/*
 * SimpleConfigConsumer.actor.cpp
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
 *
 * 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.
 */

#include "fdbserver/ConfigBroadcastInterface.h"
#include "fdbserver/SimpleConfigConsumer.h"
#include "flow/actorcompiler.h" // must be last include

class SimpleConfigConsumerImpl {
	ConfigFollowerInterface cfi;
	Version lastSeenVersion{ 0 };
	double pollingInterval;
	Optional<double> compactionInterval;

	UID id;
	CounterCollection cc;
	Counter compactRequest;
	Counter successfulChangeRequest;
	Counter failedChangeRequest;
	Counter snapshotRequest;
	Future<Void> logger;

	ACTOR static Future<Void> compactor(SimpleConfigConsumerImpl* self, ConfigBroadcaster* broadcaster) {
		if (!self->compactionInterval.present()) {
			wait(Never());
			return Void();
		}
		loop {
			state Version compactionVersion = self->lastSeenVersion;
			wait(delayJittered(self->compactionInterval.get()));
			if (self->cfi.hostname.present()) {
				wait(retryGetReplyFromHostname(ConfigFollowerCompactRequest{ compactionVersion },
				                               self->cfi.hostname.get(),
				                               WLTOKEN_CONFIGFOLLOWER_COMPACT));
			} else {
				wait(self->cfi.compact.getReply(ConfigFollowerCompactRequest{ compactionVersion }));
			}
			++self->compactRequest;
			broadcaster->compact(compactionVersion);
		}
	}

	ACTOR static Future<Version> getCommittedVersion(SimpleConfigConsumerImpl* self) {
		state ConfigFollowerGetCommittedVersionReply committedVersionReply;
		if (self->cfi.hostname.present()) {
			wait(store(committedVersionReply,
			           retryGetReplyFromHostname(ConfigFollowerGetCommittedVersionRequest{},
			                                     self->cfi.hostname.get(),
			                                     WLTOKEN_CONFIGFOLLOWER_GETCOMMITTEDVERSION)));
		} else {
			wait(store(committedVersionReply,
			           self->cfi.getCommittedVersion.getReply(ConfigFollowerGetCommittedVersionRequest{})));
		}
		return committedVersionReply.lastCommitted;
	}

	ACTOR static Future<Void> fetchChanges(SimpleConfigConsumerImpl* self, ConfigBroadcaster* broadcaster) {
		wait(getSnapshotAndChanges(self, broadcaster));
		loop {
			try {
				state Version committedVersion = wait(getCommittedVersion(self));
				ASSERT_GE(committedVersion, self->lastSeenVersion);
				if (committedVersion > self->lastSeenVersion) {
					state ConfigFollowerGetChangesReply reply;
					if (self->cfi.hostname.present()) {
						wait(store(reply,
						           retryGetReplyFromHostname(
						               ConfigFollowerGetChangesRequest{ self->lastSeenVersion, committedVersion },
						               self->cfi.hostname.get(),
						               WLTOKEN_CONFIGFOLLOWER_GETCHANGES)));
					} else {
						wait(store(reply,
						           self->cfi.getChanges.getReply(
						               ConfigFollowerGetChangesRequest{ self->lastSeenVersion, committedVersion })));
					}
					++self->successfulChangeRequest;
					for (const auto& versionedMutation : reply.changes) {
						TraceEvent te(SevDebug, "ConsumerFetchedMutation", self->id);
						te.detail("Version", versionedMutation.version)
						    .detail("ConfigClass", versionedMutation.mutation.getConfigClass())
						    .detail("KnobName", versionedMutation.mutation.getKnobName());
						if (versionedMutation.mutation.isSet()) {
							te.detail("Op", "Set")
							    .detail("KnobValue", versionedMutation.mutation.getValue().toString());
						} else {
							te.detail("Op", "Clear");
						}
					}
					self->lastSeenVersion = committedVersion;
					broadcaster->applyChanges(reply.changes, committedVersion, reply.annotations, { self->cfi });
				}
				wait(delayJittered(self->pollingInterval));
			} catch (Error& e) {
				++self->failedChangeRequest;
				if (e.code() == error_code_version_already_compacted) {
					CODE_PROBE(true, "SimpleConfigConsumer get version_already_compacted error");
					wait(getSnapshotAndChanges(self, broadcaster));
				} else {
					throw e;
				}
			}
		}
	}

