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annotate src/lru_cache.sml @ 2297:6d56080f495c

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Fix a read-after-free bug using a timestamp check
author Adam Chlipala <adam@chlipala.net>
date Thu, 19 Nov 2015 13:18:58 -0500
parents 5104e480b3e3
children 6e580e319077
rev   line source
ziv@2234 1 structure LruCache : sig
ziv@2234 2 val cache : Cache.cache
ziv@2234 3 end = struct
ziv@2234 4
ziv@2234 5
ziv@2234 6 (* Mono *)
ziv@2234 7
ziv@2234 8 open Mono
ziv@2234 9
ziv@2234 10 val dummyLoc = ErrorMsg.dummySpan
ziv@2234 11 val stringTyp = (TFfi ("Basis", "string"), dummyLoc)
ziv@2234 12 val optionStringTyp = (TOption stringTyp, dummyLoc)
ziv@2234 13 fun withTyp typ = map (fn exp => (exp, typ))
ziv@2234 14
ziv@2234 15 fun ffiAppCache' (func, index, argTyps) =
ziv@2265 16 EFfiApp ("Sqlcache", func ^ Int.toString index, argTyps)
ziv@2234 17
ziv@2234 18 fun check (index, keys) =
ziv@2234 19 ffiAppCache' ("check", index, withTyp stringTyp keys)
ziv@2234 20
ziv@2234 21 fun store (index, keys, value) =
ziv@2234 22 ffiAppCache' ("store", index, (value, stringTyp) :: withTyp stringTyp keys)
ziv@2234 23
ziv@2234 24 fun flush (index, keys) =
ziv@2234 25 ffiAppCache' ("flush", index, withTyp optionStringTyp keys)
ziv@2234 26
ziv@2286 27 fun lock (index, write) =
ziv@2286 28 ffiAppCache' ((if write then "w" else "r") ^ "lock", index, [])
ziv@2286 29
ziv@2234 30
ziv@2234 31 (* Cjr *)
ziv@2234 32
ziv@2234 33 open Print
ziv@2234 34 open Print.PD
ziv@2234 35
ziv@2234 36 fun setupQuery {index, params} =
ziv@2234 37 let
ziv@2234 38
ziv@2234 39 val i = Int.toString index
ziv@2234 40
ziv@2234 41 fun paramRepeat itemi sep =
ziv@2234 42 let
ziv@2234 43 fun f n =
ziv@2234 44 if n < 0 then ""
ziv@2234 45 else if n = 0 then itemi (Int.toString 0)
ziv@2234 46 else f (n-1) ^ sep ^ itemi (Int.toString n)
ziv@2234 47 in
ziv@2234 48 f (params - 1)
ziv@2234 49 end
ziv@2234 50
ziv@2234 51 fun paramRepeatRev itemi sep =
ziv@2234 52 let
ziv@2234 53 fun f n =
ziv@2234 54 if n < 0 then ""
ziv@2234 55 else if n = 0 then itemi (Int.toString 0)
ziv@2234 56 else itemi (Int.toString n) ^ sep ^ f (n-1)
ziv@2234 57 in
ziv@2234 58 f (params - 1)
ziv@2234 59 end
ziv@2234 60
ziv@2234 61 fun paramRepeatInit itemi sep =
ziv@2234 62 if params = 0 then "" else sep ^ paramRepeat itemi sep
ziv@2234 63
ziv@2234 64 val typedArgs = paramRepeatInit (fn p => "uw_Basis_string p" ^ p) ", "
ziv@2234 65
ziv@2234 66 val revArgs = paramRepeatRev (fn p => "p" ^ p) ", "
ziv@2234 67
ziv@2234 68 in
ziv@2234 69 Print.box
ziv@2250 70 [string ("static uw_Sqlcache_Cache cacheStruct" ^ i ^ " = {"),
ziv@2285 71 newline,
ziv@2288 72 string " .lockIn = PTHREAD_RWLOCK_INITIALIZER,",
ziv@2288 73 newline,
ziv@2288 74 string " .lockOut = PTHREAD_RWLOCK_INITIALIZER,",
ziv@2234 75 newline,
ziv@2234 76 string " .table = NULL,",
ziv@2234 77 newline,
ziv@2281 78 string (" .numKeys = " ^ Int.toString params ^ ","),
ziv@2281 79 newline,
ziv@2234 80 string " .timeInvalid = 0,",
ziv@2234 81 newline,
ziv@2279 82 string " .timeNow = 0};",
ziv@2234 83 newline,
ziv@2250 84 string ("static uw_Sqlcache_Cache *cache" ^ i ^ " = &cacheStruct" ^ i ^ ";"),
ziv@2234 85 newline,
ziv@2234 86 newline,
ziv@2234 87
ziv@2288 88 string ("static void uw_Sqlcache_rlock" ^ i ^ "(uw_context ctx) {"),
ziv@2288 89 newline,
ziv@2288 90 string (" uw_Sqlcache_rlock(ctx, cache" ^ i ^ ");"),
ziv@2288 91 newline,
ziv@2288 92 string "}",
ziv@2288 93 newline,
ziv@2288 94 newline,
ziv@2288 95
ziv@2288 96 string ("static void uw_Sqlcache_wlock" ^ i ^ "(uw_context ctx) {"),
ziv@2288 97 newline,
ziv@2288 98 string (" uw_Sqlcache_wlock(ctx, cache" ^ i ^ ");"),
