added posix_fadvise support (untested) ... this should help performance by

[rrdtool.git] / src / rrd_fetch.c

diff --git a/src/rrd_fetch.c b/src/rrd_fetch.c
index 96e2d14..7e92c2c 100644 (file)
--- a/src/rrd_fetch.c
+++ b/src/rrd_fetch.c
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * RRDtool 1.2.15  Copyright by Tobi Oetiker, 1997-2006
+ * RRDtool 1.2.23  Copyright by Tobi Oetiker, 1997-2007
  *****************************************************************************
  * rrd_fetch.c  read date from an rrd to use for further processing
  *****************************************************************************
@@ -53,6 +53,8 @@
  *****************************************************************************/
 
 #include "rrd_tool.h"
+
+#include "rrd_is_thread_safe.h"
 /*#define DEBUG*/
 
 int
@@ -71,7 +73,7 @@ rrd_fetch(int argc,
 
     long     step_tmp =1;
     time_t   start_tmp=0, end_tmp=0;
-    enum     cf_en cf_idx;
+    const char *cf;
 
     struct rrd_time_value start_tv, end_tv;
     char     *parsetime_error = NULL;
@@ -148,19 +150,39 @@ rrd_fetch(int argc,
        rrd_set_error("not enough arguments");
        return -1;
     }
-    
-    if ((int)(cf_idx=cf_conv(argv[optind+1])) == -1 ){
-       return -1;
-    }
 
-    if (rrd_fetch_fn(argv[optind],cf_idx,start,end,step,ds_cnt,ds_namv,data) == -1)
+    cf = argv[optind+1];
+
+    if (rrd_fetch_r(argv[optind],cf,start,end,step,ds_cnt,ds_namv,data) == -1)
        return(-1);
     return (0);
 }
 
 int
+rrd_fetch_r(
+    const char           *filename,  /* name of the rrd */
+    const char           *cf,        /* which consolidation function ?*/
+    time_t         *start,
+    time_t         *end,       /* which time frame do you want ?
+                                * will be changed to represent reality */
+    unsigned long  *step,      /* which stepsize do you want? 
+                                * will be changed to represent reality */
+    unsigned long  *ds_cnt,    /* number of data sources in file */
+    char           ***ds_namv, /* names of data_sources */
+    rrd_value_t    **data)     /* two dimensional array containing the data */
+{
+    enum     cf_en cf_idx;
+
+    if ((int)(cf_idx=cf_conv(cf)) == -1 ){
+        return -1;
+    }
+
+    return (rrd_fetch_fn(filename,cf_idx,start,end,step,ds_cnt,ds_namv,data));
+}
+
+int
 rrd_fetch_fn(
-    char           *filename,  /* name of the rrd */
+    const char     *filename,  /* name of the rrd */
     enum cf_en     cf_idx,         /* which consolidation function ?*/
     time_t         *start,
     time_t         *end,       /* which time frame do you want ?
@@ -183,6 +205,7 @@ rrd_fetch_fn(
     rrd_t     rrd;
     rrd_value_t    *data_ptr;
     unsigned long  rows;
+    long  rrd_head_size;
 
 #ifdef DEBUG
 fprintf(stderr,"Entered rrd_fetch_fn() searching for the best match\n");
@@ -192,6 +215,8 @@ fprintf(stderr,"Looking for: start %10lu end %10lu step %5lu\n",
 
     if(rrd_open(filename,&in_file,&rrd, RRD_READONLY)==-1)
        return(-1);
+
+    rrd_head_size = ftell(in_file);
     
     /* when was the really last update of this file ? */
 
@@ -431,6 +456,16 @@ fprintf(stderr,"partial match, not best\n");
                fclose(in_file);
                return(-1);
            }
+#ifdef POSIX_FADVISE
+       /* don't pollute the buffer cache with data read from the file. We do this while reading to 
+          keep damage minimal */
+       if (0 != posix_fadvise(fileno(in_file), rrd_head_size, ftell(in_file), POSIX_FADV_DONTNEED)) {
+           rrd_set_error("setting POSIX_FADV_DONTNEED on '%s': %s",file_name, rrd_strerror(errno));
+           fclose(in_file);
+           return(-1);
+       } 
+#endif
+
 #ifdef DEBUG
            fprintf(stderr,"post fetch %li -- ",i);
            for(ii=0;ii<*ds_cnt;ii++)
@@ -445,6 +480,14 @@ fprintf(stderr,"partial match, not best\n");
        
     }
     rrd_free(&rrd);
+#ifdef POSIX_FADVISE
+    /* and just to be sure we drop everything except the header at the end */
+    if (0 != posix_fadvise(fileno(in_file), rrd_head_size, 0, POSIX_FADV_DONTNEED)) {
+           rrd_set_error("setting POSIX_FADV_DONTNEED on '%s': %s",file_name, rrd_strerror(errno));
+           fclose(in_file);
+           return(-1);
+    } 
+#endif     
     fclose(in_file);
     return(0);
 }