1PMPARSEHOSTATTRSSPEC(3) Library Functions Manual PMPARSEHOSTATTRSSPEC(3)
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6 __pmParseHostAttrsSpec, __pmUnparseHostAttrsSpec, __pmFreeHostAt‐
7 trsSpec, __pmFreeAttrsSpec - host and attributes specification parser
8
10 #include <pcp/pmapi.h>
11 #include <pcp/impl.h>
12 int __pmParseHostAttrsSpec(const char *string, pmHostSpec **hostsp,
14 int *count, __pmHashCtl *attrs, char **errmsg);
15 int __pmUnparseHostAttrsSpec(pmHostSpec *hostsp, int *count,
16 __pmHashCtl *attrs, char *string, size_t size);
17 void __pmFreeHostAttrsSpec(pmHostSpec *hosts, int count,
18 __pmHashCtl *attrs);
19 void __pmFreeAttrsSpec(__pmHashCtl *attrs);
20 cc ... -lpcp
22
24 __pmParseHostAttrsSpec accepts a string specifying the location of a
25 PCP performance metric collector daemon, and any attributes that should
26 be associated with the connection to that daemon.
27 The syntax allows the optional specification of a protocol (native PCP
29 protocol, encrypted PCP protocol or unix domain socket protocol).
30 If the specified protocol is native PCP protocol, or encrypted PCP pro‐
32 tocol, an initial pmcd(1) hostname with optional port numbers and op‐
33 tional proxy host, and optional attributes which are to be associated
34 with the connection may be specified. Some examples follow:
35 pcp://nas1.servers.com:44321@firewalls.r.us?compress
37 pcps://nas1.servers.com?user=otto&pass=blotto&compress
38 If the specified protocol is a unix domain socket protocol, the path to
40 the socket in the local file system may be specified along with option‐
41 al attributes which are to be associated with the connection. For ex‐
42 ample:
43 unix://$PCP_RUN_DIR/pmcd.socket:?compress
45 local://my/local/pmcd.socket:?user=otto&pass=blotto&compress
46 If the optional protocol component is not specified, then the default
48 setting will be used - which is the native PCP binary protocol. Howev‐
49 er, this can still be overwritten via the environment as described in
50 PCPIntro(1). If the protocol prefix is specified, it must be one of
51 either "pcp://" (clear), "pcps://" (secure, encrypted), "unix://" (au‐
52 thenticated local) or "local://" ("unix://" then "pcp://").
53 The path specified for the "unix://" and "local://" protocols will al‐
55 ways be interpreted as an absolute path name. For example, the follow‐
56 ing are all interpreted identically as $PCP_RUN_DIR/pmcd.socket.
57 unix://$PCP_RUN_DIR/pmcd.socket
59 unix:/$PCP_RUN_DIR/pmcd.socket
60 unix:$PCP_RUN_DIR/pmcd.socket
61 Refer to __pmParseHostSpec(3) for further details of the host and proxy
63 host components.
64 If any optional connection attributes are to be specified, these are
66 separated from the hostname component via the '?' character. Each at‐
67 tribute is separated by the '&' character, and each can be either a
68 simple attribute flag (such as "compress") or a name=value pair (such
69 as "username=fred").
70 __pmParseHostAttrsSpec takes a null-terminated host-and-attributes
72 specification string and returns an array of pmHostSpec structures,
73 where the array has count entries, and an attrs hash table containing
74 any attributes (including the optional protocol, if it was specified).
75 Full details of the pmHostSpec structures are provided in __pmParse‐
77 HostSpec(3).
78 The __pmHashCtl structure that is filled out on return via attributes,
80 represents each individual attribute in the specification string with
81 any associated value. It should be considered an opaque structure and
82 should be zeroed beforehand.
83 The returned hash table control structure can be iterated using one of
85 the supplied iteration mechanisms - __pmHashWalkCB (a callback-based
86 mechanism) or __pmHashWalk (a simple procedural mechanism). These pro‐
87 vide access to the individual hash nodes, as __pmHashNode entries,
88 which provide access to decoded attributes and their (optional) values.
89 typedef struct __pmHashNode {
91 __pmHashNode *next; /* next node in hash bucket (internal) */
92 unsigned int key; /* key identifying particular attribute */
93 void *data; /* attributes value (optional, string) */
94 } __pmHashNode;
95 There are a set number of valid attributes, however these may be ex‐
97 tended in future releases as new connection parameters become needed.
98 These can be identified via the PCP_ATTR_* macros in the PCP header
99 files.
100 __pmUnparseHostSpec performs the inverse operation, creating a string
102 representation from hosts and attributes structures. The size of the
103 supplied string buffer must be provided by the caller using the size
104 parameter.
105
107 If the given string is successfully parsed __pmParseHostAttrsSpec re‐
108 turns zero. In this case the dynamic storage allocated by __pmParse‐
109 HostAttrsSpec can be released by calling __pmFreeHostAttrsSpec using
110 the addresses returned from __pmParseHostAttrsSpec
111 Alternatively, the hosts and attributes memory can be freed separately,
113 using __pmFreeHostSpec(3) and __pmFreeAttrsSpec.
114 __pmParseHostAttrsSpec returns PM_ERR_GENERIC and a dynamically allo‐
116 cated error message string in errmsg, if the given string does not
117 parse, and the user-supplied errmsg pointer is non-null. Be sure to
118 free(3) the error message string in this situation.
119 In the case of an error, both hosts and attributes are undefined. In
121 the case of success, errmsg is undefined.
122 On success __pmUnparseHostAttrsSpec returns a positive value indicating
124 the number of characters written into the supplied buffer. However, if
125 the supplied buffer was too small, a negative status code of -E2BIG
126 will be returned.
127
129 pmcd(1), pmproxy(1), pmchart(1), __pmParseHostSpec(3), PMAPI(3) and pm‐
130 NewContext(3).
131Performance Co-Pilot PCP PMPARSEHOSTATTRSSPEC(3)