Commit 46b614ed authored by Pieter Noordhuis's avatar Pieter Noordhuis
Browse files

Merge branch 'master' into integration

parents fdfb02e7 30dd89b6
...@@ -12,3 +12,4 @@ mkrelease.sh ...@@ -12,3 +12,4 @@ mkrelease.sh
release release
myredis.conf myredis.conf
misc/* misc/*
release.h
2010-05-16 Redis version is now 1.3.12 (antirez)
2010-05-16 redis version is now 1.3.11 (antirez)
2010-05-16 random refactoring and speedups (antirez)
2010-05-16 faster INCR with very little efforts... (antirez)
2010-05-15 Merge branch 'redis-cli-fix' of http://github.com/tizoc/redis (antirez)
2010-05-15 added pid info to the check memory leaks test, so that those tests don't appear to be duplicated (antirez)
2010-05-15 Merge branch 'integration' of git://github.com/pietern/redis (antirez)
2010-05-14 more endianess detection fix for SHA1 (antirez)
2010-05-14 fixed a warning seen with some GCC version under Linux (antirez)
2010-05-14 initial rough integration test for replication (Pieter Noordhuis)
2010-05-14 store entire server object on the stack instead of just the client (Pieter Noordhuis)
2010-05-14 proc to retrieve values from INFO properties (Pieter Noordhuis)
2010-05-14 one more fix for endianess detection (antirez)
2010-05-14 Fixed sha1.c compilation on Linux, due to endianess detection lameness (antirez)
2010-05-14 ZUNION,ZINTER -> ZUNIONSTORE,ZINTERSTORE (antirez)
2010-05-14 minor fixes to the new test suite, html doc updated (antirez)
2010-05-14 wait for redis-server to be settled and ready for connections (Pieter Noordhuis)
2010-05-14 fix cleaning up tmp folder (Pieter Noordhuis)
2010-05-14 update makefile to use the new test suite (Pieter Noordhuis)
2010-05-14 check for memory leaks before killing a server (Pieter Noordhuis)
2010-05-14 extract code to kill a server to a separate proc (Pieter Noordhuis)
2010-05-14 start servers on different ports to prevent conflicts (Pieter Noordhuis)
2010-05-14 use DEBUG DIGEST in new test suite (Pieter Noordhuis)
2010-05-14 split test suite into multiple files; runs redis-server in isolation (Pieter Noordhuis)
2010-05-14 use DEBUG DIGEST in the test instead of a function that was doing a similar work, but in a much slower and buggy way (antirez)
2010-05-14 Don't rely on cliReadReply being able to return on shutdown (Bruno Deferrari)
2010-05-14 If command is a shutdown, ignore errors on reply (Bruno Deferrari)
2010-05-14 DEBUG DIGEST implemented, in order to improve the ability to test persistence and replication consistency (antirez)
2010-05-13 makefile deps updated (antirez)
2010-05-13 conflicts resolved (antirez)
2010-05-13 feed SETEX as SET and EXPIREAT to AOF (Pieter Noordhuis)
2010-05-13 very strong speedup in saving time performance when there are many integers in the dataset. Instead of decoding the object before to pass them to the rdbSaveObject layer we check asap if the object is integer encoded and can be written on disk as an integer. (antirez)
2010-05-13 include limits.h otherwise no double precison macros (antirez)
2010-05-13 explicitly checks with ifdefs if our floating point and long long assumptions are verified (antirez)
2010-05-13 Yet another version of the double saving code, with comments explaining what's happening there (antirez)
2010-05-12 added overflow check in the double -> long long conversion trick to avoid integer overflows. I think this was not needed in practical terms, but it is safer (antirez)
2010-05-12 use withscores when performing the dataset digest (antirez)
2010-05-12 If a float can be casted to a long long without rounding loss, we can use the integer conversion function to write the score on disk. This is a seriuous speedup (antirez)
2010-05-12 fixed compilation warnings in the AOF sanity check tool (antirez)
2010-05-12 Merge branch 'vm-speedup' (antirez)
2010-05-11 fix to return error when calling INCR on a non-string type (Pieter Noordhuis)
2010-05-11 load objects encoded from disk directly without useless conversion (antirez)
2010-05-11 fixed a problem leading to crashes, as keys can't be currently specially encoded, so we can't encode integers at object loading time... For now this can be fixed passing a few flags, or later can be fixed allowing encoded keys as well (antirez)
2010-05-11 long long to string conversion speedup applied in other places as well. Still the code has bugs, fixing right now... (antirez)
2010-05-11 hand written code to turn a long long into a string -> very big speed win (antirez)
2010-05-11 added specialized function to compare string objects for perfect match that is optimized for this task (antirez)
