515 lines
19 KiB
C++
515 lines
19 KiB
C++
/*
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* pubsub.cpp
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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 2013-2026 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 <cinttypes>
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#include "fdbclient/NativeAPI.actor.h"
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#include "pubsub.h"
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Value uInt64ToValue(uint64_t v) {
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return StringRef(format("%016llx", v));
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}
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uint64_t valueToUInt64(const StringRef& v) {
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uint64_t x = 0;
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sscanf(v.toString().c_str(), "%" SCNx64, &x);
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return x;
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}
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Key keyForInbox(uint64_t inbox) {
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return StringRef(format("i/%016llx", inbox));
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}
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Key keyForInboxSubscription(uint64_t inbox, uint64_t feed) {
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return StringRef(format("i/%016llx/subs/%016llx", inbox, feed));
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}
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Key keyForInboxSubscriptionCount(uint64_t inbox) {
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return StringRef(format("i/%016llx/subsCnt", inbox));
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}
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Key keyForInboxStalePrefix(uint64_t inbox) {
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return StringRef(format("i/%016llx/stale/", inbox));
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}
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Key keyForInboxStaleFeed(uint64_t inbox, uint64_t feed) {
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return StringRef(format("i/%016llx/stale/%016llx", inbox, feed));
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}
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Key keyForInboxCacheByIDPrefix(uint64_t inbox) {
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return StringRef(format("i/%016llx/cid/", inbox));
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}
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Key keyForInboxCacheByID(uint64_t inbox, uint64_t messageId) {
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return StringRef(format("i/%016llx/cid/%016llx", inbox, messageId));
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}
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Key keyForInboxCacheByFeed(uint64_t inbox, uint64_t feed) {
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return StringRef(format("i/%016llx/cf/%016llx", inbox, feed));
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}
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Key keyForFeed(uint64_t feed) {
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return StringRef(format("f/%016llx", feed));
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}
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Key keyForFeedSubscriber(uint64_t feed, uint64_t inbox) {
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return StringRef(format("f/%016llx/subs/%016llx", feed, inbox));
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}
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Key keyForFeedSubscriberCount(uint64_t feed) {
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return StringRef(format("f/%016llx/subscCnt", feed));
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}
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Key keyForFeedMessage(uint64_t feed, uint64_t message) {
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return StringRef(format("f/%016llx/m/%016llx", feed, message));
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}
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Key keyForFeedMessagePrefix(uint64_t feed) {
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return StringRef(format("f/%016llx/m/", feed));
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}
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Key keyForFeedMessageCount(uint64_t feed) {
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return StringRef(format("f/%016llx/messCount", feed));
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}
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// the following should go at some point: change over to range query of count 1 from feed message list
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Key keyForFeedLatestMessage(uint64_t feed) {
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return StringRef(format("f/%016llx/latestMessID", feed));
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}
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Key keyForFeedWatcherPrefix(uint64_t feed) {
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return StringRef(format("f/%016llx/watchers/", feed));
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}
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Key keyForFeedWatcher(uint64_t feed, uint64_t inbox) {
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return StringRef(format("f/%016llx/watchers/%016llx", feed, inbox));
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}
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Standalone<StringRef> messagePrefix("m/"_sr);
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Key keyForMessage(uint64_t message) {
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return StringRef(format("m/%016llx", message));
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}
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Key keyForDisptchEntry(uint64_t message) {
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return StringRef(format("d/%016llx", message));
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}
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PubSub::PubSub(Database _cx) : cx(_cx) {}
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Future<uint64_t> _createFeed(Database cx, Standalone<StringRef> metadata) {
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uint64_t id(deterministicRandom()->randomUniqueID().first()); // SOMEDAY: this should be an atomic increment
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TraceEvent("PubSubCreateFeed").detail("Feed", id);
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Transaction tr(cx);
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while (true) {
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Error err;
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try {
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Optional<Value> val = co_await tr.get(keyForFeed(id));
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while (val.present()) {
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id = id + deterministicRandom()->randomInt(1, 100);
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Optional<Value> v = co_await tr.get(keyForFeed(id));
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val = v;
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}
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tr.set(keyForFeed(id), metadata);
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tr.set(keyForFeedSubscriberCount(id), uInt64ToValue(0));
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tr.set(keyForFeedMessageCount(id), uInt64ToValue(0));
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co_await tr.commit();
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break;
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} catch (Error& e) {
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err = e;
