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327 lines
10 KiB
327 lines
10 KiB
commit c226e98096c7bdb6296a96257439724e1f68217e
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Author: Nathan Scott <nathans@redhat.com>
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Date: Tue Apr 26 12:00:32 2022 +1000
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libpcp: optimize indom handling in fetchgroup code
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Looking into some pcp-ss issues I immediately encountered a
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noticable elapsed time difference between executing just ss
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versus pcp-ss. It turned out it was due to fetchgroup code
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not really understanding how the underlying indom APIs work
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and repeatedly refreshing shared indoms (all metrics in the
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pcp-ss tool actually share one indom) once for every metric
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that happens to use that indom - i.e. many times per fetch.
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These changes resulted in a 5x speedup in pcp-ss and it now
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completes instantly as expected. Additionally, we use alot
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less memory now for the many-metrics-sharing-an-indom case.
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diff -Naurp pcp-5.3.7.patched/src/libpcp/src/fetchgroup.c pcp-5.3.7/src/libpcp/src/fetchgroup.c
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--- pcp-5.3.7.patched/src/libpcp/src/fetchgroup.c 2022-04-05 09:05:43.000000000 +1000
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+++ pcp-5.3.7/src/libpcp/src/fetchgroup.c 2023-03-08 18:46:43.486916630 +1100
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@@ -34,6 +34,19 @@
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/* ------------------------------------------------------------------------ */
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/*
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+ * Cache to avoid unnecessary repeated calls to pmGetInDom for individual
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+ * instance domains. This involves a round trip to pmcd and it does not
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+ * change frequently (certainly not for processing results of one sample).
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+ */
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+struct __pmInDomCache {
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+ pmInDom indom;
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+ int *codes; /* saved from pmGetInDom */
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+ char **names;
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+ unsigned int size;
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+ int refreshed;
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+};
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+
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+/*
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* An individual fetch-group is a linked list of requests tied to a
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* particular pcp context (which the fetchgroup owns). NB: This is
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* opaque to the PMAPI client.
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@@ -43,8 +56,10 @@ struct __pmFetchGroup {
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int wrap; /* wrap-handling flag, set at fg-create-time */
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pmResult *prevResult;
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struct __pmFetchGroupItem *items;
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+ struct __pmInDomCache *unique_indoms;
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pmID *unique_pmids;
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size_t num_unique_pmids;
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+ size_t num_unique_indoms;
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};
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/*
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@@ -81,9 +96,6 @@ struct __pmFetchGroupItem {
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struct {
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pmID metric_pmid;
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pmDesc metric_desc;
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- int *indom_codes; /* saved from pmGetInDom */
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- char **indom_names;
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- unsigned indom_size;
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struct __pmFetchGroupConversionSpec conv;
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int *output_inst_codes; /* NB: may be NULL */
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char **output_inst_names; /* NB: may be NULL */
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@@ -168,9 +180,7 @@ pmfg_add_pmid(pmFG pmfg, pmID pmid)
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/*
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* Populate given pmFGI item structure based on common lookup &
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* verification for pmfg inputs. Adjust instance profile to
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- * include requested instance. If it's a derived metric, we
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- * don't know what instance domain(s) it could involve, so we
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- * clear the instance profile entirely.
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+ * include requested instance.
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*/
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static int
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pmfg_lookup_item(const char *metric, const char *instance, pmFGI item)
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@@ -206,9 +216,12 @@ pmfg_lookup_item(const char *metric, con
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/* Same for a whole indom. Add the whole instance profile. */
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static int
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-pmfg_lookup_indom(const char *metric, pmFGI item)
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+pmfg_lookup_indom(pmFG pmfg, const char *metric, pmFGI item)
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{
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- int sts;
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+ struct __pmInDomCache *indoms;
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+ pmInDom indom;
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+ size_t size;
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+ int i, sts;
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assert(item != NULL);
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assert(item->type == pmfg_indom);
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@@ -221,14 +234,34 @@ pmfg_lookup_indom(const char *metric, pm
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return sts;
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/* As a convenience to users, we also accept non-indom'd metrics */
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- if (item->u.indom.metric_desc.indom == PM_INDOM_NULL)
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+ if ((indom = item->u.indom.metric_desc.indom) == PM_INDOM_NULL)
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return 0;
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/*
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+ * Insert into the instance domain cache if not seen previously
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+ */
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+ for (i = 0; i < pmfg->num_unique_indoms; i++) {
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+ if (pmfg->unique_indoms[i].indom == indom)
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+ return 0;
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+ }
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+
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+ size = sizeof(struct __pmInDomCache) * (pmfg->num_unique_indoms + 1);
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+ indoms = realloc(pmfg->unique_indoms, size);
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+
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+ if (indoms == NULL)
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+ return -ENOMEM;
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+ pmfg->unique_indoms = indoms;
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+ pmfg->unique_indoms[pmfg->num_unique_indoms].indom = indom;
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+ pmfg->unique_indoms[pmfg->num_unique_indoms].codes = NULL;
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+ pmfg->unique_indoms[pmfg->num_unique_indoms].names = NULL;
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+ pmfg->unique_indoms[pmfg->num_unique_indoms].refreshed = 0;
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+ pmfg->num_unique_indoms++;
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+
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+ /*
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* Add all instances; this will override any other past or future
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* piecemeal instance requests from __pmExtendFetchGroup_lookup.
