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NAME | C SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
PMPARSEHOSTATTRSSPEC(3) Library Functions Manual PMPARSEHOSTATTRSSPEC(3)
__pmParseHostAttrsSpec, __pmUnparseHostAttrsSpec, __pmFreeHostAt‐
trsSpec, __pmFreeAttrsSpec - host and attributes specification parser
#include <pcp/pmapi.h>
#include <pcp/impl.h>
int __pmParseHostAttrsSpec(const char *string, pmHostSpec **hostsp,
int *count, __pmHashCtl *attrs, char **errmsg);
int __pmUnparseHostAttrsSpec(pmHostSpec *hostsp, int *count,
__pmHashCtl *attrs, char *string, size_t size);
void __pmFreeHostAttrsSpec(pmHostSpec *hosts, int count,
__pmHashCtl *attrs);
void __pmFreeAttrsSpec(__pmHashCtl *attrs);
cc ... -lpcp
__pmParseHostAttrsSpec accepts a string specifying the location of a
PCP performance metric collector daemon, and any attributes that
should be associated with the connection to that daemon.
The syntax allows the optional specification of a protocol (native
PCP protocol, encrypted PCP protocol or unix domain socket protocol).
If the specified protocol is native PCP protocol, or encrypted PCP
protocol, an initial pmcd(1) hostname with optional port numbers and
optional proxy host, and optional attributes which are to be
associated with the connection may be specified. Some examples
follow:
pcp://nas1.servers.com:44321@firewalls.r.us?compress
pcps://nas1.servers.com?user=otto&pass=blotto&compress
If the specified protocol is a unix domain socket protocol, the path
to the socket in the local file system may be specified along with
optional attributes which are to be associated with the connection.
For example:
unix://$PCP_RUN_DIR/pmcd.socket:?compress
local://my/local/pmcd.socket:?user=otto&pass=blotto&compress
If the optional protocol component is not specified, then the default
setting will be used - which is the native PCP binary protocol.
However, this can still be overwritten via the environment as
described in PCPIntro(1). If the protocol prefix is specified, it
must be one of either "pcp://" (clear), "pcps://" (secure,
encrypted), "unix://" (authenticated local) or "local://" ("unix://"
then "pcp://").
The path specified for the "unix://" and "local://" protocols will
always be interpreted as an absolute path name. For example, the
following are all interpreted identically as
$PCP_RUN_DIR/pmcd.socket.
unix://$PCP_RUN_DIR/pmcd.socket
unix:/$PCP_RUN_DIR/pmcd.socket
unix:$PCP_RUN_DIR/pmcd.socket
Refer to __pmParseHostSpec(3) for further details of the host and
proxy host components.
If any optional connection attributes are to be specified, these are
separated from the hostname component via the '?' character. Each
attribute is separated by the '&' character, and each can be either a
simple attribute flag (such as "compress") or a name=value pair (such
as "username=fred").
__pmParseHostAttrsSpec takes a null-terminated host-and-attributes
specification string and returns an array of pmHostSpec structures,
where the array has count entries, and an attrs hash table containing
any attributes (including the optional protocol, if it was
specified).
Full details of the pmHostSpec structures are provided in
__pmParseHostSpec(3).
The __pmHashCtl structure that is filled out on return via
attributes, represents each individual attribute in the specification
string with any associated value. It should be considered an opaque
structure and should be zeroed beforehand.
The returned hash table control structure can be iterated using one
of the supplied iteration mechanisms - __pmHashWalkCB (a callback-
based mechanism) or __pmHashWalk (a simple procedural mechanism).
These provide access to the individual hash nodes, as __pmHashNode
entries, which provide access to decoded attributes and their
(optional) values.
typedef struct __pmHashNode {
__pmHashNode *next; /* next node in hash bucket (internal) */
unsigned int key; /* key identifying particular attribute */
void *data; /* attributes value (optional, string) */
} __pmHashNode;
There are a set number of valid attributes, however these may be
extended in future releases as new connection parameters become
needed. These can be identified via the PCP_ATTR_* macros in the PCP
header files.
__pmUnparseHostSpec performs the inverse operation, creating a string
representation from hosts and attributes structures. The size of the
supplied string buffer must be provided by the caller using the size
parameter.
If the given string is successfully parsed __pmParseHostAttrsSpec
returns zero. In this case the dynamic storage allocated by
__pmParseHostAttrsSpec can be released by calling
__pmFreeHostAttrsSpec using the addresses returned from
__pmParseHostAttrsSpec
Alternatively, the hosts and attributes memory can be freed
separately, using __pmFreeHostSpec(3) and __pmFreeAttrsSpec.
__pmParseHostAttrsSpec returns PM_ERR_GENERIC and a dynamically
allocated error message string in errmsg, if the given string does
not parse, and the user-supplied errmsg pointer is non-null. Be sure
to free(3) the error message string in this situation.
In the case of an error, both hosts and attributes are undefined. In
the case of success, errmsg is undefined.
On success __pmUnparseHostAttrsSpec returns a positive value
indicating the number of characters written into the supplied buffer.
However, if the supplied buffer was too small, a negative status code
of -E2BIG will be returned.
pmcd(1), pmproxy(1), pmchart(1), __pmParseHostSpec(3), PMAPI(3) and
pmNewContext(3).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at ⟨http://www.pcp.io/⟩.
If you have a bug report for this manual page, send it to
pcp@oss.sgi.com. This page was obtained from the project's upstream
Git repository ⟨git://git.pcp.io/pcp⟩ on 2017-07-05. If you discover
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you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
Performance Co-Pilot PCP PMPARSEHOSTATTRSSPEC(3)
Pages that refer to this page: pmparsehostspec(3)