%% This Source Code Form is subject to the terms of the Mozilla Public %% License, v. 2.0. If a copy of the MPL was not distributed with this %% file, You can obtain one at https://mozilla.org/MPL/2.0/. %% %% Copyright (c) 2021-2022 VMware, Inc. or its affiliates. All rights reserved. %% %% @doc %% Khepri low-level API. %% %% This module exposes the "low-level" API to the Khepri database and state %% machine. All functions in {@link khepri} are built on top of this module. %% %% The API is divided into two parts: %%
    %%
  1. Functions to manipulate a simple set of tree nodes directly.
    2. %%
  2. Functions to perform transactional queries and updates.
    3. %%
%% %% == The store ID == %% %% All functions require a store ID ({@link store_id/0}). The store ID %% corresponds to the name of the Ra cluster Khepri was started with. %% %% See {@link khepri} for more details about Ra systems and clusters. %% %% == Direct manipulation on tree nodes == %% %% The API provides the following three functions: %% %% %% All functions take a native path pattern. They do not accept Unix-like %% paths. %% %% All functions return one of these tuples: %% %% %% == Transactional queries and updates == %% %% Transactions are handled by {@link transaction/2} and {@link %% transaction/3}. %% %% Both functions take an anonymous function. See {@link khepri_tx} for more %% details about those functions and in particular their restrictions. %% %% The return value is whatever the anonymous function returns if it succeeded %% or the reason why it aborted, similar to what {@link mnesia:transaction/1} %% returns. -module(khepri_machine). -behaviour(ra_machine). -include_lib("kernel/include/logger.hrl"). -include_lib("stdlib/include/assert.hrl"). -include("include/khepri.hrl"). -include("src/internal.hrl"). -include("src/khepri_machine.hrl"). -export([put/3, put/4, get/2, get/3, delete/2, transaction/2, transaction/3, run_sproc/3, register_trigger/4]). -export([get_keep_while_conds_state/1]). -export([init/1, apply/3, state_enter/2]). %% For internal user only. -export([ack_triggers_execution/2, find_matching_nodes/3, insert_or_update_node/4, delete_matching_nodes/2]). -ifdef(TEST). -export([are_keep_while_conditions_met/2, get_root/1, get_keep_while_conds/1, get_keep_while_conds_revidx/1]). -endif. -compile({no_auto_import, [apply/3]}). -type data() :: any(). %% Data stored in a node's payload. -type payload_version() :: pos_integer(). %% Number of changes made to the payload of a node. %% %% The payload version starts at 1 when a node is created. It is increased by 1 %% each time the payload is added, modified or removed. -type child_list_version() :: pos_integer(). %% Number of changes made to the list of child nodes of a node (child nodes %% added or removed). %% %% The child list version starts at 1 when a node is created. It is increased %% by 1 each time a child is added or removed. Changes made to existing nodes %% are not reflected in this version. -type child_list_length() :: non_neg_integer(). %% Number of direct child nodes under a tree node. -type node_props() :: #{data => data(), sproc => khepri_fun:standalone_fun(), payload_version => payload_version(), child_list_version => child_list_version(), child_list_length => child_list_length(), child_nodes => #{khepri_path:node_id() => node_props()}}. %% Structure used to return properties, payload and child nodes for a specific %% node. %% %% -type node_props_map() :: #{khepri_path:path() => node_props()}. %% Structure used to return a map of nodes and their associated properties, %% payload and child nodes. %% %% This structure is used in the return value of all commands and queries. -type result() :: khepri:ok(node_props_map()) | khepri:error(). %% Return value of a command or query. -type stat() :: #{payload_version := payload_version(), child_list_version := child_list_version()}. %% Stats attached to each node in the tree structure. -type payload_data() :: #kpayload_data{}. -type payload_sproc() :: #kpayload_sproc{}. -type payload() :: none | payload_data() | payload_sproc(). %% All types of payload stored in the nodes of the tree structure. %% %% Beside the absence of payload, the only type of payload supported is data. -type tree_node() :: #node{}. %% A node in the tree structure. -type trigger_id() :: atom(). %% An ID to identify a registered trigger. -type event_filter_tree() :: #kevf_tree{}. -type event_filter() :: event_filter_tree(). -type triggered() :: #triggered{}. -type command() :: #put{} | #delete{} | #tx{} | #register_trigger{} | #ack_triggered{}. %% Commands specific to this Ra machine. -type machine_init_args() :: #{store_id := khepri:store_id(), snapshot_interval => non_neg_integer(), commands => [command()], atom() => any()}. %% Structure passed to {@link init/1}. -type machine_config() :: #config{}. %% Configuration record, holding read-only or rarely changing fields. -type keep_while_conds_map() :: #{khepri_path:path() => khepri_condition:keep_while()}. %% Internal index of the per-node keep_while conditions. -type keep_while_conds_revidx() :: #{khepri_path:path() => #{khepri_path:path() => ok}}. %% Internal reverse index of the keep_while conditions. If node A depends on a %% condition on node B, then this reverse index will have a "node B => node A" %% entry. -type keep_while_aftermath() :: #{khepri_path:path() => node_props() | delete}. %% Internal index of the per-node changes which happened during a traversal. %% This is used when the tree is walked back up to determine the list of tree %% nodes to remove after some keep_while condition evaluates to false. -type operation_options() :: #{expect_specific_node => boolean(), include_child_names => boolean()}. %% Options used in {@link find_matching_nodes/3}. -type state() :: #?MODULE{}. %% State of this Ra state machine. -type query_fun() :: fun((state()) -> any()). %% Function representing a query and used {@link process_query/2}. -type walk_down_the_tree_extra() :: #{include_root_props => boolean(), keep_while_conds => keep_while_conds_map(), keep_while_conds_revidx => keep_while_conds_revidx(), keep_while_aftermath => keep_while_aftermath()}. -type walk_down_the_tree_fun() :: fun((khepri_path:path(), khepri:ok(tree_node()) | error(any(), map()), Acc :: any()) -> ok(tree_node() | keep | delete, any()) | khepri:error()). %% Function called to handle a node found (or an error) and used in {@link %% walk_down_the_tree/6}. -type ok(Type1, Type2) :: {ok, Type1, Type2}. -type ok(Type1, Type2, Type3) :: {ok, Type1, Type2, Type3}. -type error(Type1, Type2) :: {error, Type1, Type2}. -export_type([data/0, stat/0, payload/0, payload_data/0, payload_sproc/0, tree_node/0, trigger_id/0, event_filter/0, event_filter_tree/0, triggered/0, payload_version/0, child_list_version/0, child_list_length/0, node_props/0, node_props_map/0, result/0, operation_options/0]). -export_type([state/0, machine_config/0, keep_while_conds_map/0, keep_while_conds_revidx/0]). %% ------------------------------------------------------------------- %% Machine protocol. %% ------------------------------------------------------------------- %% TODO: Verify arguments carefully to avoid the construction of an invalid %% command. -spec put(StoreId, PathPattern, Payload) -> Result when StoreId :: khepri:store_id(), PathPattern :: khepri_path:pattern(), Payload :: payload(), Result :: result(). %% @doc Creates or modifies a specific tree node in the tree structure. %% %% Calling this function is the same as calling %% `put(StoreId, PathPattern, Payload, #{})'. %% %% @see put/4. put(StoreId, PathPattern, Payload) -> put(StoreId, PathPattern, Payload, #{}). -spec put(StoreId, PathPattern, Payload, Extra) -> Result when StoreId :: khepri:store_id(), PathPattern :: khepri_path:pattern(), Payload :: payload(), Extra :: #{keep_while => keep_while_conds_map()}, Result :: result(). %% @doc Creates or modifies a specific tree node in the tree structure. %% %% The path or path pattern must target a specific tree node. %% %% When using a simple path, if the target node does not exists, it is created %% using the given payload. If the target node exists, it is updated with the %% given