парсер спецификации хоста и атрибутов (host and attributes specification parser)
Имя (Name)
__pmParseHostAttrsSpec, __pmUnparseHostAttrsSpec,
__pmFreeHostAttrsSpec, __pmFreeAttrsSpec - host and attributes
specification parser
Синопсис C (C Synopsis)
#include "pmapi.h"
#include "libpcp.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
Предостережение (Caveat)
This documentation is intended for internal Performance Co-Pilot
(PCP) developer use.
These interfaces are not part of the PCP APIs that are guaranteed
to remain fixed across releases, and they may not work, or may
provide different semantics at some point in the future.
Описание (Description)
__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.
Возвращаемое значение (Return value)
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.
Смотри также (See also)
pmcd(1), pmproxy(1), pmchart(1), __pmParseHostSpec(3), PMAPI(3)
and pmNewContext(3).
