nickva commented on a change in pull request #470: Scheduling Replicator URL: https://github.com/apache/couchdb/pull/470#discussion_r111456689
########## File path: src/couch_replicator/src/couch_replicator_scheduler.erl ########## @@ -0,0 +1,1430 @@ +% 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). + +-export([ + start_link/0 +]). + +-export([ + init/1, + terminate/2, + handle_call/3, + handle_info/2, + handle_cast/2, + code_change/3, + format_status/2 +]). + +-export([ + add_job/1, + remove_job/1, + reschedule/0, + rep_state/1, + find_jobs_by_dbname/1, + find_jobs_by_doc/2, + job_summary/2, + health_threshold/0, + jobs/0, + job/1 +]). + +%% config_listener callbacks +-export([ + handle_config_change/5, + handle_config_terminate/3 +]). + +%% for status updater process to allow hot code loading +-export([ + stats_updater_loop/1 +]). + +-include("couch_replicator_scheduler.hrl"). +-include("couch_replicator.hrl"). +-include("couch_replicator_api_wrap.hrl"). +-include_lib("couch/include/couch_db.hrl"). + +%% 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(STATS_UPDATE_WAIT, 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, stats_pid}). +-record(job, { + id :: job_id() | '$1' | '_', + rep :: #rep{} | '_', + pid :: undefined | pid() | '$1' | '_', + monitor :: undefined | reference() | '_', + history :: history() | '_' +}). + +-record(stats_acc, { + 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. + + +% Health threshold is the minimum amount of time an unhealthy job should run +% crashing before it is considered to be healthy again. HealtThreashold should +% not be 0 as jobs could start and immediately crash, and it shouldn't be +% infinity, since then consecutive crashes would accumulate forever even if +% job is back to normal. +-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), Review comment: Good catch! ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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