payload and its payload version is increased by one. Missing parent %% nodes are created on the way. %% %% When using a path pattern, the behavior is the same. However if a condition %% in the path pattern is not met, an error is returned and the tree structure %% is not modified. %% %% If the target node is modified, the returned structure in the "ok" tuple %% will have a single key corresponding to the path of the target node. That %% key will point to a map containing the properties and payload (if any) of %% the node before the modification. %% %% If the target node is created , the returned structure in the "ok" tuple %% will have a single key corresponding to the path of the target node. That %% key will point to empty map, indicating there was no existing node (i.e. %% there was no properties or payload to return). %% %% The payload must be one of the following form: %% %% %% Example: %% ``` %% %% Insert a node at `/foo/bar', overwriting the previous value. %% Result = khepri_machine:put( %% ra_cluster_name, [foo, bar], #kpayload_data{data = new_value}), %% %% %% Here is the content of `Result'. %% {ok, #{[foo, bar] => #{data => old_value, %% payload_version => 1, %% child_list_version => 1, %% child_list_length => 0}}} = Result. %% ''' %% %% @param StoreId the name of the Ra cluster. %% @param PathPattern the path (or path pattern) to the node to create or %% modify. %% @param Payload the payload to put in the specified node. %% @param Extra extra options such as `keep_while' conditions. %% %% @returns an "ok" tuple with a map with one entry, or an "error" tuple. put(StoreId, PathPattern, Payload, Extra) when ?IS_KHEPRI_PAYLOAD(Payload) -> khepri_path:ensure_is_valid(PathPattern), Payload1 = prepare_payload(Payload), Command = #put{path = PathPattern, payload = Payload1, extra = Extra}, process_command(StoreId, Command); put(_StoreId, PathPattern, Payload, _Extra) -> throw({invalid_payload, PathPattern, Payload}). prepare_payload(none = Payload) -> Payload; prepare_payload(#kpayload_data{} = Payload) -> Payload; prepare_payload(#kpayload_sproc{sproc = Fun} = Payload) when is_function(Fun) -> StandaloneFun = khepri_sproc:to_standalone_fun(Fun), Payload#kpayload_sproc{sproc = StandaloneFun}. -spec get(StoreId, PathPattern) -> Result when StoreId :: khepri:store_id(), PathPattern :: khepri_path:pattern(), Result :: result(). %% @doc Returns all tree nodes matching the path pattern. %% %% Calling this function is the same as calling %% `get(StoreId, PathPattern, #{})'. %% %% @see get/3. get(StoreId, PathPattern) -> get(StoreId, PathPattern, #{}). -spec get(StoreId, PathPattern, Options) -> Result when StoreId :: khepri:store_id(), PathPattern :: khepri_path:pattern(), Options :: operation_options(), Result :: result(). %% @doc Returns all tree nodes matching the path pattern. %% %% The returned structure in the "ok" tuple will have a key corresponding to %% the path per node which matched the pattern. Each key will point to a map %% containing the properties and payload of that matching node. %% %% Example: %% ``` %% %% Query the node at `/foo/bar'. %% Result = khepri_machine:get(ra_cluster_name, [foo, bar]), %% %% %% Here is the content of `Result'. %% {ok, #{[foo, bar] => #{data => new_value, %% payload_version => 2, %% child_list_version => 1, %% child_list_length => 0}}} = Result. %% ''' %% %% @param StoreId the name of the Ra cluster. %% @param PathPattern the path (or path pattern) to match against the nodes to %% retrieve. %% @param Options options to tune the tree traversal or the returned structure %% content. %% %% @returns an "ok" tuple with a map with zero, one or more entries, or an %% "error" tuple. get(StoreId, PathPattern, Options) -> khepri_path:ensure_is_valid(PathPattern), Query = fun(#?MODULE{root = Root}) -> find_matching_nodes(Root, PathPattern, Options) end, process_query(StoreId, Query). -spec delete(StoreId, PathPattern) -> Result when StoreId :: khepri:store_id(), PathPattern :: khepri_path:pattern(), Result :: result(). %% @doc Deletes all tree nodes matching the path pattern. %% %% The returned structure in the "ok" tuple will have a key corresponding to %% the path per node which was deleted. Each key will point to a map containing %% the properties and payload of that deleted node. %% %% Example: %% ``` %% %% Delete the node at `/foo/bar'. %% Result = khepri_machine:delete(ra_cluster_name, [foo, bar]), %% %% %% Here is the content of `Result'. %% {ok, #{[foo, bar] => #{data => new_value, %% payload_version => 2, %% child_list_version => 1, %% child_list_length => 0}}} = Result. %% ''' %% %% @param StoreId the name of the Ra cluster. %% @param PathPattern the path (or path pattern) to match against the nodes to %% delete. %% %% @returns an "ok" tuple with a map with zero, one or more entries, or an %% "error" tuple. delete(StoreId, PathPattern) -> khepri_path:ensure_is_valid(PathPattern), Command = #delete{path = PathPattern}, process_command(StoreId, Command). -spec transaction(StoreId, Fun) -> Ret when StoreId :: khepri:store_id(), Fun :: khepri_tx:tx_fun(), Ret :: Atomic | Aborted, Atomic :: {atomic, khepri_tx:tx_fun_result()}, Aborted :: khepri_tx:tx_abort(). %% @doc Runs a transaction and returns the result. %% %% Calling this function is the same as calling %% `transaction(StoreId, Fun, auto)'. %% %% @see transaction/3. transaction(StoreId, Fun) -> transaction(StoreId, Fun, auto). -spec transaction(StoreId, Fun, ReadWrite) -> Ret when StoreId :: khepri:store_id(), Fun :: khepri_tx:tx_fun(), ReadWrite :: ro | rw | auto, Ret :: Atomic | Aborted, Atomic :: {atomic, khepri_tx:tx_fun_result()}, Aborted :: khepri_tx:tx_abort(). %% @doc Runs a transaction and returns the result. %% %% `Fun' is an arbitrary anonymous function which takes no arguments. %% %% The `ReadWrite' flag determines what the anonymous function is allowed to %% do and in which context it runs: %% %% %% %% The result of `Fun' can be any term. That result is returned in an %% `{atomic, Result}' tuple. %% %% @param StoreId the name of the Ra cluster. %% @param Fun an arbitrary anonymous function. %% %% @returns `{atomic, Result}' with the return value of `Fun', or `{aborted, %% Reason}' if the anonymous function was aborted. transaction(StoreId, Fun, auto = ReadWrite) when is_function(Fun, 0) -> case khepri_tx:to_standalone_fun(Fun, auto = ReadWrite) of #standalone_fun{} = StandaloneFun -> readwrite_transaction(StoreId, StandaloneFun); _ -> readonly_transaction(StoreId, Fun) end; transaction(StoreId, Fun, rw = ReadWrite) when is_function(Fun, 0) -> StandaloneFun = khepri_tx:to_standalone_fun(Fun, ReadWrite), readwrite_transaction(StoreId, StandaloneFun); transaction(StoreId, Fun, ro) when is_function(Fun, 0) -> readonly_transaction(StoreId, Fun); transaction(_StoreId, Fun, _ReadWrite) when is_function(Fun) -> {arity, Arity} = erlang:fun_info(Fun, arity), throw({invalid_tx_fun, {requires_args, Arity}}); transaction(_StoreId, Term, _ReadWrite) -> throw({invalid_tx_fun, Term}). readonly_transaction(StoreId, Fun) when is_function(Fun, 0) -> Query = fun(State) -> %% It is a read-only transaction, therefore we assert that %% the state is unchanged and that there are no side %% effects. {State, Ret, []} = khepri_tx:run(State, Fun, false), Ret end, case process_query(StoreId, Query) of {exception, _, {aborted, _} = Aborted, _} -> Aborted; {exception, Class, Reason, Stacktrace} -> erlang:raise(Class, Reason, Stacktrace); Ret -> {atomic, Ret} end. readwrite_transaction(StoreId, StandaloneFun) -> Command = #tx{'fun' = StandaloneFun}, case process_command(StoreId, Command) of {exception, _, {aborted, _} = Aborted, _} -> Aborted; {exception, Class, Reason, Stacktrace} -> erlang:raise(Class, Reason, Stacktrace); Ret -> {atomic, Ret} end. -spec run_sproc(StoreId, PathPattern, Args) -> Ret when StoreId :: khepri:store_id(), PathPattern :: khepri_path:pattern(), Args :: [any()], Ret :: any(). %% @doc Executes a stored procedure. %% %% The stored procedure is executed in the context of the caller of {@link %% run_sproc/3}. %% %% @param StoreId the name of the Ra cluster. %% @param PathPattern the path to the stored procedure. %% @param Args the list of