From daf7c86c01b17de2705a8410691c7b13693a7878 Mon Sep 17 00:00:00 2001
From: Jim Warner <james.warner@comcast.net>
Date: Thu, 7 Sep 2017 00:00:00 -0500
Subject: [PATCH] library: add delta values with swap too, <meminfo> api

As an oversight, delta values for SWAP amounts weren't
included in the <meminfo> API. Since any runtime costs
of including them only amount to slightly more storage
this commit will simply correct the earlier oversight.

Signed-off-by: Jim Warner <james.warner@comcast.net>
---
 proc/meminfo.c | 14 +++++++++++++-
 proc/meminfo.h |  7 ++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/proc/meminfo.c b/proc/meminfo.c
index a03afe66..3fc3b36d 100644
--- a/proc/meminfo.c
+++ b/proc/meminfo.c
@@ -233,6 +233,11 @@ MEM_set(SWAP_FREE,              ul_int,  SwapFree)
 MEM_set(SWAP_TOTAL,             ul_int,  SwapTotal)
 MEM_set(SWAP_USED,              ul_int,  derived_swap_used)
 
+HST_set(SWAP_DELTA_CACHED,       s_int,  SwapCached)
+HST_set(SWAP_DELTA_FREE,         s_int,  SwapFree)
+HST_set(SWAP_DELTA_TOTAL,        s_int,  SwapTotal)
+HST_set(SWAP_DELTA_USED,         s_int,  derived_swap_used)
+
 #undef setDECL
 #undef MEM_set
 #undef HST_set
@@ -358,13 +363,18 @@ static struct {
   { RS(SWAP_TOTAL),            TS(ul_int) },
   { RS(SWAP_USED),             TS(ul_int) },
 
+  { RS(SWAP_DELTA_CACHED),     TS(s_int)  },
+  { RS(SWAP_DELTA_FREE),       TS(s_int)  },
+  { RS(SWAP_DELTA_TOTAL),      TS(s_int)  },
+  { RS(SWAP_DELTA_USED),       TS(s_int)  },
+
  // dummy entry corresponding to MEMINFO_logical_end ...
   { NULL,                      NULL       }
 };
 
     /* please note,
      * this enum MUST be 1 greater than the highest value of any enum */
-enum meminfo_item MEMINFO_logical_end = MEMINFO_SWAP_USED + 1;
+enum meminfo_item MEMINFO_logical_end = MEMINFO_SWAP_DELTA_USED + 1;
 
 #undef setNAME
 #undef RS
@@ -646,6 +656,8 @@ static int meminfo_read_failed (
 
     if (mHr(SwapFree) < mHr(SwapTotal))
         mHr(derived_swap_used) = mHr(SwapTotal) - mHr(SwapFree);
+    else
+        mHr(derived_swap_used) = 0;
 
     return 0;
  #undef mHr
diff --git a/proc/meminfo.h b/proc/meminfo.h
index 673d0414..1e363846 100644
--- a/proc/meminfo.h
+++ b/proc/meminfo.h
@@ -126,7 +126,12 @@ enum meminfo_item {
     MEMINFO_SWAP_CACHED,           //  ul_int
     MEMINFO_SWAP_FREE,             //  ul_int
     MEMINFO_SWAP_TOTAL,            //  ul_int
-    MEMINFO_SWAP_USED              //  ul_int
+    MEMINFO_SWAP_USED,             //  ul_int
+
+    MEMINFO_SWAP_DELTA_CACHED,     //   s_int
+    MEMINFO_SWAP_DELTA_FREE,       //   s_int
+    MEMINFO_SWAP_DELTA_TOTAL,      //   s_int
+    MEMINFO_SWAP_DELTA_USED        //   s_int
 };