Optimize assignTexters()

[bchrobot]

Clean up src/workers/jobs.js::assignTexters()

[ben-pr-p]

The way to parallelize this would be to replace

for (let index = 0; index < texters.length; index++) {
    // a bunch of asynchronous work
}

with

const textAssignmentPromiseGenerators = texters.map(texter => {
    return () => (async () {
        // a bunch of async stuff here
    }())
})

const chunks = _.chunk(textAssignmentPromiseGenerators, CHUNK_SIZE);
for (let chunk of chunks) {
    await Promise.all(chunk.map(c => c()));
}

Basically what you will have done is created a bunch of functions that, when called, will create a promise with the texter in their closure, and then you get to create all of the stuff in one loop and control the execution nicely

[ben-pr-p]

Ok wait, you were right about this, since if you run all of the last 5 texters at the same time, they'll all fetch contactsAvailable from the state left at the finish of the previous chunks.lenght - 5, which is not ok!

The way to improve the speed of this if we ever need to is to gather the info up front, compute the amount of texts we'll want to assign to each, and then do what I said in the previous comment