2010-05-11 better use of encoding inforamtion in dictEncObjKeyCompare (antirez)
2010-05-10 CONFIG now can change appendfsync policy at run time (antirez)
2010-05-10 CONFIG command now supports hot modification of RDB saving parameters. (antirez)
2010-05-10 while loading the rdb file don't add the key to the dictionary at all if it's already expired, instead of removing it just after the insertion. (antirez)
2010-05-10 Merge branch 'check-aof' of git://github.com/pietern/redis (antirez)
2010-05-08 minor changes to improve code readability (antirez)
2010-05-08 swap objects out directly while loading an RDB file if we detect we can't stay in the vm max memory limits anyway (antirez)
2010-05-07 change command names no longer used to zunion/zinter (Pieter Noordhuis)
2010-05-07 DEBUG POPULATE command for fast creation of test databases (antirez)
2010-05-07 update TODO (Pieter Noordhuis)
2010-05-07 swap arguments in blockClientOnSwappedKeys to be consistent (Pieter Noordhuis)
2010-05-07 added function that preloads all keys needed to execute a MULTI/EXEC block (Pieter Noordhuis)
2010-05-07 add sanity check to zunionInterBlockClientOnSwappedKeys, as the number of keys used is provided as argument to the function (Pieter Noordhuis)
2010-05-07 make prototype of custom function to preload keys from the vm match the prototype of waitForMultipleSwappedKeys (Pieter Noordhuis)
2010-05-07 extract preloading of multiple keys according to the command prototype to a separate function (Pieter Noordhuis)
2010-05-07 make append only filename configurable (Pieter Noordhuis)
2010-05-07 don't load value from VM for EXISTS (Pieter Noordhuis)
2010-05-07 swap file name pid expansion removed. Not suited for mission critical software... (antirez)
2010-05-07 Swap file is now locked (antirez)
2010-05-06 Merge branch 'master' into aof-speedup (antirez)
2010-05-06 log error and quit when the AOF contains an unfinished MULTI (antirez)
2010-05-06 log error and quit when the AOF contains an unfinished MULTI (Pieter Noordhuis)
2010-05-06 Merge branch 'master' into check-aof (Pieter Noordhuis)
2010-05-06 hincrby should report an error when called against a hash key that doesn't contain an integer (Pieter Noordhuis)
2010-05-06 AOF writes are now accumulated into a buffer and flushed into disk just before re-entering the event loop. A lot less writes but still this guarantees that AOF is written before the client gets a positive reply about a write operation, as no reply is trasnmitted before re-entering into the event loop. (antirez)
2010-05-06 clarified a few messages in redis.conf (antirez)
2010-05-05 ask for confirmation before AOF is truncated (Pieter Noordhuis)
2010-05-05 str can be free'd outside readString (Pieter Noordhuis)
2010-05-05 moved argument parsing around (Pieter Noordhuis)
2010-05-05 ignore redis-check-aof binary (Pieter Noordhuis)
2010-05-05 allow AOF to be fixed by truncating to the portion of the file that is valid (Pieter Noordhuis)
2010-05-05 tool to check if AOF is valid (Pieter Noordhuis)
2010-05-02 included fmacros.h in linenose.c to avoid compilation warnings on Linux (antirez)
2010-05-02 compilation fix for mac os x (antirez)
2010-05-02 Merge branch 'master' of git@github.com:antirez/redis (antirez)
2010-05-02 On Linux now fdatasync() is used insetad of fsync() in order to flush the AOF file kernel buffers (antirez)
2010-04-30 More tests for APPEND and tests for SUBSTR (antirez)
2010-04-30 linenoise.c updated, now redis-cli can be used in a pipe (antirez) 2010-04-30 linenoise.c updated, now redis-cli can be used in a pipe (antirez)
2010-04-29 redis-cli minor fix (less segfault is better) (antirez) 2010-04-29 redis-cli minor fix (less segfault is better) (antirez)
2010-04-29 New MONITOR output format with timestamp, every command in a single line, string representations (antirez) 2010-04-29 New MONITOR output format with timestamp, every command in a single line, string representations (antirez)
......
...@@ -2,6 +2,7 @@ ...@@ -2,6 +2,7 @@
# Copyright (C) 2009 Salvatore Sanfilippo <antirez at gmail dot com> # Copyright (C) 2009 Salvatore Sanfilippo <antirez at gmail dot com>
# This file is released under the BSD license, see the COPYING file # This file is released under the BSD license, see the COPYING file
release_hdr := $(shell sh -c './mkreleasehdr.sh')
uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not') uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
OPTIMIZATION?=-O2 OPTIMIZATION?=-O2
ifeq ($(uname_S),SunOS) ifeq ($(uname_S),SunOS)
......
