In #7875 (Redis 6.2), we changed the sds alloc to be the usable allocation
size in order to:
> reduce the need for realloc calls by making the sds implicitly take over
the internal fragmentation
This change was done most sds functions, excluding `sdsRemoveFreeSpace` and
`sdsResize`, the reason is that in some places (e.g. clientsCronResizeQueryBuffer)
we call sdsRemoveFreeSpace when we see excessive free space and want to trim it.
so if we don't trim it exactly to size, the caller may still see excessive free space and
call it again and again.
However, this resulted in some excessive calls to realloc, even when there's no need
and it's gonna be a no-op (e.g. when reducing 15 bytes allocation to 13).
It turns out that a call for realloc with jemalloc can be expensive even if it ends up
doing nothing, so this PR adds a check using `je_nallocx`, which is cheap to avoid
the call for realloc.
in addition to that this PR unifies sdsResize and sdsRemoveFreeSpace into common
code. the difference between them was that sdsResize would avoid using SDS_TYPE_5,
since it want to keep the string ready to be resized again, while sdsRemoveFreeSpace
would permit using SDS_TYPE_5 and get an optimal memory consumption.
now both methods take a `would_regrow` argument that makes it more explicit.
the only actual impact of that is that in clientsCronResizeQueryBuffer we call both sdsResize
and sdsRemoveFreeSpace for in different cases, and we now prevent the use of SDS_TYPE_5 in both.
The new test that was added to cover this concern used to pass before this PR as well,
this PR is just a performance optimization and cleanup.
Benchmark:
`redis-benchmark -c 100 -t set -d 512 -P 10 -n 100000000`
on i7-9850H with jemalloc, shows improvement from 1021k ops/sec to 1067k (average of 3 runs).
some 4.5% improvement.
Co-authored-by: Oran Agra <oran@redislabs.com>
Before this PR, we use sdsMakeRoomFor() to expand the size of hyperloglog
string (sparse representation). And because sdsMakeRoomFor() uses a greedy
strategy (allocate about twice what we need), the memory we allocated for the
hyperloglog may be more than `server.hll_sparse_max_bytes` bytes.
The memory more than` server.hll_sparse_max_bytes` will be wasted.
In this pull request, tone down the greediness of the allocation growth, and also
make sure it'll never request more than `server.hll_sparse_max_bytes`.
This could in theory mean the size of the hyperloglog string is insufficient for the
increment we need, should be ok since in this case we promote the hyperloglog
to dense representation, an assertion was added to make sure.
This PR also add some tests and fixes some typo and indentation issues.
Fixing few macros that doesn't follows most basic safety conventions
which is wrapping any usage of passed variable
with parentheses and if written more than one command, then wrap
it with do-while(0) (or parentheses).
There are some commands that has the wrong key specs.
This PR adds a key-spec related check in generate-command-code.py.
Check if the index is valid, or if there is an unused index.
The check result will look like:
```
[root]# python utils/generate-command-code.py
Processing json files...
Linking container command to subcommands...
Checking all commands...
command: RESTORE_ASKING may have unused key_spec
command: RENAME may have unused key_spec
command: PFDEBUG may have unused key_spec
command: WATCH key_specs missing flags
command: LCS arg: key2 key_spec_index error
command: RENAMENX may have unused key_spec
Error: There are errors in the commands check, please check the above logs.
```
The following commands have been fixed according to the check results:
- RESTORE ASKING: add missing arguments section (and history section)
- RENAME: newkey's key_spec_index should be 1
- PFDEBUG: add missing arguments (and change the arity from -3 to 3)
- WATCH: add missing key_specs flags: RO, like EXIST (it allow you to know the key exists, or is modified, but doesn't "leak" the data)
- LCS: key2 key_spec_index error, there is only one key-spec
- RENAMENX: newkey's key_spec_index should be 1
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.
- Added sanitizer support. `address`, `undefined` and `thread` sanitizers are available.
- To build Redis with desired sanitizer : `make SANITIZER=undefined`
- There were some sanitizer findings, cleaned up codebase
- Added tests with address and undefined behavior sanitizers to daily CI.
