From: oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa>
Date: Tue, 19 Feb 2008 12:56:44 +0000 (+0000)
Subject: Generate a random cur_row for each RRA during
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=0595044bb29c5babe84f2bb41f282e69ff6303d1;p=rrdtool.git

Generate a random cur_row for each RRA during
create/restore operations. This effectively randomizes the block crossings
among RRDs created around the same time. Previously, RRDs that were
created/restored en masse would cross block boundaries simultaneously, which
is sub-optimal.

Also, this patch enables the user to see the RRA's cur_row pointer via
rrdinfo. This was useful during debugging.

-- kevin brintnall kbrint qwest.net



git-svn-id: svn://svn.oetiker.ch/rrdtool/branches/1.2/program@1290 a5681a0c-68f1-0310-ab6d-d61299d08faa
---

diff --git a/src/rrd_create.c b/src/rrd_create.c
index 9e5b055..d9ab8f4 100644
--- a/src/rrd_create.c
+++ b/src/rrd_create.c
@@ -4,6 +4,9 @@
  * rrd_create.c  creates new rrds
  *****************************************************************************/
 
+#include <stdlib.h>
+#include <time.h>
+
 #include "rrd_tool.h"
 #include "rrd_rpncalc.h"
 #include "rrd_hw.h"
@@ -13,6 +16,7 @@
 unsigned long FnvHash(const char *str);
 int create_hw_contingent_rras(rrd_t *rrd, unsigned short period, unsigned long hashed_name);
 void parseGENERIC_DS(const char *def,rrd_t *rrd, int ds_idx);
+long int rra_random_row(rra_def_t *);
 
 int
 rrd_create(int argc, char **argv) 
@@ -650,7 +654,7 @@ rrd_create_fn(const char *file_name, rrd_t *rrd)
      * the pointer a priori. */
     for (i=0; i < rrd->stat_head->rra_cnt; i++)
     {
-        rrd->rra_ptr->cur_row = rrd->rra_def[i].row_cnt - 1;
+        rrd->rra_ptr->cur_row = rra_random_row(&rrd->rra_def[i]);
         fwrite( rrd->rra_ptr, sizeof(rra_ptr_t),1,rrd_file);
     }
     
@@ -686,3 +690,17 @@ rrd_create_fn(const char *file_name, rrd_t *rrd)
     rrd_free(rrd);
     return (0);
 }
+
+static int rand_init = 0;
+
+long int
+rra_random_row(rra_def_t *rra)
+{
+    if (!rand_init)
+    {
+        srandom((unsigned int)time(NULL) + (unsigned int)getpid());
+        rand_init++;
+    }
+    
+    return random() % rra->row_cnt;
+}
diff --git a/src/rrd_info.c b/src/rrd_info.c
index b2a55d9..ebb1b8d 100644
--- a/src/rrd_info.c
+++ b/src/rrd_info.c
@@ -155,6 +155,9 @@ rrd_info_r(char *filename) {
 	info.u_cnt=rrd.rra_def[i].row_cnt;
 	cd=info_push(cd,sprintf_alloc("rra[%d].rows",i),  RD_I_CNT,   info);
 
+	info.u_cnt=rrd.rra_ptr[i].cur_row;
+	cd=info_push(cd,sprintf_alloc("rra[%d].cur_row",i),  RD_I_CNT,   info);
+
 	info.u_cnt=rrd.rra_def[i].pdp_cnt;
 	cd=info_push(cd,sprintf_alloc("rra[%d].pdp_per_row",i),  RD_I_CNT,   info);
 
diff --git a/src/rrd_restore.c b/src/rrd_restore.c
index 4fb1dab..42c316c 100644
--- a/src/rrd_restore.c
+++ b/src/rrd_restore.c
@@ -26,6 +26,7 @@ int rrd_write(char *, rrd_t *, char);
 void parse_patch1028_RRA_params(char **buf, rrd_t *rrd, int rra_index);
 void parse_patch1028_CDP_params(char **buf, rrd_t *rrd, int rra_index, int ds_index);
 void parse_FAILURES_history(char **buf, rrd_t *rrd, int rra_index, int ds_index);
+long int rra_random_row(rra_def_t *);
 
 /* convert all occurrences of <BlaBlaBla> to <blablabla> */
 
@@ -443,12 +444,6 @@ int xml2rrd(char* buf, rrd_t* rrd, char rc){
       return(-1);
   }
 
-  for(i=0; i < (int)rrd->stat_head->rra_cnt; i++) {
-	  /* last row in the xml file is the most recent; as
-	   * rrd_update increments the current row pointer, set cur_row
-	   * here to the last row. */
-      rrd->rra_ptr[i].cur_row = rrd->rra_def[i].row_cnt-1;
-  }
   if (ptr==NULL)
       return -1;
   return 1;
@@ -463,7 +458,7 @@ int xml2rrd(char* buf, rrd_t* rrd, char rc){
 int
 rrd_write(char *file_name, rrd_t *rrd, char force_overwrite)
 {
-    unsigned long    i,ii,val_cnt;
+    unsigned long    i,ii,rra_offset;
     FILE             *rrd_file=NULL;
     int			fdflags;
     int			fd;
@@ -502,16 +497,30 @@ rrd_write(char *file_name, rrd_t *rrd, char force_overwrite)
     
     fwrite( rrd->cdp_prep, sizeof(cdp_prep_t),rrd->stat_head->rra_cnt*
 	    rrd->stat_head->ds_cnt,rrd_file);
+
+    for(i=0; i < rrd->stat_head->rra_cnt; i++)
+      rrd->rra_ptr[i].cur_row = rra_random_row(&rrd->rra_def[i]);
+
     fwrite( rrd->rra_ptr, sizeof(rra_ptr_t), rrd->stat_head->rra_cnt,rrd_file);
 
 
 
-    /* calculate the number of rrd_values to dump */
-    val_cnt=0;
+    /* Dump RRD values */
+    rra_offset=0;
     for(i=0; i <  rrd->stat_head->rra_cnt; i++)
-	for(ii=0; ii <  rrd->rra_def[i].row_cnt * rrd->stat_head->ds_cnt;ii++)
-	    val_cnt++;
-    fwrite( rrd->rrd_value, sizeof(rrd_value_t),val_cnt,rrd_file);
+    {
+        unsigned long num_rows = rrd->rra_def[i].row_cnt;
+        unsigned long cur_row = rrd->rra_ptr[i].cur_row;
+        unsigned long ds_cnt = rrd->stat_head->ds_cnt;
+
+        fwrite(rrd->rrd_value + (rra_offset + num_rows-1 - cur_row) * ds_cnt,
+               sizeof(rrd_value_t), (cur_row+1)*ds_cnt, rrd_file);
+
+        fwrite(rrd->rrd_value + rra_offset * ds_cnt,
+               sizeof(rrd_value_t), (num_rows-1 - cur_row)*ds_cnt, rrd_file);
+
+        rra_offset += num_rows;
+    }
 
     /* lets see if we had an error */
     if(ferror(rrd_file)){