http://www.runoob.com/memcached/memcached-cas.html
https://github.com/memcached/memcached/blob/master/doc/protocol.txt 很重要，解释了所有相关含义
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[root@cn-21 ~]# ps -ef|grep mem
systemd+ 3338 3319 0 2017 ? 01:13:09 memcachedroot 29927 29897 0 15:34 pts/1 00:00:00 grep --color=auto mem[root@cn-21 ~]# rpm -qa|grep memmemcached-1.4.15-10.el7_3.1.x86_64[root@cn-21 ~]# rpm -ql memcached/etc/sysconfig/memcached/usr/bin/memcached/usr/bin/memcached-tool/usr/lib/systemd/system/memcached.service/usr/share/doc/memcached-1.4.15/usr/share/doc/memcached-1.4.15/AUTHORS/usr/share/doc/memcached-1.4.15/CONTRIBUTORS/usr/share/doc/memcached-1.4.15/COPYING/usr/share/doc/memcached-1.4.15/ChangeLog/usr/share/doc/memcached-1.4.15/NEWS/usr/share/doc/memcached-1.4.15/README.md/usr/share/doc/memcached-1.4.15/protocol.txt/usr/share/doc/memcached-1.4.15/readme.txt/usr/share/doc/memcached-1.4.15/threads.txt/usr/share/man/man1/memcached-tool.1.gz/usr/share/man/man1/memcached.1.gz[root@cn-21 ~]# cat /etc/sysconfig/memcachedPORT="11211"USER="memcached"MAXCONN="1024"CACHESIZE="64"OPTIONS=""==============================
Memcached本身是使用C开发的，客户端可以是php、C#、或者java。
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命令汇总stats itemsstats sizesset runoob 0 900 9get runoobflush_all===============================[root@cn-21 ~]# telnet localhost 11211Trying ::1...Connected to localhost.Escape character is '^]'.stats itemsENDstats slabsSTAT 7:chunk_size 384STAT 7:chunks_per_page 2730STAT 7:total_pages 1STAT 7:total_chunks 2730STAT 7:used_chunks 0STAT 7:free_chunks 2730STAT 7:free_chunks_end 0STAT 7:mem_requested 0STAT 7:get_hits 72STAT 7:cmd_set 49STAT 7:delete_hits 18STAT 7:incr_hits 0STAT 7:decr_hits 0STAT 7:cas_hits 0STAT 7:cas_badval 0STAT 7:touch_hits 0STAT 9:chunk_size 600STAT 9:chunks_per_page 1747STAT 9:total_pages 1STAT 9:total_chunks 1747STAT 9:used_chunks 0STAT 9:free_chunks 1747STAT 9:free_chunks_end 0STAT 9:mem_requested 0STAT 9:get_hits 4STAT 9:cmd_set 2STAT 9:delete_hits 0STAT 9:incr_hits 0STAT 9:decr_hits 0STAT 9:cas_hits 0STAT 9:cas_badval 0STAT 9:touch_hits 0STAT 10:chunk_size 752STAT 10:chunks_per_page 1394STAT 10:total_pages 1STAT 10:total_chunks 1394STAT 10:used_chunks 0STAT 10:free_chunks 1394STAT 10:free_chunks_end 0STAT 10:mem_requested 0STAT 10:get_hits 82STAT 10:cmd_set 44STAT 10:delete_hits 0STAT 10:incr_hits 0STAT 10:decr_hits 0STAT 10:cas_hits 0STAT 10:cas_badval 0STAT 10:touch_hits 0STAT 11:chunk_size 944STAT 11:chunks_per_page 1110STAT 11:total_pages 1STAT 11:total_chunks 1110STAT 11:used_chunks 0STAT 11:free_chunks 1110STAT 11:free_chunks_end 0STAT 11:mem_requested 0STAT 11:get_hits 8STAT 11:cmd_set 2STAT 11:delete_hits 0STAT 11:incr_hits 0STAT 11:decr_hits 0STAT 11:cas_hits 0STAT 11:cas_badval 0STAT 11:touch_hits 0STAT active_slabs 4STAT total_malloced 4194304END=====================
stats settings
STAT maxbytes 67108864STAT maxconns 1024STAT tcpport 11211STAT udpport 11211STAT inter NULLSTAT verbosity 0STAT oldest 0STAT evictions onSTAT domain_socket NULLSTAT umask 700STAT growth_factor 1.25STAT chunk_size 48STAT num_threads 4STAT num_threads_per_udp 4STAT stat_key_prefix :STAT detail_enabled noSTAT reqs_per_event 20STAT cas_enabled yesSTAT tcp_backlog 1024STAT binding_protocol auto-negotiateSTAT auth_enabled_sasl noSTAT item_size_max 1048576END=====================
stats sizesSTAT sizes_status disabledset runoob 0 900 9memcachedSTOREDget runoobVALUE runoob 0 9memcachedENDflush_allOKget runoobEND======================
<command name> <key> <flags> <exptime> <bytes> [noreply]\r\n
cas <key> <flags> <exptime> <bytes> <cas unique> [noreply]\r\n按秒算，5是数据库的长度，即5字节，多于5和小于5都会报错set file 0 300 5iiiiiiCLIENT_ERROR bad data chunkERRORset file 0 300 5iiiiCLIENT_ERROR bad data chunkERRORset file 0 300 5iiiiiSTORED======================
[root@cn-21 ~]# memcached-tool localhost:11211 stats
#localhost:11211 Field Value accepting_conns 1 auth_cmds 0 auth_errors 0 bytes 0 bytes_read 139360283 bytes_written 232272906 cas_badval 0 cas_hits 0 cas_misses 0 cmd_flush 147 cmd_get 298 cmd_set 99 cmd_touch 0 conn_yields 0 connection_structures 52 crawler_items_checked 1 crawler_reclaimed 0 curr_connections 38 curr_items 0 decr_hits 0 decr_misses 0 delete_hits 18 delete_misses 0 direct_reclaims 0 evicted_active 0 evicted_unfetched 0 evictions 0 expired_unfetched 34 get_expired 0 get_flushed 0 get_hits 168 get_misses 130 hash_bytes 524288 hash_is_expanding 0 hash_power_level 16 incr_hits 0 incr_misses 0 libevent 2.0.21-stable limit_maxbytes 67108864 listen_disabled_num 0 log_watcher_sent 0 log_watcher_skipped 0 log_worker_dropped 0 log_worker_written 0 lru_bumps_dropped 0 lru_crawler_running 0 lru_crawler_starts 203490 lru_maintainer_juggles 12327347 lrutail_reflocked 22 malloc_fails 0 max_connections 1024 moves_to_cold 112 moves_to_warm 27 moves_within_lru 0 pid 1 pointer_size 64 reclaimed 41 rejected_connections 0 reserved_fds 20 rusage_system 3602.709727 rusage_user 795.646915 slab_global_page_pool 0slab_reassign_busy_deletes 0slab_reassign_busy_items 0slab_reassign_chunk_rescues 0slab_reassign_evictions_nomem 0slab_reassign_inline_reclaim 0 slab_reassign_rescues 0 slab_reassign_running 0 slabs_moved 0 threads 4 time 1515488925time_in_listen_disabled_us 0 total_connections 177 total_items 98 touch_hits 0 touch_misses 0 uptime 2770390 version 1.5.3