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*/
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- return pmAddProfile(item->u.indom.metric_desc.indom, 0, NULL);
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+ return pmAddProfile(indom, 0, NULL);
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}
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/* Same for an event field. */
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@@ -581,7 +614,7 @@ pmfg_reinit_indom(pmFGI item)
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if (item->u.indom.output_inst_names)
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for (i = 0; i < item->u.indom.output_maxnum; i++)
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- item->u.indom.output_inst_names[i] = NULL; /* break ref into indom_names[] */
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+ item->u.indom.output_inst_names[i] = NULL; /* ptr into names[] */
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if (item->u.indom.output_stss)
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for (i = 0; i < item->u.indom.output_maxnum; i++)
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@@ -857,11 +890,11 @@ pmfg_fetch_timestamp(pmFG pmfg, pmFGI it
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static void
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pmfg_fetch_indom(pmFG pmfg, pmFGI item, pmResult *newResult)
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{
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- int sts = 0;
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- int i;
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- unsigned j;
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- int need_indom_refresh;
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+ int i, sts = 0;
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+ unsigned int j, k;
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+ struct __pmInDomCache *cache;
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const pmValueSet *iv;
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+ pmInDom indom;
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assert(item != NULL);
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assert(item->type == pmfg_indom);
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@@ -901,36 +934,43 @@ pmfg_fetch_indom(pmFG pmfg, pmFGI item,
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/*
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* Analyze newResult to see whether it only contains instances we
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- * already know. This is unfortunately an O(N**2) operation. It
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- * could be made a bit faster if we build a pmGetInDom()- variant
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- * that provides instances in sorted order.
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+ * already know.
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*/
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- need_indom_refresh = 0;
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- if (item->u.indom.output_inst_names) { /* Caller interested at all? */
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- for (j = 0; j < (unsigned)iv->numval; j++) {
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- unsigned k;
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- for (k = 0; k < item->u.indom.indom_size; k++)
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- if (item->u.indom.indom_codes[k] == iv->vlist[j].inst)
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+ cache = NULL;
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+ indom = item->u.indom.metric_desc.indom;
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+ for (j = 0; j < pmfg->num_unique_indoms; j++) {
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+ if (indom != pmfg->unique_indoms[j].indom)
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+ continue;
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+ cache = &pmfg->unique_indoms[j];
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+ break;
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+ }
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+ if (cache && cache->refreshed &&
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+ item->u.indom.output_inst_names) { /* Caller interested at all? */
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+ for (j = 0; j < (unsigned int)iv->numval; j++) {
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+ for (k = 0; k < cache->size; k++)
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+ if (cache->codes[k] == iv->vlist[j].inst)
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break;
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- if (k >= item->u.indom.indom_size) {
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- need_indom_refresh = 1;
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+ if (k >= cache->size) {
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+ cache->refreshed = 0;
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break;
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}
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}
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}
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- if (need_indom_refresh) {
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- free(item->u.indom.indom_codes);
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- free(item->u.indom.indom_names);
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- sts = pmGetInDom(item->u.indom.metric_desc.indom,
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- &item->u.indom.indom_codes, &item->u.indom.indom_names);
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+ if (cache && !cache->refreshed) {
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+ cache->refreshed = 1;
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+ free(cache->codes);
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+ free(cache->names);
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+ sts = pmGetInDom(indom, &cache->codes, &cache->names);
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if (sts < 1) {
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/* Need to manually clear; pmGetInDom claims they are undefined. */
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- item->u.indom.indom_codes = NULL;
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- item->u.indom.indom_names = NULL;
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- item->u.indom.indom_size = 0;
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+ cache->codes = NULL;
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+ cache->names = NULL;
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+ cache->size = 0;
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}
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else {
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- item->u.indom.indom_size = sts;
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+ if (sts < 0)
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+ cache->refreshed = 0;
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+ cache->size = sts;
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}
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/*
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* NB: Even if the pmGetInDom failed, we can proceed with
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@@ -965,18 +1005,19 @@ pmfg_fetch_indom(pmFG pmfg, pmFGI item,
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* results from pmGetIndom.
