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cache.c
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cache.c
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/*********************************************************************
* Copyright 1993, UCAR/Unidata
* See netcdf/COPYRIGHT file for copying and redistribution conditions.
*********************************************************************/
#include "ncdap.h"
#include "dapdump.h"
/*
Grads servers always require a constraint,
which does not necessarily happen during prefetch.
So this flag controls this. By default, it is on.
*/
#define GRADS_PREFETCH
static int iscacheableconstraint(DCEconstraint* con);
/* Return 1 if we can reuse cached data to address
the current get_vara request; return 0 otherwise.
Target is in the constrained tree space.
Currently, if the target matches a cache that is not
a whole variable, then match is false.
*/
int
iscached(NCDAPCOMMON* nccomm, CDFnode* target, NCcachenode** cachenodep)
{
int i,j,found,index;
NCcache* cache;
NCcachenode* cachenode;
found = 0;
if(target == NULL) goto done;
/* Match the target variable against the prefetch, if any */
/* Note that prefetches are always whole variable */
cache = nccomm->cdf.cache;
cachenode = cache->prefetch;
if(cachenode!= NULL) {
for(found=0,i=0;i<nclistlength(cachenode->vars);i++) {
CDFnode* var = (CDFnode*)nclistget(cachenode->vars,i);
if(var == target) {
if(cachenodep) *cachenodep = cachenode;
found=1;
goto done;
}
}
}
/*search other cache nodes starting at latest first */
index = 0;
for(i=nclistlength(cache->nodes)-1;i>=0;i--) {
cachenode = (NCcachenode*)nclistget(cache->nodes,i);
/* We currently do not try to match constraints;
If the cachenode is constrained by more than
simple wholevariable projections, then skip it.
*/
if(!cachenode->wholevariable) continue;
for(found=0,j=0;j<nclistlength(cachenode->vars);j++) {
CDFnode* var = (CDFnode*)nclistget(cachenode->vars,j);
if(var == target) {found=1;index=i;break;}
}
if(found) break;
}
if(found) {
ASSERT((cachenode != NULL));
if(nclistlength(cache->nodes) > 1) {
/* Manage the cache nodes as LRU */
nclistremove(cache->nodes,index);
nclistpush(cache->nodes,(void*)cachenode);
}
if(cachenodep) *cachenodep = cachenode;
}
done:
#ifdef DEBUG
fprintf(stderr,"iscached: search: %s\n",makecdfpathstring(target,"."));
if(found)
fprintf(stderr,"iscached: found: %s\n",dumpcachenode(cachenode));
else
fprintf(stderr,"iscached: notfound\n");
#endif
return found;
}
/* Compute the set of prefetched data.
Notes:
1. All prefetches are whole variable fetches.
2. If the data set is unconstrainable, we
will prefetch the whole thing
*/
NCerror
prefetchdata(NCDAPCOMMON* nccomm)
{
int i;
NCFLAGS flags;
NCerror ncstat = NC_NOERR;
NClist* allvars = nccomm->cdf.ddsroot->tree->varnodes;
DCEconstraint* urlconstraint = nccomm->oc.dapconstraint;
NClist* vars = nclistnew();
NCcachenode* cache = NULL;
DCEconstraint* newconstraint = NULL;
if(FLAGSET(nccomm->controls,NCF_UNCONSTRAINABLE)) {
/* If we cannot constrain and caching is enabled,
then pull in everything */
if(FLAGSET(nccomm->controls,NCF_CACHE)) {
for(i=0;i<nclistlength(allvars);i++) {
nclistpush(vars,nclistget(allvars,i));
}
} else { /* do no prefetching */
nccomm->cdf.cache->prefetch = NULL;
goto done;
}
} else {
/* pull in those variables previously marked as prefetchable */
for(i=0;i<nclistlength(allvars);i++) {
CDFnode* var = (CDFnode*)nclistget(allvars,i);
/* Most of the important testing was already done */
if(!var->basenode->prefetchable)
continue;
/* Do not attempt to prefetch any variables in the
nc_open url's projection list
*/
if(nclistcontains(nccomm->cdf.projectedvars,(void*)var))
continue;
/* Should be prefetchable */
nclistpush(vars,(void*)var);
if(SHOWFETCH) {
nclog(NCLOGDBG,"prefetch: %s",var->ncfullname);
}
}
}
/* If there are no vars, then do nothing */
if(nclistlength(vars) == 0) {
nccomm->cdf.cache->prefetch = NULL;
goto done;
}
/* Create a single constraint consisting of the projections for the variables;
each projection is whole variable. The selections are passed on as is.
Conditionally, The exception is if we are prefetching everything.
