Module `Rrd`Source

This module provides a util that records data in a way that's compatible with rrdtool.

Sourcemodule Fring = Rrd_fring

Sourcemodule Utils = Rrd_utils

Sourceexception No_RRA_Available

Sourceexception Invalid_data_source of string

Sourcetype ds_owner =

| VM of string
| Host
| SR of string

Sourcetype ds_type =

| Absolute
| Gauge
| Derive

Data source types - see ds datatype

Sourceval rpc_of_ds_type : ds_type -> Rpc.t

Sourceval ds_type_of_rpc : Rpc.t -> ds_type

Sourcetype cf_type =

| CF_Average
| CF_Min
| CF_Max
| CF_Last

Consolidation function - see RRA datatype

Sourcetype ds_value_type =

| VT_Float of float
| VT_Int64 of int64
| VT_Unknown

Container so that we can handle different typed inputs

Sourceval rpc_of_ds_value_type : ds_value_type -> Rpc.t

Sourceval ds_value_type_of_rpc : Rpc.t -> ds_value_type

Sourcetype sampling_frequency =

| Five_Seconds

Sourceval rpc_of_sampling_frequency : sampling_frequency -> Rpc.t

Sourceval sampling_frequency_of_rpc : Rpc.t -> sampling_frequency

Sourceval (+++) : int64 -> int64 -> int64

Sourceval (---) : int64 -> int64 -> int64

Sourceval (***) : int64 -> int64 -> int64

Sourceval (///) : int64 -> int64 -> int64

Sourceval ds_type_to_string : ds_type -> string

Sourceval cf_type_of_string : string -> cf_type

Sourceval cf_type_to_string : cf_type -> string

Sourceval ds_value_to_string : ds_value_type -> string

The CDP preparation scratch area. The 'value' field should be accumulated in such a way that it always contains the value that will eventually be the CDP. This means that for averages, we accumulate 1/n * the PDP, and renormalise when we have unknown PDPs. For the other types it's much easier

Sourcetype cdp_prep = {

mutable cdp_value : float;
mutable cdp_unknown_pdps : int;
(*
How may PDPs have been unknown so far
*)

}

DS - a data source This defines how we deal with incoming data. Type is one of:

Absolute: meaning that the incoming data is an absolute rate
Derive: meaning that the rate must come from the difference between the incoming data and the previous value
Gauge: meaning that the value isn't a rate at all (e.g. temperature, load avg)

Optionally, there is a maximum time greater than which we mark the PDPs as unknown.

Sourcetype ds = {

ds_name : string;
(*
Name
*)
ds_ty : ds_type;
(*
Type of rate the input must be processed as, see above
*)
ds_min : float;
ds_max : float;
ds_mrhb : float;
(*
Maximum time between updates
*)
mutable ds_last : ds_value_type;
(*
Last raw value that was processed
*)
mutable ds_value : float;
(*
Current calculated rate of the PDP
*)
mutable ds_unknown_sec : float;
(*
Number of seconds that are unknown in the current PDP
*)

}

Sourceval rpc_of_ds : ds -> Rpc.t

Sourceval ds_of_rpc : Rpc.t -> ds

RRA - RRD archive This is an archive that holds consolidated data points (CDPs) belonging to a single consolidation function. They are stored in rings buffers, each one related to a single different data-source. It defines the type of consolidation that happens (average, max, min or last), the number of primary data points (PDPs) that go to make a CDP, and the number of CDPs to store.

To better visualize how the datapoints are stored:

│ Datasources ┃ ┃ ┃ └─────────────────┨ Memory ┃ cputime ┃ Consolidators ┃ ┃ ┃ ━━━━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━━━┫ Average ┃ Fring of CDPs ┃ Fring of CDPs ┃ ← RRA ━━━━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━━━╋━━━━━━━━━━━━━━━━━┫ Max ┃ Fring of CDPs ┃ Fring of CDPs ┃ ← RRA ━━━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━━━┛

Sourcetype rra = {

rra_cf : cf_type;
(*
consolidation function
*)
rra_row_cnt : int;
(*
number of entries to store
*)
rra_pdp_cnt : int;
(*
number of pdps per cdp
*)
rra_xff : float;
(*
proportion of missing pdps at which we mark the cdp as unknown
*)
rra_data : Fring.t array;
(*
Stored data, one ring per datasource
*)
rra_cdps : cdp_prep array;
(*
scratch area for consolidated datapoint preparation
*)
mutable rra_updatehook : (rrd -> int -> unit) option;
(*
Hook that gets called when an update happens
*)

}

The container for the DSs and RRAs. Also specifies the period between pdps

Sourceand rrd = {

mutable last_updated : float;
(*
Last updated time in seconds
*)
timestep : int64;
(*
Period between PDPs
*)
rrd_dss : ds array;
rrd_rras : rra array;

}

Sourceval copy_cdp_prep : cdp_prep -> cdp_prep

Sourceval copy_rra : rra -> rra

Sourceval copy_ds : ds -> ds

Sourceval copy_rrd : rrd -> rrd

Sourceval cf_init_value : cf_type -> ds -> float

Sourceval get_times : float -> int64 -> int64 * float

Helper function to get the start time and age of the current/last PDP

Sourceval do_cfs : rra -> int -> float array -> unit

Update the CDP value with a number (start_pdp_offset) of PDPs.

Sourceval rra_update : rrd -> int64 -> int -> float array -> unit

Update the RRAs with a number of PDPs.

Sourceval process_ds_value : ds -> ds_value_type -> float -> bool -> float

Source

val ds_update : 
  rrd ->
  float ->
  ds_value_type array ->
  (float -> float) array ->
  bool ->
  unit

Source

val ds_update_named : 
  rrd ->
  float ->
  new_domid:bool ->
  (string * (ds_value_type * (float -> float))) list ->
  unit

Update the rrd with named values rather than just an ordered array

Sourceval ds_names : rrd -> string list

Get registered DS names

Sourceval rra_create : cf_type -> int -> int -> float -> rra

create an rra structure

Source

val ds_create : 
  string ->
  ds_type ->
  ?min:float ->
  ?max:float ->
  ?mrhb:float ->
  ds_value_type ->
  ds

Sourceval rrd_create : ds array -> rra array -> int64 -> float -> rrd

Add in a new DS into a pre-existing RRD. Preserves data of all the other archives and fills the new one full of NaNs. Note that this doesn't fill in the CDP values correctly at the moment!

parameter now
= Unix.gettimeofday ()

Sourceval rrd_add_ds : rrd -> float -> ds -> rrd

Sourceval rrd_remove_ds : rrd -> string -> rrd

Remove the named DS from an RRD. Removes all of the data associated with it, too

Sourceval find_best_rras : rrd -> int -> cf_type option -> int64 -> rra list

Find the RRA with a particular CF that contains a particular start time, and also has a minimum pdp_cnt. If it can't find an appropriate one, either return the RRA with the correct CF that has the most ancient data, or raise No_RRA_Available if there's not archive with the correct CF. Assumes the RRAs are stored in increasing time-length

Sourceval query_named_ds : rrd -> float -> string -> cf_type -> float

Sourceval from_xml : Xmlm.input -> rrd

Sourceval xml_to_output : rrd -> Xmlm.output -> unit

Sourcemodule Json : sig ... end

Sourceval json_to_string : rrd -> string

Sourcemodule Statefile_latency : sig ... end

package xapi-rrd

Module RrdSource

Module `Rrd`Source