davisp commented on a change in pull request #470: Scheduling Replicator URL: https://github.com/apache/couchdb/pull/470#discussion_r110435918
########## File path: src/couch_replicator/src/couch_replicator_scheduler.erl ########## @@ -0,0 +1,1380 @@ +% Licensed under the Apache License, Version 2.0 (the "License"); you may not +% use this file except in compliance with the License. You may obtain a copy of +% the License at +% +% http://www.apache.org/licenses/LICENSE-2.0 +% +% Unless required by applicable law or agreed to in writing, software +% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +% License for the specific language governing permissions and limitations under +% the License. + +-module(couch_replicator_scheduler). +-behaviour(gen_server). +-behaviour(config_listener). +-vsn(1). + +-include("couch_replicator_scheduler.hrl"). +-include("couch_replicator.hrl"). +-include("couch_replicator_api_wrap.hrl"). +-include_lib("couch/include/couch_db.hrl"). + +%% public api +-export([start_link/0, add_job/1, remove_job/1, reschedule/0]). +-export([rep_state/1, find_jobs_by_dbname/1, find_jobs_by_doc/2]). +-export([job_summary/2, health_threshold/0]). +-export([jobs/0, job/1]). + +%% gen_server callbacks +-export([init/1, terminate/2, code_change/3]). +-export([handle_call/3, handle_cast/2, handle_info/2]). +-export([format_status/2]). + +%% config_listener callback +-export([handle_config_change/5, handle_config_terminate/3]). + +%% types +-type event_type() :: added | started | stopped | {crashed, any()}. +-type event() :: {Type:: event_type(), When :: erlang:timestamp()}. +-type history() :: nonempty_list(event()). + +%% definitions +-define(MAX_BACKOFF_EXPONENT, 10). +-define(BACKOFF_INTERVAL_MICROS, 30 * 1000 * 1000). +-define(DEFAULT_HEALTH_THRESHOLD_SEC, 2 * 60). +-define(RELISTEN_DELAY, 5000). + +-define(DEFAULT_MAX_JOBS, 500). +-define(DEFAULT_MAX_CHURN, 20). +-define(DEFAULT_MAX_HISTORY, 20). +-define(DEFAULT_SCHEDULER_INTERVAL, 60000). +-record(state, {interval, timer, max_jobs, max_churn, max_history}). +-record(job, { + id :: job_id() | '$1' | '_', + rep :: #rep{} | '_', + pid :: undefined | pid() | '$1' | '_', + monitor :: undefined | reference() | '_', + history :: history() | '_'}). + +-record(stats_acc, { + now :: erlang:timestamp(), + pending_t = 0 :: non_neg_integer(), + running_t = 0 :: non_neg_integer(), + crashed_t = 0 :: non_neg_integer(), + pending_n = 0 :: non_neg_integer(), + running_n = 0 :: non_neg_integer(), + crashed_n = 0 :: non_neg_integer()}). + + +%% public functions + +-spec start_link() -> {ok, pid()} | ignore | {error, term()}. +start_link() -> + gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). + + +-spec add_job(#rep{}) -> ok. +add_job(#rep{} = Rep) when Rep#rep.id /= undefined -> + Job = #job{ + id = Rep#rep.id, + rep = Rep, + history = [{added, os:timestamp()}]}, + gen_server:call(?MODULE, {add_job, Job}, infinity). + + +-spec remove_job(job_id()) -> ok. +remove_job(Id) -> + gen_server:call(?MODULE, {remove_job, Id}, infinity). + + +-spec reschedule() -> ok. +% Trigger a manual reschedule. Used for testing and/or ops. +reschedule() -> + gen_server:call(?MODULE, reschedule, infinity). + + +-spec rep_state(rep_id()) -> #rep{} | nil. +rep_state(RepId) -> + case (catch ets:lookup_element(?MODULE, RepId, #job.rep)) of + {'EXIT',{badarg, _}} -> + nil; + Rep -> + Rep + end. + + +-spec job_summary(job_id(), non_neg_integer()) -> [_] | nil. +job_summary(JobId, HealthThreshold) -> + case job_by_id(JobId) of + {ok, #job{pid = Pid, history = History, rep = Rep}} -> + ErrorCount = consecutive_crashes(History, HealthThreshold), + {State, Info} = case {Pid, ErrorCount} of + {undefined, 0} -> + {pending, null}; + {undefined, ErrorCount} when ErrorCount > 0 -> + [{{crashed, Error}, _When} | _] = History, + ErrMsg = couch_replicator_utils:rep_error_to_binary(Error), + {crashing, ErrMsg}; + {Pid, ErrorCount} when is_pid(Pid) -> + {running, null} + end, + [ + {source, iolist_to_binary(ejson_url(Rep#rep.source))}, + {target, iolist_to_binary(ejson_url(Rep#rep.target))}, + {state, State}, + {info, Info}, + {error_count, ErrorCount}, + {last_updated, last_updated(History)}, + {start_time, couch_replicator_utils:iso8601(Rep#rep.start_time)}, + {proxy, job_proxy_url(Rep#rep.source)} + ]; + {error, not_found} -> + nil % Job might have just completed + end. + + +job_proxy_url(#httpdb{proxy_url = ProxyUrl}) when is_list(ProxyUrl) -> + list_to_binary(couch_util:url_strip_password(ProxyUrl)); + +job_proxy_url(_Endpoint) -> + null. + + +-spec health_threshold() -> non_neg_integer(). +health_threshold() -> + config:get_integer("replicator", "health_threshold", + ?DEFAULT_HEALTH_THRESHOLD_SEC). + + +-spec find_jobs_by_dbname(binary()) -> list(#rep{}). +find_jobs_by_dbname(DbName) -> + Rep = #rep{db_name = DbName, _ = '_'}, + MatchSpec = #job{id = '$1', rep = Rep, _ = '_'}, + [RepId || [RepId] <- ets:match(?MODULE, MatchSpec)]. + + +-spec find_jobs_by_doc(binary(), binary()) -> list(#rep{}). +find_jobs_by_doc(DbName, DocId) -> + Rep = #rep{db_name = DbName, doc_id = DocId, _ = '_'}, + MatchSpec = #job{id = '$1', rep = Rep, _ = '_'}, + [RepId || [RepId] <- ets:match(?MODULE, MatchSpec)]. + + + + +%% gen_server functions + +init(_) -> + EtsOpts = [named_table, {read_concurrency, true}, {keypos, #job.id}], + ?MODULE = ets:new(?MODULE, EtsOpts), + ok = config:listen_for_changes(?MODULE, nil), + Interval = config:get_integer("replicator", "interval", ?DEFAULT_SCHEDULER_INTERVAL), + MaxJobs = config:get_integer("replicator", "max_jobs", ?DEFAULT_MAX_JOBS), + MaxChurn = config:get_integer("replicator", "max_churn", ?DEFAULT_MAX_CHURN), + MaxHistory = config:get_integer("replicator", "max_history", ?DEFAULT_MAX_HISTORY), + {ok, Timer} = timer:send_after(Interval, reschedule), + State = #state{ + interval = Interval, + max_jobs = MaxJobs, + max_churn = MaxChurn, + max_history = MaxHistory, + timer = Timer + }, + {ok, State}. + + +handle_call({add_job, Job}, _From, State) -> + ok = maybe_remove_job_int(Job#job.id, State), + true = add_job_int(Job), + ok = maybe_start_newly_added_job(Job, State), + couch_stats:increment_counter([couch_replicator, jobs, adds]), + TotalJobs = ets:info(?MODULE, size), + couch_stats:update_gauge([couch_replicator, jobs, total], TotalJobs), + {reply, ok, State}; + +handle_call({remove_job, Id}, _From, State) -> + ok = maybe_remove_job_int(Id, State), + {reply, ok, State}; + +handle_call(reschedule, _From, State) -> + ok = reschedule(State), + {reply, ok, State}; + +handle_call(_, _From, State) -> + {noreply, State}. + + +handle_cast({set_max_jobs, MaxJobs}, State) when is_integer(MaxJobs), MaxJobs >= 0 -> + couch_log:notice("~p: max_jobs set to ~B", [?MODULE, MaxJobs]), + {noreply, State#state{max_jobs = MaxJobs}}; + +handle_cast({set_max_churn, MaxChurn}, State) when is_integer(MaxChurn), MaxChurn > 0 -> + couch_log:notice("~p: max_churn set to ~B", [?MODULE, MaxChurn]), + {noreply, State#state{max_churn = MaxChurn}}; + +handle_cast({set_max_history, MaxHistory}, State) when is_integer(MaxHistory), MaxHistory > 0 -> + couch_log:notice("~p: max_history set to ~B", [?MODULE, MaxHistory]), + {noreply, State#state{max_history = MaxHistory}}; + +handle_cast({set_interval, Interval}, State) when is_integer(Interval), Interval > 0 -> + couch_log:notice("~p: interval set to ~B", [?MODULE, Interval]), + {noreply, State#state{interval = Interval}}; + +handle_cast(_, State) -> + {noreply, State}. + + +handle_info(reschedule, State) -> + ok = reschedule(State), + {ok, cancel} = timer:cancel(State#state.timer), + {ok, Timer} = timer:send_after(State#state.interval, reschedule), + {noreply, State#state{timer = Timer}}; + +handle_info({'DOWN', _Ref, process, Pid, normal}, State) -> + {ok, Job} = job_by_pid(Pid), + couch_log:notice("~p: Job ~p completed normally", [?MODULE, Job#job.id]), + remove_job_int(Job), + update_running_jobs_stats(), + {noreply, State}; + +handle_info({'DOWN', _Ref, process, Pid, Reason}, State) -> + {ok, Job} = job_by_pid(Pid), + ok = handle_crashed_job(Job, Reason, State), + {noreply, State}; + +handle_info(restart_config_listener, State) -> + ok = config:listen_for_changes(?MODULE, nil), + {noreply, State}; + +handle_info(_, State) -> + {noreply, State}. + + +code_change(_OldVsn, State, _Extra) -> + {ok, State}. + + +terminate(_Reason, _State) -> + ok. + + +format_status(_Opt, [_PDict, State]) -> + [{max_jobs, State#state.max_jobs}, Review comment: Just Say No to Visual Indents! ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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