package hack_parallel
Parallel and shared memory library
Install
Dune Dependency
Authors
Maintainers
Sources
1.0.1.tar.gz
md5=ba7c72bc207e326b72e294fc76f6ad2c
sha512=5020d47f97bea2f88e2a40411894d03232a7f2282606926c93c7d4c96d72e94a966be852897a9b16f7e0893ba376512045abb9d93020a7c03c3def4f3d918f8e
doc/src/hack_parallel.heap/sharedMem.ml.html
Source file sharedMem.ml
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(** * Copyright (c) 2015, Facebook, Inc. * All rights reserved. * * This source code is licensed under the MIT license found in the * LICENSE file in the "hack" directory of this source tree. * *) open Hack_core (* Don't change the ordering of this record without updating hh_shared_init in * hh_shared.c, which indexes into config objects *) type config = { global_size : int; heap_size : int; dep_table_pow : int; hash_table_pow : int; shm_dirs : string list; shm_min_avail : int; log_level : int; } (* Allocated in C only. *) type handle = private { h_fd: Unix.file_descr; h_global_size: int; h_heap_size: int; } let kind_of_int x = match x with | 0 -> `ConstantK | 1 -> `ClassK | 2 -> `FuncK | _ when x < 0 -> failwith "kind_of_int: attempted to convert from negative int" | _ -> assert (x > 0); failwith "kind_of_int: int too large, no corresponding kind" let _kind_of_int = kind_of_int exception Hash_table_full exception Dep_table_full exception Heap_full exception Revision_length_is_zero exception Sql_assertion_failure of int exception Failed_anonymous_memfd_init exception Less_than_minimum_available of int exception Failed_to_use_shm_dir of string exception C_assertion_failure of string let () = Callback.register_exception "out_of_shared_memory" Out_of_shared_memory; Callback.register_exception "hash_table_full" Hash_table_full; Callback.register_exception "dep_table_full" Dep_table_full; Callback.register_exception "heap_full" Heap_full; Callback.register_exception "revision_length_is_zero" Revision_length_is_zero; Callback.register_exception "sql_assertion_failure" (Sql_assertion_failure 0); Callback.register_exception "failed_anonymous_memfd_init" Failed_anonymous_memfd_init; Callback.register_exception "less_than_minimum_available" (Less_than_minimum_available 0); Callback.register_exception "c_assertion_failure" (C_assertion_failure "dummy string") (*****************************************************************************) (* Initializes the shared memory. Must be called before forking. *) (*****************************************************************************) let anonymous_init config = hh_shared_init ~config ~shm_dir: None let rec shm_dir_init config = function | [] -> Hh_logger.log "We've run out of filesystems to use for shared memory"; raise Out_of_shared_memory | shm_dir::shm_dirs -> let shm_min_avail = config.shm_min_avail in begin try (* For some reason statvfs is segfaulting when the directory doesn't * exist, instead of returning -1 and an errno *) if not (Sys.file_exists shm_dir) then raise (Failed_to_use_shm_dir "shm_dir does not exist"); hh_shared_init ~config ~shm_dir:(Some shm_dir) with | Less_than_minimum_available avail -> EventLogger.(log_if_initialized (fun () -> sharedmem_less_than_minimum_available ~shm_dir ~shm_min_avail ~avail )); if !Utils.debug then Hh_logger.log "Filesystem %s only has %d bytes available, \ which is less than the minimum %d bytes" shm_dir avail config.shm_min_avail; shm_dir_init config shm_dirs | Unix.Unix_error (e, fn, arg) -> let fn_string = if fn = "" then "" else Utils.spf " thrown by %s(%s)" fn arg in let reason = Utils.spf "Unix error%s: %s" fn_string (Unix.error_message e) in EventLogger.(log_if_initialized (fun () -> sharedmem_failed_to_use_shm_dir ~shm_dir ~reason )); if !Utils.debug then Hh_logger.log "Failed to use shm dir `%s`: %s" shm_dir reason; shm_dir_init config shm_dirs | Failed_to_use_shm_dir reason -> EventLogger.(log_if_initialized (fun () -> sharedmem_failed_to_use_shm_dir ~shm_dir ~reason )); if !Utils.debug then Hh_logger.log "Failed to use shm dir `%s`: %s" shm_dir reason; shm_dir_init config shm_dirs end let init config = try anonymous_init config with Failed_anonymous_memfd_init -> EventLogger.