDb` as it's more natural to access it from both server.db
  and the tempDb that is passed around.
- Because this is affecting replicas only, we assume that if they are not readonly and write commands
  during replication, they are lost after SYNC same way as before, but we're still denying CONFIG SET
  here anyways to avoid complications.

Considerations for review:
- We have many cases where server.loading flag is used and even though I tried my best, there may
  be cases where async_loading should be checked as well and cases where it shouldn't (would require
  very good understanding of whole code)
- Several places that had different behavior depending on the loading flag where actually meant to just
  handle commands coming from the AOF client differently than ones coming from real clients, changed
  to check CLIENT_ID_AOF instead.

**Additional for Release Notes**
- Bugfix - server.dirty was not incremented for any kind of diskless replication, as effect it wouldn't
  contribute on triggering next database SAVE
- New flag for RM_GetContextFlags module API: REDISMODULE_CTX_FLAGS_ASYNC_LOADING
- Deprecated RedisModuleEvent_ReplBackup. Starting from Redis 7.0, we don't fire this event.
  Instead, we have the new RedisModuleEvent_ReplAsyncLoad holding 3 sub-events: STARTED,
  ABORTED and COMPLETED.
- New module flag REDISMODULE_OPTIONS_HANDLE_REPL_ASYNC_LOAD for RedisModule_SetModuleOptions
  to allow modules to declare they support the diskless replication with async loading (when absent, we fall
  back to disk-based loading).

Co-authored-by: Eduardo Semprebon <edus@saxobank.com>
Co-authored-by: Oran Agra <oran@redislabs.com>
2021-11-04 10:46:50 +02:00
..
assets Add support for list type to store elements larger than 4GB (#9357) 2021-11-03 20:47:18 +02:00
cluster Replica keep serving data during repl-diskless-load=swapdb for better availability (#9323) 2021-11-04 10:46:50 +02:00
helpers When redis-cli received ASK, it didn't handle it (#8930) 2021-08-02 14:59:08 +03:00
integration Replica keep serving data during repl-diskless-load=swapdb for better availability (#9323) 2021-11-04 10:46:50 +02:00
modules Replica keep serving data during repl-diskless-load=swapdb for better availability (#9323) 2021-11-04 10:46:50 +02:00
sentinel Sentinel: Fix failed daily tests, due to race condition (#9501) 2021-09-15 13:39:50 +03:00
support Add support for list type to store elements larger than 4GB (#9357) 2021-11-03 20:47:18 +02:00
tmp minor fixes to the new test suite, html doc updated 2010-05-14 18:48:33 +02:00
unit Replica keep serving data during repl-diskless-load=swapdb for better availability (#9323) 2021-11-04 10:46:50 +02:00
instances.tcl Fix failing cluster tests (#9707) 2021-10-31 19:22:21 +02:00
README.md Add support for list type to store elements larger than 4GB (#9357) 2021-11-03 20:47:18 +02:00
test_helper.tcl Add support for list type to store elements larger than 4GB (#9357) 2021-11-03 20:47:18 +02:00

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_server context
  • tags context 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 campatible 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