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<b>AppendCommand: Contents</b><br>&nbsp;&nbsp;<a href="#APPEND _key_ _value_">APPEND _key_ _value_</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Examples">Examples</a>
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<h1 class="wikiname">AppendCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="StringCommandsSidebar.html">StringCommandsSidebar</a><h1><a name="APPEND _key_ _value_">APPEND _key_ _value_</a></h1>
<i>Time complexity: O(1). The amortized time complexity is O(1) assuming the appended value is small and the already present value is of any size, since the dynamic string library used by Redis will double the free space available on every reallocation.</i><blockquote>If the <i>key</i> already exists and is a string, this command appends theprovided value at the end of the string.If the <i>key</i> does not exist it is created and set as an empty string, soAPPEND will be very similar to SET in this special case.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically the total length of the string after the append operation.<h2><a name="Examples">Examples</a></h2><pre class="codeblock python" name="code">
redis&gt; exists mykey
(integer) 0
redis&gt; append mykey &quot;Hello &quot;
(integer) 6
redis&gt; append mykey &quot;World&quot;
(integer) 11
redis&gt; get mykey
&quot;Hello World&quot;
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<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. -->
<b>BlpopCommand: Contents</b><br>&nbsp;&nbsp;<a href="#BLPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;">BLPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;</a><br>&nbsp;&nbsp;<a href="#BRPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;">BRPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Non blocking behavior">Non blocking behavior</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Blocking behavior">Blocking behavior</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Multiple clients blocking for the same keys">Multiple clients blocking for the same keys</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">BlpopCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="ListCommandsSidebar.html">ListCommandsSidebar</a><h1><a name="BLPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;">BLPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;</a></h1> 1.3.1) =
<h1><a name="BRPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;">BRPOP _key1_ _key2_ ... _keyN_ _timeout_ (Redis &gt;</a></h1> 1.3.1) =
<i>Time complexity: O(1)</i><blockquote>BLPOP (and BRPOP) is a blocking list pop primitive. You can see this commandsas blocking versions of <a href="LpopCommand.html">LPOP</a> and <a href="LpopCommand.html">RPOP</a> able toblock if the specified keys don't exist or contain empty lists.</blockquote>
<blockquote>The following is a description of the exact semantic. We describe BLPOP butthe two commands are identical, the only difference is that BLPOP pops theelement from the left (head) of the list, and BRPOP pops from the right (tail).</blockquote>
<h2><a name="Non blocking behavior">Non blocking behavior</a></h2><blockquote>When BLPOP is called, if at least one of the specified keys contain a nonempty list, an element is popped from the head of the list and returned tothe caller together with the name of the key (BLPOP returns a two elementsarray, the first element is the key, the second the popped value).</blockquote>
<blockquote>Keys are scanned from left to right, so for instance if youissue <b>BLPOP list1 list2 list3 0</b> against a dataset where <b>list1</b> does notexist but <b>list2</b> and <b>list3</b> contain non empty lists, BLPOP guaranteesto return an element from the list stored at <b>list2</b> (since it is the firstnon empty list starting from the left).</blockquote>
<h2><a name="Blocking behavior">Blocking behavior</a></h2><blockquote>If none of the specified keys exist or contain non empty lists, BLPOPblocks until some other client performs a <a href="RpushCommand.html">LPUSH</a> oran <a href="RpushCommand.html">RPUSH</a> operation against one of the lists.</blockquote>
<blockquote>Once new data is present on one of the lists, the client finally returnswith the name of the key unblocking it and the popped value.</blockquote>
<blockquote>When blocking, if a non-zero timeout is specified, the client will unblockreturning a nil special value if the specified amount of seconds passedwithout a push operation against at least one of the specified keys.</blockquote>
<blockquote>A timeout of zero means instead to block forever.</blockquote>
<h2><a name="Multiple clients blocking for the same keys">Multiple clients blocking for the same keys</a></h2><blockquote>Multiple clients can block for the same key. They are put intoa queue, so the first to be served will be the one that started to waitearlier, in a first-blpopping first-served fashion.</blockquote>
<h2><a name="Return value">Return value</a></h2><blockquote>BLPOP returns a two-elements array via a multi bulk reply in order to returnboth the unblocking key and the popped value.</blockquote>