args to pass to the stored procedure; its length %% must be equal to the stored procedure arity. %% %% @returns the return value of the stored procedure. run_sproc(StoreId, PathPattern, Args) when is_list(Args) -> Options = #{expect_specific_node => true}, case get(StoreId, PathPattern, Options) of {ok, Result} -> [Value] = maps:values(Result), case Value of #{sproc := StandaloneFun} -> khepri_sproc:run(StandaloneFun, Args); _ -> [Path] = maps:keys(Result), throw({invalid_sproc_fun, {no_sproc, Path, Value}}) end; Error -> throw({invalid_sproc_fun, Error}) end. -spec register_trigger(StoreId, TriggerId, EventFilter, StoredProcPath) -> Ret when StoreId :: khepri:store_id(), TriggerId :: trigger_id(), EventFilter :: event_filter(), StoredProcPath :: khepri_path:path(), Ret :: ok | khepri:error(). %% @doc Registers a trigger. %% %% A trigger is based on an event filter. It associates an event with a stored %% procedure. When an event matching the event filter is emitted, the stored %% procedure is executed. Here is an example of an event filter: %% %% ``` %% EventFilter = #kevf_tree{path = [stock, wood, <<"oak">>], %% Required %% props = #{on_actions => [delete], %% Optional %% priority => 10}}, %% Optional %% ''' %% %% The stored procedure is expected to accept a single argument. This argument %% is a map containing the event properties. Here is an example: %% %% ``` %% my_stored_procedure(Props) -> %% #{path := Path}, %% on_action => Action} = Props. %% ''' %% %% The stored procedure is executed on the leader's Erlang node. %% %% It is guarantied to run at least once. It could be executed multiple times %% if the Ra leader changes, therefore the stored procedure must be %% idempotent. %% %% @param StoreId the name of the Ra cluster. %% @param TriggerId the name of the trigger. %% @param EventFilter the event filter used to associate an event with a stored %% procedure. %% @param StoredProcPath the path to the stored procedure to execute when the %% corresponding event occurs. %% %% @returns `ok' if the trigger was registered, an "error" tuple otherwise. register_trigger(StoreId, TriggerId, EventFilter, StoredProcPath) -> Command = #register_trigger{id = TriggerId, sproc = StoredProcPath, event_filter = EventFilter}, process_command(StoreId, Command). -spec ack_triggers_execution(StoreId, TriggeredStoredProcs) -> Ret when StoreId :: khepri:store_id(), TriggeredStoredProcs :: [triggered()], Ret :: ok | khepri:error(). %% @doc Acknowledges the execution of a trigger. %% %% This is part of a mechanism to ensure that a trigger is executed at least %% once. %% %% @private ack_triggers_execution(StoreId, TriggeredStoredProcs) -> Command = #ack_triggered{triggered = TriggeredStoredProcs}, process_command(StoreId, Command). -spec get_keep_while_conds_state(StoreId) -> Ret when StoreId :: khepri:store_id(), Ret :: {ok, keep_while_conds_map()} | khepri:error(). %% @doc Returns the `keep_while' conditions internal state. %% %% The returned state consists of all the `keep_while' condition set so far. %% However, it doesn't include the reverse index. %% %% @param StoreId the name of the Ra cluster. %% %% @returns the `keep_while' conditions internal state. %% %% @private get_keep_while_conds_state(StoreId) -> Query = fun(#?MODULE{keep_while_conds = KeepWhileConds}) -> {ok, KeepWhileConds} end, process_query(StoreId, Query). -spec process_command(StoreId, Command) -> Ret when StoreId :: khepri:store_id(), Command :: command(), Ret :: any(). %% @doc Processes a command which is appended to the Ra log and processed by %% this state machine code. %% %% `Command' may modify the state of the machine. %% %% The command associated code is executed in the context of the state machine %% process on each Ra members. %% %% @param StoreId the name of the Ra cluster. %% %% @returns the result of the command or an "error" tuple. %% %% @private process_command(StoreId, Command) -> %% StoreId is the same as Ra's cluster name. case ra_leaderboard:lookup_leader(StoreId) of undefined -> {error, ra_leader_unknown}; LeaderId -> case ra:process_command(LeaderId, Command) of {ok, Ret, _LeaderId} -> Ret; {timeout, _} = Timeout -> {error, Timeout}; {error, _} = Error -> Error end end. -spec process_query(StoreId, QueryFun) -> Ret when StoreId :: khepri:store_id(), QueryFun :: query_fun(), Ret :: any(). %% @doc Processes a query which is by the Ra leader. %% %% The `QueryFun' function takes the machine state as an argument and can %% return anything. However, the machine state is never modified. The query %% does not go through the Ra log and is not replicated. %% %% The `QueryFun' function is executed from a process on the leader Ra member. %% %% @param StoreId the name of the Ra cluster. %% %% @returns the result of the query or an "error" tuple. %% %% @private process_query(StoreId, QueryFun) -> %% StoreId is the same as Ra's cluster name. case ra_leaderboard:lookup_leader(StoreId) of undefined -> {error, ra_leader_unknown}; LeaderId -> %% TODO: Leader vs. consistent? case ra:leader_query(LeaderId, QueryFun) of {ok, {_RaIndex, Ret}, _} -> Ret; {timeout, _} = Timeout -> {error, Timeout}; {error, _} = Error -> Error end end. %% ------------------------------------------------------------------- %% ra_machine callbacks. %% ------------------------------------------------------------------- -spec init(machine_init_args()) -> state(). %% @private init(#{store_id := StoreId} = Params) -> Config = case Params of #{snapshot_interval := SnapshotInterval} -> #config{store_id = StoreId, snapshot_interval = SnapshotInterval}; _ -> #config{store_id = StoreId} end, State = #?MODULE{config = Config}, %% Create initial "schema" if provided. Commands = maps:get(commands, Params, []), State3 = lists:foldl( fun (Command, State1) -> Meta = #{index => 0, term => 0, system_time => 0}, {S, _, _} = apply(Meta, Command, State1), S end, State, Commands), reset_applied_command_count(State3). -spec apply(Meta, Command, State) -> {State, Ret, SideEffects} when Meta :: ra_machine:command_meta_data(), Command :: command(), State :: state(), Ret :: any(), SideEffects :: ra_machine:effects(). %% @private %% TODO: Handle unknown/invalid commands. apply( Meta, #put{path = PathPattern, payload = Payload, extra = Extra}, State) -> Ret = insert_or_update_node(State, PathPattern, Payload, Extra), bump_applied_command_count(Ret, Meta); apply( Meta, #delete{path = PathPattern}, State) -> Ret = delete_matching_nodes(State, PathPattern), bump_applied_command_count(Ret, Meta); apply( Meta, #tx{'fun' = StandaloneFun}, State) -> Fun = case is_function(StandaloneFun) of false -> fun() -> khepri_fun:exec(StandaloneFun, []) end; true -> StandaloneFun end, Ret = khepri_tx:run(State, Fun, true), bump_applied_command_count(Ret, Meta); apply( Meta, #register_trigger{id = TriggerId, sproc = StoredProcPath, event_filter = EventFilter}, #?MODULE{triggers = Triggers} = State) -> StoredProcPath1 = khepri_path:realpath(StoredProcPath), EventFilter1 = case EventFilter of #kevf_tree{path = Path} -> Path1 = khepri_path:realpath(Path), EventFilter#kevf_tree{path = Path1} end, Triggers1 = Triggers#{TriggerId => #{sproc => StoredProcPath1, event_filter => EventFilter1}}, State1 = State#?MODULE{triggers = Triggers1}, Ret = {State1, ok}, bump_applied_command_count(Ret, Meta); apply( Meta, #ack_triggered{triggered = ProcessedTriggers}, #?MODULE{emitted_triggers = EmittedTriggers} = State) -> EmittedTriggers1 = EmittedTriggers -- ProcessedTriggers, State1 = State#?MODULE{emitted_triggers = EmittedTriggers1}, Ret = {State1, ok}, bump_applied_command_count(Ret, Meta). -spec bump_applied_command_count(ApplyRet, Meta) -> {State, Ret, SideEffects} when ApplyRet :: {State, Ret} | {State, Ret, SideEffects}, State :: state(), Ret :: any(), Meta :: ra_machine:command_meta_data(), SideEffects :: ra_machine:effects(). %% @private bump_applied_command_count({State, Result}, Meta) -> bump_applied_command_count({State, Result, []}, Meta); bump_applied_command_count( {#?MODULE{config = #config{snapshot_interval = SnapshotInterval}, metrics = Metrics} = State, Result, SideEffects}, #{index := RaftIndex}) -> AppliedCmdCount0 = maps:get(applied_command_count, Metrics, 