(log_if_initialized (fun () -> sharedmem_failed_anonymous_memfd_init () )); if !Utils.debug then Hh_logger.log "Failed to use anonymous memfd init"; shm_dir_init config config.shm_dirs external connect : handle -> unit = "hh_connect" (*****************************************************************************) (* The shared memory garbage collector. It must be called every time we * free data (cf hh_shared.c for the underlying C implementation). *) (*****************************************************************************) external hh_collect: unit -> unit = "hh_collect" [@@noalloc] (*****************************************************************************) (* Serializes the dependency table and writes it to a file *) (*****************************************************************************) external loaded_dep_table_filename_c: unit -> string = "hh_get_loaded_dep_table_filename" let loaded_dep_table_filename () = let fn = loaded_dep_table_filename_c () in if String.equal "" fn then None else Some fn (** Returns number of dependency edges added. *) external save_dep_table_sqlite_c: string -> string -> int = "hh_save_dep_table_sqlite" let save_dep_table_sqlite : string -> string -> int = fun fn build_revision -> if (loaded_dep_table_filename ()) <> None then failwith "save_dep_table_sqlite not supported when server is loaded from a saved state"; Hh_logger.log "Dumping a saved state deptable."; save_dep_table_sqlite_c fn build_revision (*****************************************************************************) (* Loads the dependency table by reading from a file *) (*****************************************************************************) external load_dep_table_sqlite_c: string -> bool -> int = "hh_load_dep_table_sqlite" let load_dep_table_sqlite : string -> bool -> int = fun fn ignore_hh_version -> load_dep_table_sqlite_c fn ignore_hh_version (*****************************************************************************) (* Serializes & loads the hash table directly into memory *) (*****************************************************************************) external save_table: string -> unit = "hh_save_table" external load_table: string -> unit = "hh_load_table" (*****************************************************************************) (* Serializes the hash table to sqlite *) (*****************************************************************************) external hh_save_table_sqlite: string -> int = "hh_save_table_sqlite" let save_table_sqlite filename = hh_save_table_sqlite filename external hh_save_table_keys_sqlite: string -> string array -> int = "hh_save_table_keys_sqlite" let save_table_keys_sqlite filename keys = hh_save_table_keys_sqlite filename keys (*****************************************************************************) (* Loads the hash table by reading from a file *) (*****************************************************************************) external hh_load_table_sqlite: string -> bool -> int = "hh_load_table_sqlite" let load_table_sqlite filename verify = hh_load_table_sqlite filename verify (*****************************************************************************) (* Cleans up the artifacts generated by SQL *) (*****************************************************************************) external cleanup_sqlite: unit -> unit = "hh_cleanup_sqlite" (*****************************************************************************) (* The size of the dynamically allocated shared memory section *) (*****************************************************************************) external heap_size: unit -> int = "hh_used_heap_size" [@@noalloc] (*****************************************************************************) (* Part of the heap not reachable from hashtable entries. *) (*****************************************************************************) external wasted_heap_size: unit -> int = "hh_wasted_heap_size" [@@noalloc] (*****************************************************************************) (* The logging level for shared memory statistics *) (* 0 = nothing *) (* 1 = log totals, averages, min, max bytes marshalled and unmarshalled *) (*****************************************************************************) external hh_log_level : unit -> int = "hh_log_level" [@@noalloc] (*****************************************************************************) (* The number of used slots in our hashtable *) (*****************************************************************************) external hash_used_slots : unit -> int * int = "hh_hash_used_slots" (*****************************************************************************) (* The total number of slots in our hashtable *) (*****************************************************************************) external hash_slots : unit -> int = "hh_hash_slots" (*****************************************************************************) (* The number of used slots in our dependency table *) (*****************************************************************************) external dep_used_slots : unit -> int = "hh_dep_used_slots" (*****************************************************************************) (* The total number of slots in our dependency table *) (*****************************************************************************) external dep_slots : unit -> int = "hh_dep_slots" (*****************************************************************************) (* Must be called after the initialization of the hack server is over. * (cf serverInit.ml). *) (*****************************************************************************) external hh_check_heap_overflow: unit -> bool = "hh_check_heap_overflow" let init_done () = EventLogger.sharedmem_init_done (heap_size ()) type table_stats = { nonempty_slots : int; used_slots : int; slots : int; } let dep_stats () = let used = dep_used_slots () in { nonempty_slots = used; used_slots = used; slots = dep_slots (); } let hash_stats () = let used_slots, nonempty_slots = hash_used_slots () in { nonempty_slots; used_slots; slots = hash_slots (); } let should_collect (effort : [ `gentle | `aggressive | `always_TEST ]) = let overhead = match effort with | `always_TEST -> 1.0 | `aggressive -> 1.2 | `gentle -> 2.0 in let used = heap_size () in let wasted = wasted_heap_size () in let reachable = used - wasted in used >= truncate ((float reachable) *. overhead) let collect (effort : [ `gentle | `aggressive | `always_TEST ]) = let old_size = heap_size () in Stats.update_max_heap_size old_size; let start_t = Unix.gettimeofday () in (* The wrapper is used to run the function in a worker instead of master. *) if should_collect effort then hh_collect (); let new_size = heap_size () in let time_taken = Unix.gettimeofday () -. start_t in if old_size <> new_size then begin EventLogger.sharedmem_gc_ran effort old_size new_size time_taken end let is_heap_overflow () = hh_check_heap_overflow () (*****************************************************************************) (* Compute size of values in the garbage-collected heap *) (*****************************************************************************) module HeapSize = struct let rec traverse ((visited:ISet.t), acc) r = if Obj.is_block r then begin let p:int = Obj.magic r in if ISet.mem p visited then (visited,acc) else begin let visited' = ISet.add p visited in let n = Obj.size r in let acc' = acc + 1 + n in if Obj.tag r < Obj.no_scan_tag then traverse_fields (visited', acc') r n else (visited', acc') end end else (visited, acc) and traverse_fields acc r i = let i = i - 1 in if i < 0 then acc else traverse_fields (traverse acc (Obj.field r i)) r i (* Return size in bytes that o occupies in GC heap *) let size r = let (_, w) = traverse (ISet.empty, 0) r in w * (Sys.word_size / 8) end let value_size = HeapSize.size (*****************************************************************************) (* Module returning the MD5 of the key. It's because the code in C land * expects this format. I prefer to make it an abstract type to make sure * we don't forget to give the MD5 instead of the key itself. *) (*****************************************************************************) module type Key = sig (* The type of keys that OCaml-land callers try to insert *) type userkey (* The type of keys that get stored in the C hashtable *) type t (* The type of old keys that get stored in the C hashtable *) type old (* The md5 of an old or a new key *) type md5 (* Creation/conversion primitives *) val make : Prefix.t -> userkey -> t val make_old : Prefix.t -> userkey -> old val to_old : t -> old val new_from_old : old -> t (* Md5 primitives *) val md5 : t -> md5 val md5_old : old -> md5 val string_of_md5 : md5 -> string end module KeyFunctor (UserKeyType : sig type t val to_string : t -> string end) : Key with type userkey = UserKeyType.t = struct type userkey = UserKeyType.t type t = string type old = string type md5 = string (* The prefix we use for old keys. The prefix guarantees that we never * mix old and new data, because a key can never start with the prefix * "old_", it always starts with a number (cf Prefix.make()). *) let old_prefix = "old_" let make prefix x = Prefix.make_key prefix (UserKeyType.to_string x) let make_old prefix x = old_prefix^Prefix.make_key prefix (UserKeyType.to_string x) let to_old x = old_prefix^x let new_from_old x = let module S = String in S.sub x (S.length old_prefix) (S.length x - S.length old_prefix) let md5 = Digest.string let md5_old = Digest.string let string_of_md5 x = x end (*****************************************************************************) (* Raw interface to shared memory (cf hh_shared.c for the underlying * representation). *) (*****************************************************************************) module Raw (Key: Key) (Value:Value.Type): sig val add : Key.md5 -> Value.t -> unit val mem : Key.md5 -> bool val get : Key.md5 -> Value.t val remove : Key.md5 -> unit val move : Key.md5 -> Key.md5 -> unit module LocalChanges : sig val has_local_changes : unit -> bool val push_stack : unit -> unit val pop_stack : unit -> unit val revert : Key.md5 -> unit val commit : Key.md5 -> unit val revert_all : unit -> unit val commit_all : unit -> unit end end = struct (* Returns the number of bytes allocated in the heap, or a negative number * if no new memory was allocated *) external hh_get_size : Key.md5 -> int = "hh_get_size" external hh_remove : Key.md5 -> unit = "hh_remove" external hh_move : Key.md5 -> Key.md5 -> unit = "hh_move" let hh_mem_status x = WorkerCancel.with_worker_exit (fun () -> hh_mem_status x) let _ = hh_mem_status let hh_mem x = WorkerCancel.with_worker_exit (fun () -> hh_mem x) let hh_add x y = WorkerCancel.with_worker_exit (fun () -> hh_add x y) let hh_get_and_deserialize x = WorkerCancel.with_worker_exit (fun () -> hh_get_and_deserialize x) let log_serialize compressed original = let compressed = float compressed in let original = float original in let saved = original -. compressed in let ratio = compressed /. original in Measure.sample (Value.description ^ " (bytes serialized into shared heap)") compressed; Measure.sample ("ALL bytes serialized into shared heap") compressed; Measure.sample (Value.description ^ " (bytes saved in shared heap due to compression)") saved; Measure.sample ("ALL bytes saved in shared heap due to compression") saved; Measure.sample (Value.description ^ " (shared heap compression ratio)") ratio; Measure.sample ("ALL bytes shared heap compression ratio") ratio let log_deserialize l r = let = float l in Measure.sample (Value.description ^ " (bytes deserialized from shared heap)") sharedheap; Measure.sample ("ALL bytes deserialized from shared heap") sharedheap; if hh_log_level() > 1 then begin (* value_size is a bit expensive to call this often, so only run with log levels >= 2 *) let localheap = float (value_size r) in Measure.sample (Value.description ^ " (bytes allocated for deserialized value)") localheap; Measure.sample ("ALL bytes allocated for deserialized value") localheap end (** * Represents a set of local changes to the view of the shared memory heap * WITHOUT materializing to the changes in the actual heap. This allows us to * make speculative changes to the view of the world that can be reverted * quickly and correctly. * * A LocalChanges maintains the same invariants as the shared heap. Except * add are allowed to overwrite filled keys. This is for convenience so we * do not need to remove filled keys upfront. * * LocalChanges can be committed. This will apply the changes to the previous * stack, or directly to shared memory if there are no other active stacks. * Since changes are kept local to the process, this is NOT compatible with * the parallelism provided by MultiWorker.ml *) module LocalChanges = struct type action = (* The value does not exist in the current stack. When committed this * action will invoke remove on the previous stack. *) | Remove (* The value is added to a previously empty slot. When committed this * action will invoke add on the previous stack. *) | Add of Value.t (* The value is replacing a value already associated with a key in the * previous stack. When committed this action will invoke remove then * add on the previous stack. *) | Replace of Value.t type t = { current : (Key.md5, action) Hashtbl.t; prev : t option; } let stack: t option ref = ref None let has_local_changes () = Core_kernel.Option.is_some (!stack) let rec mem stack_opt key = match stack_opt with | None -> hh_mem key | Some stack -> try Hashtbl.find stack.current key <> Remove with Not_found -> mem stack.prev key let rec get stack_opt key = match stack_opt with | None -> let v = hh_get_and_deserialize key in if hh_log_level() > 0 then (log_deserialize (hh_get_size key) (Obj.repr v)); v | Some stack -> try match Hashtbl.find stack.current key with | Remove -> failwith "Trying to get a non-existent value" | Replace value | Add value -> value with Not_found -> get stack.prev key (** * For remove/add it is best to think of them in terms of a state machine. * A key can be in the following states: * * Remove: * Local changeset removes a key from the previous stack * Replace: * Local changeset replaces value of a key in previous stack * Add: * Local changeset associates a value with a key. The key is not * present in the previous stacks * Empty: * No local changes and key is not present in previous stack * Filled: * No local changes and key has an associated value in previous stack * *Error*: * This means an exception will occur * * * Transitions table: * Remove -> *Error* * Replace -> Remove * Add -> Empty * Empty -> *Error* * Filled -> Remove *) let remove stack_opt key = match stack_opt with | None -> hh_remove key | Some stack -> try match Hashtbl.find stack.current key with | Remove -> failwith "Trying to remove a non-existent value" | Replace _ -> Hashtbl.replace stack.current key Remove | Add _ -> Hashtbl.remove stack.current key with Not_found -> if mem stack.prev key then Hashtbl.replace stack.current key Remove else failwith "Trying to remove a non-existent value" (** * Transitions table: * Remove -> Replace * Replace -> Replace * Add -> Add * Empty -> Add * Filled -> Replace *) let add stack_opt key value = match stack_opt with | None -> let compressed_size, original_size = hh_add key value in if hh_log_level() > 0 && compressed_size > 0 then log_serialize compressed_size original_size | Some stack -> try match Hashtbl.find stack.current key with | Remove | Replace _ -> Hashtbl.replace stack.current key (Replace value) | Add _ -> Hashtbl.replace stack.current key (Add value) with Not_found -> if mem stack.prev key then Hashtbl.replace stack.current key (Replace value) else Hashtbl.replace stack.current key (Add value) let move stack_opt from_key to_key = match stack_opt with | None -> hh_move from_key to_key | Some _stack -> assert (mem stack_opt from_key); assert (not @@ mem stack_opt to_key); let value = get stack_opt from_key in remove stack_opt from_key; add stack_opt to_key value let commit_action changeset key elem = match elem with | Remove -> remove changeset key | Add value -> add changeset key value | Replace value -> remove changeset key; add changeset key value (** Public API **) let push_stack () = stack := Some ({ current = Hashtbl.create 128; prev = !stack; }) let pop_stack () = match !stack with | None -> failwith "There are no active local change stacks. Nothing to pop!" | Some { prev; _ } -> stack := prev let revert key = match !stack with | None -> () | Some changeset -> Hashtbl.remove changeset.current key let commit key = match !stack with | None -> () | Some changeset -> try commit_action changeset.prev key @@ Hashtbl.find changeset.current key with Not_found -> () let revert_all () = match !stack with | None -> () | Some changeset -> Hashtbl.clear changeset.current let commit_all () = match !stack with | None -> () | Some changeset -> Hashtbl.iter (commit_action changeset.prev) changeset.current end let add key value = LocalChanges.(add !stack key value) let mem key = LocalChanges.(mem !stack key) let get key = LocalChanges.(get !stack key) let remove key = LocalChanges.(remove !stack key) let move from_key to_key = LocalChanges.(move !stack from_key to_key) end (*****************************************************************************) (* Module used to access "new" values (as opposed to old ones). * There are several cases where we need to compare the old and the new * representation of objects (to determine what has changed). * The "old" representation is the value that was bound to that key in the * last round of type-checking. * Despite the fact that the same storage is used under the hood, it's good * to separate the two interfaces to make sure we never mix old and new * values. *) (*****************************************************************************) module New : functor (Key : Key) -> functor(Value: Value.Type) -> sig (* Adds a binding to the table, the table is left unchanged if the * key was already bound. *) val add : Key.t -> Value.t -> unit val get : Key.t -> Value.t option val find_unsafe : Key.t -> Value.t val remove : Key.t -> unit val mem : Key.t -> bool (* Binds the key to the old one. * If 'mykey' is bound to 'myvalue', oldifying 'mykey' makes 