In some cases processMultibulkBuffer uses sdsMakeRoomFor to
expand the querybuf, but later in some cases it uses that query
buffer as is for an argv element (see "Optimization"), which means
that the sds in argv may have a lot of wasted space, and then in case
modules keep that argv RedisString inside their data structure, this
space waste will remain for long (until restarted from rdb).
- protocol parsing (processMultibulkBuffer) was limitted to 32big positions in the buffer
readQueryFromClient potential overflow
- rioWriteBulkCount used int, although rioWriteBulkString gave it size_t
- several places in sds.c that used int for string length or index.
- bugfix in RM_SaveAuxField (return was 1 or -1 and not length)
- RM_SaveStringBuffer was limitted to 32bit length
Since SDS v2, we no longer have a single header, so the function to
rewrite the SDS in terms of the minimum space required, instead of just
using realloc() and let the underlying allocator decide what to do,
was doing an allocation + copy every time the minimum possible header
needed to represent the string was different than the current one.
This could be often a bit wasteful, because if we go, for instance, from
the 32 bit fields header to the 16 bit fields header, the overhead of
the header is normally very small. With this commit we call realloc
instead, unless the change in header size is very significant in relation
to the string length.
Redis-cli handles the debugger "eval" command in a special way since
sdssplitargs() would not be ok: we need to send the Redis debugger the
whole Lua script without any parsing. However in order to later free the
argument vector inside redis-cli using just sdsfreesplitres(), we need
to allocate the array of SDS pointers using the same allocator SDS is
using, that may differ to what Redis is using.
So now a newer version of SDS exports sds_malloc() and other allocator
functions to give access, to the program it is linked to, the allocator
used internally by SDS.
When empty strings are created, or when sdsMakeRoomFor() is called, we
are likely into an appending pattern. Use at least type 8 SDS strings
since TYPE 5 does not remember the free allocation size and requires to
call sdsMakeRoomFor() at every new piece appended.
This is an attempt to use the refcount feature of the sds.c fork
provided in the Pull Request #2509. A new type, SDS_TYPE_5 is introduced
having a one byte header with just the string length, without
information about the available additional length at the end of the
string (this means that sdsMakeRoomFor() will be required each time
we want to append something, since the string will always report to have
0 bytes available).
More work needed in order to avoid common SDS functions will pay the
cost of this type. For example both sdscatprintf() and sdscatfmt()
should try to upgrade to SDS_TYPE_8 ASAP when appending chars.
Use the existing memory space for an SDS to convert it to a regular
character buffer so we don't need to allocate duplicate space just
to extract a usable buffer for native operations.
Previously, many files had individual main() functions for testing,
but each required being compiled with their own testing flags.
That gets difficult when you have 8 different flags you need
to set just to run all tests (plus, some test files required
other files to be compiled aaginst them, and it seems some didn't
build at all without including the rest of Redis).
Now all individual test main() funcions are renamed to a test
function for the file itself and one global REDIS_TEST define enables
testing across the entire codebase.
Tests can now be run with:
- `./redis-server test <test>`
e.g. ./redis-server test ziplist
If REDIS_TEST is not defined, then no tests get included and no
tests are included in the final redis-server binary.
in the case (all chars of the string s found in 'cset' ),
line[573] will no more do the same thing line[572] did.
this will be more faster especially in the case that the string s is very long and all chars of string s found in 'cset'
This commit also fixes a bug in the implementation of sdscatfmt()
resulting from stale references to the SDS string header after
sdsMakeRoomFor() calls.
sdscatprintf() relies on printf() family libc functions and is sometimes
too slow in critical code paths. sdscatfmt() is an alternative which is:
1) Far less capable.
2) Format specifier uncompatible.
3) Faster.
It is suitable to be used in those speed critical code paths such as
CLIENT LIST output generation.
For small content the function now tries to use a static buffer to avoid
a malloc/free cycle that is too costly when the function is used in the
context of performance critical code path such as INFO output generation.
This change was verified to have positive effects in the execution speed
of the INFO command.
sdscatvprintf() uses a loop where it tries to output the formatted
string in a buffer of the initial length, if there was not enough room,
a buffer of doubled size is tried and so forth.
The initial guess for the buffer length was very poor, an hardcoded
"16". This caused the printf to be processed multiple times without a
good reason. Given that printf functions are already not fast, the
overhead was significant.
The new heuristic is to use a buffer 4 times the length of the format
buffer, and 32 as minimal size. This appears to be a good balance for
typical uses of the function inside the Redis code base.
This change improved INFO command performances 3 times.
