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comparison src/layout/StreamedGraphClient.ts @ 107:042bd3361339

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author drewp@bigasterisk.com
date Sun, 13 Mar 2022 22:02:30 -0700
parents src/layout/streamed_graph_client.ts@2468f2227d22
children 5a1a79f54779
comparison
equal deleted inserted replaced
106:2468f2227d22 107:042bd3361339
1 import { eachJsonLdQuad } from "./json_ld_quads";
2 import { Store } from "n3";
3
4 export class StreamedGraphClient {
5 // holds a n3 Store, which is synced to a server-side
6 // store that sends patches over SSE
7
8 onStatus: (msg: string) => void = function (m) {};
9 onGraphChanged: () => void = function () {};
10 store: Store;
11 _deletedCount: number = 0;
12 events!: EventSource;
13 constructor(
14 eventsUrl: string,
15 onGraphChanged: () => void,
16 onStatus: (status: string) => void,
17 prefixes: Array<Record<string, string>>,
18 staticGraphUrls: Array<string>
19 ) {
20 console.log("new StreamedGraph", eventsUrl);
21 this.onStatus = onStatus;
22 this.onGraphChanged = onGraphChanged;
23 this.onStatus("startup...");
24
25 this.store = new Store();
26
27 // Object.keys(prefixes).forEach((prefix) => {
28 // this.store.setPrefix(prefix, prefixes[prefix]);
29 // });
30
31 this.connect(eventsUrl);
32 this.reconnectOnWake();
33
34 // staticGraphUrls.forEach((url) => {
35 // fetch(url).then((response) => response.text())
36 // .then((body) => {
37 // // parse with n3, add to output
38 // });
39 // });
40 }
41
42 _vacuum() {
43 // workaround for the growing _ids map
44 this.store = new Store(this.store.getQuads(null, null, null, null));
45 }
46
47 reconnectOnWake() {
48 // it's not this, which fires on every mouse-in on a browser window, and doesn't seem to work for screen-turned-back-on
49 //window.addEventListener('focus', function() { this.connect(eventsUrl); }.bind(this));
50 }
51
52 connect(eventsUrl: string) {
53 // need to exit here if this obj has been replaced
54
55 this.onStatus("start connect...");
56 this.close();
57 if (this.events && this.events.readyState != EventSource.CLOSED) {
58 this.onStatus("zombie");
59 throw new Error("zombie eventsource");
60 }
61
62 this.events = new EventSource(eventsUrl, { withCredentials: true });
63
64 this.events.addEventListener("error", (ev) => {
65 // todo: this is piling up tons of retries and eventually multiple connections
66 this.testEventUrl(eventsUrl);
67 this.onStatus("connection lost- retrying");
68 setTimeout(() => {
69 requestAnimationFrame(() => {
70 this.connect(eventsUrl);
71 });
72 }, 3000);
73 });
74
75 this.events.addEventListener("fullGraph", async (ev) => {
76 this.onStatus("sync- full graph update");
77 await this.replaceFullGraph((ev as MessageEvent).data);
78 this.onStatus(`synced ${this.store.size}`);
79 this.onGraphChanged();
80 });
81
82 this.events.addEventListener("patch", async (ev) => {
83 this.onStatus("sync- updating");
84 await this.patchGraph((ev as MessageEvent).data);
85 window.setTimeout(() => {
86 this.onStatus(`synced ${this.store.size}`);
87 }, 60);
88 this.onGraphChanged();
89 });
90 this.onStatus("connecting...");
91 }
92
93 // these need some locks
94 async replaceFullGraph(jsonLdText: string) {
95 this.store = new Store();
96 await eachJsonLdQuad(
97 JSON.parse(jsonLdText),
98 this.store.addQuad.bind(this.store)
99 );
100 }
101
102 async patchGraph(patchJson: string) {
103 var patch = JSON.parse(patchJson).patch;
104
105 await eachJsonLdQuad(patch.deletes, (quad) => {
106 this.store.removeQuad(quad);
107 this._deletedCount++;
108 });
109 await eachJsonLdQuad(patch.adds, this.store.addQuad.bind(this.store));
110
111 if (this._deletedCount > 100) {
112 this._vacuum();
113 this._deletedCount = 0;
114 }
115 }
116
117 close() {
118 if (this.events) {
119 this.events.close();
120 }
121 }
122
123 async testEventUrl(eventsUrl: string): Promise<void> {
124 return new Promise<void>((resolve, reject) => {
125 this.onStatus("testing connection");
126 fetch(eventsUrl, {
127 method: "HEAD",
128 credentials: "include",
129 })
130 .then((value) => {
131 if (value.status == 403) {
132 reject();
133 return;
134 }
135 resolve();
136 })
137 .catch((err) => {
138 reject();
139 });
140 });
141 }
142 }