--- /dev/null
+module Database.RRDtool.Create
+ ( DataSource(..)
+ , createRRD
+
+ -- Data.HList
+ , (.*.)
+ , HNil(..)
+
+ -- Database.RRDtool.Expression
+ , Constant(..)
+ , IsVarName(..)
+ , Variable(..)
+ , CommonUnaryOp(..)
+ , CommonBinaryOp(..)
+ , CommonTrinaryOp(..)
+ , CommonSetOp(..)
+ , TrendOp(..)
+ , VariableShiftPredictOp(..)
+ , FixedShiftPredictOp(..)
+ , CommonValue(..)
+ )
+ where
+
+import Data.HList
+import Data.Time.Clock
+import Data.Time.Clock.POSIX
+import Database.RRDtool.Expression
+
+
+-- |A single RRD can accept input from several data sources (DS), for
+-- example incoming and outgoing traffic on a specific communication
+-- line. With the DS configuration option you must define some basic
+-- properties of each data source you want to store in the RRD.
+--
+-- /NOTE on COUNTER vs DERIVE/
+--
+-- by Don Baarda <don.baarda@baesystems.com>
+--
+-- If you cannot tolerate ever mistaking the occasional counter reset
+-- for a legitimate counter wrap, and would prefer \"Unknowns\" for
+-- all legitimate counter wraps and resets, always use DERIVE with
+-- @'dsMin' = 0@. Otherwise, using COUNTER with a suitable max will
+-- return correct values for all legitimate counter wraps, mark some
+-- counter resets as \"Unknown\", but can mistake some counter resets
+-- for a legitimate counter wrap.
+--
+-- For a 5 minute step and 32-bit counter, the probability of
+-- mistaking a counter reset for a legitimate wrap is arguably about
+-- 0.8% per 1Mbps of maximum bandwidth. Note that this equates to 80%
+-- for 100Mbps interfaces, so for high bandwidth interfaces and a
+-- 32bit counter, DERIVE with @'dsMin' = 0@ is probably preferable. If
+-- you are using a 64bit counter, just about any max setting will
+-- eliminate the possibility of mistaking a reset for a counter wrap.
+data DataSource
+ = -- |GAUGE is for things like temperatures or number of people in
+ -- a room or the value of a RedHat share.
+ GAUGE {
+ -- |The name you will use to reference this particular data
+ -- source from an RRD. A ds-name must be 1 to 19 characters
+ -- long in the characters @[a-zA-Z0-9_]@.
+ dsName :: !String
+ -- |Defines the maximum number of seconds that may
+ -- pass between two updates of this data source before the
+ -- value of the data source is assumed to be @*UNKNOWN*@.
+ , dsHeartbeat :: !NominalDiffTime
+ -- |'dsMin' and 'dsMax' Define the expected range values for
+ -- data supplied by a data source. If 'dsMin' and\/or 'dsMax'
+ -- any value outside the defined range will be regarded as
+ -- @*UNKNOWN*@. If you do not know or care about 'dsMin' and
+ -- 'dsMax', set them to 'Nothing' for unknown. Note that
+ -- 'dsMin' and 'dsMax' always refer to the processed values of
+ -- the DS. For a traffic-'COUNTER' type DS this would be the
+ -- maximum and minimum data-rate expected from the device.
+ --
+ -- If information on minimal\/maximal expected values is
+ -- available, always set the min and\/or max properties. This
+ -- will help RRDtool in doing a simple sanity check on the
+ -- data supplied when running update.
+ , dsMin :: !(Maybe Double)
+ -- |See 'dsMin'.
+ , dsMax :: !(Maybe Double)
+ }
+ -- |COUNTER is for continuous incrementing counters like the
+ -- ifInOctets counter in a router. The COUNTER data source assumes
+ -- that the counter never decreases, except when a counter
+ -- overflows. The update function takes the overflow into
+ -- account. The counter is stored as a per-second rate. When the
+ -- counter overflows, RRDtool checks if the overflow happened at
+ -- the 32bit or 64bit border and acts accordingly by adding an
+ -- appropriate value to the result.
