123 lines
3.2 KiB
Go
123 lines
3.2 KiB
Go
package main
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import (
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"context"
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"fmt"
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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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// Host represents a row from the hosts table.
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type Host struct {
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ID int64
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Hostname string
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Protocol string
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WarcFilename string
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WarcRecordOffset int64
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WarcRecordLength int
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}
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// ProcessResult holds everything extracted from one host's WARC record.
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type ProcessResult struct {
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Title string
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IframeAllowed bool
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Icons []Icon
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Err error
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FetchErr bool // true if error was during fetch (vs parse)
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}
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// fetchBatch gets the next batch of unparsed hosts after lastID.
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func fetchBatch(ctx context.Context, pool *pgxpool.Pool, lastID int64, limit int) ([]Host, error) {
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rows, err := pool.Query(ctx,
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`SELECT id, hostname, protocol, warc_filename, warc_record_offset, warc_record_length
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FROM hosts
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WHERE parsed = FALSE 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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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 []Host
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for rows.Next() {
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var h Host
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err := rows.Scan(&h.ID, &h.Hostname, &h.Protocol, &h.WarcFilename, &h.WarcRecordOffset, &h.WarcRecordLength)
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if 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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// WorkResult pairs a host with its parsed result for the DB writer.
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type WorkResult struct {
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Host Host
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Result ProcessResult
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}
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// flushResults writes a batch of successful results to the database.
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// Host UPDATEs use pgx.Batch. Icon INSERTs use pgx.CopyFrom for bulk throughput.
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// Returns the number of DB errors encountered.
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func flushResults(ctx context.Context, pool *pgxpool.Pool, results []WorkResult, logWriter *LogWriter) int {
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dbErrors := 0
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// 1. Batch UPDATE hosts (can't COPY an UPDATE)
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batch := &pgx.Batch{}
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for _, wr := range results {
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batch.Queue(
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`UPDATE hosts SET html_title = $1, iframe_allowed = $2, parsed = TRUE WHERE id = $3`,
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nilIfEmpty(wr.Result.Title), wr.Result.IframeAllowed, wr.Host.ID,
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)
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}
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br := pool.SendBatch(ctx, batch)
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for _, wr := range results {
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if _, err := br.Exec(); err != nil {
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dbErrors++
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logLine := fmt.Sprintf("DB_ERROR: %s hosts_update: %v", wr.Host.Hostname, err)
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fmt.Println(logLine)
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if logWriter != nil {
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logWriter.Write(logLine, true)
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}
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}
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}
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br.Close()
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// 2. COPY icons in bulk (much less IOPS than individual INSERTs)
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var iconRows [][]any
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for _, wr := range results {
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// favicon.ico entry
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faviconURL := fmt.Sprintf("%s://%s/favicon.ico", wr.Host.Protocol, wr.Host.Hostname)
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iconRows = append(iconRows, []any{wr.Host.ID, faviconURL, "favicon_ico", nil, nil})
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// link_rel entries
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for _, icon := range wr.Result.Icons {
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iconRows = append(iconRows, []any{wr.Host.ID, icon.URL, icon.Source, nilIfEmpty(icon.RelType), nilIfEmpty(icon.RelSizes)})
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}
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}
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_, err := pool.CopyFrom(ctx,
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pgx.Identifier{"icons"},
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[]string{"host_id", "url", "source", "rel_type", "rel_sizes"},
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pgx.CopyFromRows(iconRows),
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)
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if err != nil {
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dbErrors++
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logLine := fmt.Sprintf("DB_ERROR: icon COPY failed (%d rows): %v", len(iconRows), err)
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fmt.Println(logLine)
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if logWriter != nil {
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logWriter.Write(logLine, true)
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}
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}
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return dbErrors
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}
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func nilIfEmpty(s string) *string {
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if s == "" {
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return nil
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}
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return &s
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}
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