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*/
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if (item->u.indom.output_inst_names) {
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- unsigned k;
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-
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- for (k = 0; k < item->u.indom.indom_size; k++) {
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- if (item->u.indom.indom_codes[k] == jv->inst) {
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- /*
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- * NB: copy the indom name char* by value.
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- * The user is not supposed to modify / free this pointer,
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- * or use it after a subsequent fetch or delete operation.
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- */
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- item->u.indom.output_inst_names[j] =
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- item->u.indom.indom_names[k];
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- break;
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+ if (cache == NULL)
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+ item->u.indom.output_inst_names[j] = NULL;
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+ else {
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+ for (k = 0; k < cache->size; k++) {
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+ if (cache->codes[k] == jv->inst) {
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+ /*
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+ * NB: copy the indom name char* by value.
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+ * User may not modify / free this pointer,
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+ * nor use it after subsequent fetch / delete.
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+ */
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+ item->u.indom.output_inst_names[j] = cache->names[k];
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+ break;
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+ }
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}
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}
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}
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@@ -1201,8 +1242,7 @@ out:
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static int
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pmfg_clear_profile(pmFG pmfg)
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{
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- int sts;
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- pmFGI item;
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+ int i, sts;
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sts = pmUseContext(pmfg->ctx);
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if (sts != 0)
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@@ -1216,10 +1256,9 @@ pmfg_clear_profile(pmFG pmfg)
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* Any errors here are benign (or rather there's nothing we can do
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* about 'em), so ignore pmDelProfile() return value.
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*/
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- for (item = pmfg->items; item; item = item->next) {
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- if (item->u.item.metric_desc.indom != PM_INDOM_NULL)
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- (void)pmDelProfile(item->u.item.metric_desc.indom, 0, NULL);
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- }
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+ for (i = 0; i < pmfg->num_unique_indoms; i++)
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+ (void)pmDelProfile(pmfg->unique_indoms[i].indom, 0, NULL);
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+
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return 0;
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}
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@@ -1434,7 +1473,7 @@ pmExtendFetchGroup_indom(pmFG pmfg,
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item->type = pmfg_indom;
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- sts = pmfg_lookup_indom(metric, item);
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+ sts = pmfg_lookup_indom(pmfg, metric, item);
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if (sts != 0)
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goto out;
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@@ -1615,7 +1654,6 @@ pmFetchGroup(pmFG pmfg)
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if (pmfg == NULL)
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return -EINVAL;
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-
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/*
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* Walk the fetchgroup, reinitializing every output spot, regardless of
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* later errors.
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@@ -1705,6 +1743,7 @@ int
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pmClearFetchGroup(pmFG pmfg)
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{
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pmFGI item;
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+ size_t n;
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if (pmfg == NULL)
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return -EINVAL;
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@@ -1719,8 +1758,6 @@ pmClearFetchGroup(pmFG pmfg)
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break;
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case pmfg_indom:
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pmfg_reinit_indom(item);
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- free(item->u.indom.indom_codes);
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- free(item->u.indom.indom_names);
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break;
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case pmfg_event:
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pmfg_reinit_event(item);
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@@ -1739,11 +1776,21 @@ pmClearFetchGroup(pmFG pmfg)
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if (pmfg->prevResult)
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pmFreeResult(pmfg->prevResult);
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pmfg->prevResult = NULL;
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+
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if (pmfg->unique_pmids)
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free(pmfg->unique_pmids);
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pmfg->unique_pmids = NULL;
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pmfg->num_unique_pmids = 0;
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+ for (n = 0; n < pmfg->num_unique_indoms; n++) {
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+ free(pmfg->unique_indoms[n].codes);
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+ free(pmfg->unique_indoms[n].names);
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+ }
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+ if (pmfg->unique_indoms)
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+ free(pmfg->unique_indoms);
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+ pmfg->unique_indoms = NULL;
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+ pmfg->num_unique_indoms = 0;
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+
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return pmfg_clear_profile(pmfg);
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}
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