From 85f2def814fbc2d9968394c13e619a31b9efd25a Mon Sep 17 00:00:00 2001
From: "Costa Tsaousis (ktsaou)" <costa@tsaousis.gr>
Date: Fri, 27 Jan 2017 21:29:36 +0200
Subject: [PATCH] nonzero option should return all selected dimensions if they
 are all zero; fixes #1658; fixes #1514

---
 src/rrd.h      |  1 +
 src/rrd2json.c | 30 +++++++++++++++++++++++++++---
 src/rrd2json.h |  1 +
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/rrd.h b/src/rrd.h
index dbaf9865..4189d36c 100644
--- a/src/rrd.h
+++ b/src/rrd.h
@@ -124,6 +124,7 @@ struct rrddim {
 
     // FIXME
     // we need the hash_name too!
+    // needed at rrdr_disable_not_selected_dimensions()
 
     uint32_t flags;
 
diff --git a/src/rrd2json.c b/src/rrd2json.c
index 568d04e8..65346f31 100644
--- a/src/rrd2json.c
+++ b/src/rrd2json.c
@@ -543,11 +543,13 @@ static void rrdr_dump(RRDR *r)
 
 void rrdr_disable_not_selected_dimensions(RRDR *r, uint32_t options, const char *dims)
 {
+    if(unlikely(!dims || !*dims)) return;
+
     char b[strlen(dims) + 1];
     char *o = b, *tok;
     strcpy(o, dims);
 
-    long c;
+    long c, dims_selected = 0, dims_not_hidden_not_zero = 0;
     RRDDIM *d;
 
     // disable all of them
@@ -562,16 +564,38 @@ void rrdr_disable_not_selected_dimensions(RRDR *r, uint32_t options, const char
         // find it and enable it
         for(c = 0, d = r->st->dimensions; d ;c++, d = d->next) {
             if(unlikely((hash == d->hash && !strcmp(d->id, tok)) || !strcmp(d->name, tok))) {
-                r->od[c] &= ~RRDR_HIDDEN;
+                dims_selected++;
+
+                r->od[c] |= RRDR_OPTION_SELECTED;
+
+                // remove the hidden flag, if it is set
+                if(likely(r->od[c] & RRDR_HIDDEN))
+                    r->od[c] &= ~RRDR_HIDDEN;
 
                 // since the user needs this dimension
                 // make it appear as NONZERO, to return it
                 // even if the dimension has only zeros
                 // unless option non_zero is set
-                if (!(options & RRDR_OPTION_NONZERO)) r->od[c] |= RRDR_NONZERO;
+                if(likely(!(options & RRDR_OPTION_NONZERO)))
+                    r->od[c] |= RRDR_NONZERO;
+
+                // count the visible dimensions
+                if(likely(r->od[c] & RRDR_NONZERO))
+                    dims_not_hidden_not_zero++;
             }
         }
     }
+
+    // check if all dimensions are hidden
+    if(unlikely(!dims_not_hidden_not_zero && dims_selected)) {
+        // there are a few selected dimensions
+        // but they are all zero
+        // enable the selected ones
+        // to avoid returning an empty chart
+        for(c = 0, d = r->st->dimensions; d ;c++, d = d->next)
+            if(unlikely(r->od[c] & RRDR_OPTION_SELECTED))
+                r->od[c] |= RRDR_NONZERO;
+    }
 }
 
 void rrdr_buffer_print_format(BUFFER *wb, uint32_t format)
diff --git a/src/rrd2json.h b/src/rrd2json.h
index 7b140197..de82de43 100644
--- a/src/rrd2json.h
+++ b/src/rrd2json.h
@@ -57,6 +57,7 @@
 #define RRDR_OPTION_LABEL_QUOTES    0x00000400 // in CSV output, wrap header labels in double quotes
 #define RRDR_OPTION_PERCENTAGE      0x00000800 // give values as percentage of total
 #define RRDR_OPTION_NOT_ALIGNED     0x00001000 // do not align charts for persistant timeframes
+#define RRDR_OPTION_SELECTED        0x00002000 // the dimension is selected by the caller: rrdr_disable_not_selected_dimensions()
 
 extern void rrd_stats_api_v1_chart(RRDSET *st, BUFFER *wb);
 extern void rrd_stats_api_v1_charts(BUFFER *wb);
-- 
2.39.2