netapp plugin: collect_perf_disk_data: Only query "percentage-saved" if required.

Also, add support for "sis_saved_percent == 100". Probably not useful,
but better than simply skipping that case.

diff --git a/src/netapp.c b/src/netapp.c
index cbba8d6..96ca5a4 100644 (file)
--- a/src/netapp.c
+++ b/src/netapp.c
@@ -452,7 +452,7 @@ static void collect_perf_disk_data(host_config_t *host, na_elem_t *out, void *da
 } /* }}} void collect_perf_disk_data */
 
 static void collect_volume_data(host_config_t *host, na_elem_t *out, void *data) { /* {{{ */
-       na_elem_t *inst, *sis;
+       na_elem_t *inst;
        volume_t *volume;
        volume_data_t *volume_data = data;
 
@@ -460,9 +460,10 @@ static void collect_volume_data(host_config_t *host, na_elem_t *out, void *data)
        na_elem_iter_t inst_iter = na_child_iterator(out);
        for (inst = na_iterator_next(&inst_iter); inst; inst = na_iterator_next(&inst_iter)) {
                uint64_t size_free = 0, size_used = 0, snap_reserved = 0;
+
+               na_elem_t *sis;
                const char *sis_state;
                uint64_t sis_saved_reported;
-               uint64_t sis_saved_percent;
                uint64_t sis_saved;
 
                volume = get_volume(host, na_child_get_string(inst, "name"));
@@ -477,17 +478,16 @@ static void collect_volume_data(host_config_t *host, na_elem_t *out, void *data)
 
                /* 2^4 exa-bytes? This will take a while ;) */
                size_free = na_child_get_uint64(inst, "size-available", UINT64_MAX);
-               size_used = na_child_get_uint64(inst, "size-used", UINT64_MAX);
-               snap_reserved = na_child_get_uint64(inst, "snapshot-blocks-reserved", UINT64_MAX);
-
                if (size_free != UINT64_MAX)
                        submit_double (host->name, volume->name, "df_complex", "used",
                                        (double) size_used, /* time = */ 0);
 
+               size_used = na_child_get_uint64(inst, "size-used", UINT64_MAX);
                if (size_free != UINT64_MAX)
                        submit_double (host->name, volume->name, "df_complex", "free",
                                        (double) size_free, /* time = */ 0);
 
+               snap_reserved = na_child_get_uint64(inst, "snapshot-blocks-reserved", UINT64_MAX);
                if (snap_reserved != UINT64_MAX)
                        /* 1 block == 1024 bytes  as per API docs */
                        submit_double (host->name, volume->name, "df_complex", "snap_reserved",
@@ -503,10 +503,7 @@ static void collect_volume_data(host_config_t *host, na_elem_t *out, void *data)
                        continue;
 
                sis_saved_reported = na_child_get_uint64(sis, "size-saved", UINT64_MAX);
-               sis_saved_percent = na_child_get_uint64(sis, "percentage-saved", UINT64_MAX);
-
-               /* sis_saved_percent == 100 leads to division by zero below */
-               if ((sis_saved_reported == UINT64_MAX) || (sis_saved_percent > 99))
+               if (sis_saved_reported == UINT64_MAX)
                        continue;
 
                /* size-saved is actually a 32 bit number, so ... time for some guesswork. */
@@ -514,30 +511,44 @@ static void collect_volume_data(host_config_t *host, na_elem_t *out, void *data)
                        /* In case they ever fix this bug. */
                        sis_saved = sis_saved_reported;
                } else {
+                       uint64_t sis_saved_percent;
+                       uint64_t sis_saved_guess;
+                       uint64_t overflow_guess;
+                       uint64_t guess1, guess2, guess3;
+
+                       sis_saved_percent = na_child_get_uint64(sis, "percentage-saved", UINT64_MAX);
+                       if (sis_saved_percent > 100)
+                               continue;
+
                        /* The "size-saved" value is a 32bit unsigned integer. This is a bug and
                         * will hopefully be fixed in later versions. To work around the bug, try
                         * to figure out how often the 32bit integer wrapped around by using the
                         * "percentage-saved" value. Because the percentage is in the range
                         * [0-100], this should work as long as the saved space does not exceed
                         * 400 GBytes. */
-                       uint64_t real_saved = sis_saved_percent * size_used / (100 - sis_saved_percent);
-                       uint64_t overflow_guess = real_saved >> 32;
-                       uint64_t guess1 = overflow_guess ? ((overflow_guess - 1) << 32) + sis_saved_reported : sis_saved_reported;
-                       uint64_t guess2 = (overflow_guess << 32) + sis_saved_reported;
-                       uint64_t guess3 = ((overflow_guess + 1) << 32) + sis_saved_reported;
-
-                       if (real_saved < guess2) {
-                               if ((real_saved - guess1) < (guess2 - real_saved))
+                       /* percentage-saved = size-saved / (size-saved + size-used) */
+                       if (sis_saved_percent < 100)
+                               sis_saved_guess = size_used * sis_saved_percent / (100 - sis_saved_percent);
+                       else
+                               sis_saved_guess = size_used;
+
+                       overflow_guess = sis_saved_guess >> 32;
+                       guess1 = overflow_guess ? ((overflow_guess - 1) << 32) + sis_saved_reported : sis_saved_reported;
+                       guess2 = (overflow_guess << 32) + sis_saved_reported;
+                       guess3 = ((overflow_guess + 1) << 32) + sis_saved_reported;
+
+                       if (sis_saved_guess < guess2) {
+                               if ((sis_saved_guess - guess1) < (guess2 - sis_saved_guess))
                                        sis_saved = guess1;
                                else
                                        sis_saved = guess2;
                        } else {
-                               if ((real_saved - guess2) < (guess3 - real_saved))
+                               if ((sis_saved_guess - guess2) < (guess3 - sis_saved_guess))
                                        sis_saved = guess2;
                                else
                                        sis_saved = guess3;
                        }
-               }
+               } /* end of 32-bit workaround */
 
                submit_double (host->name, volume->name, "df_complex", "sis_saved",
                                (double) sis_saved, /* time = */ 0);