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}
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co_await tr.onError(err);
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}
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co_return id;
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}
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Future<uint64_t> PubSub::createFeed(Standalone<StringRef> metadata) {
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return _createFeed(cx, metadata);
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}
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Future<uint64_t> _createInbox(Database cx, Standalone<StringRef> metadata) {
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uint64_t id = deterministicRandom()->randomUniqueID().first();
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TraceEvent("PubSubCreateInbox").detail("Inbox", id);
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Transaction tr(cx);
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while (true) {
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Error err;
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try {
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Optional<Value> val = co_await tr.get(keyForInbox(id));
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while (val.present()) {
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id += deterministicRandom()->randomInt(1, 100);
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Optional<Value> v = co_await tr.get(keyForFeed(id));
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val = v;
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}
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tr.set(keyForInbox(id), metadata);
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tr.set(keyForInboxSubscriptionCount(id), uInt64ToValue(0));
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co_await tr.commit();
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break;
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} catch (Error& e) {
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err = e;
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}
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co_await tr.onError(err);
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}
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co_return id;
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}
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Future<uint64_t> PubSub::createInbox(Standalone<StringRef> metadata) {
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return _createInbox(cx, metadata);
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}
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Future<bool> _createSubscription(Database cx, uint64_t feed, uint64_t inbox) {
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Transaction tr(cx);
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TraceEvent("PubSubCreateSubscription").detail("Feed", feed).detail("Inbox", inbox);
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while (true) {
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Error err;
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try {
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Optional<Value> subscription = co_await tr.get(keyForInboxSubscription(inbox, feed));
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if (subscription.present()) {
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// For idempotency, this could exist from a previous transaction from us that succeeded
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co_return true;
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}
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Optional<Value> inboxVal = co_await tr.get(keyForInbox(inbox));
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if (!inboxVal.present()) {
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co_return false;
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}
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Optional<Value> feedVal = co_await tr.get(keyForFeed(feed));
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if (!feedVal.present()) {
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co_return false;
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}
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// Update the subscriptions of the inbox
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Optional<Value> subscriptionCountVal = co_await tr.get(keyForInboxSubscriptionCount(inbox));
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uint64_t subscriptionCount = valueToUInt64(subscriptionCountVal.get()); // throws if count not present
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tr.set(keyForInboxSubscription(inbox, feed), StringRef());
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tr.set(keyForInboxSubscriptionCount(inbox), uInt64ToValue(subscriptionCount + 1));
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// Update the subscribers of the feed
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Optional<Value> subscriberCountVal = co_await tr.get(keyForFeedSubscriberCount(feed));
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uint64_t subscriberCount = valueToUInt64(subscriberCountVal.get()); // throws if count not present
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tr.set(keyForFeedSubscriber(feed, inbox), StringRef());
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tr.set(keyForFeedSubscriberCount(inbox), uInt64ToValue(subscriberCount + 1));
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// Add inbox as watcher of feed.
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tr.set(keyForFeedWatcher(feed, inbox), StringRef());
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co_await tr.commit();
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break;
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} catch (Error& e) {
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err = e;
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}
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co_await tr.onError(err);
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}
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co_return true;
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}
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Future<bool> PubSub::createSubscription(uint64_t feed, uint64_t inbox) {
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return _createSubscription(cx, feed, inbox);
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}
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// Since we are not relying on "read-your-own-writes", we need to keep track of
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// the highest-numbered inbox that we've cleared from the watchers list and
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// make sure that further requests start after this inbox.
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Future<Void> updateFeedWatchers(Transaction* tr, uint64_t feed) {
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Key watcherPrefix = keyForFeedWatcherPrefix(feed);
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uint64_t highestInbox{ 0 };
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bool first = true;
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while (true) {
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// Grab watching inboxes in swaths of 100
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RangeResult watchingInboxes =
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co_await (*tr).getRange(firstGreaterOrEqual(keyForFeedWatcher(feed, first ? 0 : highestInbox + 1)),
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firstGreaterOrEqual(keyForFeedWatcher(feed, UINT64_MAX)),
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100); // REVIEW: does 100 make sense?
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if (watchingInboxes.empty())
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// If there are no watchers, return.
