Files: 26423b152859d2a3cccf24570ef55cf2770aee41 / kernel.js
3172 bytesRaw
1 | const crypto = require('webcrypto-liner') |
2 | const PriorityQueue = require('fastpriorityqueue') |
3 | const EventEmitter = require('events') |
4 | const PortManager = require('./portManager.js') |
5 | |
6 | const STATES = ['idle', 'running', 'result'] |
7 | |
8 | module.exports = class Kernel extends EventEmitter { |
9 | constructor (opts = {}) { |
10 | super() |
11 | // set up the state |
12 | this.opts = {} |
13 | this._stateIndex = 0 |
14 | Object.assign(this.opts, opts) |
15 | // set up the vm |
16 | this.vm = (this.opts.codeHandler).init(this.opts.state) |
17 | this.ports = new PortManager(this) |
18 | this._waitingQueue = new PriorityQueue((a, b) => { |
19 | return a.threshold > b.threshold |
20 | }) |
21 | |
22 | this.on('result', this._runNextMessage) |
23 | } |
24 | |
25 | _updateState (message) { |
26 | this._stateIndex++ |
27 | const state = STATES[this._stateIndex] |
28 | this._emit(state, message) |
29 | } |
30 | |
31 | get state () { |
32 | return STATES[this._stateIndex] |
33 | } |
34 | |
35 | queue (message) { |
36 | this.portManager.queue(message) |
37 | if (this.state === 'idle') { |
38 | this._runNextMessage() |
39 | } |
40 | } |
41 | |
42 | _runNextMessage () { |
43 | this.portManager.getNextMessage(this.ticks).then(message => { |
44 | if (message) { |
45 | this.run(message) |
46 | } else { |
47 | this._updateState() |
48 | } |
49 | }) |
50 | } |
51 | |
52 | /** |
53 | * run the kernels code with a given enviroment |
54 | * The Kernel Stores all of its state in the Environment. The Interface is used |
55 | * to by the VM to retrive infromation from the Environment. |
56 | */ |
57 | async run (message, imports = this.imports) { |
58 | // shallow copy |
59 | const oldState = Object.assign({}, this.state) |
60 | let result |
61 | this._updateState(message) |
62 | try { |
63 | result = await this._vm.run(message, this, imports) || {} |
64 | } catch (e) { |
65 | result = { |
66 | exception: true, |
67 | exceptionError: e |
68 | } |
69 | } |
70 | |
71 | if (result.exception) { |
72 | // revert to the old state |
73 | clearObject(this.opts.state) |
74 | Object.assign(this.opts.state, oldState) |
75 | } |
76 | |
77 | this._updateState(result) |
78 | return result |
79 | } |
80 | |
81 | // returns a promise that resolves once the kernel hits the threshould tick |
82 | // count |
83 | async wait (threshold) { |
84 | if (this._state === 'idle' && threshold > this.ticks) { |
85 | // the cotract is at idle so wait |
86 | return this.portManager.wait(threshold) |
87 | } else { |
88 | return new Promise((resolve, reject) => { |
89 | if (threshold <= this.ticks) { |
90 | resolve(this.ticks) |
91 | } else { |
92 | this._waitingQueue.add({ |
93 | threshold: threshold, |
94 | resolve: resolve |
95 | }) |
96 | } |
97 | }) |
98 | } |
99 | } |
100 | |
101 | _updateTickCount (count) { |
102 | this.ticks = count |
103 | while (this._waitingQueue.peek().threshold <= count) { |
104 | this._waitingQueue.poll().resolve(count) |
105 | } |
106 | } |
107 | |
108 | createPort () { |
109 | return { |
110 | id: { |
111 | '/': [this.nonce++, this.id] |
112 | }, |
113 | link: { |
114 | '/': {} |
115 | } |
116 | } |
117 | } |
118 | |
119 | async send (port, message) { |
120 | return this.opts.hypervisor.send(port, message) |
121 | } |
122 | |
123 | id () { |
124 | return Kernel.id(this._opts, this._opts) |
125 | } |
126 | |
127 | static id (id) { |
128 | return crypto.subtle.digest('SHA-256', Buffer.concat(id.parentId, id.nonce)) |
129 | } |
130 | } |
131 | |
132 | function clearObject (myObject) { |
133 | for (var member in myObject) { |
134 | delete myObject[member] |
135 | } |
136 | } |
137 |
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