*/
newconstraint = (DCEconstraint*)dcecreate(CES_CONSTRAINT);
newconstraint->projections = nclistnew();
newconstraint->selections = dceclonelist(urlconstraint->selections);
for(i=0;i<nclistlength(vars);i++) {
CDFnode* var = (CDFnode*)nclistget(vars,i);
DCEprojection* varprojection;
/* convert var to a projection */
ncstat = dapvar2projection(var,&varprojection);
if(ncstat != NC_NOERR) {THROWCHK(ncstat); goto done;}
nclistpush(newconstraint->projections,(void*)varprojection);
}
if(SHOWFETCH) {
char* s = dumpprojections(newconstraint->projections);
LOG1(NCLOGNOTE,"prefetch.final: %s",s);
nullfree(s);
}
flags = NCF_PREFETCH;
#ifndef GRADS_PREFETCH
if(nclistlength(allvars) == nclistlength(vars)) flags |= NCF_PREFETCH_ALL;
#endif
ncstat = buildcachenode(nccomm,newconstraint,vars,&cache,flags);
newconstraint = NULL; /* buildcachenodetakes control of newconstraint */
if(ncstat != OC_NOERR) goto done;
else if(cache == NULL) goto done;
else
cache->wholevariable = 1; /* All prefetches are whole variable */
/* Make cache node be the prefetch node */
nccomm->cdf.cache->prefetch = cache;
if(SHOWFETCH) {
LOG0(NCLOGNOTE,"prefetch.complete");
}
if(SHOWFETCH) {
char* s = NULL;
/* Log the set of prefetch variables */
NCbytes* buf = ncbytesnew();
ncbytescat(buf,"prefetch.vars: ");
for(i=0;i<nclistlength(vars);i++) {
CDFnode* var = (CDFnode*)nclistget(vars,i);
ncbytescat(buf," ");
s = makecdfpathstring(var,".");
ncbytescat(buf,s);
nullfree(s);
}
ncbytescat(buf,"\n");
nclog(NCLOGNOTE,"%s",ncbytescontents(buf));
ncbytesfree(buf);
}
done:
nclistfree(vars);
dcefree((DCEnode*)newconstraint);
if(ncstat && cache != NULL) freenccachenode(nccomm,cache);
return THROW(ncstat);
}
NCerror
buildcachenode(NCDAPCOMMON* nccomm,
DCEconstraint* constraint,
NClist* varlist,
NCcachenode** cachep,
NCFLAGS flags)
{
NCerror ncstat = NC_NOERR;
OCerror ocstat = OC_NOERR;
OClink conn = nccomm->oc.conn;
OCddsnode ocroot = NULL;
CDFnode* dxdroot = NULL;
NCcachenode* cachenode = NULL;
char* ce = NULL;
int isprefetch = 0;
if((flags & NCF_PREFETCH) != 0)
isprefetch = 1;
#ifndef GRADS_PREFETCH
if((flags & NCF_PREFETCH_ALL) == 0)
#endif
ce = dcebuildconstraintstring(constraint);
ncstat = dap_fetch(nccomm,conn,ce,OCDATADDS,&ocroot);
nullfree(ce);
if(ncstat != NC_NOERR) {THROWCHK(ncstat); goto done;}
ncstat = buildcdftree(nccomm,ocroot,OCDATA,&dxdroot);
if(ncstat) {THROWCHK(ncstat); goto done;}
/* re-struct*/
if(!FLAGSET(nccomm->controls,NCF_UNCONSTRAINABLE)) {
ncstat = restruct(nccomm,dxdroot,nccomm->cdf.fullddsroot,
constraint->projections);
if(ncstat) {THROWCHK(ncstat); goto done;}
}
/* create the cache node */
cachenode = createnccachenode();
cachenode->isprefetch = isprefetch;
cachenode->vars = nclistclone(varlist);
cachenode->datadds = dxdroot;
/* Give the constraint over to the cachenode */
cachenode->constraint = constraint;
constraint = NULL;
cachenode->wholevariable = iscacheableconstraint(cachenode->constraint);
/* save the root content*/
cachenode->ocroot = ocroot;
ocstat = oc_data_getroot(conn,ocroot,&cachenode->content);
if(ocstat) {THROWCHK(ocerrtoncerr(ocstat)); goto done;}
/* capture the packet size */
ocstat = oc_raw_xdrsize(conn,ocroot,&cachenode->xdrsize);
if(ocstat) {THROWCHK(ocerrtoncerr(ocstat)); goto done;}
#ifdef DEBUG
fprintf(stderr,"buildcachenode: new cache node: %s\n",
dumpcachenode(cachenode));
#endif
/* Insert into the cache. If not caching, then
remove any previous cache node
*/
if(!isprefetch) {
NCcache* cache = nccomm->cdf.cache;
if(cache->nodes == NULL) cache->nodes = nclistnew();
/* remove cache nodes to get below the max cache size */
while(cache->cachesize + cachenode->xdrsize > cache->cachelimit
&& nclistlength(cache->nodes) > 0) {
NCcachenode* node = (NCcachenode*)nclistremove(cache->nodes,0);
#ifdef DEBUG
