htop/DynamicMeter.h

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Add a new DynamicMeter class for runtime Meter extension This commit is based on exploratory work by Sohaib Mohamed. The end goal is two-fold - to support addition of Meters we build via configuration files for both the PCP platform and for scripts ( https://github.com/htop-dev/htop/issues/526 ) Here, we focus on generic code and the PCP support. A new class DynamicMeter is introduced - it uses the special case 'param' field handling that previously was used only by the CPUMeter, such that every runtime-configured Meter is given a unique identifier. Unlike with the CPUMeter this is used internally only. When reading/writing to htoprc instead of CPU(N) - where N is an integer param (CPU number) - we use the string name for each meter. For example, if we have a configuration for a DynamicMeter for some Redis metrics, we might read and write "Dynamic(redis)". This identifier is subsequently matched (back) up to the configuration file so we're able to re-create arbitrary user configurations. The PCP platform configuration file format is fairly simple. We expand configs from several directories, including the users homedir alongside htoprc (below htop/meters/) and also /etc/pcp/htop/meters. The format will be described via a new pcp-htop(5) man page, but its basically ini-style and each Meter has one or more metric expressions associated, as well as specifications for labels, color and so on via a dot separated notation for individual metrics within the Meter. A few initial sample configuration files are provided below ./pcp/meters that give the general idea. The PCP "derived" metric specification - see pmRegisterDerived(3) - is used as the syntax for specifying metrics in PCP DynamicMeters.
2021-06-23 07:44:56 +00:00
#ifndef HEADER_DynamicMeter
#define HEADER_DynamicMeter
#include "Meter.h"
typedef struct DynamicMeter_ {
char name[32]; /* unique name, cannot contain spaces */
char* caption;
char* description;
unsigned int type;
double maximum;
void* dynamicData; /* platform-specific meter data */
} DynamicMeter;
Hashtable* DynamicMeters_new(void);
const char* DynamicMeter_lookup(const ProcessList* pl, unsigned int param);
unsigned int DynamicMeter_search(const ProcessList* pl, const char* name);
extern const MeterClass DynamicMeter_class;
#endif