git ssb

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module.exports = class LockMap {
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  constructor () {
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    this._map = new Map()
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  }
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  /**
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   * Creates a lock on a given ID and returns a resolve function to unlock the
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   * lock
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   * @param {*} id
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   * @return {function} the resolve function to call once it to unlock
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   */
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  lock (id) {
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    let r
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    const promise = new Promise((resolve, reject) => {
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      r = resolve
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    })
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    promise.then(() => {
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      this._map.delete(id)
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    })
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    this._map.set(id, promise)
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    return r
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  }
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  /**
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   * gets the current lock if any for a given id. If there is a lock this will
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   * return a promise that resolves once the lock is unlocked
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   * return {Promise}
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   */
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  getLock (id) {
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    return this._map.get(id)
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  }
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}
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