Merge pull request #77 from Poincare/patch-1

[redis.git] / TODO

diff --git a/TODO b/TODO
index cfd21b763cb3ae8d8c2454d139e1587d19fa8300..aeb58229b21acaa424a532a23a363a3132ae3ac0 100644 (file)
--- a/TODO
+++ b/TODO
@@ -1,86 +1,69 @@
-Redis TODO and Roadmap
+Redis TODO
+----------

 
 

-VERSION 1.4 TODO (Hash type)
-============================
+WARNING: are you a possible Redis contributor?
+         Before implementing what is listed what is listed in this file
+         please drop a message in the Redis google group or chat with
+         antirez or pietern on irc.freenode.org #redis to check if the work
+         is already in progress and if the feature is still interesting for
+         us, and *how* exactly this can be implemented to have good changes
+         of a merge. Otherwise it is probably wasted work! Thank you

 
 

-* BRPOPLPUSH
-* RPOPLPUSH should notify blocking POP operations
-* List ops like L/RPUSH L/RPOP should return the new list length.
-* Save dataset / fsync() on SIGTERM
-* MULTI/EXEC should support the "EXEC FSYNC" form
-* Synchronous Virtual Memory
-* BLPOP & C. tests (write a non blocking Tcl client as first step)

 
 

-Virtual Memory sub-TODO:
-* Check if the page selection algorithm is working well.
-* Divide swappability of objects by refcount
-* vm-swap-file <filename>. The swap file should go where the user wants, and if it's already there and of the right size we can avoid to create it again.
-* it should be possible to give the vm-max-memory option in megabyte, gigabyte, ..., just using 2GB, 100MB, and so forth.
-* Make sure to wait all the IO threads are done before to fork() for BGSAVE and BGREWRITEAOF
+API CHANGES
+===========

 
 

-VERSION 1.6 TODO (Virtual memory)
-=================================
+* Turn commands into variadic versions when it makes sense, that is, when
+  the variable number of arguments represent values, and there is no conflict
+  with the return value of the command.

 
 

-* Asynchronous Virtual Memory
-* Hashes (HSET, HGET, HEXISTS, HLEN, ...).
+CLUSTER
+=======

 
 

-VERSION 1.8 TODO (Fault tollerant sharding)
-===========================================
+* Implement rehashing and cluster check in redis-trib.
+* Reimplement MIGRATE / RESTORE to use just in memory buffers (no disk at
+  all). This will require touching a lot of the RDB stuff around, but we may
+  hand with faster persistence for RDB.
+* Implement the slave nodes semantics and election.
+* Allow redis-trib to create a cluster-wide snapshot (using SYNC).
+* Allow redis-trib to restore a cluster-wide snapshot (implement UPLOAD?).

 
 

-* Redis-cluster, a fast intermediate layer (proxy) that implements consistent hashing and fault tollerant nodes handling.
+SCRIPTING
+=========

 
 

-Interesting readings about this:
+* MULTI/EXEC/...: should we do more than simply ignoring it?
+* Prevent Lua from calling itself with redis("eval",...)
+* SCRIPT FLUSH or alike to start a fresh interpreter?
+* http://redis.io/topics/sponsors

 
 

-    - http://ayende.com/Blog/archive/2009/04/06/designing-rhino-dht-a-fault-tolerant-dynamically-distributed-hash.aspx
+APPEND ONLY FILE
+================

 
 

-VERSION 2.0 TODO (Optimizations and latency)
-============================================
+* in AOF rewirte use HMSET to rewrite small hashes instead of multiple calls
+  to HSET.

 
 

-* Lower the CPU usage.
-* Lower the RAM usage everywhere possible.
-* Use epool and alike to rewrite ae.c for Linux and other platforms suppporting fater-than-select() mutiplexing APIs.
-* Implement an UDP interface for low-latency GET/SET operations.
+OPTIMIZATIONS
+=============

 
 