- Added tests with address sanitizer to the per-PR CI (smoke out mem leaks sooner).
Basically, there are three types of issues :
**1- Unaligned load/store** : Most probably, this issue may cause a crash on a platform that
does not support unaligned access. Redis does unaligned access only on supported platforms.
**2- Signed integer overflow.** Although, signed overflow issue can be problematic time to time
and change how compiler generates code, current findings mostly about signed shift or simple
addition overflow. For most platforms Redis can be compiled for, this wouldn't cause any issue
as far as I can tell (checked generated code on godbolt.org).
**3 -Minor leak** (redis-cli), **use-after-free**(just before calling exit());
UB means nothing guaranteed and risky to reason about program behavior but I don't think any
of the fixes here worth backporting. As sanitizers are now part of the CI, preventing new issues
will be the real benefit.
This PR adds a spell checker CI action that will fail future PRs if they introduce typos and spelling mistakes.
This spell checker is based on blacklist of common spelling mistakes, so it will not catch everything,
but at least it is also unlikely to cause false positives.
Besides that, the PR also fixes many spelling mistakes and types, not all are a result of the spell checker we use.
Here's a summary of other changes:
1. Scanned the entire source code and fixes all sorts of typos and spelling mistakes (including missing or extra spaces).
2. Outdated function / variable / argument names in comments
3. Fix outdated keyspace masks error log when we check `config.notify-keyspace-events` in loadServerConfigFromString.
4. Trim the white space at the end of line in `module.c`. Check: https://github.com/redis/redis/pull/7751
5. Some outdated https link URLs.
6. Fix some outdated comment. Such as:
- In README: about the rdb, we used to said create a `thread`, change to `process`
- dbRandomKey function coment (about the dictGetRandomKey, change to dictGetFairRandomKey)
- notifyKeyspaceEvent fucntion comment (add type arg)
- Some others minor fix in comment (Most of them are incorrectly quoted by variable names)
7. Modified the error log so that users can easily distinguish between TCP and TLS in `changeBindAddr`
Fix wrong server dirty increment in
* spopWithCountCommand
* hsetCommand
* ltrimCommand
* pfaddCommand
Some didn't increment the amount of fields (just one per command).
Others had excessive increments.
The commit splits the add functions into a set() and add() set of
functions, so that it's possible to set registers in an independent way
just having the index and count.
Related to #3819, otherwise a fix is not possible.
However note that in architectures supporting 64 bit unaligned
accesses memcpy(...,...,8) is likely translated to a simple
word memory movement anyway.
The new algorithm provides the same speed with a smaller error for
cardinalities in the range 0-100k. Before switching, the new and old
algorithm behavior was studied in details in the context of
issue #3677. You can find a few graphs and motivations there.
Otherwise for small cardinalities the algorithm will output something
like, for example, 4.99 for a candinality of 5, that will be converted
to 4 producing a huge error.
Slaves key expire is orchestrated by the master. Sometimes the master
will send the synthesized DEL to expire keys on the slave with a non
trivial delay (when the key is not accessed, only the incremental expiry
algorithm will expire it in background).
During that time, a key is logically expired, but slaves still return
the key if you GET (or whatever) it. This is a bad behavior.
However we can't simply trust the slave view of the key, since we need
the master to be able to send write commands to update the slave data
set, and DELs should only happen when the key is expired in the master
in order to ensure consistency.
However 99.99% of the issues with this behavior is when a client which
is not a master sends a read only command. In this case we are safe and
can consider the key as non existing.
This commit does a few changes in order to make this sane:
1. lookupKeyRead() is modified in order to return NULL if the above
conditions are met.
2. Calls to lookupKeyRead() in commands actually writing to the data set
are repliaced with calls to lookupKeyWrite().
There are redundand checks, so for example, if in "2" something was
overlooked, we should be still safe, since anyway, when the master
writes the behavior is to don't care about what expireIfneeded()
returns.
This commit is related to #1768, #1770, #2131.
