STYLE: reset parameters in memInfo::update()

- avoids old values if the read from /proc/.../status somehow failed

src/OSspecific/POSIX/memInfo/memInfo.C

@@ -47,6 +47,8 @@ Foam::memInfo::~memInfo()
 
 const Foam::memInfo& Foam::memInfo::update()
 {
+    // reset to invalid values first
+    peak_ = size_ = rss_ = -1;
     IFstream is("/proc/" + name(pid()) + "/status");
 
     while (is.good())

src/OSspecific/POSIX/memInfo/memInfo.H

@@ -27,6 +27,9 @@ Class
 Description
     Memory usage information for the process running this object.
 
+Note
+    Uses the information from /proc/\<pid\>/status
+
 SourceFiles
     memInfo.C
 
@@ -52,13 +55,13 @@ class memInfo
 {
     // Private data
 
-        //- Peak memory used by the process (VmPeak in /proc/<pid>/status)
+        //- Peak memory used by the process (VmPeak in /proc/\<pid\>/status)
         int peak_;
 
-        //- Memory used by the process (VmSize in /proc/<pid>/status)
+        //- Memory used by the process (VmSize in /proc/\<pid\>/status)
         int size_;
 
-        //- Resident set size of the process (VmRSS in /proc/<pid>/status)
+        //- Resident set size of the process (VmRSS in /proc/\<pid\>/status)
         int rss_;
 
 
@@ -76,24 +79,27 @@ public:
 
     // Member Functions
 
-        //- Parse /proc/<pid>/status
+        //- Parse /proc/\<pid\>/status
         const memInfo& update();
 
         // Access
 
-            //- Access the stored peak memory
+            //- Access the stored peak memory (VmPeak in /proc/\<pid\>/status)
+            //  The value is stored from the previous update()
             int peak() const
             {
                 return peak_;
             }
 
-            //- Access the stored memory size
+            //- Access the stored memory size (VmSize in /proc/\<pid\>/status)
+            //  The value is stored from the previous update()
             int size() const
             {
                 return size_;
             }
 
-            //- Access the stored rss value
+            //- Access the stored rss value (VmRSS in /proc/\<pid\>/status)
+            //  The value is stored from the previous update()
             int rss() const
             {
                 return rss_;
@@ -102,7 +108,10 @@ public:
 
     // IOstream Operators
 
+        //- Read peak/size/rss from stream
         friend Istream& operator>>(Istream&, memInfo&);
+
+        //- Write peak/size/rss to stream
         friend Ostream& operator<<(Ostream&, const memInfo&);
 };