	ACTOR static Future<Void> getSnapshotAndChanges(SimpleConfigConsumerImpl* self, ConfigBroadcaster* broadcaster) {
		state Version committedVersion = wait(getCommittedVersion(self));
		state ConfigFollowerGetSnapshotAndChangesReply reply;
		if (self->cfi.hostname.present()) {
			wait(store(reply,
			           retryGetReplyFromHostname(ConfigFollowerGetSnapshotAndChangesRequest{ committedVersion },
			                                     self->cfi.hostname.get(),
			                                     WLTOKEN_CONFIGFOLLOWER_GETSNAPSHOTANDCHANGES)));
		} else {
			wait(store(reply,
			           self->cfi.getSnapshotAndChanges.getReply(
			               ConfigFollowerGetSnapshotAndChangesRequest{ committedVersion })));
		}
		++self->snapshotRequest;
		TraceEvent(SevDebug, "ConfigConsumerGotSnapshotAndChanges", self->id)
		    .detail("SnapshotVersion", reply.snapshotVersion)
		    .detail("SnapshotSize", reply.snapshot.size())
		    .detail("ChangesVersion", committedVersion)
		    .detail("ChangesSize", reply.changes.size())
		    .detail("AnnotationsSize", reply.annotations.size());
		ASSERT_GE(committedVersion, self->lastSeenVersion);
		self->lastSeenVersion = committedVersion;
		broadcaster->applySnapshotAndChanges(std::move(reply.snapshot),
		                                     reply.snapshotVersion,
		                                     reply.changes,
		                                     committedVersion,
		                                     reply.annotations,
		                                     { self->cfi });
		return Void();
	}

	static ConfigFollowerInterface getConfigFollowerInterface(ConfigFollowerInterface const& cfi) { return cfi; }

	static ConfigFollowerInterface getConfigFollowerInterface(ServerCoordinators const& coordinators) {
		return ConfigFollowerInterface(coordinators.configServers[0]);
	}

public:
	template <class ConfigSource>
	SimpleConfigConsumerImpl(ConfigSource const& configSource,
	                         double const& pollingInterval,
	                         Optional<double> const& compactionInterval)
	  : pollingInterval(pollingInterval), compactionInterval(compactionInterval),
	    id(deterministicRandom()->randomUniqueID()), cc("ConfigConsumer"), compactRequest("CompactRequest", cc),
	    successfulChangeRequest("SuccessfulChangeRequest", cc), failedChangeRequest("FailedChangeRequest", cc),
	    snapshotRequest("SnapshotRequest", cc) {
		cfi = getConfigFollowerInterface(configSource);
		logger = traceCounters(
		    "ConfigConsumerMetrics", id, SERVER_KNOBS->WORKER_LOGGING_INTERVAL, &cc, "ConfigConsumerMetrics");
	}

	Future<Void> consume(ConfigBroadcaster& broadcaster) {
		return fetchChanges(this, &broadcaster) || compactor(this, &broadcaster);
	}

	UID getID() const { return id; }
};

SimpleConfigConsumer::SimpleConfigConsumer(ConfigFollowerInterface const& cfi,
                                           double pollingInterval,
                                           Optional<double> compactionInterval)
  : impl(PImpl<SimpleConfigConsumerImpl>::create(cfi, pollingInterval, compactionInterval)) {}

SimpleConfigConsumer::SimpleConfigConsumer(ServerCoordinators const& coordinators,
                                           double pollingInterval,
                                           Optional<double> compactionInterval)
  : impl(PImpl<SimpleConfigConsumerImpl>::create(coordinators, pollingInterval, compactionInterval)) {}

Future<Void> SimpleConfigConsumer::consume(ConfigBroadcaster& broadcaster) {
	return impl->consume(broadcaster);
}

SimpleConfigConsumer::~SimpleConfigConsumer() = default;

UID SimpleConfigConsumer::getID() const {
	return impl->getID();
}