'mykey' * accessible to the "Old" module, in other words: "Old.mem mykey" returns * true and "New.mem mykey" returns false after oldifying. *) val oldify : Key.t -> unit module Raw: module type of Raw (Key) (Value) end = functor (Key : Key) -> functor (Value : Value.Type) -> struct module Raw = Raw (Key) (Value) let add key value = Raw.add (Key.md5 key) value let mem key = Raw.mem (Key.md5 key) let get key = let key = Key.md5 key in if Raw.mem key then Some (Raw.get key) else None let find_unsafe key = match get key with | None -> raise Not_found | Some x -> x let remove key = let key = Key.md5 key in if Raw.mem key then begin Raw.remove key; assert (not (Raw.mem key)); end else () let oldify key = if mem key then let old_key = Key.to_old key in Raw.move (Key.md5 key) (Key.md5_old old_key) else () end (* Same as new, but for old values *) module Old : functor (Key : Key) -> functor (Value : Value.Type) -> functor (Raw : module type of Raw (Key) (Value)) -> sig val get : Key.old -> Value.t option val remove : Key.old -> unit val mem : Key.old -> bool (* Takes an old value and moves it back to a "new" one *) val revive : Key.old -> unit end = functor (Key : Key) -> functor (Value: Value.Type) -> functor (Raw : module type of Raw (Key) (Value)) -> struct let get key = let key = Key.md5_old key in if Raw.mem key then Some (Raw.get key) else None let mem key = Raw.mem (Key.md5_old key) let remove key = if mem key then Raw.remove (Key.md5_old key) let revive key = if mem key then let new_key = Key.new_from_old key in let new_key = Key.md5 new_key in let old_key = Key.md5_old key in if Raw.mem new_key then Raw.remove new_key; Raw.move old_key new_key end (*****************************************************************************) (* The signatures of what we are actually going to expose to the user *) (*****************************************************************************) module type NoCache = sig type key type t module KeySet : Set.S with type elt = key module KeyMap : MyMap.S with type key = key val add : key -> t -> unit val get : key -> t option val get_old : key -> t option val get_old_batch : KeySet.t -> t option KeyMap.t val remove_old_batch : KeySet.t -> unit val find_unsafe : key -> t val get_batch : KeySet.t -> t option KeyMap.t val remove_batch : KeySet.t -> unit val string_of_key : key -> string val mem : key -> bool val mem_old : key -> bool val oldify_batch : KeySet.t -> unit val revive_batch : KeySet.t -> unit module LocalChanges : sig val has_local_changes : unit -> bool val push_stack : unit -> unit val pop_stack : unit -> unit val revert_batch : KeySet.t -> unit val commit_batch : KeySet.t -> unit val revert_all : unit -> unit val commit_all : unit -> unit end end module type WithCache = sig include NoCache val write_through : key -> t -> unit val get_no_cache: key -> t option end (*****************************************************************************) (* The interface that all keys need to implement *) (*****************************************************************************) module type UserKeyType = sig type t val to_string : t -> string val compare : t -> t -> int end (*****************************************************************************) (* A functor returning an implementation of the S module without caching. *) (*****************************************************************************) module NoCache (UserKeyType : UserKeyType) (Value : Value.Type) = struct module Key = KeyFunctor (UserKeyType) module New = New (Key) (Value) module Old = Old (Key) (Value) (New.Raw) module KeySet = Set.Make (UserKeyType) module KeyMap = MyMap.Make (UserKeyType) type key = UserKeyType.t type t = Value.t let string_of_key key = key |> Key.make Value.prefix |> Key.md5 |> Key.string_of_md5;; let add x y = New.add (Key.make Value.prefix x) y let find_unsafe x = New.find_unsafe (Key.make Value.prefix x) let get x = try Some (find_unsafe x) with Not_found -> None let get_old x = let key = Key.make_old Value.prefix x in Old.get key let get_old_batch xs = KeySet.fold begin fun str_key acc -> let key = Key.make_old Value.prefix str_key in KeyMap.add str_key (Old.get key) acc end xs KeyMap.empty let remove_batch xs = KeySet.iter begin fun str_key -> let key = Key.make Value.prefix str_key in New.remove key end xs let oldify_batch xs = KeySet.iter begin fun str_key -> let key = Key.make Value.prefix str_key in if New.mem key then New.oldify key else let key = Key.make_old Value.prefix str_key in