git ssb

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const Port = require('./port.js')
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// decides which message to go firts
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function messageArbiter (portA, portB) {
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  const a = portA.peek()
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  const b = portB.peek()
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  if (!a) {
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    return b
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  } else if (!b) {
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    return a
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  }
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  const aGasPrice = a.resources.gasPrice
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  const bGasPrice = b.resources.gasPrice
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  if (a.ticks !== b.ticks) {
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    return a.ticks < b.ticks ? a : b
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  } else if (aGasPrice === bGasPrice) {
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    return a.hash() > b.hash() ? a : b
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  } else {
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    return aGasPrice > bGasPrice ? a : b
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  }
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}
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module.exports = class PortManager {
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  constructor (kernel) {
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    this.kernel = kernel
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    this.hypervisor = kernel._opts.hypervisor
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    this.ports = kernel._opts.state['/'].ports
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    this._portMap = new Map()
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  }
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  async start () {
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    // map ports to thier id's
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    let ports = Object.keys(this.ports).map(name => {
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      const port = this.ports[name]
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      this.hypervisor.generateID(port).then(id => {
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        return [id, new Port(name)]
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      })
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    })
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    // create the parent port
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    ports = await Promise.all(ports)
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    this._portMap = new Map(ports)
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    // add the parent port
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    let parent = await this.hypervisor.graph.get(this.kernel._opts.id, 'parent')
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    parent = parent === null ? 'root' : parent
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    this._portMap.set(parent, new Port('parent'))
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  }
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  queue (message) {
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    this._portMap.get(message.fromPort).queue(message)
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  }
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  create (name, value) {
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    this.ports[name] = value
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  }
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  del (name) {
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    delete this.ports[name]
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  }
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  move (from, to) {
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    this.ports[to] = this.ports[from]
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    delete this.ports[from]
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  }
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  async get (name) {
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    const port = await this.graph.get(this.state.ports, name)
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    const id = await this.hypervisor.generateID(port)
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    return this._portMap.get(id)
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  }
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  async getParent () {
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    const id = await this.hypervisor.generateID(this.kernel._opts)
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    return this._portMap.get(id)
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  }
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  // waits till all ports have reached a threshold tick count
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  async wait (threshold) {
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    // find the ports that have a smaller tick count then the threshold tick count
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    const unkownPorts = [...this._portMap].filter(([id, port]) => {
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      return port._ticks < threshold
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    })
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    const promises = unkownPorts.map(([id, port]) => {
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      this.hypervisor.wait(id, threshold).then(ticks => {
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        // update the port's tick count
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        port.ticks = ticks
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      })
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    })
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    await Promise.all(promises)
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  }
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  async getNextMessage (ticks) {
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    await this.wait(ticks)
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    return [...this._portMap].reduce(messageArbiter)[1].shift()
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  }
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}
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