1DC_SERVER(1) distcache DC_SERVER(1)
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6 dc_server - Distributed session cache server
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9 dc_server -listen <address> [options]
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12 dc_server runs a cache server and starts listening on a configurable
13 network address for connections. Incoming connections are expected to
14 communicate using the distcache(8) protocol, and would typically be
15 instances of dc_client(1) running on other machines.
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18 -daemon
19 After initialising, dc_server will detach from the parent process,
20 close standard file-descriptors, etc. If this flag is not set,
21 dc_server will run in the foreground. It is recommended to use this
22 flag in combination with the pidfile flag to simplify stopping and
23 restarting services.
24 -user user
26 This switch will attempt to change user privileges of dc_server to
27 the given user ID after initialising its listening socket. On most
28 systems, this can only work if dc_server is started as the root
29 user. It is important to note that the change of user ID occurs
30 after the listening socket is create. This ensures that the listen‐
31 ing socket is created with the most restrictive permissions, and
32 that the ability to connect to servers at run-time corresponds to
33 the given user (rather than having unusual root permissions on
34 startup).
35 -listen address
37 Configures the address on which dc_server should listen for incom‐
38 ing connections. The syntax is that defined by the libnal API.
39 Some examples follow;
40 # Listen on port 9001 for all TCP/IPv4 interfaces
42 dc_server -listen IP:9001
43 # Listen on port 9001 on a specific TCP/IPv4 interface
45 dc_server -listen IP:192.168.0.1:9001
46 dc_server -listen IP:cacheserver.localnet:9001
47 # Listen on a unix domain socket in the /tmp directory
49 dc_server -listen UNIX:/tmp/cacheserver
50 -sockowner user
52 This switch is only useful when listening (see -listen) on unix
53 domain sockets. It will attempt to change ownership of the created
54 socket file.
55 -sockgroup group
57 This switch is only useful when listening (see -listen) on unix
58 domain sockets. It will attempt to change group ownership of the
59 created socket file.
60 -sockperms perms
62 This switch is only useful when listening (see -listen) on unix
63 domain sockets. It will attempt to change file permissions for the
64 created socket file, and is specified in the standard octal nota‐
65 tion used for unix file permissions. Eg. to start dc_server to run
66 as the nobody user, listening on a unix domain socket that can only
67 be connected to by the root user or members of the dcclient group;
68 # dc_server -listen UNIX:/tmp/cacheserver -user nobody \
70 -sockgroup dcclient -sockperms 440
71 -sessions num
73 Specifies a maximum number of sessions that should be stored in the
74 cache. All sessions in a cache have an expiry time so that they
75 will, if they have not been forcibly removed before that time, be
76 expired out of the cache. If it is desirable to allow long session
77 timeouts under normal situations yet protect against the session
78 cache growing without limit periods of high-load, this limit can
79 provide the required balance. If the session cache reaches this
80 limit, it will automatically rotate out those sessions in the cache
81 that are due to expire soonest. It is not (yet) possible to have no
82 limit at all, though a future version should support this by allow‐
83 ing the user to specify zero.
84 The default value for this flag is 512.
86 -progress num
88 dc_server will, by default, log a line of output to stdout whenever
89 there is cache activity, but will make sure to do so no more often
90 than once a second. If -progress is specified, this will take
91 precedence so that output will be emitted whenever num operations
92 have occurred since the last output, irrespective of how little
93 time has elapsed. The once-a-second logic remains behind this, so
94 that if less than num operations has taken place but at least one
95 second has passed, output will still be logged. This flag has no
96 effect if -daemon is used.
97 -pidfile path
99 This is a standard flag for many programs, and most useful in com‐
100 bination with -daemon. When -pidfile is specified dc_server will
101 write its process ID to a file at the specified path upon success‐
102 ful initialisation. To use this path file to later kill the running
103 dc_server instance, use something like (where pidfile.pid is what‐
104 ever path was);
105 kill `cat pidfile.pid`
107 -killable
109 The default behaviour of dc_server is to silently ignore SIGUSR1
110 and SIGUSR2 signals, but with this switch enabled it will handle
111 these signals and close down cleanly (mainly useful for developers
112 as an alternative to SIGKILL which is less useful for debugging
113 memory leaks).
114 -h, -help, -?
116 Any of these flags will cause dc_server to display a brief usage
117 summary to the console and exit cleanly. Any other flags are
118 ignored.
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121 dc_client(1)
122 Distributed caching client proxy.
123 dc_snoop(1)
125 Distcache protocol analyser and debugging tool.
126 distcache(8)
128 Overview of the distcache architecture.
129 http://www.distcache.org/
131 Distcache home page.
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134 This toolkit was designed and implemented by Geoff Thorpe for Crypto‐
135 graphic Appliances Incorporated. Since the project was released into
136 open source, it has a home page and a project environment where devel‐
137 opment, mailing lists, and releases are organised. For problems with
138 the software or this man page please check for new releases at the
139 project web-site below, mail the users mailing list described there, or
140 contact the author at geoff@geoffthorpe.net.
141 Home Page: http://www.distcache.org
1431.4.5 2004.03.23 DC_SERVER(1)