e1b3629186
Our current replica can initiate a failover without restriction when it detects that the primary node is offline. This is generally not a problem. However, consider the following scenarios: 1. In slot migration, a primary loses its last slot and then becomes a replica. When it is fully synchronized with the new primary, the new primary downs. 2. In CLUSTER REPLICATE command, a replica becomes a replica of another primary. When it is fully synchronized with the new primary, the new primary downs. In the above scenario, case 1 may cause the empty primary to be elected as the new primary, resulting in primary data loss. Case 2 may cause the non-empty replica to be elected as the new primary, resulting in data loss and confusion. The reason is that we have cached primary logic, which is used for psync. In the above scenario, when clusterSetPrimary is called, myself will cache server.primary in server.cached_primary for psync. In replicationGetReplicaOffset, we get server.cached_primary->reploff for offset, gossip it and rank it, which causes the replica to use the old historical offset to initiate failover, and it get a good rank, initiates election first, and then is elected as the new primary. The main problem here is that when the replica has not completed full sync, it may get the historical offset in replicationGetReplicaOffset. The fix is to clear cached_primary in these places where full sync is obviously needed, and let the replica use offset == 0 to participate in the election. In this way, this unhealthy replica has a worse rank and is not easy to be elected. Of course, it is possible that it will be elected with offset == 0. In the future, we may need to prohibit the replica with offset == 0 from having the right to initiate elections. Another point worth mentioning, in above cases: 1. In the ROLE command, the replica status will be handshake, and the offset will be -1. 2. Before this PR, in the CLUSTER SHARD command, the replica status will be online, and the offset will be the old cached value (which is wrong). 3. After this PR, in the CLUSTER SHARD, the replica status will be loading, and the offset will be 0. Signed-off-by: Binbin <binloveplay1314@qq.com>
Valkey Test Suite
Overview
Integration tests are written in Tcl, a high-level, general-purpose, interpreted, dynamic programming language [source].
runtest is the main entrance point for running integration tests.
For example, to run a single test;
./runtest --single unit/your_test_name
# For additional arguments, you may refer to the `runtest` script itself.
The normal execution mode of the test suite involves starting and manipulating
local valkey-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 Valkey Cluster compatibility mode. |
--large-memory |
Enables tests that consume more than 100mb |
Debugging
You can set a breakpoint and invoke a minimal debugger using the bp function.
... your test code before break-point
bp 1
... your test code after break-point
The bp 1 will give back the tcl interpreter to the developer, and allow you to interactively print local variables (through puts), run functions and so forth [source].
bp takes a single argument, which is 1 for the case above, and is used to label a breakpoint with a string.
Labels are printed out when breakpoints are hit, so you can identify which breakpoint was triggered.
Breakpoints can be skipped by setting the global variable ::bp_skip, and by providing the labels you want to skip.
The minimal debugger comes with the following predefined functions.
- Press
cto continue past the breakpoint. - Press
ito print local variables.
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 REFCOUNT). |
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 or BGSAVE 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