PCP: support for 'dynamic columns' added at runtime

Implements support for arbitrary Performance Co-Pilot
metrics with per-process instance domains to form new
htop columns.  The column-to-metric mappings are setup
using configuration files which will be documented via
man pages as part of a follow-up commit.

We provide an initial set of column configurations so
as to provide new capabilities to pcp-htop: including
configs for containers, open fd counts, scheduler run
queue time, tcp/udp bytes/calls sent/recv, delay acct,
virtual machine guests, detailed virtual memory, swap.

Note there is a change to the configuration file path
resolution algorithm introduced for 'dynamic meters'.
First, look in any custom PCP_HTOP_DIR location.  Then
iterate, in priority order, users home directory, then
local sysadmins files in /etc/pcp/htop, then readonly
configuration files below /usr/share/pcp/htop.  This
final location becomes the preferred place for our own
shipped meter and column files.

The Settings file (htoprc) writing code is updated to
not using the numeric identifier for dynamic columns.
The same strategy used for dynamic meters is used here
where we write Dynamic(name) so the name can be setup
once more at start.  Regular (static) columns writing
to htoprc - i.e. numerically indexed - is unchanged.

1 files changed, 45 insertions, 9 deletions

diff --git a/AvailableColumnsPanel.c b/AvailableColumnsPanel.c
index 04e4fa58..f6c1868e 100644
--- a/AvailableColumnsPanel.c
+++ b/AvailableColumnsPanel.c
@@ -7,15 +7,20 @@ in the source distribution for its full text.
 
 #include "AvailableColumnsPanel.h"
 
+#include <assert.h>
 #include <ctype.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
 #include "ColumnsPanel.h"
+#include "DynamicColumn.h"
 #include "FunctionBar.h"
+#include "Hashtable.h"
 #include "ListItem.h"
+#include "Macros.h"
 #include "Object.h"
 #include "Process.h"
+#include "ProcessList.h"
 #include "ProvideCurses.h"
 #include "XUtils.h"
 
@@ -29,6 +34,15 @@ static void AvailableColumnsPanel_delete(Object* object) {
    free(this);
 }
 
+static void AvailableColumnsPanel_insert(AvailableColumnsPanel* this, int at, int key) {
+   const char* name;
+   if (key >= LAST_PROCESSFIELD)
+      name = DynamicColumn_init(key);
+   else
+      name = Process_fields[key].name;
+   Panel_insert(this->columns, at, (Object*) ListItem_new(name, key));
+}
+
 static HandlerResult AvailableColumnsPanel_eventHandler(Panel* super, int ch) {
    AvailableColumnsPanel* this = (AvailableColumnsPanel*) super;
    HandlerResult result = IGNORED;
@@ -42,10 +56,9 @@ static HandlerResult AvailableColumnsPanel_eventHandler(Panel* super, int ch) {
          if (!selected)
             break;
 
-         int key = selected->key;
          int at = Panel_getSelectedIndex(this->columns);
-         Panel_insert(this->columns, at, (Object*) ListItem_new(Process_fields[key].name, key));
-         Panel_setSelected(this->columns, at+1);
+         AvailableColumnsPanel_insert(this, at, selected->key);
+         Panel_setSelected(this->columns, at + 1);
          ColumnsPanel_update(this->columns);
          result = HANDLED;
          break;
@@ -68,14 +81,25 @@ const PanelClass AvailableColumnsPanel_class = {
    .eventHandler = AvailableColumnsPanel_eventHandler
 };
 
-AvailableColumnsPanel* AvailableColumnsPanel_new(Panel* columns) {
-   AvailableColumnsPanel* this = AllocThis(AvailableColumnsPanel);
-   Panel* super = (Panel*) this;
-   FunctionBar* fuBar = FunctionBar_new(AvailableColumnsFunctions, NULL, NULL);
-   Panel_init(super, 1, 1, 1, 1, Class(ListItem), true, fuBar);
+static void AvailableColumnsPanel_addDynamicColumn(ht_key_t key, void* value, void* data) {
+   const DynamicColumn* column = (const DynamicColumn*) value;
+   Panel* super = (Panel*) data;
+   const char* title = column->caption ? column->caption : column->heading;
+   if (!title)
+      title = column->name;  // fallback to the only mandatory field
+   char description[256];
+   xSnprintf(description, sizeof(description), "%s - %s", title, column->description);
+   Panel_add(super, (Object*) ListItem_new(description, key));
+}
 
-   Panel_setHeader(super, "Available Columns");
+// Handle DynamicColumns entries in the AvailableColumnsPanel
+static void AvailableColumnsPanel_addDynamicColumns(Panel* super, Hashtable* dynamicColumns) {
+   assert(dynamicColumns);
+   Hashtable_foreach(dynamicColumns, AvailableColumnsPanel_addDynamicColumn, super);
+}
 
+// Handle remaining Platform Meter entries in the AvailableColumnsPanel
+static void AvailableColumnsPanel_addPlatformColumn(Panel* super) {
    for (int i = 1; i < LAST_PROCESSFIELD; i++) {
       if (i != COMM && Process_fields[i].description) {
          char description[256];
@@ -83,6 +107,18 @@ AvailableColumnsPanel* AvailableColumnsPanel_new(Panel* columns) {
          Panel_add(super, (Object*) ListItem_new(description, i));
       }
    }
+}
+
+AvailableColumnsPanel* AvailableColumnsPanel_new(Panel* columns, Hashtable* dynamicColumns) {
+   AvailableColumnsPanel* this = AllocThis(AvailableColumnsPanel);
+   Panel* super = (Panel*) this;
+   FunctionBar* fuBar = FunctionBar_new(AvailableColumnsFunctions, NULL, NULL);
+   Panel_init(super, 1, 1, 1, 1, Class(ListItem), true, fuBar);
+
+   Panel_setHeader(super, "Available Columns");
+   AvailableColumnsPanel_addPlatformColumn(super);
+   AvailableColumnsPanel_addDynamicColumns(super, dynamicColumns);
+
    this->columns = columns;
    return this;
 }