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v/examples/news_fetcher.v

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// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
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import net.http
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import json
import sync
struct Story {
title string
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url string
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}
fn worker_fetch(p &sync.PoolProcessor, cursor int, worker_id int) voidptr {
id := p.get_item<int>(cursor)
resp := http.get('https://hacker-news.firebaseio.com/v0/item/${id}.json') or {
println('failed to fetch data from /v0/item/${id}.json')
return sync.no_result
}
story := json.decode(Story,resp.text) or {
println('failed to decode a story')
return sync.no_result
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}
println('# $cursor) $story.title | $story.url')
return sync.no_result
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}
// Fetches top HN stories in parallel, depending on how many cores you have
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fn main() {
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resp := http.get('https://hacker-news.firebaseio.com/v0/topstories.json') or {
println('failed to fetch data from /v0/topstories.json')
return
}
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mut ids := json.decode([]int,resp.text) or {
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println('failed to decode topstories.json')
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return
}
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if ids.len > 10 {
ids = ids[0..10]
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}
mut fetcher_pool := sync.new_pool_processor({
callback: worker_fetch
})
// NB: if you do not call set_max_jobs, the pool will try to use an optimal
// number of threads, one per each core in your system, which in most
// cases is what you want anyway... You can override the automatic choice
// by setting the VJOBS environment variable too.
// fetcher_pool.set_max_jobs( 4 )
fetcher_pool.work_on_items<int>(ids)
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}