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co_return;
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first = false;
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for (int idx = 0; idx < watchingInboxes.size(); idx++) {
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KeyRef key = watchingInboxes[idx].key;
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StringRef inboxStr = key.removePrefix(watcherPrefix);
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uint64_t inbox = valueToUInt64(inboxStr);
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// add this feed to the stale list of inbox
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(*tr).set(keyForInboxStaleFeed(inbox, feed), StringRef());
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// remove the inbox from the list of watchers on this feed
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(*tr).clear(key);
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highestInbox = inbox;
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}
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if (watchingInboxes.size() < 100)
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// If there were fewer watchers returned that we asked for, we're done.
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co_return;
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}
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}
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/*
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* Posts a message to a feed. This updates the list of stale feeds to all watchers.
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* Return: a per-feed (non-global) message ID.
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*
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* This needs many additions to make it "real"
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* SOMEDAY: create better global message table to enforce cross-feed ordering.
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* SOMEDAY: create a global "dispatching" list for feeds that have yet to fully update inboxes.
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* Move feed in and remove watchers in one transaction, possibly
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* SOMEDAY: create a global list of the most-subscribed-to feeds that all inbox reads check
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*/
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Future<uint64_t> _postMessage(Database cx, uint64_t feed, Standalone<StringRef> data) {
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Transaction tr(cx);
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uint64_t messageId = UINT64_MAX - (uint64_t)now();
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TraceEvent("PubSubPost").detail("Feed", feed).detail("Message", messageId);
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while (true) {
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Error err;
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try {
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Optional<Value> feedValue = co_await tr.get(keyForFeed(feed));
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if (!feedValue.present()) {
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// No such feed!!
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co_return uint64_t(0);
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}
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// Get globally latest message, set our ID to that less one
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RangeResult latestMessage = co_await tr.getRange(
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firstGreaterOrEqual(keyForMessage(0)), firstGreaterOrEqual(keyForMessage(UINT64_MAX)), 1);
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if (latestMessage.empty()) {
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messageId = UINT64_MAX - 1;
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} else {
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StringRef messageStr = latestMessage[0].key.removePrefix(messagePrefix);
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messageId = valueToUInt64(messageStr) - 1;
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}
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tr.set(keyForMessage(messageId), StringRef());
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tr.set(keyForDisptchEntry(messageId), StringRef());
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co_await tr.commit();
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break;
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} catch (Error& e) {
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err = e;
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}
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co_await tr.onError(err);
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}
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tr = Transaction(cx);
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while (true) {
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Error err;
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try {
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// Record this ID as the "latest message" for a feed
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tr.set(keyForFeedLatestMessage(feed), uInt64ToValue(messageId));
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// Store message in list of feed's messages
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tr.set(keyForFeedMessage(feed, messageId), StringRef());
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// Update the count of message that this feed has published
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Optional<Value> cntValue = co_await tr.get(keyForFeedMessageCount(feed));
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uint64_t messageCount(valueToUInt64(cntValue.get()) + 1);
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tr.set(keyForFeedMessageCount(feed), uInt64ToValue(messageCount));
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// Go through the list of watching inboxes
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co_await updateFeedWatchers(&tr, feed);
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// Post the real message data; clear the "dispatching" entry
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tr.set(keyForMessage(messageId), data);
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tr.clear(keyForDisptchEntry(messageId));
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co_await tr.commit();
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break;
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} catch (Error& e) {
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err = e;
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}
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co_await tr.onError(err);
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}
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co_return messageId;
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}
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Future<uint64_t> PubSub::postMessage(uint64_t feed, Standalone<StringRef> data) {
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return _postMessage(cx, feed, data);
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}
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Future<int> singlePassInboxCacheUpdate(Database cx, uint64_t inbox, int swath) {
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Transaction tr(cx);
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while (true) {
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Error err;
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try {
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// For each stale feed, update cache with latest message id
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RangeResult staleFeeds = co_await tr.getRange(firstGreaterOrEqual(keyForInboxStaleFeed(inbox, 0)),
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firstGreaterOrEqual(keyForInboxStaleFeed(inbox, UINT64_MAX)),
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swath); // REVIEW: does 100 make sense?
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// printf(" --> stale feeds list size: %d\n", staleFeeds.size());
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if (staleFeeds.empty())
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// If there are no stale feeds, return.