<blockquote>When a non-zero timeout is specified, and the BLPOP operation timed out,the return value is a nil multi bulk reply. Most client values will returnfalse or nil accordingly to the programming language used.</blockquote>
<a href="ReplyTypes.html">Multi bulk reply</a>
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...@@ -37,7 +37,7 @@ ...@@ -37,7 +37,7 @@
<h2><a name="Transactions">Transactions</a></h2><ul><li> <a href="MultiExecCommand.html">MULTI/EXEC/DISCARD</a> <code name="code" class="python">Redis atomic transactions</code></li></ul> <h2><a name="Transactions">Transactions</a></h2><ul><li> <a href="MultiExecCommand.html">MULTI/EXEC/DISCARD</a> <code name="code" class="python">Redis atomic transactions</code></li></ul>
<h2><a name="Publish/Subscribe">Publish/Subscribe</a></h2><ul><li> <a href="PublishSubscribe.html">SUBSCRIBE/UNSUBSCRIBE/PUBLISH</a> <code name="code" class="python">Redis Public/Subscribe messaging paradigm implementation</code></li></ul> <h2><a name="Publish/Subscribe">Publish/Subscribe</a></h2><ul><li> <a href="PublishSubscribe.html">SUBSCRIBE/UNSUBSCRIBE/PUBLISH</a> <code name="code" class="python">Redis Public/Subscribe messaging paradigm implementation</code></li></ul>
<h2><a name="Persistence control commands">Persistence control commands</a></h2><ul><li> <a href="SaveCommand.html">SAVE</a> <code name="code" class="python">Synchronously save the DB on disk</code></li><li> <a href="BgsaveCommand.html">BGSAVE</a> <code name="code" class="python">Asynchronously save the DB on disk</code></li><li> <a href="LastsaveCommand.html">LASTSAVE</a> <code name="code" class="python">Return the UNIX time stamp of the last successfully saving of the dataset on disk</code></li><li> <a href="ShutdownCommand.html">SHUTDOWN</a> <code name="code" class="python">Synchronously save the DB on disk, then shutdown the server</code></li><li> <a href="BgrewriteaofCommand.html">BGREWRITEAOF</a> <code name="code" class="python">Rewrite the append only file in background when it gets too big</code></li></ul> <h2><a name="Persistence control commands">Persistence control commands</a></h2><ul><li> <a href="SaveCommand.html">SAVE</a> <code name="code" class="python">Synchronously save the DB on disk</code></li><li> <a href="BgsaveCommand.html">BGSAVE</a> <code name="code" class="python">Asynchronously save the DB on disk</code></li><li> <a href="LastsaveCommand.html">LASTSAVE</a> <code name="code" class="python">Return the UNIX time stamp of the last successfully saving of the dataset on disk</code></li><li> <a href="ShutdownCommand.html">SHUTDOWN</a> <code name="code" class="python">Synchronously save the DB on disk, then shutdown the server</code></li><li> <a href="BgrewriteaofCommand.html">BGREWRITEAOF</a> <code name="code" class="python">Rewrite the append only file in background when it gets too big</code></li></ul>
<h2><a name="Remote server control commands">Remote server control commands</a></h2><ul><li> <a href="InfoCommand.html">INFO</a> <code name="code" class="python">Provide information and statistics about the server</code></li><li> <a href="MonitorCommand.html">MONITOR</a> <code name="code" class="python">Dump all the received requests in real time</code></li><li> <a href="SlaveofCommand.html">SLAVEOF</a> <code name="code" class="python">Change the replication settings</code></li></ul> <h2><a name="Remote server control commands">Remote server control commands</a></h2><ul><li> <a href="InfoCommand.html">INFO</a> <code name="code" class="python">Provide information and statistics about the server</code></li><li> <a href="MonitorCommand.html">MONITOR</a> <code name="code" class="python">Dump all the received requests in real time</code></li><li> <a href="SlaveofCommand.html">SLAVEOF</a> <code name="code" class="python">Change the replication settings</code></li><li> <a href="ConfigCommand.html">CONFIG</a> <code name="code" class="python">Configure a Redis server at runtime</code></li></ul>
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<b>ConfigCommand: Contents</b><br>&nbsp;&nbsp;<a href="#CONFIG GET _pattern_ (Redis &gt;">CONFIG GET _pattern_ (Redis &gt;</a><br>&nbsp;&nbsp;<a href="#CONFIG SET _parameter_ _value_ (Redis &gt;">CONFIG SET _parameter_ _value_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#CONFIG GET _pattern_">CONFIG GET _pattern_</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#CONFIG SET _parameter_ _value_">CONFIG SET _parameter_ _value_</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Parameters value format">Parameters value format</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#See Also">See Also</a>
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<h1 class="wikiname">ConfigCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="ControlCommandsSidebar.html">ControlCommandsSidebar</a><h1><a name="CONFIG GET _pattern_ (Redis &gt;">CONFIG GET _pattern_ (Redis &gt;</a></h1> 2.0)=
<h1><a name="CONFIG SET _parameter_ _value_ (Redis &gt;">CONFIG SET _parameter_ _value_ (Redis &gt;</a></h1> 2.0)=<br/><br/><blockquote>The CONFIG command is able to retrieve or alter the configuration of a runningRedis server. Not all the configuration parameters are supported.</blockquote>