0), AppliedCmdCount = AppliedCmdCount0 + 1, case AppliedCmdCount < SnapshotInterval of true -> Metrics1 = Metrics#{applied_command_count => AppliedCmdCount}, State1 = State#?MODULE{metrics = Metrics1}, {State1, Result, SideEffects}; false -> ?LOG_DEBUG( "Move release cursor after ~b commands applied " "(>= ~b commands)", [AppliedCmdCount, SnapshotInterval], #{domain => [khepri, ra_machine]}), State1 = reset_applied_command_count(State), ReleaseCursor = {release_cursor, RaftIndex, State1}, SideEffects1 = [ReleaseCursor | SideEffects], {State1, Result, SideEffects1} end. reset_applied_command_count(#?MODULE{metrics = Metrics} = State) -> Metrics1 = maps:remove(applied_command_count, Metrics), State#?MODULE{metrics = Metrics1}. %% @private state_enter( leader, #?MODULE{emitted_triggers = []}) -> []; state_enter( leader, #?MODULE{config = #config{store_id = StoreId}, emitted_triggers = EmittedTriggers}) -> SideEffect = {mod_call, khepri_event_handler, handle_triggered_sprocs, [StoreId, EmittedTriggers]}, [SideEffect]; state_enter(_StateName, _State) -> []. %% ------------------------------------------------------------------- %% Internal functions. %% ------------------------------------------------------------------- -spec create_node_record(Payload) -> Node when Payload :: payload(), Node :: tree_node(). %% @private create_node_record(Payload) -> #node{stat = ?INIT_NODE_STAT, payload = Payload}. -spec set_node_payload(tree_node(), payload()) -> tree_node(). %% @private set_node_payload(#node{payload = Payload} = Node, Payload) -> Node; set_node_payload(#node{stat = #{payload_version := DVersion} = Stat} = Node, Payload) -> Stat1 = Stat#{payload_version => DVersion + 1}, Node#node{stat = Stat1, payload = Payload}. -spec remove_node_payload(tree_node()) -> tree_node(). %% @private remove_node_payload( #node{payload = none} = Node) -> Node; remove_node_payload( #node{stat = #{payload_version := DVersion} = Stat} = Node) -> Stat1 = Stat#{payload_version => DVersion + 1}, Node#node{stat = Stat1, payload = none}. -spec add_node_child(tree_node(), khepri_path:component(), tree_node()) -> tree_node(). add_node_child(#node{stat = #{child_list_version := CVersion} = Stat, child_nodes = Children} = Node, ChildName, Child) -> Children1 = Children#{ChildName => Child}, Stat1 = Stat#{child_list_version => CVersion + 1}, Node#node{stat = Stat1, child_nodes = Children1}. -spec update_node_child(tree_node(), khepri_path:component(), tree_node()) -> tree_node(). update_node_child(#node{child_nodes = Children} = Node, ChildName, Child) -> Children1 = Children#{ChildName => Child}, Node#node{child_nodes = Children1}. -spec remove_node_child(tree_node(), khepri_path:component()) -> tree_node(). remove_node_child(#node{stat = #{child_list_version := CVersion} = Stat, child_nodes = Children} = Node, ChildName) -> ?assert(maps:is_key(ChildName, Children)), Stat1 = Stat#{child_list_version => CVersion + 1}, Children1 = maps:remove(ChildName, Children), Node#node{stat = Stat1, child_nodes = Children1}. -spec remove_node_child_nodes(tree_node()) -> tree_node(). remove_node_child_nodes( #node{child_nodes = Children} = Node) when Children =:= #{} -> Node; remove_node_child_nodes( #node{stat = #{child_list_version := CVersion} = Stat} = Node) -> Stat1 = Stat#{child_list_version => CVersion + 1}, Node#node{stat = Stat1, child_nodes = #{}}. -spec gather_node_props(tree_node(), operation_options()) -> node_props(). gather_node_props(#node{stat = #{payload_version := DVersion, child_list_version := CVersion}, payload = Payload, child_nodes = Children}, Options) -> Result0 = #{payload_version => DVersion, child_list_version => CVersion, child_list_length => maps:size(Children)}, Result1 = case Options of #{include_child_names := true} -> Result0#{child_names => maps:keys(Children)}; _ -> Result0 end, case Payload of #kpayload_data{data = Data} -> Result1#{data => Data}; #kpayload_sproc{sproc = Fun} -> Result1#{sproc => Fun}; _ -> Result1 end. -spec to_absolute_keep_while(BasePath, KeepWhile) -> KeepWhile when BasePath :: khepri_path:path(), KeepWhile :: khepri_condition:keep_while(). %% @private to_absolute_keep_while(BasePath, KeepWhile) -> maps:fold( fun(Path, Cond, Acc) -> AbsPath = khepri_path:abspath(Path, BasePath), Acc#{AbsPath => Cond} end, #{}, KeepWhile). -spec are_keep_while_conditions_met( tree_node(), khepri_condition:keep_while()) -> true | {false, any()}. %% @private are_keep_while_conditions_met(_, KeepWhile) when KeepWhile =:= #{} -> true; are_keep_while_conditions_met(Root, KeepWhile) -> maps:fold( fun (Path, Condition, true) -> case find_matching_nodes(Root, Path, #{}) of {ok, Result} when Result =/= #{} -> are_keep_while_conditions_met1(Result, Condition); {ok, _} -> {false, {pattern_matches_no_nodes, Path}}; {error, Reason} -> {false, Reason} end; (_, _, False) -> False end, true, KeepWhile). are_keep_while_conditions_met1(Result, Condition) -> maps:fold( fun (Path, NodeProps, true) -> khepri_condition:is_met(Condition, Path, NodeProps); (_, _, False) -> False end, true, Result). is_keep_while_condition_met_on_self( Path, Node, #{keep_while_conds := KeepWhileConds}) -> case KeepWhileConds of #{Path := #{Path := Condition}} -> khepri_condition:is_met(Condition, Path, Node); _ -> true end; is_keep_while_condition_met_on_self(_, _, _) -> true. -spec update_keep_while_conds_revidx( keep_while_conds_map(), keep_while_conds_revidx(), khepri_path:path(), khepri_condition:keep_while()) -> keep_while_conds_revidx(). update_keep_while_conds_revidx( KeepWhileConds, KeepWhileCondsRevIdx, Watcher, KeepWhile) -> %% First, clean up reversed index where a watched path isn't watched %% anymore in the new keep_while. OldWatcheds = maps:get(Watcher, KeepWhileConds, #{}), KeepWhileCondsRevIdx1 = maps:fold( fun(Watched, _, KWRevIdx) -> Watchers = maps:get(Watched, KWRevIdx), Watchers1 = maps:remove(Watcher, Watchers), case maps:size(Watchers1) of 0 -> maps:remove(Watched, KWRevIdx); _ -> KWRevIdx#{Watched => Watchers1} end end, KeepWhileCondsRevIdx, OldWatcheds), %% Then, record the watched paths. maps:fold( fun(Watched, _, KWRevIdx) -> Watchers = maps:get(Watched, KWRevIdx, #{}), Watchers1 = Watchers#{Watcher => ok}, KWRevIdx#{Watched => Watchers1} end, KeepWhileCondsRevIdx1, KeepWhile). -spec find_matching_nodes( tree_node(), khepri_path:pattern(), operation_options()) -> result(). %% @private find_matching_nodes(Root, PathPattern, Options) -> Fun = fun(Path, Node, Result) -> find_matching_nodes_cb(Path, Node, Options, Result) end, WorkOnWhat = case Options of #{expect_specific_node := true} -> specific_node; _ -> many_nodes end, IncludeRootProps = khepri_path:pattern_includes_root_node(PathPattern), Extra = #{include_root_props => IncludeRootProps}, case walk_down_the_tree(Root, PathPattern, WorkOnWhat, Extra, Fun, #{}) of {ok, NewRoot, _, Result} -> ?assertEqual(Root, NewRoot), {ok, Result}; Error -> Error end. find_matching_nodes_cb(Path, #node{} = Node, Options, Result) -> NodeProps = gather_node_props(Node, Options), {ok, keep, Result#{Path => NodeProps}}; find_matching_nodes_cb( _, {interrupted, node_not_found = Reason, Info}, #{expect_specific_node := true}, _) -> {error, {Reason, Info}}; find_matching_nodes_cb(_, {interrupted, _, _}, _, Result) -> {ok, keep, Result}. -spec insert_or_update_node( state(), khepri_path:pattern(), payload(), #{keep_while => khepri_condition:keep_while()}) -> {state(), result()} | {state(), result(), ra_machine:effects()}. %% @private insert_or_update_node( #?MODULE{root = Root, keep_while_conds = KeepWhileConds, keep_while_conds_revidx = KeepWhileCondsRevIdx} = State, PathPattern, Payload, #{keep_while := KeepWhile}) -> Fun = fun(Path, Node, {_, _, Result}) -> Ret = insert_or_update_node_cb( Path, Node, Payload, Result), case Ret of {ok, Node1, Result1} when Result1 =/= #{} -> AbsKeepWhile = to_absolute_keep_while( Path, KeepWhile), KeepWhileOnOthers = maps:remove(Path, AbsKeepWhile), KWMet = are_keep_while_conditions_met( Root, KeepWhileOnOthers), case KWMet of true -> {ok, Node1, {updated, Path, Result1}}; {false, Reason} -> %% The keep_while condition is not met. We %% can't insert the node and return an %% error. NodeName = case Path of [] -> ?ROOT_NODE; _ -> lists:last(Path) end, Info = #{node_name => NodeName, node_path => Path, keep_while_reason => Reason}, {error, {keep_while_conditions_not_met, Info}} end; {ok, Node1, Result1} -> {ok, Node1, {updated, Path, Result1}}; Error -> Error end end, %% TODO: Should we support setting many nodes with the same value? Ret1 = walk_down_the_tree( Root, PathPattern, specific_node, #{keep_while_conds => KeepWhileConds, keep_while_conds_revidx => KeepWhileCondsRevIdx, keep_while_aftermath => #{}}, Fun, {undefined, [], #{}}), case Ret1 of {ok, Root1, #{keep_while_conds := KeepWhileConds1, keep_while_conds_revidx := KeepWhileCondsRevIdx1, keep_while_aftermath := KeepWhileAftermath}, {updated, ResolvedPath, Ret2}} -> AbsKeepWhile = to_absolute_keep_while(ResolvedPath, KeepWhile), KeepWhileCondsRevIdx2 = update_keep_while_conds_revidx( KeepWhileConds1, KeepWhileCondsRevIdx1, ResolvedPath, AbsKeepWhile), KeepWhileConds2 = KeepWhileConds1#{ResolvedPath => AbsKeepWhile}, State1 = State#?MODULE{root = Root1, keep_while_conds = KeepWhileConds2, keep_while_conds_revidx = KeepWhileCondsRevIdx2}, {State2, SideEffects} = create_tree_change_side_effects( State, State1, Ret2, KeepWhileAftermath), {State2, {ok, Ret2}, SideEffects}; Error -> ?assertMatch({error, _}, Error), {State, Error} end; insert_or_update_node( #?MODULE{root = Root, keep_while_conds = KeepWhileConds, keep_while_conds_revidx = KeepWhileCondsRevIdx} = State, PathPattern, Payload, _Extra) -> Fun = fun(Path, Node, Result) -> insert_or_update_node_cb( Path, Node, Payload, Result) end, Ret1 = walk_down_the_tree( Root, PathPattern, specific_node, #{keep_while_conds => KeepWhileConds, keep_while_conds_revidx => KeepWhileCondsRevIdx, keep_while_aftermath => #{}}, Fun, #{}), case Ret1 of {ok, Root1, #{keep_while_conds := KeepWhileConds1, keep_while_conds_revidx := KeepWhileCondsRevIdx1, keep_while_aftermath := KeepWhileAftermath}, Ret2} -> State1 = State#?MODULE{root = Root1, keep_while_conds = KeepWhileConds1, keep_while_conds_revidx = KeepWhileCondsRevIdx1}, {State2, SideEffects} = create_tree_change_side_effects( State, State1, Ret2, KeepWhileAftermath), {State2, {ok, Ret2}, SideEffects}; Error -> ?assertMatch({error, _}, Error), {State, Error} end. insert_or_update_node_cb( Path, #node{} = Node, Payload, Result) -> case maps:is_key(Path, Result) of false -> Node1 = set_node_payload(Node, Payload), NodeProps = gather_node_props(Node, #{}), {ok, Node1, Result#{Path => NodeProps}}; true -> {ok, Node, Result} end; insert_or_update_node_cb( Path, {interrupted, node_not_found = Reason, Info}, Payload, Result) -> %% We store the payload when we reached the target node only, not in the %% parent nodes we have to create in between. IsTarget = maps:get(node_is_target, Info), case can_continue_update_after_node_not_found(Info) of true when IsTarget -> Node = create_node_record(Payload), NodeProps = #{}, {ok, Node, Result#{Path => NodeProps}}; true -> Node = create_node_record(none), {ok, Node, Result}; false -> {error, {Reason, Info}} end; insert_or_update_node_cb(_, {interrupted, Reason, Info}, _, _) -> {error, {Reason, Info}}. can_continue_update_after_node_not_found(#{condition := Condition}) -> can_continue_update_after_node_not_found1(Condition); can_continue_update_after_node_not_found(#{node_name := NodeName}) -> can_continue_update_after_node_not_found1(NodeName). can_continue_update_after_node_not_found1(ChildName) when ?IS_PATH_COMPONENT(ChildName) -> true; can_continue_update_after_node_not_found1(#if_node_exists{exists = false}) -> true; can_continue_update_after_node_not_found1(#if_all{conditions = Conds}) -> lists:all(fun can_continue_update_after_node_not_found1/1, Conds); can_continue_update_after_node_not_found1(#if_any{conditions = Conds}) -> lists:any(fun can_continue_update_after_node_not_found1/1, Conds); can_continue_update_after_node_not_found1(_) -> false. -spec delete_matching_nodes(state(), khepri_path:pattern()) -> {state(), result()} | {state(), result(), ra_machine:effects()}. %% @private delete_matching_nodes( #?MODULE{root = Root, keep_while_conds = KeepWhileConds, keep_while_conds_revidx = KeepWhileCondsRevIdx} = State, PathPattern) -> Ret1 = do_delete_matching_nodes( PathPattern, Root, #{keep_while_conds => KeepWhileConds, keep_while_conds_revidx => KeepWhileCondsRevIdx, keep_while_aftermath => #{}}), case Ret1 of {ok, Root1, #{keep_while_conds := KeepWhileConds1, keep_while_conds_revidx := KeepWhileCondsRevIdx1, keep_while_aftermath := KeepWhileAftermath}, Ret2} -> State1 = State#?MODULE{root = Root1, keep_while_conds = KeepWhileConds1, keep_while_conds_revidx = KeepWhileCondsRevIdx1}, {State2, SideEffects} = create_tree_change_side_effects( State, State1, Ret2, KeepWhileAftermath), {State2, {ok, Ret2}, SideEffects}; Error -> {State, Error} end. do_delete_matching_nodes(PathPattern, Root, Extra) -> Fun = fun delete_matching_nodes_cb/3, walk_down_the_tree(Root, PathPattern, many_nodes, Extra, Fun, #{}). delete_matching_nodes_cb([] = Path, #node{} = Node, Result) -> Node1 = remove_node_payload(Node), Node2 = remove_node_child_nodes(Node1), NodeProps = gather_node_props(Node, #{}), {ok, Node2, Result#{Path => NodeProps}}; delete_matching_nodes_cb(Path, #node{} = Node, Result) -> NodeProps = gather_node_props(Node, #{}), {ok, delete, Result#{Path => NodeProps}}; delete_matching_nodes_cb(_, {interrupted, _, _}, Result) -> {ok, keep, Result}. create_tree_change_side_effects( #?MODULE{triggers = Triggers} = _InitialState, NewState, _Ret, _KeepWhileAftermath) when Triggers =:= #{} -> {NewState, []}; create_tree_change_side_effects( %% We want to consider the new state (with the updated tree), but we want %% to use triggers from the initial state, in case they were updated too. %% In other words, we want to evaluate triggers in the state they were at %% the time the change to the tree was requested. #?MODULE{triggers = Triggers, emitted_triggers = EmittedTriggers} = _InitialState, #?MODULE{config = #config{store_id = StoreId}, root = Root} = NewState, Ret, KeepWhileAftermath) -> %% We make a map where for each affected tree node, we indicate the type %% of change. Changes0 = maps:merge(Ret, KeepWhileAftermath), Changes1 = maps:map( fun (_, NodeProps) when NodeProps =:= #{} -> create; (_, #{} = _NodeProps) -> update; (_, delete) -> delete end, Changes0), TriggeredStoredProcs = list_triggered_sprocs(Root, Changes1, Triggers), %% We record the list of triggered stored procedures in the state %% machine's state. This is used to guaranty at-least-once execution of %% the trigger: the event handler process is supposed to ack when it %% executed the triggered stored procedure. If the Ra cluster changes %% leader in between, we know that we need to retry the execution. %% %% This could lead to multiple execution of the same trigger, therefore %% the stored procedure must be idempotent. NewState1 = NewState#?MODULE{ emitted_triggers = EmittedTriggers ++ TriggeredStoredProcs}, %% We still emit a `mod_call' effect to wake up the event handler process %% so it doesn't have to poll the internal list. SideEffect = {mod_call, khepri_event_handler, handle_triggered_sprocs, [StoreId, TriggeredStoredProcs]}, {NewState1, [SideEffect]}. list_triggered_sprocs(Root, Changes, Triggers) -> TriggeredStoredProcs = maps:fold( fun(Path, Change, SPP) -> % For each change, we evaluate each trigger. maps:fold( fun (TriggerId, #{sproc := StoredProcPath, event_filter := #kevf_tree{path = PathPattern, props = EventFilterProps} = EventFilter}, SPP1) -> %% For each trigger based on a tree event: %% 1. we verify the path of the changed tree node %% matches the monitored path pattern in the %% event filter. %% 2. we verify the type of change matches the %% change filter in the event filter. PathMatches = does_path_match( Path, PathPattern, [], Root), DefaultWatchedChanges = [create, update, delete], WatchedChanges = case EventFilterProps of #{on_actions := []} -> DefaultWatchedChanges; #{on_actions := OnActions} when is_list(OnActions) -> OnActions; _ -> DefaultWatchedChanges end, ChangeMatches = lists:member(Change, WatchedChanges), case PathMatches andalso ChangeMatches of true -> %% We then locate the stored procedure. If the %% path doesn't point to an existing tree %% node, or if this tree node is not a stored %% procedure, the trigger is ignored. %% %% TODO: Should we return an error or at least %% log something? This could be considered %% noise if the trigger exists regardless of %% the presence of the stored procedure on %% purpose (for instance the caller code is %% being updated). case find_stored_proc(Root, StoredProcPath) of undefined -> SPP1; StoredProc -> %% TODO: Use a record to format %% stored procedure arguments? EventProps = #{path => Path, on_action => Change}, Triggered = #triggered{ id = TriggerId, event_filter = EventFilter, sproc = StoredProc, props = EventProps }, [Triggered | SPP1] end; false -> SPP1 end; (_TriggerId, _Trigger, SPP1) -> SPP1 end, SPP, Triggers) end, [], Changes), sort_triggered_sprocs(TriggeredStoredProcs). does_path_match(PathRest, PathRest, _ReversedPath, _Root) -> true; does_path_match([], _PathPatternRest, _ReversedPath, _Root) -> false; does_path_match(_PathRest, [], _ReversedPath, _Root) -> false; does_path_match( [Component | Path], [Component | PathPattern], ReversedPath, Root) when ?IS_PATH_COMPONENT(Component) -> does_path_match(Path, PathPattern, [Component | ReversedPath], Root); does_path_match( [Component | _Path], [Condition | _PathPattern], _ReversedPath, _Root) when ?IS_PATH_COMPONENT(Component) andalso ?IS_PATH_COMPONENT(Condition) -> false; does_path_match( [Component | Path], [Condition | PathPattern], ReversedPath, Root) -> %% Query the tree node, required to evaluate the condition. ReversedPath1 = [Component | ReversedPath], CurrentPath = lists:reverse(ReversedPath1), {ok, #{CurrentPath := Node}} = khepri_machine:find_matching_nodes( Root, lists:reverse([Component | ReversedPath]), #{expect_specific_node => true}), case khepri_condition:is_met(Condition, Component, Node) of true -> does_path_match(Path, PathPattern, ReversedPath1, Root); {false, _} -> false end. find_stored_proc(Root, StoredProcPath) -> Ret = khepri_machine:find_matching_nodes( Root, StoredProcPath, #{expect_specific_node => true}), %% Non-existing nodes and nodes which are not stored procedures are %% ignored. case Ret of {ok, #{StoredProcPath := #{sproc := StoredProc}}} -> StoredProc; _ -> undefined end. sort_triggered_sprocs(TriggeredStoredProcs) -> %% We first sort by priority, then by trigged ID if priorities are equal. %% The priority can be any integer (even negative integers). The default %% priority is 0. %% %% A higher priority (a greater integer) means that the triggered stored %% procedure will be executed before another one with lower priority %% (smaller integer). %% %% If the priorities are equal, a trigger with an ID earlier in %% alphabetical order will be executed before another one with an ID later %% in alphabetical order. lists:sort( fun(#triggered{id = IdA, event_filter = EventFilterA}, #triggered{id = IdB, event_filter = EventFilterB}) -> PrioA = get_event_filter_priority(EventFilterA), PrioB = get_event_filter_priority(EventFilterB), if PrioA =:= PrioB -> IdA =< IdB; true -> PrioA > PrioB end end, TriggeredStoredProcs). get_event_filter_priority(#kevf_tree{props = #{priority := Priority}}) when is_integer(Priority) -> Priority; get_event_filter_priority(_EventFilter) -> 0. %% ------- -spec walk_down_the_tree( tree_node(), khepri_path:pattern(), specific_node | many_nodes, walk_down_the_tree_extra(), walk_down_the_tree_fun(), any()) -> ok(tree_node(), walk_down_the_tree_extra(), any()) | khepri:error(). %% @private walk_down_the_tree(Root, PathPattern, WorkOnWhat, Extra, Fun, FunAcc) -> CompiledPathPattern = khepri_path:compile(PathPattern), walk_down_the_tree1( Root, CompiledPathPattern, WorkOnWhat, [], %% Used to remember the path of the node currently on. [], %% Used to update parents up in the tree in a tail-recursive %% function. Extra, Fun, FunAcc). -spec walk_down_the_tree1( tree_node(), khepri_path:pattern(), specific_node | many_nodes, khepri_path:pattern(), [tree_node() | {tree_node(), child_created}], walk_down_the_tree_extra(), walk_down_the_tree_fun(), any()) -> ok(tree_node(), walk_down_the_tree_extra(), any()) | khepri:error(). %% @private walk_down_the_tree1( CurrentNode, [?ROOT_NODE | PathPattern], WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) -> ?assertEqual([], ReversedPath), ?assertEqual([], ReversedParentTree), walk_down_the_tree1( CurrentNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc); walk_down_the_tree1( CurrentNode, [?THIS_NODE | PathPattern], WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) -> walk_down_the_tree1( CurrentNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc); walk_down_the_tree1( _CurrentNode, [?PARENT_NODE | PathPattern], WorkOnWhat, [_CurrentName | ReversedPath], [ParentNode0 | ReversedParentTree], Extra, Fun, FunAcc) -> ParentNode = case ParentNode0 of {PN, child_created} -> PN; _ -> ParentNode0 end, walk_down_the_tree1( ParentNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc); walk_down_the_tree1( CurrentNode, [?PARENT_NODE | PathPattern], WorkOnWhat, [] = ReversedPath, [] = ReversedParentTree, Extra, Fun, FunAcc) -> %% The path tries to go above the root node, like "cd /..". In this case, %% we stay on the root node. walk_down_the_tree1( CurrentNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc); walk_down_the_tree1( #node{child_nodes = Children} = CurrentNode, [ChildName | PathPattern], WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) when ?IS_NODE_ID(ChildName) -> case Children of #{ChildName := Child} -> walk_down_the_tree1( Child, PathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode | ReversedParentTree], Extra, Fun, FunAcc); _ -> interrupted_walk_down( node_not_found, #{node_name => ChildName, node_path => lists:reverse([ChildName | ReversedPath])}, PathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode | ReversedParentTree], Extra, Fun, FunAcc) end; walk_down_the_tree1( #node{child_nodes = Children} = CurrentNode, [Condition | PathPattern], specific_node = WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) when ?IS_CONDITION(Condition) -> %% We distinguish the case where the condition must be verified against the %% current node (i.e. the node name is ?ROOT_NODE or ?THIS_NODE in the %% condition) instead of its child nodes. SpecificNode = khepri_path:component_targets_specific_node(Condition), case SpecificNode of {true, NodeName} when NodeName =:= ?ROOT_NODE orelse NodeName =:= ?THIS_NODE -> CurrentName = special_component_to_node_name( NodeName, ReversedPath), CondMet = khepri_condition:is_met( Condition, CurrentName, CurrentNode), case CondMet of true -> walk_down_the_tree1( CurrentNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc); {false, Cond} -> interrupted_walk_down( mismatching_node, #{node_name => CurrentName, node_path => lists:reverse(ReversedPath), node_props => gather_node_props(CurrentNode, #{}), condition => Cond}, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) end; {true, ChildName} when ChildName =/= ?PARENT_NODE -> case Children of #{ChildName := Child} -> CondMet = khepri_condition:is_met( Condition, ChildName, Child), case CondMet of true -> walk_down_the_tree1( Child, PathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode | ReversedParentTree], Extra, Fun, FunAcc); {false, Cond} -> interrupted_walk_down( mismatching_node, #{node_name => ChildName, node_path => lists:reverse( [ChildName | ReversedPath]), node_props => gather_node_props(Child, #{}), condition => Cond}, PathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode | ReversedParentTree], Extra, Fun, FunAcc) end; _ -> interrupted_walk_down( node_not_found, #{node_name => ChildName, node_path => lists:reverse([ChildName | ReversedPath]), condition => Condition}, PathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode | ReversedParentTree], Extra, Fun, FunAcc) end; {true, ?PARENT_NODE} -> %% TODO: Support calling Fun() with parent node based on %% conditions on child nodes. {error, targets_dot_dot}; false -> %% TODO: Should we provide more details about the error, like the %% list of matching nodes? {error, matches_many_nodes} end; walk_down_the_tree1( #node{child_nodes = Children} = CurrentNode, [Condition | PathPattern] = WholePathPattern, many_nodes = WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) when ?IS_CONDITION(Condition) -> %% Like with WorkOnWhat =:= specific_node function clause above, We %% distinguish the case where the condition must be verified against the %% current node (i.e. the node name is ?ROOT_NODE or ?THIS_NODE in the %% condition) instead of its child nodes. SpecificNode = khepri_path:component_targets_specific_node(Condition), case SpecificNode of {true, NodeName} when NodeName =:= ?ROOT_NODE orelse NodeName =:= ?THIS_NODE -> CurrentName = special_component_to_node_name( NodeName, ReversedPath), CondMet = khepri_condition:is_met( Condition, CurrentName, CurrentNode), case CondMet of true -> walk_down_the_tree1( CurrentNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc); {false, _} -> StartingNode = starting_node_in_rev_parent_tree( ReversedParentTree, CurrentNode), {ok, StartingNode, Extra, FunAcc} end; {true, ?PARENT_NODE} -> %% TODO: Support calling Fun() with parent node based on %% conditions on child nodes. {error, targets_parent_node}; _ -> %% There is a special case if the current node is the root node %% and the pattern is of the form of e.g. [#if_name_matches{regex %% = any}]. In this situation, we consider the condition should be %% compared to that root node as well. This allows to get its %% props and payload atomically in a single suery. IsRoot = ReversedPath =:= [], IncludeRootProps = maps:get(include_root_props, Extra, false), Ret0 = case IsRoot andalso IncludeRootProps of true -> walk_down_the_tree1( CurrentNode, [], WorkOnWhat, [], [], Extra, Fun, FunAcc); _ -> {ok, CurrentNode, Extra, FunAcc} end, %% The result of the first part (the special case for the root %% node if relevant) is used as a starting point for handling all %% child nodes. Ret1 = maps:fold( fun (ChildName, Child, {ok, CurNode, Extra1, FunAcc1}) -> handle_branch( CurNode, ChildName, Child, WholePathPattern, WorkOnWhat, ReversedPath, Extra1, Fun, FunAcc1); (_, _, Error) -> Error end, Ret0, Children), case Ret1 of {ok, CurrentNode, Extra2, FunAcc2} -> %% The current node didn't change, no need to update the %% tree and evaluate keep_while conditions. ?assertEqual(Extra, Extra2), StartingNode = starting_node_in_rev_parent_tree( ReversedParentTree, CurrentNode), {ok, StartingNode, Extra, FunAcc2}; {ok, CurrentNode1, Extra2, FunAcc2} -> %% Because of the loop, payload & child list versions may %% have been increased multiple times. We want them to %% increase once for the whole (atomic) operation. CurrentNode2 = squash_version_bumps( CurrentNode, CurrentNode1), walk_back_up_the_tree( CurrentNode2, ReversedPath, ReversedParentTree, Extra2, FunAcc2); Error -> Error end end; walk_down_the_tree1( #node{} = CurrentNode, [], _, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) -> CurrentPath = lists:reverse(ReversedPath), case Fun(CurrentPath, CurrentNode, FunAcc) of {ok, keep, FunAcc1} -> StartingNode = starting_node_in_rev_parent_tree( ReversedParentTree, CurrentNode), {ok, StartingNode, Extra, FunAcc1}; {ok, delete, FunAcc1} -> walk_back_up_the_tree( delete, ReversedPath, ReversedParentTree, Extra, FunAcc1); {ok, #node{} = CurrentNode1, FunAcc1} -> walk_back_up_the_tree( CurrentNode1, ReversedPath, ReversedParentTree, Extra, FunAcc1); Error -> Error end. -spec special_component_to_node_name( ?ROOT_NODE | ?THIS_NODE, khepri_path:pattern()) -> khepri_path:component(). special_component_to_node_name(?ROOT_NODE = NodeName, []) -> NodeName; special_component_to_node_name(?THIS_NODE, [NodeName | _]) -> NodeName; special_component_to_node_name(?THIS_NODE, []) -> ?ROOT_NODE. -spec starting_node_in_rev_parent_tree([tree_node()]) -> tree_node(). %% @private starting_node_in_rev_parent_tree(ReversedParentTree) -> hd(lists:reverse(ReversedParentTree)). -spec starting_node_in_rev_parent_tree([tree_node()], tree_node()) -> tree_node(). %% @private starting_node_in_rev_parent_tree([], CurrentNode) -> CurrentNode; starting_node_in_rev_parent_tree(ReversedParentTree, _) -> starting_node_in_rev_parent_tree(ReversedParentTree). -spec handle_branch( tree_node(), khepri_path:component(), tree_node(), khepri_path:pattern(), specific_node | many_nodes, [tree_node() | {tree_node(), child_created}], walk_down_the_tree_extra(), walk_down_the_tree_fun(), any()) -> ok(tree_node(), walk_down_the_tree_extra(), any()) | khepri:error(). %% @private handle_branch( CurrentNode, ChildName, Child, [Condition | PathPattern] = WholePathPattern, WorkOnWhat, ReversedPath, Extra, Fun, FunAcc) -> %% FIXME: A condition such as #if_path_matches{regex = any} at the end of %% a path matches non-leaf nodes as well: we should call Fun() for them! CondMet = khepri_condition:is_met( Condition, ChildName, Child), Ret = case CondMet of true -> walk_down_the_tree1( Child, PathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode], Extra, Fun, FunAcc); {false, _} -> {ok, CurrentNode, Extra, FunAcc} end, case Ret of {ok, CurrentNode1, Extra1, FunAcc1} -> case khepri_condition:applies_to_grandchildren(Condition) of false -> Ret; true -> walk_down_the_tree1( Child, WholePathPattern, WorkOnWhat, [ChildName | ReversedPath], [CurrentNode1], Extra1, Fun, FunAcc1) end; Error -> Error end. -spec interrupted_walk_down( mismatching_node | node_not_found, map(), khepri_path:pattern(), specific_node | many_nodes, khepri_path:path(), [tree_node() | {tree_node(), child_created}], walk_down_the_tree_extra(), walk_down_the_tree_fun(), any()) -> ok(tree_node(), walk_down_the_tree_extra(), any()) | khepri:error(). %% @private interrupted_walk_down( Reason, Info, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree, Extra, Fun, FunAcc) -> NodePath = lists:reverse(ReversedPath), IsTarget = khepri_path:realpath(PathPattern) =:= [], Info1 = Info#{node_is_target => IsTarget}, ErrorTuple = {interrupted, Reason, Info1}, case Fun(NodePath, ErrorTuple, FunAcc) of {ok, ToDo, FunAcc1} when ToDo =:= keep orelse ToDo =:= delete -> ?assertNotEqual([], ReversedParentTree), StartingNode = starting_node_in_rev_parent_tree( ReversedParentTree), {ok, StartingNode, Extra, FunAcc1}; {ok, #node{} = NewNode, FunAcc1} -> ReversedParentTree1 = case Reason of node_not_found -> %% We record the fact the child is a new node. This is used %% to reset the child's stats if it got new payload or %% child nodes at the same time. [{hd(ReversedParentTree), child_created} | tl(ReversedParentTree)]; _ -> ReversedParentTree end, case PathPattern of [] -> %% We reached the target node. We could call %% walk_down_the_tree1() again, but it would call Fun() a %% second time. walk_back_up_the_tree( NewNode, ReversedPath, ReversedParentTree1, Extra, FunAcc1); _ -> walk_down_the_tree1( NewNode, PathPattern, WorkOnWhat, ReversedPath, ReversedParentTree1, Extra, Fun, FunAcc1) end; Error -> Error end. -spec reset_versions(tree_node()) -> tree_node(). %% @private reset_versions(#node{stat = Stat} = CurrentNode) -> Stat1 = Stat#{payload_version => ?INIT_DATA_VERSION, child_list_version => ?INIT_CHILD_LIST_VERSION}, CurrentNode#node{stat = Stat1}. -spec squash_version_bumps(tree_node(), tree_node()) -> tree_node(). %% @private squash_version_bumps( #node{stat = #{payload_version := DVersion, child_list_version := CVersion}}, #node{stat = #{payload_version := DVersion, child_list_version := CVersion}} = CurrentNode) -> CurrentNode; squash_version_bumps( #node{stat = #{payload_version := OldDVersion, child_list_version := OldCVersion}}, #node{stat = #{payload_version := NewDVersion, child_list_version := NewCVersion} = Stat} = CurrentNode) -> DVersion = case NewDVersion > OldDVersion of true -> OldDVersion + 1; false -> OldDVersion end, CVersion = case NewCVersion > OldCVersion of true -> OldCVersion + 1; false -> OldCVersion end, Stat1 = Stat#{payload_version => DVersion, child_list_version => CVersion}, CurrentNode#node{stat = Stat1}. -spec walk_back_up_the_tree( tree_node() | delete, khepri_path:path(), [tree_node() | {tree_node(), child_created}], walk_down_the_tree_extra(), any()) -> ok(tree_node(), walk_down_the_tree_extra(), any()). %% @private