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co_return 0;
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Key stalePrefix = keyForInboxStalePrefix(inbox);
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for (int idx = 0; idx < staleFeeds.size(); idx++) {
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StringRef feedStr = staleFeeds[idx].key.removePrefix(stalePrefix);
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// printf(" --> clearing stale entry: %s\n", feedStr.toString().c_str());
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uint64_t feed = valueToUInt64(feedStr);
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// SOMEDAY: change this to be a range query for the highest #'ed message
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Optional<Value> v = co_await tr.get(keyForFeedLatestMessage(feed));
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Value latestMessageValue = v.get();
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// printf(" --> latest message from feed: %s\n", latestMessageValue.toString().c_str());
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// find the messageID which is currently cached for this feed
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Optional<Value> lastCachedValue = co_await tr.get(keyForInboxCacheByFeed(inbox, feed));
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if (lastCachedValue.present()) {
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uint64_t lastCachedId = valueToUInt64(lastCachedValue.get());
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// clear out the cache entry in the "by-ID" list for this feed
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// SOMEDAY: should we leave this in there in some way, or should we pull a better/more recent cache?
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tr.clear(keyForInboxCacheByID(inbox, lastCachedId));
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}
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// printf(" --> caching message by ID: %s\n", keyForInboxCacheByID(inbox,
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// valueToUInt64(latestMessageValue)).toString().c_str());
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tr.set(keyForInboxCacheByID(inbox, valueToUInt64(latestMessageValue)), uInt64ToValue(feed));
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// set the latest message
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tr.set(keyForInboxCacheByFeed(inbox, feed), latestMessageValue);
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tr.clear(staleFeeds[idx].key);
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// place watch back on feed
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tr.set(keyForFeedWatcher(feed, inbox), StringRef());
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// printf(" --> adding watch to feed: %s\n", keyForFeedWatcher(feed, inbox).toString().c_str());
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}
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co_await tr.commit();
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co_return staleFeeds.size();
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} catch (Error& e) {
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err = e;
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}
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co_await tr.onError(err);
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}
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}
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// SOMEDAY: evaluate if this could lead to painful loop if there's one frequent feed.
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Future<Void> updateInboxCache(Database cx, uint64_t inbox) {
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int swath = 100;
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int updatedEntries = swath;
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while (updatedEntries >= swath) {
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updatedEntries = co_await singlePassInboxCacheUpdate(cx, inbox, swath);
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}
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}
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Future<MessageId> getFeedLatestAtOrAfter(Transaction* tr, Feed feed, MessageId position) {
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RangeResult lastMessageRange = co_await (*tr).getRange(firstGreaterOrEqual(keyForFeedMessage(feed, position)),
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firstGreaterOrEqual(keyForFeedMessage(feed, UINT64_MAX)),
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1);
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if (lastMessageRange.empty())
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co_return uint64_t(0);
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KeyValueRef m = lastMessageRange[0];
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Key prefix = keyForFeedMessagePrefix(feed);
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StringRef mIdStr = m.key.removePrefix(prefix);
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co_return valueToUInt64(mIdStr);
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}
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Future<Message> getMessage(Transaction* tr, Feed feed, MessageId id) {
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Message m;
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m.originatorFeed = feed;
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m.messageId = id;
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Optional<Value> data = co_await tr->get(keyForMessage(id));
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m.data = data.get();
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co_return m;
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}
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Future<std::vector<Message>> _listInboxMessages(Database cx, uint64_t inbox, int count, uint64_t cursor);
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// inboxes with MANY fast feeds may be punished by the following checks
