1 {-# LANGUAGE Rank2Types #-}
3 {-| Implementation of the Ganeti Query2 filterning.
5 The filtering of results should be done in two phases.
7 In the first phase, before contacting any remote nodes for runtime
8 data, the filtering should be executed with 'Nothing' for the runtime
9 context. This will make all non-runtime filters filter correctly,
10 whereas all runtime filters will respond successfully. As described in
11 the Python version too, this makes for example /Or/ filters very
12 inefficient if they contain runtime fields.
14 Once this first filtering phase has been done, we hopefully eliminated
15 some remote nodes out of the list of candidates, we run the remote
16 data gathering, and we evaluate the filter again, this time with a
17 'Just' runtime context. This will make all filters work correctly.
19 Note that the second run will re-evaluate the config/simple fields,
20 without caching; this is not perfect, but we consider config accesses
21 very cheap (and the configuration snapshot we have won't change
22 between the two runs, hence we will not get inconsistent results).
28 Copyright (C) 2012 Google Inc.
30 This program is free software; you can redistribute it and/or modify
31 it under the terms of the GNU General Public License as published by
32 the Free Software Foundation; either version 2 of the License, or
33 (at your option) any later version.
35 This program is distributed in the hope that it will be useful, but
36 WITHOUT ANY WARRANTY; without even the implied warranty of
37 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
38 General Public License for more details.
40 You should have received a copy of the GNU General Public License
41 along with this program; if not, write to the Free Software
42 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
47 module Ganeti.Query.Filter
54 import Control.Applicative
55 import Control.Monad (liftM)
56 import qualified Data.Map as Map
57 import Data.Traversable (traverse)
58 import Text.JSON (JSValue(..), fromJSString)
59 import Text.JSON.Pretty (pp_value)
60 import qualified Text.Regex.PCRE as PCRE
62 import Ganeti.BasicTypes
65 import Ganeti.Query.Language
66 import Ganeti.Query.Types
69 -- | Compiles a filter based on field names to one based on getters.
70 compileFilter :: FieldMap a b
72 -> ErrorResult (Filter (FieldGetter a b, QffMode))
74 traverse (\field -> maybe
75 (Bad . ParameterError $ "Can't find field named '" ++
77 (\(_, g, q) -> Ok (g, q)) (field `Map.lookup` fm))
79 -- | Processes a field value given a QffMode.
80 qffField :: QffMode -> JSValue -> ErrorResult JSValue
81 qffField QffNormal v = Ok v
82 qffField QffTimestamp v =
84 JSArray [secs@(JSRational _ _), JSRational _ _] -> return secs
85 _ -> Bad $ ProgrammerError
86 "Internal error: Getter returned non-timestamp for QffTimestamp"
88 -- | Wraps a getter, filter pair. If the getter is 'FieldRuntime' but
89 -- we don't have a runtime context, we skip the filtering, returning
90 -- \"pass\". Otherwise, we pass the actual value to the filter.
91 wrapGetter :: ConfigData
94 -> (FieldGetter a b, QffMode)
95 -> (JSValue -> ErrorResult Bool)
97 wrapGetter cfg b a (getter, qff) faction =
98 case tryGetter cfg b a getter of
99 Nothing -> Ok True -- runtime missing, accepting the value
102 ResultEntry RSNormal (Just fval) -> qffField qff fval >>= faction
103 ResultEntry RSNormal Nothing ->
104 Bad $ ProgrammerError
105 "Internal error: Getter returned RSNormal/Nothing"
106 _ -> Ok True -- filter has no data to work, accepting it
108 -- | Helper to evaluate a filter getter (and the value it generates) in
109 -- a boolean context.
110 trueFilter :: JSValue -> ErrorResult Bool
111 trueFilter (JSBool x) = Ok $! x
112 trueFilter v = Bad . ParameterError $
113 "Unexpected value '" ++ show (pp_value v) ++
114 "' in boolean context"
116 -- | A type synonim for a rank-2 comparator function. This is used so
117 -- that we can pass the usual '<=', '>', '==' functions to 'binOpFilter'
118 -- and for them to be used in multiple contexts.
119 type Comparator = (Eq a, Ord a) => a -> a -> Bool
121 -- | Helper to evaluate a filder getter (and the value it generates)
122 -- in a boolean context. Note the order of arguments is reversed from
123 -- the filter definitions (due to the call chain), make sure to
124 -- compare in the reverse order too!.