-VERSION 2.2 TODO (Optimizations and latency)
-============================================
-
-* JSON command able to access data serialized in JSON format. For instance if I've a key foobar with a json object I can alter the "name" file using somthing like: "JSON SET foobar name Kevin". We should have GET and INCRBY as well.
-
-OTHER IMPORTANT THINGS THAT WILL BE ADDED BUT I'M NOT SURE WHEN
-===============================================================
-
-BIG ONES:
-
-* Specially encoded memory-saving integer sets.
-* A command to export a JSON dump (there should be mostly working patch needing major reworking).
-* Specially encoded sets of integers (this includes a big refactoring providing an higher level layer for Sets manipulation)
-* ZRANK: http://docs.google.com/viewer?a=v&q=cache:tCQaP3ZeN4YJ:courses.csail.mit.edu/6.046/spring04/handouts/ps5-sol.pdf+skip+list+rank+operation+augmented&hl=en&pid=bl&srcid=ADGEEShXuNjTcZyXw_1cq9OaWpSXy3PprjXqVzmM-LE0ETFznLyrDXJKQ_mBPNT10R8ErkoiXD9JbMw_FaoHmOA4yoGVrA7tZWiy393JwfCwuewuP93sjbkzZ_gnEp83jYhPYjThaIzw&sig=AHIEtbRF0GkYCdYRFtTJBE69senXZwFY0w
-
-SMALL ONES:
+* Avoid COW due to incrementing the dict iterators counter.
+* SORT: Don't copy the list into a vector when BY argument is constant.
+* Write the hash table size of every db in the dump, so that Redis can resize the hash table just one time when loading a big DB.
+* Read-only mode for slaves.
+* Redis big lists as linked lists of small ziplists?
+  Possibly a simple heuristic that join near nodes when some node gets smaller than the low_level, and split it into two if gets bigger than high_level.

 
 

-* Give errors when incrementing a key that does not look like an integer, when providing as a sorted set score something can't be parsed as a double, and so forth.
-* MSADD (n keys) (n values). See this thread in the Redis google group: http://groups.google.com/group/redis-db/browse_thread/thread/e766d84eb375cd41
-* Don't save empty lists / sets / zsets on disk with snapshotting.
-* Remove keys when a list / set / zset reaches length of 0.
+RANDOM
+======

 
 

-THE "MAYBE" TODO LIST: things that may or may not get implemented
-=================================================================
+* Server should abort when getcwd() fails if there is some kind of persistence configured. Check this in the cron loop.
+* Clients should be closed as far as the output buffer list is bigger than a given number of elements (configurable in redis.conf)
+* Should the redis default configuration, and the default redis.conf, just bind 127.0.0.1?

 
 

-Most of this can be seen just as proposals, the fact they are in this list
-it's not a guarantee they'll ever get implemented ;)
+KNOWN BUGS
+==========

 
 

-* Move dict.c from hash table to skip list, in order to avoid the blocking resize operation needed for the hash table.
-* FORK command (fork()s executing the commands received by the current
-  client in the new process). Hint: large SORTs can use more cores,
-  copy-on-write will avoid memory problems.
-* DUP command? DUP srckey dstkey, creates an exact clone of srckey value in dstkey.
-* SORT: Don't copy the list into a vector when BY argument is constant.
-* Write the hash table size of every db in the dump, so that Redis can resize the hash table just one time when loading a big DB.
-* LOCK / TRYLOCK / UNLOCK as described many times in the google group
-* Replication automated tests
-* Byte Array type (BA prefixed commands): BASETBIT BAGETBIT BASETU8 U16 U32 U64 S8 S16 S32 S64, ability to atomically INCRBY all the base types. BARANGE to get a range of bytes as a bulk value, BASETRANGE to set a range of bytes.
-* zmalloc() should avoid to add a private header for archs where there is some other kind of libc-specific way to get the size of a malloced block. Already done for Mac OS X.
-* Read-only mode.
-* Pattern-matching replication.
-* Add an option to relax the delete-expiring-keys-on-write semantic *denying* replication and AOF when this is on? Can be handy sometimes, when using Redis for non persistent state, but can create problems. For instance should rename and move also "move" the timeouts? How does this affect other commands?
-* Multiple BY in SORT.
+* #519: Slave may have expired keys that were never read in the master (so a DEL
+  is not sent in the replication channel) but are already expired since
+  a lot of time. Maybe after a given delay that is undoubltly greater than
+  the replication link latency we should expire this key on the slave on
+  access?