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// SOMEDAY: add a check on global lists (or on dispatching list)
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Future<std::vector<Message>> _listInboxMessages(Database cx, uint64_t inbox, int count, uint64_t cursor) {
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TraceEvent("PubSubListInbox").detail("Inbox", inbox).detail("Count", count).detail("Cursor", cursor);
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co_await updateInboxCache(cx, inbox);
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Key perIdPrefix = keyForInboxCacheByIDPrefix(inbox);
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while (true) {
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Transaction tr(cx);
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std::vector<Message> messages;
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std::map<MessageId, Feed> feedLatest;
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Error err;
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try {
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// Fetch all cached entries for all the feeds to which we are subscribed
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Optional<Value> cntValue = co_await tr.get(keyForInboxSubscriptionCount(inbox));
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uint64_t subscriptions = valueToUInt64(cntValue.get());
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RangeResult feeds = co_await tr.getRange(firstGreaterOrEqual(keyForInboxCacheByID(inbox, 0)),
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firstGreaterOrEqual(keyForInboxCacheByID(inbox, UINT64_MAX)),
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subscriptions);
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if (feeds.empty())
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co_return messages;
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// read cache into map, replace entries newer than cursor with the newest older than cursor
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for (int idx = 0; idx < feeds.size(); idx++) {
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StringRef mIdStr = feeds[idx].key.removePrefix(perIdPrefix);
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MessageId messageId = valueToUInt64(mIdStr);
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Feed feed = valueToUInt64(feeds[idx].value);
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// printf(" -> cached message %016llx from feed %016llx\n", messageId, feed);
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if (messageId >= cursor) {
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// printf(" -> entering message %016llx from feed %016llx\n", messageId, feed);
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feedLatest.emplace(messageId, feed);
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} else {
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// replace this with the first message older than the cursor
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MessageId mId = co_await getFeedLatestAtOrAfter(&tr, feed, cursor);
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if (mId) {
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feedLatest.emplace(mId, feed);
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}
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}
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}
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// There were some cached feeds, but none with messages older than "cursor"
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if (feedLatest.empty())
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co_return messages;
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// Check the list of dispatching messages to make sure there are no older ones than ours
|
|
MessageId earliestMessage = feedLatest.begin()->first;
|
|
RangeResult dispatching = co_await tr.getRange(firstGreaterOrEqual(keyForDisptchEntry(earliestMessage)),
|
|
firstGreaterOrEqual(keyForDisptchEntry(UINT64_MAX)),
|
|
1);
|
|
// If there are messages "older" than ours, try this again
|
|
// (with a new transaction and a flush of the "stale" feeds
|
|
if (!dispatching.empty()) {
|
|
std::vector<Message> r = co_await _listInboxMessages(cx, inbox, count, earliestMessage);
|
|
co_return r;
|
|
}
|
|
|
|
while (messages.size() < count && !feedLatest.empty()) {
|
|
auto latest = feedLatest.begin();
|
|
MessageId id = latest->first;
|
|
Feed f = latest->second;
|
|
feedLatest.erase(latest);
|
|
|
|
Message m = co_await getMessage(&tr, f, id);
|
|
messages.push_back(m);
|
|
|
|
MessageId nextMessage = co_await getFeedLatestAtOrAfter(&tr, f, id + 1);
|
|
if (nextMessage) {
|
|
feedLatest.emplace(nextMessage, f);
|
|
}
|
|
}
|
|
|
|
co_return messages;
|
|
} catch (Error& e) {
|
|
err = e;
|
|
}
|
|
co_await tr.onError(err);
|
|
}
|
|
}
|
|
|
|
Future<std::vector<Message>> PubSub::listInboxMessages(uint64_t inbox, int count, uint64_t cursor) {
|
|
return _listInboxMessages(cx, inbox, count, cursor);
|
|
}
|
|
|
|
Future<std::vector<Message>> _listFeedMessages(Database cx, Feed feed, int count, uint64_t cursor) {
|
|
std::vector<Message> messages;
|
|
Transaction tr(cx);
|
|
TraceEvent("PubSubListFeed").detail("Feed", feed).detail("Count", count).detail("Cursor", cursor);
|
|
while (true) {
|
|
Error err;
|
|
try {
|
|
RangeResult messageIds = co_await tr.getRange(firstGreaterOrEqual(keyForFeedMessage(feed, cursor)),
|
|
firstGreaterOrEqual(keyForFeedMessage(feed, UINT64_MAX)),
|
|
count);
|
|
if (messageIds.empty())
|
|
co_return messages;
|
|
|
|
for (int idx = 0; idx < messageIds.size(); idx++) {
|
|
StringRef mIdStr = messageIds[idx].key.removePrefix(keyForFeedMessagePrefix(feed));
|
|
MessageId messageId = valueToUInt64(mIdStr);
|
|
Message m = co_await getMessage(&tr, feed, messageId);
|
|
messages.push_back(m);
|
|
}
|
|
co_return messages;
|
|
} catch (Error& e) {
|
|
err = e;
|
|
}
|
|
co_await tr.onError(err);
|
|
}
|
|
}
|
|
|
|
Future<std::vector<Message>> PubSub::listFeedMessages(Feed feed, int count, uint64_t cursor) {
|
|
return _listFeedMessages(cx, feed, count, cursor);
|
|
}
|