ziv@2288 99 newline,
ziv@2288 100 string "}",
ziv@2288 101 newline,
ziv@2288 102 newline,
ziv@2288 103
ziv@2234 104 string ("static uw_Basis_string uw_Sqlcache_check" ^ i),
ziv@2234 105 string ("(uw_context ctx" ^ typedArgs ^ ") {"),
ziv@2234 106 newline,
ziv@2234 107 string (" char *ks[] = {" ^ revArgs ^ "};"),
ziv@2234 108 newline,
ziv@2285 109 string (" uw_Sqlcache_Value *v = uw_Sqlcache_check(ctx, cache" ^ i ^ ", ks);"),
ziv@2234 110 newline,
ziv@2262 111 (* If the output is null, it means we had too much recursion, so it's a miss. *)
ziv@2262 112 string " if (v && v->output != NULL) {",
ziv@2234 113 newline,
adam@2296 114 (*string (" puts(\"SQLCACHE: hit " ^ i ^ ".\");"),
adam@2296 115 newline,*)
ziv@2234 116 string " uw_write(ctx, v->output);",
ziv@2234 117 newline,
ziv@2234 118 string " return v->result;",
ziv@2234 119 newline,
ziv@2234 120 string " } else {",
ziv@2234 121 newline,
adam@2296 122 (*string (" puts(\"SQLCACHE: miss " ^ i ^ ".\");"),
adam@2296 123 newline,*)
ziv@2234 124 string " uw_recordingStart(ctx);",
ziv@2234 125 newline,
ziv@2234 126 string " return NULL;",
ziv@2234 127 newline,
ziv@2234 128 string " }",
ziv@2234 129 newline,
ziv@2234 130 string "}",
ziv@2234 131 newline,
ziv@2234 132 newline,
ziv@2234 133
ziv@2234 134 string ("static uw_unit uw_Sqlcache_store" ^ i),
ziv@2234 135 string ("(uw_context ctx, uw_Basis_string s" ^ typedArgs ^ ") {"),
ziv@2234 136 newline,
ziv@2234 137 string (" char *ks[] = {" ^ revArgs ^ "};"),
ziv@2234 138 newline,
adam@2297 139 string (" uw_Sqlcache_Value *v = malloc(sizeof(uw_Sqlcache_Value));"),
ziv@2234 140 newline,
ziv@2234 141 string " v->result = strdup(s);",
ziv@2234 142 newline,
ziv@2234 143 string " v->output = uw_recordingRead(ctx);",
ziv@2234 144 newline,
adam@2296 145 (*string (" puts(\"SQLCACHE: stored " ^ i ^ ".\");"),
adam@2296 146 newline,*)
ziv@2285 147 string (" uw_Sqlcache_store(ctx, cache" ^ i ^ ", ks, v);"),
ziv@2234 148 newline,
ziv@2234 149 string " return uw_unit_v;",
ziv@2234 150 newline,
ziv@2234 151 string "}",
ziv@2234 152 newline,
ziv@2234 153 newline,
ziv@2234 154
ziv@2234 155 string ("static uw_unit uw_Sqlcache_flush" ^ i),
ziv@2234 156 string ("(uw_context ctx" ^ typedArgs ^ ") {"),
ziv@2234 157 newline,
ziv@2234 158 string (" char *ks[] = {" ^ revArgs ^ "};"),
ziv@2234 159 newline,
ziv@2284 160 string (" uw_Sqlcache_flush(ctx, cache" ^ i ^ ", ks);"),
ziv@2234 161 newline,
ziv@2234 162 string " return uw_unit_v;",
ziv@2234 163 newline,
ziv@2234 164 string "}",
ziv@2234 165 newline,
ziv@2234 166 newline]
ziv@2234 167 end
ziv@2234 168
ziv@2234 169 val setupGlobal = string "/* No global setup for LRU cache. */"
ziv@2234 170
ziv@2234 171
ziv@2234 172 (* Bundled up. *)
ziv@2234 173
ziv@2234 174 (* For now, use the toy implementation if there are no arguments. *)
ziv@2234 175 fun toyIfNoKeys numKeys implLru implToy args =
ziv@2234 176 if numKeys args = 0
ziv@2234 177 then implToy args
ziv@2234 178 else implLru args
ziv@2234 179
ziv@2234 180 val cache =
ziv@2286 181 (* let *)
ziv@2286 182 (* val {check = toyCheck, *)
ziv@2286 183 (* store = toyStore, *)
ziv@2286 184 (* flush = toyFlush, *)
ziv@2286 185 (* setupQuery = toySetupQuery, *)
ziv@2286 186 (* ...} = ToyCache.cache *)
ziv@2286 187 (* in *)
ziv@2286 188 (* {check = toyIfNoKeys (length o #2) check toyCheck, *)
ziv@2286 189 (* store = toyIfNoKeys (length o #2) store toyStore, *)
ziv@2286 190 (* flush = toyIfNoKeys (length o #2) flush toyFlush, *)
ziv@2286 191 {check = check, store = store, flush = flush, lock = lock,
ziv@2286 192 setupQuery = setupQuery, setupGlobal = setupGlobal}
ziv@2286 193 (* end *)
ziv@2234 194
ziv@2234 195 end