+ | COUNTER {
+ dsName :: !String
+ , dsHeartbeat :: !NominalDiffTime
+ , dsMin :: !(Maybe Double)
+ , dsMax :: !(Maybe Double)
+ }
+ -- |DERIVE will store the derivative of the line going from the
+ -- last to the current value of the data source. This can be
+ -- useful for gauges, for example, to measure the rate of people
+ -- entering or leaving a room. Internally, derive works exactly
+ -- like COUNTER but without overflow checks. So if your counter
+ -- does not reset at 32 or 64 bit you might want to use DERIVE and
+ -- combine it with a 'dsMin' value of 0.
+ | DERIVE {
+ dsName :: !String
+ , dsHeartbeat :: !NominalDiffTime
+ , dsMin :: !(Maybe Double)
+ , dsMax :: !(Maybe Double)
+ }
+ -- |ABSOLUTE is for counters which get reset upon reading. This is
+ -- used for fast counters which tend to overflow. So instead of
+ -- reading them normally you reset them after every read to make
+ -- sure you have a maximum time available before the next
+ -- overflow. Another usage is for things you count like number of
+ -- messages since the last update.
+ | ABSOLUTE {
+ dsName :: !String
+ , dsHeartbeat :: !NominalDiffTime
+ , dsMin :: !(Maybe Double)
+ , dsMax :: !(Maybe Double)
+ }
+ -- |COMPUTE is for storing the result of a formula applied to
+ -- other data sources in the RRD. This data source is not supplied
+ -- a value on update, but rather its Primary Data Points (PDPs)
+ -- are computed from the PDPs of the data sources according to the
+ -- rpn-expression that defines the formula. Consolidation
+ -- functions are then applied normally to the PDPs of the COMPUTE
+ -- data source (that is the rpn-expression is only applied to
+ -- generate PDPs). In database software, such data sets are
+ -- referred to as \"virtual\" or \"computed\" columns.
+ --
+ -- FIXME: doc links
+ | forall a. IsCommonExpr a => COMPUTE {
+ dsName :: !String
+ -- |rpn-expression defines the formula used to compute the
+ -- PDPs of a COMPUTE data source from other data sources in
+ -- the same \<RRD\>. It is similar to defining a CDEF argument
+ -- for the graph command. For COMPUTE data sources, the
+ -- following RPN operations are not supported: COUNT, PREV,
+ -- TIME, and LTIME. In addition, in defining the RPN
+ -- expression, the COMPUTE data source may only refer to the
+ -- names of data source listed previously in the create
+ -- command. This is similar to the restriction that CDEFs must
+ -- refer only to DEFs and CDEFs previously defined in the same
+ -- graph command.
+ --
+ -- FIXME: doc links
+ , dsExpr :: !a
+ }
+
+dsTest :: DataSource
+dsTest = COMPUTE {
+ dsName = "foo"
+-- , dsExpr = Previous :<: Const 100
+-- , dsExpr = Var "foo" :<: Const 100
+ , dsExpr = AverageOf (Const 100 .*. Const 200 .*. HNil)
+ }
+
+-- |The 'createRRD' function lets you set up new Round Robin Database
+-- (RRD) files. The file is created at its final, full size and filled
+-- with @*UNKNOWN*@ data.
+createRRD
+ :: FilePath -- ^The name of the RRD you want to create. RRD files
+ -- should end with the extension @.rrd@. However,
+ -- RRDtool will accept any filename.
+ -> Bool -- ^Do not clobber an existing file of the same name.
+ -> Maybe POSIXTime -- ^Specifies the time in seconds since
+ -- @1970-01-01 UTC@ when the first value should
+ -- be added to the RRD. RRDtool will not accept
+ -- any data timed before or at the time
+ -- specified. (default: @now - 10s@)
+ -> Maybe NominalDiffTime -- ^Specifies the base interval in
+ -- seconds with which data will be fed
+ -- into the RRD. (default: 300 sec)
+ -> [DataSource] -- ^Data sources to accept input from.
+ -> IO ()
+createRRD = error "FIXME"
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