Random command like SPOP with count is replicated as
some SREM operations, and store them in also_propagate
array to propagate after the call, but this would break
atomicity.
To keep the command's atomicity, wrap also_propagate
array with MULTI/EXEC.
* Introduce a connection abstraction layer for all socket operations and
integrate it across the code base.
* Provide an optional TLS connections implementation based on OpenSSL.
* Pull a newer version of hiredis with TLS support.
* Tests, redis-cli updates for TLS support.
since the slowlog and other means that can help you detect the bad script
are only exposed after the script is done. it might be a good idea to at least
print the script name (sha) to the log when it timeouts.
Here we introduce a change in the way we convert values from Lua to
Redis when RESP3 is selected: this is possible without breaking the fact
we can return directly what a command returned, because there is no
Redis command in RESP2 that returns true or false to Lua, so the
conversion in the case of RESP2 is totally arbitrary. When a script is
written selecting RESP3 from Lua, it totally makes sense to change such
behavior and return RESP3 true/false when Lua true/false is returned.
We want all the scripts to run in RESP2 mode by default. It's up to the
caller to switch to V3 using redis.setresp() if it is really needed.
This way most scripts written for past Redis versions will continue to
work with Redis >= 6 even if the client is in RESP3 mode.
* create module API for forking child processes.
* refactor duplicate code around creating and tracking forks by AOF and RDB.
* child processes listen to SIGUSR1 and dies exitFromChild in order to
eliminate a valgrind warning of unhandled signal.
* note that BGSAVE error reply has changed.
valgrind error is:
Process terminating with default action of signal 10 (SIGUSR1)
sdsZmallocSize assumes a dynamically allocated SDS. When given a string
object created by createEmbeddedStringObject, it calls zmalloc_size on a
pointer that isn't the one returned by zmalloc
Here the idea is that we do not want freeMemoryIfNeeded() to propagate a
DEL command before the script and change what happens in the script
execution once it reaches the slave. For example see this potential
issue (in the words of @soloestoy):
On master, we run the following script:
if redis.call('get','key')
then
redis.call('set','xxx','yyy')
end
redis.call('set','c','d')
Then when redis attempts to execute redis.call('set','xxx','yyy'), we call freeMemoryIfNeeded(), and the key may get deleted, and because redis.call('set','xxx','yyy') has already been executed on master, this script will be replicated to slave.
But the slave received "DEL key" before the script, and will ignore maxmemory, so after that master has xxx and c, slave has only one key c.
Note that this patch (and other related work) was authored collaboratively in
issue #5250 with the help of @soloestoy and @oranagra.
Related to issue #5250.
Technically speaking we don't really need to put the master client in
the clients that need to be processed, since in practice the PING
commands from the master will take care, however it is conceptually more
sane to do so.
A) slave buffers didn't count internal fragmentation and sds unused space,
this caused them to induce eviction although we didn't mean for it.
B) slave buffers were consuming about twice the memory of what they actually needed.
- this was mainly due to sdsMakeRoomFor growing to twice as much as needed each time
but networking.c not storing more than 16k (partially fixed recently in 237a38737).
- besides it wasn't able to store half of the new string into one buffer and the
other half into the next (so the above mentioned fix helped mainly for small items).
- lastly, the sds buffers had up to 30% internal fragmentation that was wasted,
consumed but not used.
C) inefficient performance due to starting from a small string and reallocing many times.
what i changed:
- creating dedicated buffers for reply list, counting their size with zmalloc_size
- when creating a new reply node from, preallocate it to at least 16k.
- when appending a new reply to the buffer, first fill all the unused space of the
previous node before starting a new one.
other changes:
- expose mem_not_counted_for_evict info field for the benefit of the test suite
- add a test to make sure slave buffers are counted correctly and that they don't cause eviction
Implementation notes: as INFO is "already broken", I didn't want to break it further. Instead of computing the server.lua_script dict size on every call, I'm keeping a running sum of the body's length and dict overheads.
This implementation is naive as it **does not** take into consideration dict rehashing, but that inaccuracy pays off in speed ;)
Demo time:
```bash
$ redis-cli info memory | grep "script"
used_memory_scripts:96
used_memory_scripts_human:96B
number_of_cached_scripts:0
$ redis-cli eval "" 0 ; redis-cli info memory | grep "script"
(nil)
used_memory_scripts:120
used_memory_scripts_human:120B
number_of_cached_scripts:1
$ redis-cli script flush ; redis-cli info memory | grep "script"
OK
used_memory_scripts:96
used_memory_scripts_human:96B
number_of_cached_scripts:0
$ redis-cli eval "return('Hello, Script Cache :)')" 0 ; redis-cli info memory | grep "script"
"Hello, Script Cache :)"
used_memory_scripts:152
used_memory_scripts_human:152B
number_of_cached_scripts:1
$ redis-cli eval "return redis.sha1hex(\"return('Hello, Script Cache :)')\")" 0 ; redis-cli info memory | grep "script"
"1be72729d43da5114929c1260a749073732dc822"
used_memory_scripts:232
used_memory_scripts_human:232B
number_of_cached_scripts:2
✔ 19:03:54 redis [lua_scripts-in-info-memory L ✚…⚑] $ redis-cli evalsha 1be72729d43da5114929c1260a749073732dc822 0
"Hello, Script Cache :)"
```
The main change introduced by this commit is pretending that help
arrays are more text than code, thus indenting them at level 0. This
improves readability, and is an old practice when defining arrays of
C strings describing text.
Additionally a few useless return statements are removed, and the HELP
subcommand capitalized when printed to the user.
