69 lines
2.1 KiB
Go
69 lines
2.1 KiB
Go
package main
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import (
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"context"
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"time"
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"github.com/jackc/pgx/v5"
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"github.com/jackc/pgx/v5/pgxpool"
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)
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type HostRow struct {
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ID int64
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Hostname string
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Protocol string
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HtmlTitle string
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IframeAllowed bool
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BestIconHash string
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IconDownloadedAt *time.Time
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}
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// fetchHostsPage gets a page of hosts with titles, ordered by icon_downloaded_at for disk locality.
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// Icons written to disk at similar times are physically adjacent on the EBS volume —
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// reading in write order maximizes OS readahead cache hits.
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func fetchHostsPage(ctx context.Context, pool *pgxpool.Pool, lastTime *time.Time, lastID int64, limit int) ([]HostRow, error) {
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// Two-phase: first hosts with icons (ordered by download time), then hosts without
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var rows pgx.Rows
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var err error
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if lastTime != nil {
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rows, err = pool.Query(ctx, `
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SELECT id, hostname, protocol, html_title, COALESCE(iframe_allowed, true), COALESCE(best_icon_hash, ''), icon_downloaded_at
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FROM hosts
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WHERE html_title IS NOT NULL AND icon_downloaded_at > $1
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ORDER BY icon_downloaded_at
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LIMIT $2
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`, lastTime, limit)
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} else if lastID > 0 {
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// No more timestamped hosts — fetch remaining (no icon) by id
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rows, err = pool.Query(ctx, `
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SELECT id, hostname, protocol, html_title, COALESCE(iframe_allowed, true), '', NULL::timestamptz
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FROM hosts
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WHERE html_title IS NOT NULL AND icon_downloaded_at IS NULL AND id > $1
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ORDER BY id
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LIMIT $2
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`, lastID, limit)
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} else {
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// Start: fetch timestamped hosts first
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rows, err = pool.Query(ctx, `
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SELECT id, hostname, protocol, html_title, COALESCE(iframe_allowed, true), COALESCE(best_icon_hash, ''), icon_downloaded_at
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FROM hosts
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WHERE html_title IS NOT NULL AND icon_downloaded_at IS NOT NULL
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ORDER BY icon_downloaded_at
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LIMIT $1
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`, limit)
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}
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if err != nil {
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return nil, err
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}
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defer rows.Close()
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var hosts []HostRow
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for rows.Next() {
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var h HostRow
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if err := rows.Scan(&h.ID, &h.Hostname, &h.Protocol, &h.HtmlTitle, &h.IframeAllowed, &h.BestIconHash, &h.IconDownloadedAt); err != nil {
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return nil, err
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}
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hosts = append(hosts, h)
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}
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return hosts, rows.Err()
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}
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