<blockquote>CONFIG has two sub commands, GET and SET. The GET command is used to readthe configuration, while the SET command is used to alter the configuration.</blockquote>
<h2><a name="CONFIG GET _pattern_">CONFIG GET _pattern_</a></h2><blockquote>CONFIG GET returns the current configuration parameters. This sub commandonly accepts a single argument, that is glob style pattern. All theconfiguration parameters matching this parameter are reported as alist of key-value pairs. Example:</blockquote><pre class="codeblock python" name="code">
$ redis-cli config get '*'
1. &quot;dbfilename&quot;
2. &quot;dump.rdb&quot;
3. &quot;requirepass&quot;
4. (nil)
5. &quot;masterauth&quot;
6. (nil)
7. &quot;maxmemory&quot;
8. &quot;0\n&quot;
9. &quot;appendfsync&quot;
10. &quot;everysec&quot;
11. &quot;save&quot;
12. &quot;3600 1 300 100 60 10000&quot;
$ redis-cli config get 'm*'
1. &quot;masterauth&quot;
2. (nil)
3. &quot;maxmemory&quot;
4. &quot;0\n&quot;
</pre>The return type of the command is a <a href="ReplyTypes.html">bulk reply</a>.<h2><a name="CONFIG SET _parameter_ _value_">CONFIG SET _parameter_ _value_</a></h2><blockquote>CONFIG SET is used in order to reconfigure the server, setting a specificconfiguration parameter to a new value.</blockquote>
<blockquote>The list of configuration parameters supported by CONFIG SET can beobtained issuing a <code name="code" class="python">CONFIG GET *</code> command.</blockquote>
<blockquote>The configuration set using CONFIG SET is immediately loaded by the Redisserver that will start acting as specified starting from the next command.</blockquote>
<blockquote>Example:</blockquote><pre class="codeblock python python" name="code">
$ ./redis-cli
redis&gt; set x 10
OK
redis&gt; config set maxmemory 200
OK
redis&gt; set y 20
(error) ERR command not allowed when used memory &gt; 'maxmemory'
redis&gt; config set maxmemory 0
OK
redis&gt; set y 20
OK
</pre><h2><a name="Parameters value format">Parameters value format</a></h2><blockquote>The value of the configuration parameter is the same as the one of thesame parameter in the Redis configuration file, with the following exceptions:</blockquote>
<ul><li> The <code name="code" class="python">save</code> paramter is a list of space-separated integers. Every pair of integers specify the time and number of changes limit to trigger a save. For instance the command <code name="code" class="python">CONFIG SET save &quot;3600 10 60 10000&quot;</code> will configure the server to issue a background saving of the RDB file every 3600 seconds if there are at least 10 changes in the dataset, and every 60 seconds if there are at least 10000 changes. To completely disable automatic snapshots just set the parameter as an empty string.</li><li> All the integer parameters representing memory are returned and accepted only using bytes as unit.</li></ul>
<h2><a name="See Also">See Also</a></h2>The <a href="InfoCommand.html">INFO</a> command can be used in order to read configuriaton parameters that are not available in the CONFIG command.
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<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. -->
<b>EventLibray: Contents</b><br>&nbsp;&nbsp;<a href="#Event Library">Event Library</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Why is an Event Library needed at all?">Why is an Event Library needed at all?</a>
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<h1 class="wikiname">EventLibray</h1>
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<h1><a name="Event Library">Event Library</a></h1><h2><a name="Why is an Event Library needed at all?">Why is an Event Library needed at all?</a></h2>Let us figure it out through a series of Q&amp;As.<br/><br/>Q: What do you expect a network server to be doing all the time? &lt;br/&gt;
A: Watch for inbound connections on the port its listening and accept them.<br/><br/>Q: Calling <a href="http://man.cx/accept%282%29" target="_blank">accept</a> yields a descriptor. What do I do with it?&lt;br/&gt;
A: Save the descriptor and do a non-blocking read/write operation on it.<br/><br/>Q: Why does the read/write have to be non-blocking?&lt;br/&gt;
A: If the file operation ( even a socket in Unix is a file ) is blocking how could the server for example accept other connection requests when its blocked in a file I/O operation.<br/><br/>Q: I guess I have to do many such non-blocking operations on the socket to see when it's ready. Am I right?&lt;br/&gt;
A: Yes. That is what an event library does for you. Now you get it.<br/><br/>Q: How do Event Libraries do what they do?&lt;br/&gt;
A: They use the operating system's <a href="http://www.devshed.com/c/a/BrainDump/Linux-Files-and-the-Event-Poll-Interface/" target="_blank">polling</a> facility along with timers.<br/><br/>Q: So are there any open source event libraries that do what you just described? &lt;br/&gt;
A: Yes. Libevent and Libev are two such event libraries that I can recall off the top of my head.<br/><br/>Q: Does Redis use such open source event libraries for handling socket I/O?&lt;br/&gt;
A: No. For various <a href="http://groups.google.com/group/redis-db/browse_thread/thread/b52814e9ef15b8d0/" target="_blank">reasons</a> Redis uses its own event library.
