Linux: Add SwapCached to the swap meter

According to the Linux kernel documentation, "SwapCached" tracks "memory
that once was swapped out, is swapped back in but still also is
in the swapfile (if memory is needed it doesn't need to be swapped out
AGAIN because it is already in the swapfile. This saves I/O)."

Action.c

@@ -528,7 +528,13 @@ static Htop_Reaction actionHelp(State* st) {
    mvaddstr(line++, 0, "Swap bar:      ");
    addattrstr(CRT_colors[BAR_BORDER], "[");
    addattrstr(CRT_colors[SWAP], "used");
+#ifdef HTOP_LINUX
+   addattrstr(CRT_colors[BAR_SHADOW], "/");
+   addattrstr(CRT_colors[SWAP_CACHE], "cache");
+   addattrstr(CRT_colors[BAR_SHADOW], "                                    used/total");
+#else
    addattrstr(CRT_colors[BAR_SHADOW], "                                          used/total");
+#endif
    addattrstr(CRT_colors[BAR_BORDER], "]");
    attrset(CRT_colors[DEFAULT_COLOR]);
    mvaddstr(line++, 0, "Type and layout of header meters are configurable in the setup screen.");

CRT.c

@@ -144,6 +144,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [BAR_BORDER] = A_BOLD,
       [BAR_SHADOW] = A_BOLD | ColorPairGrayBlack,
       [SWAP] = ColorPair(Red, Black),
+      [SWAP_CACHE] = ColorPair(Yellow, Black),
       [GRAPH_1] = A_BOLD | ColorPair(Cyan, Black),
       [GRAPH_2] = ColorPair(Cyan, Black),
       [MEMORY_USED] = ColorPair(Green, Black),
@@ -229,6 +230,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [BAR_BORDER] = A_BOLD,
       [BAR_SHADOW] = A_DIM,
       [SWAP] = A_BOLD,
+      [SWAP_CACHE] = A_NORMAL,
       [GRAPH_1] = A_BOLD,
       [GRAPH_2] = A_NORMAL,
       [MEMORY_USED] = A_BOLD,
@@ -314,6 +316,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [BAR_BORDER] = ColorPair(Blue, White),
       [BAR_SHADOW] = ColorPair(Black, White),
       [SWAP] = ColorPair(Red, White),
+      [SWAP_CACHE] = ColorPair(Yellow, White),
       [GRAPH_1] = A_BOLD | ColorPair(Blue, White),
       [GRAPH_2] = ColorPair(Blue, White),
       [MEMORY_USED] = ColorPair(Green, White),
@@ -399,6 +402,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [BAR_BORDER] = ColorPair(Blue, Black),
       [BAR_SHADOW] = ColorPairGrayBlack,
       [SWAP] = ColorPair(Red, Black),
+      [SWAP_CACHE] = ColorPair(Yellow, Black),
       [GRAPH_1] = A_BOLD | ColorPair(Cyan, Black),
       [GRAPH_2] = ColorPair(Cyan, Black),
       [MEMORY_USED] = ColorPair(Green, Black),
@@ -484,6 +488,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [BAR_BORDER] = A_BOLD | ColorPair(Yellow, Blue),
       [BAR_SHADOW] = ColorPair(Cyan, Blue),
       [SWAP] = ColorPair(Red, Blue),
+      [SWAP_CACHE] = A_BOLD | ColorPair(Yellow, Blue),
       [GRAPH_1] = A_BOLD | ColorPair(Cyan, Blue),
       [GRAPH_2] = ColorPair(Cyan, Blue),
       [MEMORY_USED] = A_BOLD | ColorPair(Green, Blue),
@@ -569,6 +574,7 @@ static int CRT_colorSchemes[LAST_COLORSCHEME][LAST_COLORELEMENT] = {
       [BAR_BORDER] = A_BOLD | ColorPair(Green, Black),
       [BAR_SHADOW] = ColorPair(Cyan, Black),
       [SWAP] = ColorPair(Red, Black),
+      [SWAP_CACHE] = ColorPair(Yellow, Black),
       [GRAPH_1] = A_BOLD | ColorPair(Green, Black),
       [GRAPH_2] = ColorPair(Green, Black),
       [MEMORY_USED] = ColorPair(Green, Black),

CRT.h

@@ -65,6 +65,7 @@ typedef enum ColorElements_ {
    BATTERY,
    TASKS_RUNNING,
    SWAP,
+   SWAP_CACHE,
    PROCESS,
    PROCESS_SHADOW,
    PROCESS_TAG,

