77 lines
1.4 KiB
Go
77 lines
1.4 KiB
Go
// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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import http
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import json
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import sync
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const (
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NR_THREADS = 4
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)
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struct Story {
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title string
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url string
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}
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struct Fetcher {
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mut:
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mu sync.Mutex
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ids []int
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cursor int
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wg &sync.WaitGroup
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}
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fn (f mut Fetcher) fetch() {
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for {
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f.mu.lock()
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if f.cursor >= f.ids.len {
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return
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}
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id := f.ids[f.cursor]
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f.cursor++
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cursor := f.cursor
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f.mu.unlock()
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resp := http.get('https://hacker-news.firebaseio.com/v0/item/${id}.json') or {
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println('failed to fetch data from /v0/item/${id}.json')
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exit(1)
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}
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story := json.decode(Story, resp) or {
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println('failed to decode a story')
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exit(1)
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}
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f.wg.done()
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println('#$cursor) $story.title | $story.url')
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}
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}
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// Fetches top HN stories in 4 coroutines
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fn main() {
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resp := http.get('https://hacker-news.firebaseio.com/v0/topstories.json') or {
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println('failed to fetch data from /v0/topstories.json')
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return
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}
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mut ids := json.decode([]int, resp) or {
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println('failed to decode topstories.json')
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return
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}
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if ids.len > 10 {
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// ids = ids[:10]
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mut tmp := [0 ; 10]
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for i := 0 ; i < 10 ; i++ {
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tmp[i] = ids[i]
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}
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ids = tmp
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}
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mut wg := &sync.WaitGroup{}
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fetcher := &Fetcher{ids: ids, wg: wg} // wg sent via ptr
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wg.add(ids.len)
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for i := 0; i < NR_THREADS; i++ {
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go fetcher.fetch()
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}
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wg.wait()
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}
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