95 lines
2.9 KiB
C++
95 lines
2.9 KiB
C++
/*
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* pubsub.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2022 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "fdbclient/NativeAPI.actor.h"
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/*
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* ///////////////
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* General FDB data model of Pub/Sub model
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* Feeds, Inboxes, Messages
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*
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* Message - publisher (feed), data
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*
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* Inbox - message cache, dirty list, list of subscribed-to feeds
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*
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* Feed - messages, list of inboxes to notify
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*
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* Structures for scalability: global list of dispatching feeds, feeds to consider
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* dirty for all operation
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*
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* ///////////////
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* Basic Processes: post message, list messages
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*
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* Post (in one transaction):
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* 1. Add message to list of message in feed history
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* 2. For each Inbox of list of watching inboxes
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* a. remove Inbox from list of watchers
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* b. mark self as 'dirty' in the Inbox's dirty list
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*
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* List recent message in Inbox (in one transaction), up to n messages:
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* 1. For each dirty Feed, update cache with latest message
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* 2. Triage list by getting latest m messages from top m feeds
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* note: these messages can be cached in memory on the server, and on paging
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* operations reused, so long as step 1 is repeated, IF there is no message deletion.
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*
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* ////////////////
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* Assumptions:
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* 1. Subscriptions are "retroactive". If a subscription is in place, the messages
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* from that feed will start to appear in the listing of that inboxes messages
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* and appear in historical lists as well. This could lead to odd behaviour
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* if paging through the contents of an inbox while a new subscrption was added
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*/
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typedef uint64_t Feed;
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typedef uint64_t Inbox;
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typedef uint64_t MessageId;
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class Message {
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public:
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Feed originatorFeed;
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MessageId messageId;
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Standalone<StringRef> data;
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template <class Ar>
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void serialize(Ar& ar) {
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serializer(ar, originatorFeed, messageId, data, data.arena());
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}
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};
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class PubSub {
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public:
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PubSub(Database cx);
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Future<Feed> createFeed(Standalone<StringRef> metadata);
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Future<Inbox> createInbox(Standalone<StringRef> metadata);
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Future<bool> createSubscription(Feed feed, Inbox inbox);
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Future<MessageId> postMessage(Feed feed, Standalone<StringRef> data);
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Future<std::vector<Message>> listFeedMessages(Feed feed, int count, MessageId cursor = 0);
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Future<std::vector<Message>> listInboxMessages(Inbox inbox, int count, MessageId cursor = 0);
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private:
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Database cx;
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};
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