blockForKeys() was not freeing the allocation holding the ID when the
key was already found busy. Fortunately the unit test checked explicitly
for blocking multiple times for the same key (copying a regression in
the blocking lists tests), so the bug was detected by the Redis test leak
checker.
XADD was suboptimal in the first incarnation of the command, not being
able to accept an ID (very useufl for replication), nor options for
having capped streams.
The keyspace notification for streams was not implemented.
A client may lose a lot of time between invocations of blocking XREAD,
for example because it is processing the messages or for any other
cause. When it returns back, it may provide a low enough message ID that
the server will block to send an unreasonable number of messages in a
single call. For this reason we set a COUNT when the client is blocked
with XREAD calls, even if no COUNT is given. This is arbitrarily set to
1000 because it's enough to avoid slowing down the reception of many
messages, but low enough to avoid to block.
With lists we need to signal only on key creation, but streams can
provide data to clients listening at every new item added.
To make this slightly more efficient we now track different classes of
blocked clients to avoid signaling keys when there is nobody listening.
A typical case is when the stream is used as a time series DB and
accessed only by range with XRANGE.
After a few attempts it looked quite saner to just add the last item ID
at the end of the serialized listpacks, instead of scanning the last
listpack loaded from head to tail just to fetch it. It's a disk space VS
CPU-and-simplicity tradeoff basically.
Related to #4483. As suggested by @soloestoy, we can retrieve the SHA1
from the body. Given that in the new implementation using AUX fields we
ended copying around a lot to create new objects and strings, extremize
such concept and trade CPU for space inside the RDB file.
This is currently needed in order to fix#4483, but this can be
useful in other contexts, so maybe later we may want to remove the
conditionals and always save/load scripts.
Note that we are using the "lua" AUX field here, in order to guarantee
backward compatibility of the RDB file. The unknown AUX fields must be
discarded by past versions of Redis.
Doing the following ended with a broken server.executable:
1. Start Redis with src/redis-server
2. Send CONFIG SET DIR /tmp/
3. Send DEBUG RESTART
At this point we called execve with an argv[0] that is no longer related
to the new path. So after the restart the absolute path of the
executable is recomputed in the wrong way. With this fix we pass the
absolute path already computed as argv[0].
This adds a new `addReplyHelp` helper that's used by commands
when returning a help text. The following commands have been
touched: DEBUG, OBJECT, COMMAND, PUBSUB, SCRIPT and SLOWLOG.
WIP
Fix entry command table entry for OBJECT for HELP option.
After #4472 the command may have just 2 arguments.
Improve OBJECT HELP descriptions.
See #4472.
WIP 2
WIP 3
See #4192, the original PR removed lines of code that are actually
needed, so thanks to @chunqiulfq for reporting the problem, but merging
solution from @jeesyn after checking, together with @artix75, that the
logic covers all the cases.
Firstly, use access time to replace the decreas time of LFU.
For function LFUDecrAndReturn,
it should only try to get decremented counter,
not update LFU fields, we will update it in an explicit way.
And we will times halve the counter according to the times of
elapsed time than server.lfu_decay_time.
Everytime a key is accessed, we should update the LFU
including update access time, and increment the counter after
call function LFUDecrAndReturn.
If a key is overwritten, the LFU should be also updated.
Then we can use `OBJECT freq` command to get a key's frequence,
and LFUDecrAndReturn should be called in `OBJECT freq` command
in case of the key has not been accessed for a long time,
because we update the access time only when the key is read or
overwritten.
getLongLongFromObject calls string2ll which has this line:
/* Return if not all bytes were used. */
so if you pass an sds with 3 characters "1\01" it will fail.
