1MMV_STATS_INIT(3)          Library Functions Manual          MMV_STATS_INIT(3)
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NAME

6       mmv_stats_init - create and initialize Memory Mapped Value file
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C SYNOPSIS

9       #include <pcp/pmapi.h> #include <pcp/mmv_stats.h>
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11       void * mmv_stats_init(const char *name,
12                      int cluster, mmv_stats_flags_t flags,
13                      const mmv_metric_t *stats, int nstats,
14                      mmv_indom_t *indoms, int nindoms);
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16       cc ... -lpcp_mmv -lpcp
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DESCRIPTION

19       mmv_stats_init creates and initializes the content of the MMV(4) file.
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21       The file is created in the $PCP_TMP_DIR/mmv directory, name argument is
22       expected to be just a name of the file, not the full path.   The  meta‐
23       data  content  of the file does not change after the file has been cre‐
24       ated.
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26       The old file is removed unconditionally unless there was an error.
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28       cluster is the preferred MMV PMDA cluster ID to be used for the metrics
29       originating  from this call to mmv_stats_init.  The flags provide addi‐
30       tional control over the behaviour  of  the  MMV  PMDA  -  e.g.  use  of
31       MMV_FLAG_PROCESS  will ensure values are only exported when the instru‐
32       mented application is running - this is verified on  each  request  for
33       new values.
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35       stats is the array of mmv_metric_t elements of length nstats. Each ele‐
36       ment of the array describes one PCP metric.
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38               typedef struct {
39                   char name[MMV_NAMEMAX];     /* Name of the metric */
40                   __uint32_t item;            /* Item component of PMID */
41                   mmv_metric_type_t type;     /* Type of the metric */
42                   mmv_metric_sem_t semantics; /* Semantics of the metric */
43                   pmUnits dimension;          /* Dimensions (TIME,SPACE,etc) */
44                   __uint32_t indom;           /* Instance domain identifier */
45                   char *shorttext;            /* Optional, one-line help */
46                   char *helptext;             /* Optional, full help text */
47               } mmv_metric_t;
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49       If indom is not zero and not PM_INDOM_NULL, then the metric has  multi‐
50       ple  values  and there must be a corresponding indom entry in the indom
51       list (uniquely identified by serial number).
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53       The stats array cannot contain any elements which have no name  -  this
54       is considered an error and no metrics will be exported in this case.
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56       indoms  is  the  array  of mmv_indom_t elements of length nindoms. Each
57       element of the array describes one PCP instance domain.
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59               typedef struct {
60                   __int32_t internal;
61                   char external[MMV_NAMEMAX];
62               } mmv_instances_t;
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64               typedef struct {
65                   __uint32_t serial;          /* Unique serial number */
66                   __uint32_t count;           /* Number of instances */
67                   mmv_instances_t *instances; /* Internal/external IDs */
68                   char *shorttext;            /* Short help text */
69                   char *helptext;             /* Long help text */
70               } mmv_indom_t;
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RETURNS

73       The function returns the address of the memory mapped region on success
74       or NULL on failure.
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SEE ALSO

77       mmv_inc_value(3), mmv_lookup_value_desc(3) and mmv(4).
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81Performance Co-Pilot                                         MMV_STATS_INIT(3)
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