BLPOP and other blocking list commands can only block on empty keys
and LPUSH only wakes up clients when the list is created.
Using the module API, it's possible to block on a non-empty key.
Unblocking a client blocked on a non-empty list (or zset) can only
be done using RedisModule_SignalKeyAsReady(). This commit tests it.
the test was misleading because the module would actually woke up on a wrong type and
re-blocked, while the test name suggests the module doesn't not wake up at all on a wrong type..
i changed the name of the test + added verification that indeed the module wakes up and gets
re-blocked after it understand it's the wrong type
This was a regression from #7625 (only in 6.2 RC2).
This makes it possible again to implement blocking list and zset
commands using the modules API.
This commit also includes a test case for the reverse: A module
unblocks a client blocked on BLPOP by inserting elements using
RedisModule_ListPush(). This already works, but it was untested.
There is an inherent race between the deferring client and the
"main" client of the test: While the deferring client issues a blocking
command, we can't know for sure that by the time the "main" client
tries to issue another command (Usually one that unblocks the deferring
client) the deferring client is even blocked...
For lack of a better choice this commit uses TCL's 'after' in order
to give some time for the deferring client to issues its blocking
command before the "main" client does its thing.
This problem probably exists in many other tests but this commit
tries to fix blockonkeys.tcl
By using a "circular BRPOPLPUSH"-like scenario it was
possible the get the same client on db->blocking_keys
twice (See comment in moduleTryServeClientBlockedOnKey)
The fix was actually already implememnted in
moduleTryServeClientBlockedOnKey but it had a bug:
the funxction should return 0 or 1 (not OK or ERR)
Other changes:
1. Added two commands to blockonkeys.c test module (To
reproduce the case described above)
2. Simplify blockonkeys.c in order to make testing easier
3. cast raxSize() to avoid warning with format spec
If a blocked module client times-out (or disconnects, unblocked
by CLIENT command, etc.) we need to call moduleUnblockClient
in order to free memory allocated by the module sub-system
and blocked-client private data
Other changes:
Made blockedonkeys.tcl tests a bit more aggressive in order
to smoke-out potential memory leaks
