1 module Database.RRDtool.Create
4 , ExternalDataSource(..)
5 , ComputedDataSource(..)
12 -- Database.RRDtool.Expression
21 , VariableShiftPredictOp(..)
22 , FixedShiftPredictOp(..)
28 import Data.Time.Clock
29 import Data.Time.Clock.POSIX
30 import Database.RRDtool.Expression
33 -- |A single RRD can accept input from several data sources (DS), for
34 -- example incoming and outgoing traffic on a specific communication
35 -- line. With the DS configuration option you must define some basic
36 -- properties of each data source you want to store in the RRD.
38 -- /NOTE on COUNTER vs DERIVE/
40 -- by Don Baarda <don.baarda@baesystems.com>
42 -- If you cannot tolerate ever mistaking the occasional counter reset
43 -- for a legitimate counter wrap, and would prefer \"Unknowns\" for
44 -- all legitimate counter wraps and resets, always use DERIVE with
45 -- @'dsMin' = 0@. Otherwise, using COUNTER with a suitable max will
46 -- return correct values for all legitimate counter wraps, mark some
47 -- counter resets as \"Unknown\", but can mistake some counter resets
48 -- for a legitimate counter wrap.
50 -- For a 5 minute step and 32-bit counter, the probability of
51 -- mistaking a counter reset for a legitimate wrap is arguably about
52 -- 0.8% per 1Mbps of maximum bandwidth. Note that this equates to 80%
53 -- for 100Mbps interfaces, so for high bandwidth interfaces and a
54 -- 32bit counter, DERIVE with @'dsMin' = 0@ is probably preferable. If
55 -- you are using a 64bit counter, just about any max setting will
56 -- eliminate the possibility of mistaking a reset for a counter wrap.
60 = GAUGE -- ^GAUGE is for things like temperatures or number of
61 -- people in a room or the value of a RedHat share.
62 | COUNTER -- ^COUNTER is for continuous incrementing counters
63 -- like the ifInOctets counter in a router. The COUNTER
64 -- data source assumes that the counter never
65 -- decreases, except when a counter overflows. The
66 -- update function takes the overflow into account. The
67 -- counter is stored as a per-second rate. When the
68 -- counter overflows, RRDtool checks if the overflow
69 -- happened at the 32bit or 64bit border and acts
70 -- accordingly by adding an appropriate value to the
72 | DERIVE -- ^DERIVE will store the derivative of the line going
73 -- from the last to the current value of the data
74 -- source. This can be useful for gauges, for example,
75 -- to measure the rate of people entering or leaving a
76 -- room. Internally, derive works exactly like COUNTER
77 -- but without overflow checks. So if your counter does
78 -- not reset at 32 or 64 bit you might want to use
79 -- DERIVE and combine it with a 'dsMin' value of 0.
80 | ABSOLUTE -- ^ABSOLUTE is for counters which get reset upon
81 -- reading. This is used for fast counters which tend
82 -- to overflow. So instead of reading them normally you
83 -- reset them after every read to make sure you have a
84 -- maximum time available before the next
85 -- overflow. Another usage is for things you count like
86 -- number of messages since the last update.
87 deriving (Show, Eq, Ord)
89 instance DataSource ExternalDSType
91 data ExternalDataSource
92 = ExternalDataSource {
93 -- |The name you will use to reference this particular data
94 -- source from an RRD. A ds name must be 1 to 19 characters
95 -- long in the characters @[a-zA-Z0-9_]@.
97 -- |The type of this data source.
98 , edsType :: !ExternalDSType
99 -- |Defines the maximum number of seconds that may pass
100 -- between two updates of this data source before the value of
101 -- the data source is assumed to be @*UNKNOWN*@.
102 , edsHeartbeat :: !NominalDiffTime
103 -- |'edsMin' and 'edsMax' Define the expected range values for
104 -- data supplied by a data source. If 'edsMin' and\/or 'edsMax'
105 -- any value outside the defined range will be regarded as
106 -- @*UNKNOWN*@. If you do not know or care about 'edsMin' and
107 -- 'edsMax', set them to 'Nothing' for unknown. Note that
108 -- 'edsMin' and 'edsMax' always refer to the processed values of
109 -- the DS. For a traffic-'COUNTER' type DS this would be the
110 -- maximum and minimum data-rate expected from the device.
112 -- If information on minimal\/maximal expected values is
113 -- available, always set the min and\/or max properties. This
114 -- will help RRDtool in doing a simple sanity check on the
115 -- data supplied when running update.
116 , edsMin :: !(Maybe Double)
118 , edsMax :: !(Maybe Double)
120 deriving (Show, Eq, Ord)
123 -- |ComputedDataSource is for storing the result of a formula applied
124 -- to other data sources in the RRD. This data source is not supplied
125 -- a value on update, but rather its Primary Data Points (PDPs) are
126 -- computed from the PDPs of the data sources according to the
127 -- rpn-expression that defines the formula. Consolidation functions
128 -- are then applied normally to the PDPs of the COMPUTE data source
129 -- (that is the rpn-expression is only applied to generate PDPs). In
130 -- database software, such data sets are referred to as \"virtual\" or
131 -- \"computed\" columns.
134 data ComputedDataSource e
135 = ComputedDataSource {
138 -- |rpn-expression defines the formula used to compute the
139 -- PDPs of a COMPUTE data source from other data sources in
140 -- the same \<RRD\>. It is similar to defining a CDEF argument
141 -- for the graph command. For COMPUTE data sources, the
142 -- following RPN operations are not supported: COUNT, PREV,
143 -- TIME, and LTIME. In addition, in defining the RPN
144 -- expression, the COMPUTE data source may only refer to the
145 -- names of data source listed previously in the create
146 -- command. This is similar to the restriction that CDEFs must
147 -- refer only to DEFs and CDEFs previously defined in the same
153 deriving (Show, Eq, Ord)
155 instance IsCommonExpr e => DataSource (ComputedDataSource e)
158 dsTest = ComputedDataSource {
160 -- , dsExpr = Previous :<: Const 100
161 -- , dsExpr = Var "foo" :<: Const 100
162 , cdsExpr = AverageOf (Const 100 .*. Const 200 .*. HNil)
165 -- |The 'createRRD' function lets you set up new Round Robin Database
166 -- (RRD) files. The file is created at its final, full size and filled
167 -- with @*UNKNOWN*@ data.
169 :: FilePath -- ^The name of the RRD you want to create. RRD files
170 -- should end with the extension @.rrd@. However,
171 -- RRDtool will accept any filename.
172 -> Bool -- ^Do not clobber an existing file of the same name.
173 -> Maybe POSIXTime -- ^Specifies the time in seconds since
174 -- @1970-01-01 UTC@ when the first value should
175 -- be added to the RRD. RRDtool will not accept
176 -- any data timed before or at the time
177 -- specified. (default: @now - 10s@)
178 -> Maybe NominalDiffTime -- ^Specifies the base interval in
179 -- seconds with which data will be fed
180 -- into the RRD. (default: 300 sec)
181 -- -> [DataSource] -- ^Data sources to accept input from.
183 createRRD = error "FIXME"