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.

2 files changed, 10 insertions, 5 deletions

diff --git a/unsupported/Platform.h b/unsupported/Platform.h
index 3f704f0d..c1591de1 100644
--- a/unsupported/Platform.h
+++ b/unsupported/Platform.h
@@ -11,6 +11,7 @@ in the source distribution for its full text.
 #include "Action.h"
 #include "BatteryMeter.h"
 #include "DiskIOMeter.h"
+#include "Hashtable.h"
 #include "NetworkIOMeter.h"
 #include "ProcessLocksScreen.h"
 #include "SignalsPanel.h"
@@ -78,9 +79,7 @@ static inline void Platform_gettime_monotonic(uint64_t* msec) {
    Generic_gettime_monotonic(msec);
 }
 
-static inline Hashtable* Platform_dynamicMeters(void) {
-   return NULL;
-}
+static inline Hashtable* Platform_dynamicMeters(void) { return NULL; }
 
 static inline void Platform_dynamicMeterInit(ATTR_UNUSED Meter* meter) { }
 
@@ -88,4 +87,10 @@ static inline void Platform_dynamicMeterUpdateValues(ATTR_UNUSED Meter* meter) {
 
 static inline void Platform_dynamicMeterDisplay(ATTR_UNUSED const Meter* meter, ATTR_UNUSED RichString* out) { }
 
+static inline Hashtable* Platform_dynamicColumns(void) { return NULL; }
+
+static inline const char* Platform_dynamicColumnInit(ATTR_UNUSED unsigned int key) { return NULL; }
+
+static inline bool Platform_dynamicColumnWriteField(ATTR_UNUSED const Process* proc, ATTR_UNUSED RichString* str, ATTR_UNUSED unsigned int key) { return false; }
+
 #endif
diff --git a/unsupported/UnsupportedProcessList.c b/unsupported/UnsupportedProcessList.c
index 16c01558..bed9ca96 100644
--- a/unsupported/UnsupportedProcessList.c
+++ b/unsupported/UnsupportedProcessList.c
@@ -14,9 +14,9 @@ in the source distribution for its full text.
 #include "UnsupportedProcess.h"
 
 
-ProcessList* ProcessList_new(UsersTable* usersTable, Hashtable* dynamicMeters, Hashtable* pidMatchList, uid_t userId) {
+ProcessList* ProcessList_new(UsersTable* usersTable, Hashtable* dynamicMeters, Hashtable* dynamicColumns, Hashtable* pidMatchList, uid_t userId) {
    ProcessList* this = xCalloc(1, sizeof(ProcessList));
-   ProcessList_init(this, Class(Process), usersTable, dynamicMeters, pidMatchList, userId);
+   ProcessList_init(this, Class(Process), usersTable, dynamicMeters, dynamicColumns, pidMatchList, userId);
 
    this->existingCPUs = 1;
    this->activeCPUs = 1;