CP-18272 change signature of rrd_sample to support testing

The commit changes the signature of rrd_sample to

    int rrd_sample(RRD_PLUGIN * plugin, time_t (*t)(time_t*));

The caller can provide a function to obtain a time stamp or provide NULL
(the typical case). This permits to control the time stamps in RRD files
for debugging and testing.

Signed-off-by: Christian Lindig <[email protected]>

Author: lindig

Makefile

@@ -55,12 +55,6 @@ indent: librrd.h librrd.c rrdtest.c
 depend: librrd.c rrdtest.c
 	$(CC) -MM $^
 
-.PHONY: parson
-parson:
-	# git submodule add https://github.com/kgabis/parson.git
-	git submodule init
-	git submodule update
-
 %.o:	%.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 

README.md

@@ -42,7 +42,7 @@ library:
     int             rrd_close(RRD_PLUGIN * plugin);
     int             rrd_add_src(RRD_PLUGIN * plugin, RRD_SOURCE * source);
     int             rrd_del_src(RRD_PLUGIN * plugin, RRD_SOURCE * source);
-    int             rrd_sample(RRD_PLUGIN * plugin);
+    int             rrd_sample(RRD_PLUGIN * plugin, time_t (*t)(time_t*));
 
 A plugin reports streams of data to the RRD service. Each such
 stream is represented as an `RRD_SOURCE` value. An `RRD_PLUGIN`
@@ -83,7 +83,7 @@ All strings are in UTF8 encoding. The library implements the following
 policy to manage memory: it does not free any memory that is hasn't
 itself allocated. This means, if the client passes dynamically allocated
 data into the library, it is the client's responsibility to de-allocate
-it. 
+it.
 
 ## Open, Sample, Close
 
@@ -102,12 +102,14 @@ considered private to the library.
     <<function declarations>>=
     RRD_PLUGIN     *rrd_open(char *name, rrd_domain_t domain, char *path);
     int             rrd_close(RRD_PLUGIN * plugin);
-    int             rrd_sample(RRD_PLUGIN * plugin);
+    int             rrd_sample(RRD_PLUGIN * plugin, time_t (*t)(time_t*));
 
 
 The name of the plugin is descriptive, as whether it reports data
 for a single machine (`RRD_LOCAL_DOMAIN`) or multiple
-(`RRD_INTER_DOMAIN`).
+(`RRD_INTER_DOMAIN`). The second parameter of `rrd_sample` is typically
+NULL. If it isn't, it us used to obtain a timestamp instead of using
+time(3).
 
 ## Data Sources
 

librrd.c

@@ -26,7 +26,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <zlib.h>
-#include <time.h>
 #include <assert.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -400,7 +399,7 @@ write_exact(int fd, const void *data, size_t size)
  * first.
  */
 int
-rrd_sample(RRD_PLUGIN * plugin)
+rrd_sample(RRD_PLUGIN * plugin, time_t (*t)(time_t*))
 {
     assert(plugin);
     JSON_Value     *json;
@@ -440,7 +439,8 @@ rrd_sample(RRD_PLUGIN * plugin)
     /*
      * update timestamp, calculate crc
      */
-    header->rrd_timestamp = htonll((uint64_t) time(NULL));
+
+    header->rrd_timestamp = htonll((uint64_t) (t ? t(NULL) : time(NULL)));
     uint32_t        crc = crc32(0L, Z_NULL, 0);
     crc = crc32(crc,
                 (unsigned char *) &header->rrd_timestamp,

librrd.h

@@ -23,6 +23,7 @@
 
 
 #include <stdint.h>
+#include <time.h>
 #include "parson/parson.h"
 
 #define RRD_MAX_SOURCES         128
@@ -124,7 +125,10 @@ int             rrd_del_src(RRD_PLUGIN * plugin, RRD_SOURCE * source);
 
 /*
  * calling rrd_sample(plugin) triggers that all data sources are sampled
- * and the results are reported to the RRD daemon. This function needs to
- * be called every 5 seconds by the client,
+ * and the results are reported to the RRD daemon. This function needs
+ * to be called every 5 seconds by the client. The second parameter is
+ * typically NULL. If it isn't, it will be used instead of time(3) to
+ * obtain the time stamp that is written to the RRD file. This can be
+ * used to create RRD files that don't depend on the current time.
  */
-int             rrd_sample(RRD_PLUGIN * plugin);
+int             rrd_sample(RRD_PLUGIN * plugin, time_t (*t)(time_t*));

rrdclient.c

@@ -73,7 +73,7 @@ main(int argc, char **argv)
     int rc;
     while (fgets(line, sizeof(line), stdin) != NULL) {
         v.int64 = (int64_t) atol(line);
-        rc = rrd_sample(plugin);
+        rc = rrd_sample(plugin, NULL);
         assert(rc == RRD_OK);
     }
 

rrdtest.c

@@ -82,7 +82,7 @@ main(int argc, char **argv)
 
     printf("adding source: %s\n", src[0].name);
     rrd_add_src(plugin, &src[0]);
-    rc = rrd_sample(plugin);
+    rc = rrd_sample(plugin, NULL);
     assert(rc == RRD_OK);
 
     src[1].name = "second";
@@ -99,12 +99,12 @@ main(int argc, char **argv)
 
     printf("adding source: %s\n", src[1].name);
     rrd_add_src(plugin, &src[1]);
-    rc = rrd_sample(plugin);
+    rc = rrd_sample(plugin, NULL);
     assert(rc == RRD_OK);
 
     printf("removing source: %s\n", src[0].name);
     rrd_del_src(plugin, &src[0]);
-    rc = rrd_sample(plugin);
+    rc = rrd_sample(plugin, NULL);
     assert(rc == RRD_OK);
 
     printf("removing source: %s\n", src[1].name);