git ssb

1
const Port = require('./port.js')
2
const BN = require('bn.js')
3
const ENTRY = Symbol('entry')
4
5
// decides which message to go first
6
function messageArbiter (pairA, pairB) {
7
  const portA = pairA[1]
8
  const portB = pairB[1]
9
  const a = portA.peek()
10
  const b = portB.peek()
11
12
  if (!a) {
13
    return pairB
14
  } else if (!b) {
15
    return pairA
16
  }
17
18
  // order by number of ticks if messages have different number of ticks
19
  if (a._fromPortTicks !== b._fromPortTicks) {
20
    return a._fromPortTicks < b._fromPortTicks ? pairA : pairB
21
  } else if (a.priority !== b.priority) {
22
    // decide by priority
23
    return a.priority > b.priority ? pairA : pairB
24
  } else if (portA.name === ENTRY) {
25
    // pairB can never be the entry port since the port map is odered by
26
    // insertion order
27
    return pairA
28
  } else {
29
    return portA.name < portB.name ? pairA : pairB
30
  }
31
}
32
33
module.exports = class PortManager {
34
  constructor (opts) {
35
    Object.assign(this, opts)
36
    this._portMap = new Map()
37
  }
38
39
  async start () {
40
    // skip the root, since it doesn't have a parent
41
    if (this.parentPort !== undefined) {
42
      this._bindRef(this.parentPort, ENTRY)
43
    }
44
    // map ports to thier id's
45
    this.ports = await this.hypervisor.graph.get(this.state, 'ports')
46
    Object.keys(this.ports).map(name => {
47
      const port = this.ports[name]
48
      this._bindRef(port, name)
49
    })
50
  }
51
52
  _bindRef (portRef, name) {
53
    const port = new Port(name)
54
    this._portMap.set(portRef, port)
55
  }
56
57
  bind (port, name) {
58
    // save the port instance
59
    this.ports[name] = port
60
    this._bindRef(port, name)
61
  }
62
63
  queue (message) {
64
    this._portMap.get(message.fromPort).queue(message)
65
  }
66
67
  get (key) {
68
    return this.ports[key]
69
  }
70
71
  delete (key) {
72
    const port = this.ports[key]
73
    delete this.ports[key]
74
    this._portMap.delete(port)
75
  }
76
77
  isValidPort (port) {
78
    return this._portMap.has(port)
79
  }
80
81
  create (type) {
82
    const VM = this.hypervisor._containerTypes[type]
83
    const parentId = this.entryPort ? this.entryPort.id : null
84
    let nonce = this.state['/'].nonce
85
86
    const portRef = {
87
      'messages': [],
88
      'id': {
89
        '/': {
90
          nonce: nonce,
91
          parent: parentId
92
        }
93
      },
94
      'type': type,
95
      'link': {
96
        '/': VM.createState()
97
      }
98
    }
99
100
    // incerment the nonce
101
    nonce = new BN(nonce)
102
    nonce.iaddn(1)
103
    this.state['/'].nonce = nonce.toArray()
104
    return portRef
105
  }
106
107
  // waits till all ports have reached a threshold tick count
108
  wait (threshold, fromPort) {
109
    // find the ports that have a smaller tick count then the threshold tick count
110
    const unkownPorts = [...this._portMap].filter(([portRef, port]) => {
111
      return port.ticks < threshold && fromPort !== portRef
112
    })
113
114
    const promises = unkownPorts.map(async ([portRef, port]) => {
115
      // update the port's tick count
116
      port.ticks = await this.hypervisor.wait(portRef, threshold, this.entryPort)
117
    })
118
119
    return Promise.all(promises)
120
  }
121
122
  async getNextMessage () {
123
    if (this._portMap.size) {
124
      await this.wait(this.kernel.ticks, this.entryPort)
125
      const portMap = [...this._portMap].reduce(messageArbiter)
126
      return portMap[1].shift()
127
    }
128
  }
129
}
130