Previously the string was created empty then re-sized
to fit the offset, but sds resize causes the sds to
over-allocate by at least 1 MB (which is a lot when
you are operating at bit-level access).
This also improves the speed of initial sets by 2% to 6%
based on quick testing.
Patch logic provided by @oranagra
Fixes#1918
Improvements:
- Return empty string if asking for non-existing section (INFO foo)
- Fix potential memory leak (caused by sdsempty() then returned if >2 args)
- Clean up argument parsing
- Allow "all" as valid section (same as "default" or zero args currently)
- Move strcasecmp to end of evaluation chain in conditionals
Also, since we're C99, I moved some variable declarations to be closer
to where they are actually used (saves us from needing to free an empty info
if detect argument errors up front).
Closes#1915Closes#1966
There is no standard cross-platform way of obtaining
system memory info, but I found a useful function
convering all common platforms. I removed support
for uncommon Redis platforms (windows, AIX) and left
others intact.
For more info, see:
http://nadeausoftware.com/articles/2012/09/c_c_tip_how_get_physical_memory_size_system
The system memory info is cached on startup, but some systems
may be able to change the amount of memory visible to Redis
at runtime if Redis is deployed in a VM or container.
Also see #1820
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.
I guess the initial goal of the initialization was to suppress GCC
warning, but if we have to initialize, we can do it with the base-case
value instead of NULL which is never retained.
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'
Track bandwidth used by clients and replication (but diskless
replication is not tracked since the actual transfer happens in the
child process).
This includes a refactoring that makes tracking new instantaneous
metrics simpler.