125 binOpFilter :: Comparator -> FilterValue -> JSValue -> ErrorResult Bool
126 binOpFilter comp (QuotedString y) (JSString x) =
127 Ok $! fromJSString x `comp` y
128 binOpFilter comp (NumericValue y) (JSRational _ x) =
129 Ok $! x `comp` fromIntegral y
130 binOpFilter _ expr actual =
131 Bad . ParameterError $ "Invalid types in comparison, trying to compare " ++
132 show (pp_value actual) ++ " with '" ++ show expr ++ "'"
134 -- | Implements the 'RegexpFilter' matching.
135 regexpFilter :: FilterRegex -> JSValue -> ErrorResult Bool
136 regexpFilter re (JSString val) =
137 Ok $! PCRE.match (compiledRegex re) (fromJSString val)
139 Bad . ParameterError $ "Invalid field value used in regexp matching,\
140 \ expecting string but got '" ++ show (pp_value x) ++ "'"
142 -- | Implements the 'ContainsFilter' matching.
143 containsFilter :: FilterValue -> JSValue -> ErrorResult Bool
144 -- note: the next two implementations are the same, but we have to
145 -- repeat them due to the encapsulation done by FilterValue
146 containsFilter (QuotedString val) lst = do
148 return $! val `elem` lst'
149 containsFilter (NumericValue val) lst = do
151 return $! val `elem` lst'
153 -- | Verifies if a given item passes a filter. The runtime context
154 -- might be missing, in which case most of the filters will consider
155 -- this as passing the filter.
157 -- Note: we use explicit recursion to reduce unneeded memory use;
158 -- 'any' and 'all' do not play nice with monadic values, resulting in
159 -- either too much memory use or in too many thunks being created.
160 evaluateFilter :: ConfigData -> Maybe b -> a
161 -> Filter (FieldGetter a b, QffMode)
163 evaluateFilter _ _ _ EmptyFilter = Ok True
164 evaluateFilter c mb a (AndFilter flts) = helper flts
165 where helper [] = Ok True
167 v <- evaluateFilter c mb a f
171 evaluateFilter c mb a (OrFilter flts) = helper flts
172 where helper [] = Ok False
174 v <- evaluateFilter c mb a f
178 evaluateFilter c mb a (NotFilter flt) =
179 not <$> evaluateFilter c mb a flt
180 evaluateFilter c mb a (TrueFilter getter) =
181 wrapGetter c mb a getter trueFilter
182 evaluateFilter c mb a (EQFilter getter val) =
183 wrapGetter c mb a getter (binOpFilter (==) val)
184 evaluateFilter c mb a (LTFilter getter val) =
185 wrapGetter c mb a getter (binOpFilter (<) val)
186 evaluateFilter c mb a (LEFilter getter val) =
187 wrapGetter c mb a getter (binOpFilter (<=) val)
188 evaluateFilter c mb a (GTFilter getter val) =
189 wrapGetter c mb a getter (binOpFilter (>) val)
190 evaluateFilter c mb a (GEFilter getter val) =
191 wrapGetter c mb a getter (binOpFilter (>=) val)
192 evaluateFilter c mb a (RegexpFilter getter re) =
193 wrapGetter c mb a getter (regexpFilter re)
194 evaluateFilter c mb a (ContainsFilter getter val) =
195 wrapGetter c mb a getter (containsFilter val)
197 -- | Runs a getter with potentially missing runtime context.
198 tryGetter :: ConfigData -> Maybe b -> a -> FieldGetter a b -> Maybe ResultEntry
199 tryGetter _ _ item (FieldSimple getter) = Just $ getter item
200 tryGetter cfg _ item (FieldConfig getter) = Just $ getter cfg item
201 tryGetter _ rt item (FieldRuntime getter) =
202 maybe Nothing (\rt' -> Just $ getter rt' item) rt
203 tryGetter _ _ _ FieldUnknown = Just $
204 ResultEntry RSUnknown Nothing
206 -- | Computes the requested names, if only names were requested (and
207 -- with equality). Otherwise returns 'Nothing'.
208 requestedNames :: FilterField -> Filter FilterField -> Maybe [FilterValue]
209 requestedNames _ EmptyFilter = Just []
210 requestedNames namefield (OrFilter flts) =
211 liftM concat $ mapM (requestedNames namefield) flts
212 requestedNames namefield (EQFilter fld val) =
216 requestedNames _ _ = Nothing
218 -- | Builds a simple filter from a list of names.
219 makeSimpleFilter :: String -> [Either String Integer] -> Filter FilterField
220 makeSimpleFilter _ [] = EmptyFilter
221 makeSimpleFilter namefield vals =
222 OrFilter $ map (EQFilter namefield . either QuotedString NumericValue) vals