fprintf(stderr,"buildcachenode: purge cache node: %s\n",
dumpcachenode(cachenode));
#endif
cache->cachesize -= node->xdrsize;
freenccachenode(nccomm,node);
}
/* Remove cache nodes to get below the max cache count */
/* If not caching, then cachecount should be 0 */
while(nclistlength(cache->nodes) > cache->cachecount) {
NCcachenode* node = (NCcachenode*)nclistremove(cache->nodes,0);
#ifdef DEBUG
fprintf(stderr,"buildcachenode: count purge cache node: %s\n",
dumpcachenode(node));
#endif
cache->cachesize -= node->xdrsize;
freenccachenode(nccomm,node);
}
nclistpush(nccomm->cdf.cache->nodes,(void*)cachenode);
cache->cachesize += cachenode->xdrsize;
}
#ifdef DEBUG
fprintf(stderr,"buildcachenode: %s\n",dumpcachenode(cachenode));
#endif
done:
if(constraint != NULL) dcefree((DCEnode*)constraint);
if(cachep) *cachep = cachenode;
if(ocstat != OC_NOERR) ncstat = ocerrtoncerr(ocstat);
if(ncstat != OC_NOERR) {
freecdfroot(dxdroot);
freenccachenode(nccomm,cachenode);
if(cachep) *cachep = NULL;
}
return THROW(ncstat);
}
NCcachenode*
createnccachenode(void)
{
NCcachenode* mem = (NCcachenode*)calloc(1,sizeof(NCcachenode));
return mem;
}
void
freenccachenode(NCDAPCOMMON* nccomm, NCcachenode* node)
{
if(node == NULL) return;
#ifdef DEBUG
fprintf(stderr,"freecachenode: %s\n",
dumpcachenode(node));
#endif
oc_data_free(nccomm->oc.conn,node->content);
dcefree((DCEnode*)node->constraint);
freecdfroot(node->datadds);
nclistfree(node->vars);
nullfree(node);
}
void
freenccache(NCDAPCOMMON* nccomm, NCcache* cache)
{
int i;
if(cache == NULL) return;
freenccachenode(nccomm,cache->prefetch);
for(i=0;i<nclistlength(cache->nodes);i++) {
freenccachenode(nccomm,(NCcachenode*)nclistget(cache->nodes,i));
}
nclistfree(cache->nodes);
nullfree(cache);
}
NCcache*
createnccache(void)
{
NCcache* c = (NCcache*)calloc(1,sizeof(NCcache));
if(c == NULL)
return NULL;
c->cachelimit = DFALTCACHELIMIT;
c->cachesize = 0;
c->nodes = nclistnew();
c->cachecount = DFALTCACHECOUNT;
return c;
}
static int
iscacheableprojection(DCEprojection* proj)
{
int i,cacheable;
if(proj->discrim != CES_VAR) return 0;
cacheable = 1; /* assume so */
for(i=0;i<nclistlength(proj->var->segments);i++) {
DCEsegment* segment = (DCEsegment*)nclistget(proj->var->segments,i);
if(!dapiswholesegment(segment)) {cacheable = 0; break;}
}
return cacheable;
}
static int
iscacheableconstraint(DCEconstraint* con)
{
int i;
if(con == NULL) return 1;
if(con->selections != NULL && nclistlength(con->selections) > 0)
return 0; /* cant deal with selections */
for(i=0;i<nclistlength(con->projections);i++) {
if(!iscacheableprojection((DCEprojection*)nclistget(con->projections,i)))
return 0;
}
return 1;
}
/*
A variable is prefetchable if
1. it is atomic
2. it's size is sufficiently small
3. it is not contained in sequence or a dimensioned structure.
*/
NCerror
markprefetch(NCDAPCOMMON* nccomm)
{
int i,j;
NClist* allvars = nccomm->cdf.fullddsroot->tree->varnodes;
assert(allvars != NULL);
/* mark those variables of sufficiently small size */
for(i=0;i<nclistlength(allvars);i++) {
CDFnode* var = (CDFnode*)nclistget(allvars,i);
size_t nelems;
/* If var is not atomic, then it is not prefetchable */
if(var->nctype != NC_Atomic)
continue;
/* if var is under a sequence, then never prefetch */
if(dapinsequence(var))
continue;
/* Compute the # of elements in the variable */
for(nelems=1,j=0;j<nclistlength(var->array.dimsettrans);j++) {
CDFnode* dim = (CDFnode*)nclistget(var->array.dimsettrans,j);
nelems *= dim->dim.declsize;
}
if(nelems <= nccomm->cdf.smallsizelimit
&& FLAGSET(nccomm->controls,NCF_PREFETCH)) {
var->prefetchable = 1;
if(SHOWFETCH)
{
extern char* ocfqn(OCddsnode);
char *tmp = ocfqn(var->ocnode);
nclog(NCLOGDBG,"prefetchable: %s=%lu",
tmp,(unsigned long)nelems);
free(tmp);
}
}
}
return NC_NOERR;
}