Old.remove key end xs let revive_batch xs = KeySet.iter begin fun str_key -> let old_key = Key.make_old Value.prefix str_key in if Old.mem old_key then Old.revive old_key else let key = Key.make Value.prefix str_key in New.remove key end xs let get_batch xs = KeySet.fold begin fun str_key acc -> let key = Key.make Value.prefix str_key in match New.get key with | None -> KeyMap.add str_key None acc | Some data -> KeyMap.add str_key (Some data) acc end xs KeyMap.empty let mem x = New.mem (Key.make Value.prefix x) let mem_old x = Old.mem (Key.make_old Value.prefix x) let remove_old_batch xs = KeySet.iter begin fun str_key -> let key = Key.make_old Value.prefix str_key in Old.remove key end xs module LocalChanges = struct include New.Raw.LocalChanges let revert_batch keys = KeySet.iter begin fun str_key -> let key = Key.make Value.prefix str_key in revert (Key.md5 key) end keys let commit_batch keys = KeySet.iter begin fun str_key -> let key = Key.make Value.prefix str_key in commit (Key.md5 key) end keys end end (*****************************************************************************) (* All the cache are configured by a module of type ConfigType *) (*****************************************************************************) module type ConfigType = sig (* The type of object we want to keep in cache *) type value (* The capacity of the cache *) val capacity : int end (*****************************************************************************) (* All the caches are functors returning a module of the following signature *) (*****************************************************************************) module type CacheType = sig type key type value val add: key -> value -> unit val get: key -> value option val remove: key -> unit val clear: unit -> unit val string_of_key : key -> string val get_size : unit -> int end (*****************************************************************************) (* Cache keeping the objects the most frequently used. *) (*****************************************************************************) module FreqCache (Key : sig type t end) (Config:ConfigType) : CacheType with type key := Key.t and type value := Config.value = struct type value = Config.value let string_of_key _key = failwith "FreqCache does not support 'string_of_key'" (* The cache itself *) let (cache: (Key.t, int ref * value) Hashtbl.t) = Hashtbl.create (2 * Config.capacity) let size = ref 0 let get_size () = !size let clear() = Hashtbl.clear cache; size := 0 (* The collection function is called when we reach twice original * capacity in size. When the collection is triggered, we only keep * the most frequently used objects. * So before collection: size = 2 * capacity * After collection: size = capacity (with the most frequently used objects) *) let collect() = if !size < 2 * Config.capacity then () else let l = ref [] in Hashtbl.iter begin fun key (freq, v) -> l := (key, !freq, v) :: !l end cache; Hashtbl.clear cache; l := List.sort ~cmp:(fun (_, x, _) (_, y, _) -> y - x) !l; let i = ref 0 in while !i < Config.capacity do match !l with | [] -> i := Config.capacity | (k, _freq, v) :: rl -> Hashtbl.replace cache k (ref 0, v); l := rl; incr i; done; size := Config.capacity; () let add x y = collect(); try let freq, y' = Hashtbl.find cache x in incr freq; if y' == y then () else Hashtbl.replace cache x (freq, y) with Not_found -> incr size; let elt = ref 0, y in Hashtbl.replace cache x elt; () let find x = let freq, value = Hashtbl.find cache x in incr freq; value let get x = try Some (find x) with Not_found -> None let remove x = if Hashtbl.mem cache x then decr size; Hashtbl.remove cache x end (*****************************************************************************) (* An ordered cache keeps the most recently used objects *) (*****************************************************************************) module OrderedCache (Key : sig type t end) (Config:ConfigType): CacheType with type key := Key.t and type value := Config.value = struct let string_of_key _key = failwith "OrderedCache does not support 'string_of_key'" let (cache: (Key.t, Config.value) Hashtbl.t) = Hashtbl.create Config.capacity let queue = Queue.create() let size = ref 0 let get_size () = !size let clear() = Hashtbl.clear cache; size := 0; Queue.clear queue; () let add x y = if !size >= Config.capacity then begin (* Remove oldest element - if it's still around. *) let elt = Queue.pop queue in if Hashtbl.mem cache elt then begin decr