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<b>HackingStrings: Contents</b><br>&nbsp;&nbsp;<a href="#Hacking Strings">Hacking Strings</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Creating Redis Strings">Creating Redis Strings</a>
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<h1 class="wikiname">HackingStrings</h1>
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<h1><a name="Hacking Strings">Hacking Strings</a></h1>The implementation of Redis strings is contained in <b></b>sds.c<b></b> ( sds stands for Simple Dynamic Strings ).<br/><br/>The C structure <i>sdshdr</i> declared in <b>sds.h</b> represents a Redis string:<br/><br/><pre class="codeblock python" name="code">
struct sdshdr {
long len;
long free;
char buf[];
};
</pre>The <i>buf</i> character array stores the actual string.<br/><br/>The <i>len</i> field stores the length of <i>buf</i>. This makes obtaining the length
of a Redis string an O(1) operation.<br/><br/>The <i>free</i> field stores the number of additional bytes available for use.<br/><br/>Together the <i>len</i> and <i>free</i> field can be thought of as holding the metadata of the
<i>buf</i> character array.<h2><a name="Creating Redis Strings">Creating Redis Strings</a></h2>A new data type named <code name="code" class="python">sds</code> is defined in <b>sds.h</b> to be a synonymn for a character pointer:<br/><br/><pre class="codeblock python python" name="code">
typedef char *sds;
</pre><code name="code" class="python">sdsnewlen</code> function defined in <b>sds.c</b> creates a new Redis String: <br/><br/><pre class="codeblock python python python" name="code">
sds sdsnewlen(const void *init, size_t initlen) {
struct sdshdr *sh;
sh = zmalloc(sizeof(struct sdshdr)+initlen+1);
#ifdef SDS_ABORT_ON_OOM
if (sh == NULL) sdsOomAbort();
#else
if (sh == NULL) return NULL;
#endif
sh-&gt;len = initlen;
sh-&gt;free = 0;
if (initlen) {
if (init) memcpy(sh-&gt;buf, init, initlen);
else memset(sh-&gt;buf,0,initlen);
}
sh-&gt;buf[initlen] = '\0';
return (char*)sh-&gt;buf;
}
</pre>Remember a Redis string is a variable of type <code name="code" class="python">struct sdshdr</code>. But <code name="code" class="python">sdsnewlen</code> returns a character pointer!!<br/><br/>That's a trick and needs some explanation.<br/><br/>Suppose I create a Redis string using <code name="code" class="python">sdsnewlen</code> like below:<br/><br/><pre class="codeblock python python python python" name="code">
sdsnewlen(&quot;redis&quot;, 5);
</pre>This creates a new variable of type <code name="code" class="python">struct sdshdr</code> allocating memory for <i>len</i> and <i>free</i>
fields as well as for the <i>buf</i> character array.<br/><br/><pre class="codeblock python python python python python" name="code">
sh = zmalloc(sizeof(struct sdshdr)+initlen+1); // initlen is length of init argument.
</pre>After <code name="code" class="python">sdsnewlen</code> succesfully creates a Redis string the result is something like:<br/><br/><pre class="codeblock python python python python python python" name="code">
-----------
|5|0|redis|
-----------
^ ^
sh sh-&gt;buf
</pre><code name="code" class="python">sdsnewlen</code> returns sh-&gt;buf to the caller.<br/><br/>What do you do if you need to free the Redis string pointed by <code name="code" class="python">sh</code>?<br/><br/>You want the pointer <code name="code" class="python">sh</code> but you only have the pointer <code name="code" class="python">sh-&gt;buf</code>.<br/><br/>Can you get the pointer <code name="code" class="python">sh</code> from <code name="code" class="python">sh-&gt;buf</code>?<br/><br/>Yes. Pointer arithmetic. Notice from the above ASCII art that if you subtract
the size of two longs from <code name="code" class="python">sh-&gt;buf</code> you get the pointer <code name="code" class="python">sh</code>. <br/><br/>The sizeof two longs happens to be the size of <code name="code" class="python">struct sdshdr</code>.<br/><br/>Look at <code name="code" class="python">sdslen</code> function and see this trick at work:<br/><br/><pre class="codeblock python python python python python python python" name="code">
size_t sdslen(const sds s) {
struct sdshdr *sh = (void*) (s-(sizeof(struct sdshdr)));
return sh-&gt;len;
}
</pre>Knowing this trick you could easily go through the rest of the functions in <b>sds.c</b>.<br/><br/>The Redis string implementation is hidden behind an interface that accepts only character pointers. The users of Redis strings need not care about how its implemented and treat Redis strings as a character pointer.
