1PMPARSEHOSTSPEC(3) Library Functions Manual PMPARSEHOSTSPEC(3)
2
6 __pmParseHostSpec, __pmUnparseHostSpec, __pmFreeHostSpec - uniform host
7 specification parser
8
10 #include "pmapi.h"
11 #include "libpcp.h"
12 int __pmParseHostSpec(const char *string, pmHostSpec **hostsp,
14 int *count, char **errmsg);
15 int __pmUnparseHostSpec(pmHostSpec *hosts, int count, char *string,
16 size_t size);
17 void __pmFreeHostSpec(pmHostSpec *hosts, int count);
18 cc ... -lpcp
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22 This documentation is intended for internal Performance Co-Pilot (PCP)
23 developer use.
24 These interfaces are not part of the PCP APIs that are guaranteed to
26 remain fixed across releases, and they may not work, or may provide
27 different semantics at some point in the future.
28
30 __pmParseHostSpec accepts a string specifying the location of a PCP
31 performance metric collector daemon. The syntax of the various formats
32 of this string is described in PCPIntro(1) where several examples are
33 also presented.
34 The syntax allows the initial pmcd(1) hostname to be optionally fol‐
36 lowed by a list of port numbers, which will be tried in order when con‐
37 necting to pmcd on that host. The portlist is separated from the host‐
38 name using a colon, and each port in the list is comma-separated.
39 In addition, one or more optional pmproxy(1) hosts can be specified
41 (currently, only one proxy host is supported by the PCP protocols).
42 These are separated from each other and from the pmcd component using
43 the @ character. These may also be followed by an optional port list,
44 using the same comma-separated syntax as before.
45 __pmParseHostSpec takes a null-terminated host specification string and
47 returns an array of pmHostSpec structures, where the array has count
48 entries.
49 These pmHostSpec structures that are returned via hostsp represent each
51 individual host in the specification string and has the following dec‐
52 laration:
53 typedef struct {
55 char *name; /* hostname (always valid) */
56 int *ports; /* array of host port numbers */
57 int nports; /* number of ports in host port array */
58 } pmHostSpec;
59 __pmUnparseHostSpec performs the inverse operation, creating a string
61 representation from a number of hosts structures. Where the count of
62 structures indicated by hosts is greater than one, the proxy syntax is
63 used to indicate a chain of proxied hosts. The size of the supplied
64 string buffer must be provided by the caller using the size parameter.
65
67 If the given string is successfully parsed __pmParseHostSpec returns
68 zero. In this case the dynamic storage allocated by __pmParseHostSpec
69 can be released by calling __pmFreeHostSpec using the address returned
70 from __pmParseHostSpec via hosts.
71 __pmParseHostSpec returns PM_ERR_GENERIC and a dynamically allocated
73 error message string in errmsg, if the given string does not parse, and
74 the user-supplied errmsg pointer is non-null. Be sure to free(3) the
75 error message string in this situation.
76 In the case of an error, hosts is undefined. In the case of success,
78 errmsg is undefined.
79 On success __pmUnparseHostSpec returns a positive value indicating the
81 number of characters written into the supplied buffer. However, if the
82 supplied buffer was too small, a negative status code of -E2BIG is re‐
83 turned.
84
86 pmcd(1), pmproxy(1), pmchart(1), __pmParseHostAttrsSpec(3), PMAPI(3)
87 and pmNewContext(3).
88Performance Co-Pilot PCP PMPARSEHOSTSPEC(3)