ProcessList.h

@@ -65,9 +65,10 @@ typedef struct ProcessList_ {
    unsigned long long int usedMem;
    unsigned long long int buffersMem;
    unsigned long long int cachedMem;
+
    unsigned long long int totalSwap;
    unsigned long long int usedSwap;
-   unsigned long long int freeSwap;
+   unsigned long long int cachedSwap;
 
    int cpuCount;
 

SwapMeter.c

@@ -14,7 +14,8 @@ in the source distribution for its full text.
 
 
 static const int SwapMeter_attributes[] = {
-   SWAP
+   SWAP,
+   SWAP_CACHE
 };
 
 static void SwapMeter_updateValues(Meter* this, char* buffer, size_t size) {
@@ -38,6 +39,12 @@ static void SwapMeter_display(const Object* cast, RichString* out) {
    Meter_humanUnit(buffer, this->values[0], sizeof(buffer));
    RichString_appendAscii(out, CRT_colors[METER_TEXT], " used:");
    RichString_appendAscii(out, CRT_colors[METER_VALUE], buffer);
+
+#ifdef HTOP_LINUX
+   Meter_humanUnit(buffer, this->values[1], sizeof(buffer));
+   RichString_appendAscii(out, CRT_colors[METER_TEXT], " cache:");
+   RichString_appendAscii(out, CRT_colors[SWAP_CACHE], buffer);
+#endif
 }
 
 const MeterClass SwapMeter_class = {
@@ -48,7 +55,7 @@ const MeterClass SwapMeter_class = {
    },
    .updateValues = SwapMeter_updateValues,
    .defaultMode = BAR_METERMODE,
-   .maxItems = 1,
+   .maxItems = 2,
    .total = 100.0,
    .attributes = SwapMeter_attributes,
    .name = "Swap",

dragonflybsd/Platform.c

@@ -205,6 +205,7 @@ void Platform_setSwapValues(Meter* this) {
    const ProcessList* pl = this->pl;
    this->total = pl->totalSwap;
    this->values[0] = pl->usedSwap;
+   this->values[1] = NAN;
 }
 
 char* Platform_getProcessEnv(pid_t pid) {

freebsd/Platform.c

@@ -225,6 +225,7 @@ void Platform_setSwapValues(Meter* this) {
    const ProcessList* pl = this->pl;
    this->total = pl->totalSwap;
    this->values[0] = pl->usedSwap;
+   this->values[1] = NAN;
 }
 
 void Platform_setZfsArcValues(Meter* this) {

linux/LinuxProcessList.c

@@ -1508,6 +1508,7 @@ static inline void LinuxProcessList_scanMemoryInfo(ProcessList* this) {
          switch (buffer[1]) {
          case 'w':
             tryRead("SwapTotal:", &this->totalSwap);
+            tryRead("SwapCached:", &this->cachedSwap);
             tryRead("SwapFree:", &swapFree);
             break;
          case 'h':
@@ -1524,7 +1525,7 @@ static inline void LinuxProcessList_scanMemoryInfo(ProcessList* this) {
 
    this->usedMem = this->totalMem - freeMem;
    this->cachedMem = this->cachedMem + sreclaimable - shmem;
-   this->usedSwap = this->totalSwap - swapFree;
+   this->usedSwap = this->totalSwap - swapFree - this->cachedSwap;
    fclose(file);
 }
 

linux/Platform.c

@@ -301,6 +301,7 @@ void Platform_setSwapValues(Meter* this) {
    const ProcessList* pl = this->pl;
    this->total = pl->totalSwap;
    this->values[0] = pl->usedSwap;
+   this->values[1] = pl->cachedSwap;
 }
 
 void Platform_setZramValues(Meter* this) {

openbsd/Platform.c

@@ -213,6 +213,7 @@ void Platform_setSwapValues(Meter* this) {
    const ProcessList* pl = this->pl;
    this->total = pl->totalSwap;
    this->values[0] = pl->usedSwap;
+   this->values[1] = NAN;
 }
 
 char* Platform_getProcessEnv(pid_t pid) {

solaris/Platform.c

@@ -223,6 +223,7 @@ void Platform_setSwapValues(Meter* this) {
    const ProcessList* pl = this->pl;
    this->total = pl->totalSwap;
    this->values[0] = pl->usedSwap;
+   this->values[1] = NAN;
 }
 
 void Platform_setZfsArcValues(Meter* this) {