This PR introduces API to query Expiration time of hash fields.
# New `RedisModule_HashFieldMinExpire()`
For a given hash, retrieves the minimum expiration time across all
fields. If no fields have expiration or if the key is not a hash then
return `REDISMODULE_NO_EXPIRE` (-1).
```
mstime_t RM_HashFieldMinExpire(RedisModuleKey *hash);
```
# Extension to `RedisModule_HashGet()`
Adds a new flag, `REDISMODULE_HASH_EXPIRE_TIME`, to retrieve the
expiration time of a specific hash field. If the field does not exist or
has no expiration, returns `REDISMODULE_NO_EXPIRE`. It is fully
backward-compatible (RM_HashGet retains its original behavior unless the
new flag is used).
Example:
```
mstime_t expiry1, expiry2;
RedisModule_HashGet(mykey, REDISMODULE_HASH_EXPIRE_TIME, "field1", &expiry1, NULL);
RedisModule_HashGet(mykey, REDISMODULE_HASH_EXPIRE_TIME, "field1", &expiry1, "field2", &expiry2, NULL);
```
The PR extends `RedisModule_OpenKey`'s flags to include
`REDISMODULE_OPEN_KEY_ACCESS_EXPIRED`, which allows to access expired
keys.
It also allows to access expired subkeys. Currently relevant only for
hash fields
and has its impact on `RM_HashGet` and `RM_Scan`.
Writable replicas now no longer use the values of expired keys. Expired keys are
deleted when lookupKeyWrite() is used, even on a writable replica. Previously,
writable replicas could use the value of an expired key in write commands such
as INCR, SUNIONSTORE, etc..
This commit also sorts out the mess around the functions lookupKeyRead() and
lookupKeyWrite() so they now indicate what we intend to do with the key and
are not affected by the command calling them.
Multi-key commands like SUNIONSTORE, ZUNIONSTORE, COPY and SORT with the
store option now use lookupKeyRead() for the keys they're reading from (which will
not allow reading from logically expired keys).
This commit also fixes a bug where PFCOUNT could return a value of an
expired key.
Test modules commands have their readonly and write flags updated to correctly
reflect their lookups for reading or writing. Modules are not required to
correctly reflect this in their command flags, but this change is made for
consistency since the tests serve as usage examples.
Fixes#6842. Fixes#7475.
The added flag affects the return value of RM_HashSet() to include
the number of inserted fields, in addition to updated and deleted
fields.
errno is set on errors, tests are added and documentation updated.
Moti Cohen