size; Hashtbl.remove cache elt end; end; (* Add the new element, but bump the size only if it's a new addition. *) Queue.push x queue; if not (Hashtbl.mem cache x) then incr size; Hashtbl.replace cache x y let find x = Hashtbl.find cache x let get x = try Some (find x) with Not_found -> None let remove x = try if Hashtbl.mem cache x then decr size; Hashtbl.remove cache x; with Not_found -> () end (*****************************************************************************) (* Every time we create a new cache, a function that knows how to clear the * cache is registered in the "invalidate_callback_list" global. *) (*****************************************************************************) let invalidate_callback_list = ref [] let invalidate_caches () = List.iter !invalidate_callback_list ~f:begin fun callback -> callback() end module LocalCache (UserKeyType : UserKeyType) (Value : Value.Type) = struct type key = UserKeyType.t type value = Value.t module ConfValue = struct type value = Value.t let capacity = 1000 end (* Young values cache *) module L1 = OrderedCache (UserKeyType) (ConfValue) (* Frequent values cache *) module L2 = FreqCache (UserKeyType) (ConfValue) let string_of_key _key = failwith "LocalCache does not support 'string_of_key'" let add x y = L1.add x y; L2.add x y let get x = match L1.get x with | None -> (match L2.get x with | None -> None | Some v as result -> L1.add x v; result ) | Some v as result -> L2.add x v; result let remove x = L1.remove x; L2.remove x let clear () = L1.clear(); L2.clear() let () = invalidate_callback_list := begin fun () -> L1.clear(); L2.clear() end :: !invalidate_callback_list let get_size () = L1.get_size () + L2.get_size () end (*****************************************************************************) (* A functor returning an implementation of the S module with caching. * We need to avoid constantly deserializing types, because it costs us too * much time. The caches keep a deserialized version of the types. *) (*****************************************************************************) module WithCache (UserKeyType : UserKeyType) (Value:Value.Type) = struct module Direct = NoCache (UserKeyType) (Value) type key = Direct.key type t = Direct.t module KeySet = Direct.KeySet module KeyMap = Direct.KeyMap module Cache = LocalCache (UserKeyType) (Value) let string_of_key key = Direct.string_of_key key let add x y = Direct.add x y; Cache.add x y let get_no_cache = Direct.get let write_through x y = (* Note that we do not need to do any cache invalidation here because * Direct.add is a no-op if the key already exists. *) Direct.add x y let log_hit_rate ~hit = Measure.sample (Value.description ^ " (cache hit rate)") (if hit then 1. else 0.); Measure.sample ("(ALL cache hit rate)") (if hit then 1. else 0.) let get x = match Cache.get x with | None -> let result = (match Direct.get x with | None -> None | Some v as result -> Cache.add x v; result ) in if hh_log_level () > 0 then log_hit_rate ~hit:false; result | Some _ as result -> if hh_log_level () > 0 then log_hit_rate ~hit:true; result (* We don't cache old objects, they are not accessed often enough. *) let get_old = Direct.get_old let get_old_batch = Direct.get_old_batch let mem_old = Direct.mem_old let find_unsafe x = match get x with | None -> raise Not_found | Some x -> x let mem x = match get x with | None -> false | Some _ -> true let get_batch keys = KeySet.fold begin fun key acc -> KeyMap.add key (get key) acc end keys KeyMap.empty let oldify_batch keys = Direct.oldify_batch keys; KeySet.iter Cache.remove keys let revive_batch keys = Direct.revive_batch keys; KeySet.iter Cache.remove keys let remove_batch xs = Direct.remove_batch xs; KeySet.iter Cache.remove xs let () = invalidate_callback_list := begin fun () -> Cache.clear() end :: !invalidate_callback_list let remove_old_batch = Direct.remove_old_batch module LocalChanges = struct let push_stack () = Direct.LocalChanges.push_stack (); Cache.clear () let pop_stack () = Direct.LocalChanges.pop_stack (); Cache.clear () let revert_batch keys = Direct.LocalChanges.revert_batch keys; KeySet.iter Cache.remove keys let commit_batch keys = Direct.LocalChanges.commit_batch keys; KeySet.iter Cache.remove keys let revert_all () = Direct.LocalChanges.revert_all (); Cache.clear () let commit_all () = Direct.LocalChanges.commit_all (); Cache.clear () let has_local_changes () = Direct.LocalChanges.has_local_changes () end end
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