but getLongDoubleFromObject calls strtold, and considers it ok if eptr[0]==`\0`
i.e. if the end of the string found by strtold ends with null terminator
127.0.0.1:6379> set a 1
OK
127.0.0.1:6379> setrange a 2 2
(integer) 3
127.0.0.1:6379> get a
"1\x002"
127.0.0.1:6379> incrbyfloat a 2
"3"
127.0.0.1:6379> get a
"3"
For example:
1. A module command called within a MULTI section.
2. A Lua script with replicate_commands() called within a MULTI section.
3. A module command called from a Lua script in the above context.
Normally in modern Redis you can't create zero-len lists, however it's
possible to load them from old RDB files generated, for instance, using
Redis 2.8 (see issue #4409). The "Right Thing" would be not loading such
lists at all, but this requires to hook in rdb.c random places in a not
great way, for a problem that is at this point, at best, minor.
Here in this commit instead I just fix the fact that zero length lists,
materialized as quicklists with the first node set to NULL, were
iterated in the wrong way while they are saved, leading to a crash.
The other parts of the list implementation are apparently able to deal
with empty lists correctly, even if they are no longer a thing.
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.
When we free the backlog, we should use a new
replication ID and clear the ID2. Since without
backlog we can not increment master_repl_offset
even do write commands, that may lead to inconsistency
when we try to connect a "slave-before" master
(if this master is our slave before, our replid
equals the master's replid2). As the master have our
history, so we can match the master's replid2 and
second_replid_offset, that make partial sync work,
but the data is inconsistent.
There was not enough sanity checking in the code loading the slots of
Redis Cluster from the nodes.conf file, this resulted into the
attacker's ability to write data at random addresses in the process
memory, by manipulating the index of the array. The bug seems
exploitable using the following techique: the config file may be altered so
that one of the nodes gets, as node ID (which is the first field inside the
structure) some data that is actually executable: then by writing this
address in selected places, this node ID part can be executed after a
jump. So it is mostly just a matter of effort in order to exploit the
bug. In practice however the issue is not very critical because the
bug requires an unprivileged user to be able to modify the Redis cluster
nodes configuration, and at the same time this should result in some
gain. However Redis normally is unprivileged as well. Yet much better to
have this fixed indeed.
Fix#4278.
Certain checks were useless, at the same time certain malformed inputs
were accepted without problems (emtpy strings parsed as zero).
Cases where strtod() returns ERANGE but we still want to parse the input
where ok in getDoubleFromObject() but not in the long variant.
As a side effect of these fixes, this commit fixes#4391.
This commit is a reinforcement of commit c1c99e9.
1. Replication information can be stored when the RDB file is
generated by a mater using server.slaveseldb when server.repl_backlog
is not NULL, or set repl_stream_db be -1. That's safe, because
NULL server.repl_backlog will trigger full synchronization,
then master will send SELECT command to replicaiton stream.
2. Only do rdbSave* when rsiptr is not NULL,
if we do rdbSave* without rdbSaveInfo, slave will miss repl-stream-db.
3. Save the replication informations also in the case of
SAVE command, FLUSHALL command and DEBUG reload.
This commit attempts to fix a number of bugs reported in #4316.
They are related to the way replication info like replication ID,
offsets, and currently selected DB in the master client, are stored
and loaded by Redis. In order to avoid inconsistencies the changes in
this commit try to enforce that:
1. Replication information are only stored when the RDB file is
generated by a slave that has a valid 'master' client, so that we can
always extract the currently selected DB.
2. When replication informations are persisted in the RDB file, all the
info for a successful PSYNC or nothing is persisted.
3. The RDB replication informations are only loaded if the instance is
configured as a slave, otherwise a master can start with IDs that relate
to a different history of the data set, and stil retain such IDs in the
future while receiving unrelated writes.
A slave may be started with an RDB file able to provide enough slave to
perform a successful partial SYNC with its master. However in such a
case, how outlined in issue #4268, the slave backlog will not be
started, since it was only initialized on full syncs attempts. This
creates different problems with successive PSYNC attempts that will
always result in full synchronizations.
Thanks to @fdingiit for discovering the issue.
antirez