walk_back_up_the_tree( Child, ReversedPath, ReversedParentTree, Extra, FunAcc) -> walk_back_up_the_tree( Child, ReversedPath, ReversedParentTree, Extra, #{}, FunAcc). -spec walk_back_up_the_tree( tree_node() | delete, khepri_path:path(), [tree_node() | {tree_node(), child_created}], walk_down_the_tree_extra(), #{khepri_path:path() => tree_node() | delete}, any()) -> ok(tree_node(), walk_down_the_tree_extra(), any()). %% @private walk_back_up_the_tree( delete, [ChildName | ReversedPath] = WholeReversedPath, [ParentNode | ReversedParentTree], Extra, KeepWhileAftermath, FunAcc) -> %% Evaluate keep_while of nodes which depended on ChildName (it is %% removed) at the end of walk_back_up_the_tree(). Path = lists:reverse(WholeReversedPath), KeepWhileAftermath1 = KeepWhileAftermath#{Path => delete}, %% Evaluate keep_while of parent node on itself right now (its child_count %% has changed). ParentNode1 = remove_node_child(ParentNode, ChildName), handle_keep_while_for_parent_update( ParentNode1, ReversedPath, ReversedParentTree, Extra, KeepWhileAftermath1, FunAcc); walk_back_up_the_tree( Child, [ChildName | ReversedPath], [{ParentNode, child_created} | ReversedParentTree], Extra, KeepWhileAftermath, FunAcc) -> %% No keep_while to evaluate, the child is new and no nodes depend on it %% at this stage. %% FIXME: Perhaps there is a condition in a if_any{}? Child1 = reset_versions(Child), %% Evaluate keep_while of parent node on itself right now (its child_count %% has changed). ParentNode1 = add_node_child(ParentNode, ChildName, Child1), handle_keep_while_for_parent_update( ParentNode1, ReversedPath, ReversedParentTree, Extra, KeepWhileAftermath, FunAcc); walk_back_up_the_tree( Child, [ChildName | ReversedPath] = WholeReversedPath, [ParentNode | ReversedParentTree], Extra, KeepWhileAftermath, FunAcc) -> %% Evaluate keep_while of nodes which depend on ChildName (it is %% modified) at the end of walk_back_up_the_tree(). Path = lists:reverse(WholeReversedPath), NodeProps = gather_node_props(Child, #{}), KeepWhileAftermath1 = KeepWhileAftermath#{Path => NodeProps}, %% No need to evaluate keep_while of ParentNode, its child_count is %% unchanged. ParentNode1 = update_node_child(ParentNode, ChildName, Child), walk_back_up_the_tree( ParentNode1, ReversedPath, ReversedParentTree, Extra, KeepWhileAftermath1, FunAcc); walk_back_up_the_tree( StartingNode, [], %% <-- We reached the root (i.e. not in a branch, see handle_branch()) [], Extra, KeepWhileAftermath, FunAcc) -> Extra1 = merge_keep_while_aftermath(Extra, KeepWhileAftermath), handle_keep_while_aftermath(StartingNode, Extra1, FunAcc); walk_back_up_the_tree( StartingNode, _ReversedPath, [], Extra, KeepWhileAftermath, FunAcc) -> Extra1 = merge_keep_while_aftermath(Extra, KeepWhileAftermath), {ok, StartingNode, Extra1, FunAcc}. handle_keep_while_for_parent_update( ParentNode, ReversedPath, ReversedParentTree, Extra, KeepWhileAftermath, FunAcc) -> ParentPath = lists:reverse(ReversedPath), IsMet = is_keep_while_condition_met_on_self( ParentPath, ParentNode, Extra), case IsMet of true -> %% We continue with the update. walk_back_up_the_tree( ParentNode, ReversedPath, ReversedParentTree, Extra, KeepWhileAftermath, FunAcc); {false, _Reason} -> %% This parent node must be removed because it doesn't meet its %% own keep_while condition. keep_while conditions for nodes %% depending on this one will be evaluated with the recursion. walk_back_up_the_tree( delete, ReversedPath, ReversedParentTree, Extra, KeepWhileAftermath, FunAcc) end. merge_keep_while_aftermath(Extra, KeepWhileAftermath) -> OldKWA = maps:get(keep_while_aftermath, Extra, #{}), NewKWA = maps:fold( fun (Path, delete, KWA1) -> KWA1#{Path => delete}; (Path, NodeProps, KWA1) -> case KWA1 of #{Path := delete} -> KWA1; _ -> KWA1#{Path => NodeProps} end end, OldKWA, KeepWhileAftermath), Extra#{keep_while_aftermath => NewKWA}. handle_keep_while_aftermath( Root, #{keep_while_aftermath := KeepWhileAftermath} = Extra, FunAcc) when KeepWhileAftermath =:= #{} -> {ok, Root, Extra, FunAcc}; handle_keep_while_aftermath( Root, #{keep_while_conds := KeepWhileConds, keep_while_conds_revidx := KeepWhileCondsRevIdx, keep_while_aftermath := KeepWhileAftermath} = Extra, FunAcc) -> ToRemove = eval_keep_while_conditions( KeepWhileAftermath, KeepWhileConds, KeepWhileCondsRevIdx, Root), {KeepWhileConds1, KeepWhileCondsRevIdx1} = maps:fold( fun (RemovedPath, delete, {KW, KWRevIdx}) -> KW1 = maps:remove(RemovedPath, KW), KWRevIdx1 = update_keep_while_conds_revidx( KW, KWRevIdx, RemovedPath, #{}), {KW1, KWRevIdx1}; (_, _, Acc) -> Acc end, {KeepWhileConds, KeepWhileCondsRevIdx}, KeepWhileAftermath), Extra1 = Extra#{keep_while_conds => KeepWhileConds1, keep_while_conds_revidx => KeepWhileCondsRevIdx1}, ToRemove1 = filter_and_sort_paths_to_remove(ToRemove, KeepWhileAftermath), remove_expired_nodes(ToRemove1, Root, Extra1, FunAcc). eval_keep_while_conditions( KeepWhileAftermath, KeepWhileConds, KeepWhileCondsRevIdx, Root) -> %% KeepWhileAftermath lists all nodes which were modified or removed. We %% want to transform that into a list of nodes to remove. %% %% Those marked as `delete' in KeepWhileAftermath are already gone. We %% need to find the nodes which depended on them, i.e. their keep_while %% condition is not met anymore. Note that removed nodes' child nodes are %% gone as well and must be handled (they are not specified in %% KeepWhileAftermath). %% %% Those modified in KeepWhileAftermath must be evaluated again to decide %% if they should be removed. maps:fold( fun (RemovedPath, remove, ToRemove) -> maps:fold( fun(Path, Watchers, ToRemove1) -> case lists:prefix(RemovedPath, Path) of true -> eval_keep_while_conditions_after_removal( Watchers, KeepWhileConds, Root, ToRemove1); false -> ToRemove1 end end, ToRemove, KeepWhileCondsRevIdx); (UpdatedPath, NodeProps, ToRemove) -> case KeepWhileCondsRevIdx of #{UpdatedPath := Watchers} -> eval_keep_while_conditions_after_update( UpdatedPath, NodeProps, Watchers, KeepWhileConds, Root, ToRemove); _ -> ToRemove end end, #{}, KeepWhileAftermath). eval_keep_while_conditions_after_update( UpdatedPath, NodeProps, Watchers, KeepWhileConds, Root, ToRemove) -> maps:fold( fun(Watcher, ok, ToRemove1) -> KeepWhile = maps:get(Watcher, KeepWhileConds), CondOnUpdated = maps:get(UpdatedPath, KeepWhile), IsMet = khepri_condition:is_met( CondOnUpdated, UpdatedPath, NodeProps), case IsMet of true -> ToRemove1; {false, _} -> case are_keep_while_conditions_met(Root, KeepWhile) of true -> ToRemove1; {false, _} -> ToRemove1#{Watcher => remove} end end end, ToRemove, Watchers). eval_keep_while_conditions_after_removal( Watchers, KeepWhileConds, Root, ToRemove) -> maps:fold( fun(Watcher, ok, ToRemove1) -> KeepWhile = maps:get(Watcher, KeepWhileConds), case are_keep_while_conditions_met(Root, KeepWhile) of true -> ToRemove1; {false, _} -> ToRemove1#{Watcher => delete} end end, ToRemove, Watchers). filter_and_sort_paths_to_remove(ToRemove, KeepWhileAftermath) -> Paths1 = lists:sort( fun (A, B) when length(A) =:= length(B) -> A < B; (A, B) -> length(A) < length(B) end, maps:keys(ToRemove)), Paths2 = lists:foldl( fun(Path, Map) -> case KeepWhileAftermath of #{Path := delete} -> Map; _ -> case is_parent_being_removed(Path, Map) of false -> Map#{Path => delete}; true -> Map end end end, #{}, Paths1), maps:keys(Paths2). is_parent_being_removed([], _) -> false; is_parent_being_removed(Path, Map) -> is_parent_being_removed1(lists:reverse(Path), Map). is_parent_being_removed1([_ | Parent], Map) -> case maps:is_key(lists:reverse(Parent), Map) of true -> true; false -> is_parent_being_removed1(Parent, Map) end; is_parent_being_removed1([], _) -> false. remove_expired_nodes([], Root, Extra, FunAcc) -> {ok, Root, Extra, FunAcc}; remove_expired_nodes([PathToRemove | Rest], Root, Extra, FunAcc) -> case do_delete_matching_nodes(PathToRemove, Root, Extra) of {ok, Root1, Extra1, _} -> remove_expired_nodes(Rest, Root1, Extra1, FunAcc) end. -ifdef(TEST). get_root(#?MODULE{root = Root}) -> Root. get_keep_while_conds( #?MODULE{keep_while_conds = KeepWhileConds}) -> KeepWhileConds. get_keep_while_conds_revidx( #?MODULE{keep_while_conds_revidx = KeepWhileCondsRevIdx}) -> KeepWhileCondsRevIdx. -endif.