fix(crawler): walk list pages incrementally; stop on empty page (0.45.1) #4

Merged
fabi merged 1 commits from bugfix/crawler-incremental-pagination into main 2026-05-31 16:37:14 +00:00
4 changed files with 27 additions and 100 deletions

2
backend/Cargo.lock generated
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@@ -1470,7 +1470,7 @@ checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
[[package]] [[package]]
name = "mangalord" name = "mangalord"
version = "0.45.0" version = "0.45.1"
dependencies = [ dependencies = [
"anyhow", "anyhow",
"argon2", "argon2",

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@@ -1,6 +1,6 @@
[package] [package]
name = "mangalord" name = "mangalord"
version = "0.45.0" version = "0.45.1"
edition = "2021" edition = "2021"
default-run = "mangalord" default-run = "mangalord"

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@@ -7,7 +7,6 @@
//! (`td:has(label:contains("Author:"))`) are implemented by walking //! (`td:has(label:contains("Author:"))`) are implemented by walking
//! the parsed tree. //! the parsed tree.
use std::collections::VecDeque;
use std::time::Duration; use std::time::Duration;
use anyhow::Context; use anyhow::Context;
@@ -75,10 +74,11 @@ impl Source for TargetSource {
&self, &self,
ctx: &FetchContext<'_>, ctx: &FetchContext<'_>,
) -> anyhow::Result<Box<dyn DiscoverWalk + Send>> { ) -> anyhow::Result<Box<dyn DiscoverWalk + Send>> {
// Always visit page 1 first because that's the only way to // Probe page 1 up front (with transient retry) for two reasons:
// discover `last_page`. Retry it on transient — a broken first // a broken first page should abort cleanly rather than mid-walk,
// page would otherwise abort the whole walk before we've even // and the HTML is handed straight to the first `next_batch` call
// started. // so the walker doesn't re-fetch it. Page count is discovered
// incrementally — see `TargetSourceWalker::next_batch`.
let first_html = retry_on_transient( let first_html = retry_on_transient(
|| async { || async {
navigate(ctx, self.base_url.as_str(), LIST_PAGE_MARKER).await navigate(ctx, self.base_url.as_str(), LIST_PAGE_MARKER).await
@@ -87,21 +87,10 @@ impl Source for TargetSource {
PAGE_TRANSIENT_RETRY_DELAY, PAGE_TRANSIENT_RETRY_DELAY,
) )
.await?; .await?;
let last_page = {
let doc = scraper::Html::parse_document(&first_html);
parse_last_page(&doc)
};
let order = build_page_order(last_page);
tracing::info!(
last_page = ?last_page,
page_count = order.len(),
"walking pagination"
);
Ok(Box::new(TargetSourceWalker { Ok(Box::new(TargetSourceWalker {
base_url: self.base_url.clone(), base_url: self.base_url.clone(),
pages_remaining: order, next_page: 1,
first_page_html: Some(first_html), first_page_html: Some(first_html),
})) }))
} }
@@ -147,24 +136,19 @@ impl Source for TargetSource {
} }
} }
/// Build the queue of page numbers `TargetSource::discover` will walk. /// Walker returned by [`TargetSource::discover`]. Walks pages `1..` in
/// The site orders by `update_date DESC`, so newest-first is just the /// order, terminating as soon as a page renders cleanly with zero entries
/// natural page order: `1..=last`. If `last_page` is unknown (source /// — that's the "we ran off the end of the index" signal. Page 1's HTML
/// surfaces no pagination) only page 1 is visited. /// is cached at construction time (discover already had to fetch it for
fn build_page_order(last_page: Option<i32>) -> VecDeque<i32> { /// the transient probe) so the first batch doesn't re-fetch.
match last_page { ///
None => VecDeque::from([1]), /// A genuinely empty `Ok(vec![])` from `parse_manga_list_from` is what
Some(last) => (1..=last).collect(), /// stops us: the parser's `#logo` sentinel converts unrendered pages
} /// into transient errors before they reach this loop, so an empty
} /// parse result reliably means "no more entries."
/// Walker returned by [`TargetSource::discover`]. Pops one source-index
/// page per `next_batch` call. Page 1's HTML is cached at construction
/// time (the discover call needed it to read `last_page` anyway) so the
/// batch covering page 1 doesn't re-fetch.
struct TargetSourceWalker { struct TargetSourceWalker {
base_url: String, base_url: String,
pages_remaining: VecDeque<i32>, next_page: i32,
first_page_html: Option<String>, first_page_html: Option<String>,
} }
@@ -174,13 +158,11 @@ impl DiscoverWalk for TargetSourceWalker {
