git ssb

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module.exports = class WasmContainer {
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  /**
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   * The interface API is the api the exposed to interfaces. All queries about
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   * the enviroment and call to the kernel go through this API
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   */
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  constructor (code) {
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    this._module = WebAssembly.Module(code)
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  }
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  static get name () {
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    return 'wasm'
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  }
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  /**
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   * Runs the core VM with a given environment and imports
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   */
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  async run (message, kernel, imports = []) {
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    const responses = {}
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    /**
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     * Builds a import map with an array of given interfaces
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     */
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    function buildImports (opts, imports) {
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      const importMap = {}
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      for (const Import of imports) {
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        const name = Import.name
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        opts.response = responses[name] = {}
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        const newInterface = new Import(opts)
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        const props = Object.getOwnPropertyNames(Import.prototype)
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        // bind the methods to the correct 'this'
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        for (const prop of props) {
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          newInterface[prop] = newInterface[prop].bind(newInterface)
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        }
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        importMap[name] = newInterface
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      }
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      return importMap
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    }
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    let instance
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    const opts = {
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      vm: {
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        /**
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         * adds an aync operation to the operations queue
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         */
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        pushOpsQueue: (promise, callbackIndex, intefaceCallback) => {
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          this._opsQueue = Promise.all([this._opsQueue, promise]).then(values => {
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            const result = intefaceCallback(values.pop())
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            instance.exports.callback.get(callbackIndex)(result)
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          })
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        },
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        memory: () => {
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          return instance.exports.memory.buffer
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        }
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      },
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      kernel: kernel,
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      message: message
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    }
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    const initializedImports = buildImports(opts, imports)
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    instance = WebAssembly.Instance(this._module, initializedImports)
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    if (instance.exports.main) {
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      instance.exports.main()
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    }
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    await this.onDone()
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    return responses
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  }
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  /**
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   * returns a promise that resolves when the wasm instance is done running
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   */
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  async onDone () {
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    let prevOps
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    while (prevOps !== this._opsQueue) {
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      prevOps = this._opsQueue
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      await this._opsQueue
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    }
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  }
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}
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