Previouly if we loaded a corrupt RDB, Redis printed an error report
with a big "REPORT ON GITHUB" message at the bottom. But, we know
RDB load failures are corrupt data, not corrupt code.
Now when RDB failure is detected (duplicate keys or unknown data
types in the file), we run check-rdb against the RDB then exit. The
automatic check-rdb hopefully gives the user instant feedback
about what is wrong instead of providing a mysterious stack
trace.
It's possible large objects could be larger than 'int', so let's
upgrade all size counters to ssize_t.
This also fixes rdbSaveObject serialized bytes calculation.
Since entire serializations of data structures can be large,
so we don't want to limit their calculated size to a 32 bit signed max.
This commit increases object size calculation and
cascades the change back up to serializedlength printing.
Before:
127.0.0.1:6379> debug object hihihi
... encoding:quicklist serializedlength:-2147483559 ...
After:
127.0.0.1:6379> debug object hihihi
... encoding:quicklist serializedlength:2147483737 ...
This commit introduces a new RDB data type called 'aux'. It is used in
order to insert inside an RDB file key-value pairs that may serve
different needs, without breaking backward compatibility when new
informations are embedded inside an RDB file. The contract between Redis
versions is to ignore unknown aux fields when encountered.
Aux fields can be used in order to:
1. Augment the RDB file with info like version of Redis that created the
RDB file, creation time, used memory while the RDB was created, and so
forth.
2. Add state about Redis inside the RDB file that we need to reload
later: replication offset, previos master run ID, in order to improve
failovers safety and allow partial resynchronization after a slave
restart.
3. Anything that we may want to add to RDB files without breaking the
ability of past versions of Redis to load the file.
The new opcode is an hint about the size of the dataset (keys and number
of expires) we are going to load for a given Redis database inside the
RDB file. Since hash tables are resized accordingly ASAP, useless
rehashing is avoided, speeding up load times significantly, in the order
of ~ 20% or more for larger data sets.
Related issue: #1719
This removes:
- list-max-ziplist-entries
- list-max-ziplist-value
This adds:
- list-max-ziplist-size
- list-compress-depth
Also updates config file with new sections and updates
tests to use quicklist settings instead of old list settings.
Let user set how many nodes to *not* compress.
We can specify a compression "depth" of how many nodes
to leave uncompressed on each end of the quicklist.
Depth 0 = disable compression.
Depth 1 = only leave head/tail uncompressed.
- (read as: "skip 1 node on each end of the list before compressing")
Depth 2 = leave head, head->next, tail->prev, tail uncompressed.
- ("skip 2 nodes on each end of the list before compressing")
Depth 3 = Depth 2 + head->next->next + tail->prev->prev
- ("skip 3 nodes...")
etc.
This also:
- updates RDB storage to use native quicklist compression (if node is
already compressed) instead of uncompressing, generating the RDB string,
then re-compressing the quicklist node.
- internalizes the "fill" parameter for the quicklist so we don't
need to pass it to _every_ function. Now it's just a property of
the list.
- allows a runtime-configurable compression option, so we can
expose a compresion parameter in the configuration file if people
want to trade slight request-per-second performance for up to 90%+
memory savings in some situations.
- updates the quicklist tests to do multiple passes: 200k+ tests now.
Turns out it's a huge improvement during save/reload/migrate/restore
because, with compression enabled, we're compressing 4k or 8k
chunks of data consisting of multiple elements in one ziplist
instead of compressing series of smaller individual elements.
This replaces individual ziplist vs. linkedlist representations
for Redis list operations.
Big thanks for all the reviews and feedback from everybody in
https://github.com/antirez/redis/pull/2143
1. Server unxtime may remain not updated while loading AOF, so ETA is
not updated correctly.
2. Number of processed byte was not initialized.
3. Possible division by zero condition (likely cause of issue #1932).
We need to avoid that a child -> slaves transfer can continue forever.
We use the same timeout used as global replication timeout, which is
documented to also affect I/O operations during bulk transfers.
To perform a socket write() for each RDB rio API write call was
extremely unefficient, so now rio has minimal buffering capabilities.
Writes are accumulated into a buffer and only when a given limit is
reacehd are actually wrote to the N slaves FDs.
Trivia: rio lacked support for buffering since our targets were:
1) Memory buffers.
2) C standard I/O.
Both were buffered already.
We need to remember what is the saving strategy of the current RDB child
process, since the configuration may be modified at runtime via CONFIG
SET and still we'll need to understand, when the child exists, what to
do and for what goal the process was initiated: to create an RDB file
on disk or to write stuff directly to slave's sockets.
When we are blocked and a few events a processed from time to time, it
is smarter to call the event handler a few times in order to handle the
accept, read, write, close cycle of a client in a single pass, otherwise
there is too much latency added for clients to receive a reply while the
server is busy in some way (for example during the DB loading).
Previously, the (!fp) would only catch lack of free space
under OS X. Linux waits to discover it can't write until
it actually writes contents to disk.
(fwrite() returns success even if the underlying file
has no free space to write into. All the errors
only show up at flush/sync/close time.)
Fixesantirez/redis#1604
server.unixtime and server.mstime are cached less precise timestamps
that we use every time we don't need an accurate time representation and
a syscall would be too slow for the number of calls we require.
Such an example is the initialization and update process of the last
interaction time with the client, that is used for timeouts.
However rdbLoad() can take some time to load the DB, but at the same
time it did not updated the time during DB loading. This resulted in the
bug described in issue #1535, where in the replication process the slave
loads the DB, creates the redisClient representation of its master, but
the timestamp is so old that the master, under certain conditions, is
sensed as already "timed out".
Thanks to @yoav-steinberg and Redis Labs Inc for the bug report and
analysis.