&mut self, &mut self,
ctx: &FetchContext<'_>, ctx: &FetchContext<'_>,
) -> anyhow::Result<Option<Vec<SourceMangaRef>>> { ) -> anyhow::Result<Option<Vec<SourceMangaRef>>> {
let Some(page_num) = self.pages_remaining.pop_front() else { let page_num = self.next_page;
return Ok(None);
};
let page_refs = if page_num == 1 { let page_refs = if page_num == 1 {
// Reuse the cached page-1 HTML from the initial probe. Take // Reuse the cached page-1 HTML from the initial probe. Take
// it (rather than clone) so a malformed page-order queue // it (rather than clone) so a future re-entry that somehow
// that re-visits page 1 still falls back to a real fetch. // revisits page 1 still falls back to a real fetch.
match self.first_page_html.take() { match self.first_page_html.take() {
Some(html) => { Some(html) => {
let doc = scraper::Html::parse_document(&html); let doc = scraper::Html::parse_document(&html);
@@ -218,6 +200,10 @@ impl DiscoverWalk for TargetSourceWalker {
.await? .await?
}; };
tracing::info!(page_num, count = page_refs.len(), "page walked"); tracing::info!(page_num, count = page_refs.len(), "page walked");
if page_refs.is_empty() {
return Ok(None);
}
self.next_page += 1;
Ok(Some(page_refs)) Ok(Some(page_refs))
} }
} }
@@ -288,20 +274,6 @@ fn classify_navigate_html(html: String) -> Result<String, PageError> {
Ok(html) Ok(html)
} }
fn parse_last_page(doc: &scraper::Html) -> Option<i32> {
// Pagination links carry their page number as text. Take the
// numeric maximum so we don't depend on a specific layout (Prev,
// Next, ellipses, etc. all get filtered out by .parse).
let sel = scraper::Selector::parse("#left_side .pagination a").unwrap();
doc.select(&sel)
.filter_map(|a| {
collapse_whitespace(&a.text().collect::<String>())
.parse::<i32>()
.ok()
})
.max()
}
/// Substitutes the first `/N/` path segment with the target page /// Substitutes the first `/N/` path segment with the target page
/// number. Source impls that paginate via a different URL shape can /// number. Source impls that paginate via a different URL shape can
/// override this — for the modeled site the segment is always present. /// override this — for the modeled site the segment is always present.
@@ -853,29 +825,6 @@ mod tests {
assert_eq!(parse_chapter_number("Special"), None); assert_eq!(parse_chapter_number("Special"), None);
} }
#[test]
fn parse_last_page_picks_highest_pagination_link() {
let html = r#"
<div id="left_side"><div class="pagination">
<a href="/list/1/">Prev</a>
<ol>
<li><a href="/list/1/">1</a></li>
<li><a href="/list/2/">2</a></li>
<li><a href="/list/47/">47</a></li>
<li><a href="/list/2/">Next</a></li>
</ol>
</div></div>
"#;
let doc = scraper::Html::parse_document(html);
assert_eq!(parse_last_page(&doc), Some(47));
}
#[test]
fn parse_last_page_none_when_no_pagination() {
let doc = scraper::Html::parse_document("<html></html>");
assert!(parse_last_page(&doc).is_none());
}
#[test] #[test]
fn page_url_substitutes_numeric_path_segment() { fn page_url_substitutes_numeric_path_segment() {
assert_eq!( assert_eq!(
@@ -1024,28 +973,6 @@ mod tests {
assert!(err.is_transient(), "got non-transient: {err}"); assert!(err.is_transient(), "got non-transient: {err}");
} }
#[test]
fn build_page_order_is_natural_one_to_last() {
// Newest-first is just the source's natural pagination order:
// (update_date DESC) lives at page 1, oldest at the last page.
let order = build_page_order(Some(3));
assert_eq!(Vec::from(order), vec![1, 2, 3]);
}
#[test]
fn build_page_order_falls_back_to_page_one_only_without_pagination() {
// Source surfaced no pagination control — visit page 1 alone
// and let the walk end after one batch.
let order = build_page_order(None);
assert_eq!(Vec::from(order), vec![1]);
}
#[test]
fn build_page_order_single_page_index_yields_one_entry() {
let order = build_page_order(Some(1));
assert_eq!(Vec::from(order), vec![1]);
}
#[test] #[test]
fn parse_chapter_list_returns_transient_when_table_missing() { fn parse_chapter_list_returns_transient_when_table_missing() {
// Partial render (post-load JS hadn't injected the table, layout // Partial render (post-load JS hadn't injected the table, layout

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@@ -1,6 +1,6 @@
{ {
"name": "mangalord-frontend", "name": "mangalord-frontend",
"version": "0.45.0", "version": "0.45.1",
"private": true, "private": true,
"type": "module", "type": "module",
"scripts": { "scripts": {