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&iuml;&raquo;&iquest;== Hash Commands ==<br/><br/><ul><li> <a href="HsetCommand.html">HSET</a></li><li> <a href="HgetCommand.html">HGET</a></li><li> <a href="HsetnxCommand.html">HSETNX</a></li><li> <a href="HmsetCommand.html">HMSET</a></li><li> <a href="HincrbyCommand.html">HINCRBY</a></li><li> <a href="HexistsCommand.html">HEXISTS</a></li><li> <a href="HdelCommand.html">HDEL</a></li><li> <a href="HlenCommand.html">HLEN</a></li><li> <a href="HgetallCommand.html">HKEYS</a></li><li> <a href="HgetallCommand.html">HVALS</a></li><li> <a href="HgetallCommand.html">HGETALL</a></li></ul>
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<b>Hashes: Contents</b><br>&nbsp;&nbsp;<a href="#Redis Hash Type">Redis Hash Type</a><br>&nbsp;&nbsp;<a href="#Implementation details">Implementation details</a>
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<h1 class="wikiname">Hashes</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="Redis Hash Type">Redis Hash Type</a></h1>Redis Hashes are unordered maps of <a href="String.html">Redis Strings</a> between fields and values. It is possible to add, remove, test for existence of fields in O(1) amortized time. It is also possible to enumerate all the keys, values, or both, in O(N) (where N is the number of fields inside the hash).<br/><br/>Redis Hashes are interesting because they are very well suited to represent objects. For instance web applications users can be represented by a Redis Hash containing fields such username, encrpypted_password, lastlogin, and so forth.<br/><br/>Another very important property of Redis Hashes is that they use very little memory for hashes composed of a small number of fields (configurable, check redis.conf for details), compared to storing every field as a top level Redis key. This is obtained using a different specialized representation for small hashes. See the implementation details paragraph below for more information.<br/><br/>Commands operating on hashes try to make a good use of the return value in order to signal the application about previous existence of fields. For instance the <a href="HsetCommand.html">HSET</a> command will return 1 if the field set was not already present in the hash, otherwise will return 0 (and the user knows this was just an update operation).<br/><br/>The max number of fields in a set is 232-1 (4294967295, more than 4 billion of members per hash).<h1><a name="Implementation details">Implementation details</a></h1>The obvious internal representation of hashes is indeed an hash table, as the name of the data structure itself suggests. Still the drawback of this representation is that there is a lot of space overhead for hash table metadata.<br/><br/>Because one of the most interesting uses of Hashes is object encoding, and objects are often composed of a few fields each, Redis uses a different internal representation for small hashes (for Redis to consider a hash small, this must be composed a limited number of fields, and each field and value can't exceed a given number of bytes. All this is user-configurable).<br/><br/>Small hashes are thus encoded using a data structure called zipmap (is not something you can find in a CS book, the name is a Redis invention), that is a very memory efficient data structure to represent string to string maps, at the cost of being O(N) instead of O(1) for most operations. Since the constant times of this data structure are very small, and the zipmaps are converted into real hash tables once they are big enough, the amortized time of Redis hashes is still O(1), and in the practice small zipmaps are not slower than small hash tables because they are designed for good cache locality and fast access.<br/><br/>The result is that small hashes are both memory efficient and fast, while bigger hashes are fast but not as memory efficient than small hashes.
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<b>HdelCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HDEL _key_ _field_ (Redis &gt;">HDEL _key_ _field_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HdelCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="HDEL _key_ _field_ (Redis &gt;">HDEL _key_ _field_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>Remove the specified <i>field</i> from an hash stored at <i>key</i>.</blockquote>
<blockquote>If the <i>field</i> was present in the hash it is returned and 1 is returned, otherwise 0 is returned and no operation is performed.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>
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<b>HexistsCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HEXISTS _key_ _field_ (Redis &gt;">HEXISTS _key_ _field_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HexistsCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="HEXISTS _key_ _field_ (Redis &gt;">HEXISTS _key_ _field_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>Return 1 if the hash stored at <i>key</i> contains the specified <i>field</i>.</blockquote>
<blockquote>Return 0 if the <i>key</i> is not found or the <i>field</i> is not present.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>
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<b>HgetCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HGET _key_ _field_ (Redis &gt;">HGET _key_ _field_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HgetCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="HGET _key_ _field_ (Redis &gt;">HGET _key_ _field_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>If <i>key</i> holds a hash, retrieve the value associated to the specified <i>field</i>.</blockquote>
<blockquote>If the <i>field</i> is not found or the <i>key</i> does not exist, a special 'nil' value is returned.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Bulk reply</a>
