sneak
f84378c426
The library needed network access on first use and its results changed under the caller between runs. blogs.json is now vendored and compiled in with go:embed, so the dataset is fixed for a given build. FetchBlogs keeps its name, signature and sync.Once memoization but now decodes the embedded bytes; its error return is only reachable if the committed blogs.json is malformed. net/http is gone from the package, and a test asserts no net/* import returns to non-test code. make update-data refreshes the vendored file, reading the upstream location from the BlogsURL constant so the URL has one definition. It downloads to a temporary file, replaces blogs.json only on a complete download, and runs the test suite against the new data. The dataset is committed verbatim as upstream serves it, which is ~8 MB of JSON in the repo and in every linking binary; most of that is per-blog post history that the Blog struct does not expose. Model: opus-5
109 lines
2.6 KiB
Go
109 lines
2.6 KiB
Go
// Package hnblogs provides access to the blogs.hn dataset.
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//
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// The dataset is vendored into this repository as blogs.json and compiled into
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// the package with go:embed, so nothing here touches the network at runtime and
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// the results are stable for a given version of the module. Refresh the
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// vendored copy with "make update-data" and commit the result.
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package hnblogs
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import (
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_ "embed"
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"encoding/json"
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"fmt"
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"math/rand"
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"sync"
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)
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// BlogsURL is the upstream source of blogs.json. It is not fetched at runtime;
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// it documents where "make update-data" pulls the vendored copy from.
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const BlogsURL = "https://raw.githubusercontent.com/surprisetalk/blogs.hn/main/blogs.json"
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// blogsJSON is the vendored dataset, refreshed by "make update-data".
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//
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//go:embed blogs.json
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var blogsJSON []byte
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var (
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blogs []Blog
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loadError error
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once sync.Once
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)
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// Blog represents a single blog entry.
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type Blog struct {
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URL string `json:"url"`
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Title string `json:"title"`
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About string `json:"about"`
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Now string `json:"now"`
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Feed string `json:"feed"`
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Desc string `json:"desc"`
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}
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// FetchBlogs returns the embedded list of blogs, decoding it on first call and
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// memoizing the result for subsequent calls.
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//
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// Despite the name it performs no I/O: the data is compiled into the binary, so
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// the only error it can return is a malformed embedded blogs.json, which would
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// mean the committed dataset is broken.
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func FetchBlogs() ([]Blog, error) {
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once.Do(func() {
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var decoded []Blog
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if err := json.Unmarshal(blogsJSON, &decoded); err != nil {
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loadError = fmt.Errorf("failed to decode embedded blogs JSON: %w", err)
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return
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}
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blogs = decoded
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})
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return blogs, loadError
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}
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// GetBlogs returns the memoized list of blogs.
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func GetBlogs() ([]Blog, error) {
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return FetchBlogs()
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}
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// RandomBlog returns a random blog from the list of blogs.
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func RandomBlog() (Blog, error) {
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blogs, err := GetBlogs()
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if err != nil {
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return Blog{}, err
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}
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return blogs[rand.Intn(len(blogs))], nil
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}
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// RandomBlogs returns n random blogs from the list of blogs.
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func RandomBlogs(n int) ([]Blog, error) {
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blogs, err := GetBlogs()
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if err != nil {
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return nil, err
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}
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if n <= 0 || n > len(blogs) {
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return nil, fmt.Errorf("invalid number of blogs requested")
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}
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selected := make([]Blog, n)
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for i := range selected {
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selected[i] = blogs[rand.Intn(len(blogs))]
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}
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return selected, nil
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}
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// NthBlog returns the nth blog from the list of blogs.
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func NthBlog(n int) (Blog, error) {
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blogs, err := GetBlogs()
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if err != nil {
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return Blog{}, err
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}
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if n < 0 || n >= len(blogs) {
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return Blog{}, fmt.Errorf("index out of range")
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}
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return blogs[n], nil
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}
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