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<b>HgetallCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HKEYS _key_ (Redis &gt;">HKEYS _key_ (Redis &gt;</a><br>&nbsp;&nbsp;<a href="#HVALS _key_ (Redis &gt;">HVALS _key_ (Redis &gt;</a><br>&nbsp;&nbsp;<a href="#HGETALL _key_ (Redis &gt;">HGETALL _key_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HgetallCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="HKEYS _key_ (Redis &gt;">HKEYS _key_ (Redis &gt;</a></h1> 1.3.10)=
<h1><a name="HVALS _key_ (Redis &gt;">HVALS _key_ (Redis &gt;</a></h1> 1.3.10)=
<h1><a name="HGETALL _key_ (Redis &gt;">HGETALL _key_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(N), where N is the total number of entries</i><blockquote>HKEYS returns all the fields names contained into a hash, HVALS all the associated values, while HGETALL returns both the fields and values in the form of <i>field1</i>, <i>value1</i>, <i>field2</i>, <i>value2</i>, ..., <i>fieldN</i>, <i>valueN</i>.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Multi Bulk Reply</a>
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<b>HincrbyCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HINCRBY _key_ _field_ _value_ (Redis &gt;">HINCRBY _key_ _field_ _value_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Examples">Examples</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HincrbyCommand</h1>
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<h1><a name="HINCRBY _key_ _field_ _value_ (Redis &gt;">HINCRBY _key_ _field_ _value_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>Increment the number stored at <i>field</i> in the hash at <i>key</i> by <i>value</i>. If <i>key</i> does not exist, a new key holding a hash is created. If <i>field</i> does not exist or holds a string, the value is set to 0 before applying the operation.</blockquote>
<blockquote>The range of values supported by HINCRBY is limited to 64 bit signed integers.</blockquote><h2><a name="Examples">Examples</a></h2>
Since the <i>value</i> argument is signed you can use this command to perform both increments and decrements:<br/><br/><pre class="codeblock python" name="code">
HINCRBY key field 1 (increment by one)
HINCRBY key field -1 (decrement by one, just like the DECR command)
HINCRBY key field -10 (decrement by 10)
</pre>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a> The new value at <i>field</i> after the increment operation.
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<b>HlenCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HLEN _key_ (Redis &gt;">HLEN _key_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HlenCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="HLEN _key_ (Redis &gt;">HLEN _key_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>Return the number of entries (fields) contained in the hash stored at <i>key</i>. If the specified <i>key</i> does not exist, 0 is returned assuming an empty hash. </blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>
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<b>HmsetCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HMSET _key_ _field1_ _value1_ ... _fieldN_ _valueN_ (Redis &gt;">HMSET _key_ _field1_ _value1_ ... _fieldN_ _valueN_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HmsetCommand</h1>
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<h1><a name="HMSET _key_ _field1_ _value1_ ... _fieldN_ _valueN_ (Redis &gt;">HMSET _key_ _field1_ _value1_ ... _fieldN_ _valueN_ (Redis &gt;</a></h1> 1.3.10) =
<i>Time complexity: O(N) (with N being the number of fields)</i><blockquote>Set the respective fields to the respective values. HMSET replaces old values with new values.</blockquote>
<blockquote>If <i>key</i> does not exist, a new key holding a hash is created.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a> Always +OK because HMSET can't fail
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<b>HsetCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HSET _key_ _field_ _value_ (Redis &gt;">HSET _key_ _field_ _value_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HsetCommand</h1>
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&iuml;&raquo;&iquest;#sidebar <a href="HashCommandsSidebar.html">HashCommandsSidebar</a><h1><a name="HSET _key_ _field_ _value_ (Redis &gt;">HSET _key_ _field_ _value_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>Set the specified hash <i>field</i> to the specified <i>value</i>.</blockquote>
<blockquote>If <i>key</i> does not exist, a new key holding a hash is created.</blockquote>
<blockquote>If the field already exists, and the HSET just produced an update of thevalue, 0 is returned, otherwise if a new field is created 1 is returned.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>
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<b>HsetnxCommand: Contents</b><br>&nbsp;&nbsp;<a href="#HSETNX _key_ _field_ _value_ (Redis &gt;">HSETNX _key_ _field_ _value_ (Redis &gt;</a><br>&nbsp;&nbsp;&nbsp;&nbsp;<a href="#Return value">Return value</a>
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<h1 class="wikiname">HsetnxCommand</h1>
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<h1><a name="HSETNX _key_ _field_ _value_ (Redis &gt;">HSETNX _key_ _field_ _value_ (Redis &gt;</a></h1> 1.3.10)=
<i>Time complexity: O(1)</i><blockquote>Set the specified hash <i>field</i> to the specified <i>value</i>, if <i>field</i> does not exist yet.</blockquote>
<blockquote>If <i>key</i> does not exist, a new key holding a hash is created.</blockquote>
<blockquote>If the field already exists, this operation has no effect and returns 0.Otherwise, the field is set to <i>value</i> and the operation returns 1.</blockquote>
<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>
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