everytab/pipeline/02_warc_parse/db.go

135 lines
3.4 KiB
Go

package main
import (
"context"
"fmt"
"github.com/jackc/pgx/v5"
"github.com/jackc/pgx/v5/pgxpool"
)
// Host represents a row from the hosts table.
type Host struct {
ID int64
Hostname string
Protocol string
WarcFilename string
WarcRecordOffset int64
WarcRecordLength int
}
// ProcessResult holds everything extracted from one host's WARC record.
type ProcessResult struct {
Title string
IframeAllowed bool
Icons []Icon
Err error
FetchErr bool // true if error was during fetch (vs parse)
}
// fetchBatch gets the next batch of unparsed hosts after lastID.
func fetchBatch(ctx context.Context, pool *pgxpool.Pool, lastID int64, limit int) ([]Host, error) {
rows, err := pool.Query(ctx,
`SELECT id, hostname, protocol, warc_filename, warc_record_offset, warc_record_length
FROM hosts
WHERE parsed = FALSE AND id > $1
ORDER BY id
LIMIT $2`,
lastID, limit)
if err != nil {
return nil, err
}
defer rows.Close()
var hosts []Host
for rows.Next() {
var h Host
err := rows.Scan(&h.ID, &h.Hostname, &h.Protocol, &h.WarcFilename, &h.WarcRecordOffset, &h.WarcRecordLength)
if err != nil {
return nil, err
}
hosts = append(hosts, h)
}
return hosts, rows.Err()
}
// WorkResult pairs a host with its parsed result for the DB writer.
type WorkResult struct {
Host Host
Result ProcessResult
}
// flushResults writes a batch of successful results to the database using pgx.Batch.
// Returns the number of DB errors encountered.
func flushResults(ctx context.Context, pool *pgxpool.Pool, results []WorkResult, logWriter *LogWriter) int {
batch := &pgx.Batch{}
// Queue all queries
for _, wr := range results {
// Update host
batch.Queue(
`UPDATE hosts SET html_title = $1, iframe_allowed = $2, parsed = TRUE WHERE id = $3`,
nilIfEmpty(wr.Result.Title), wr.Result.IframeAllowed, wr.Host.ID,
)
// Insert /favicon.ico
faviconURL := fmt.Sprintf("%s://%s/favicon.ico", wr.Host.Protocol, wr.Host.Hostname)
batch.Queue(
`INSERT INTO icons (host_id, url, source) VALUES ($1, $2, 'favicon_ico')`,
wr.Host.ID, faviconURL,
)
// Insert link_rel icons
for _, icon := range wr.Result.Icons {
batch.Queue(
`INSERT INTO icons (host_id, url, source, rel_type, rel_sizes) VALUES ($1, $2, $3, $4, $5)`,
wr.Host.ID, icon.URL, icon.Source, nilIfEmpty(icon.RelType), nilIfEmpty(icon.RelSizes),
)
}
}
// Send all queries in one round-trip
br := pool.SendBatch(ctx, batch)
// Check results
dbErrors := 0
for _, wr := range results {
// host update
if _, err := br.Exec(); err != nil {
dbErrors++
logLine := fmt.Sprintf("DB_ERROR: %s hosts_update: %v", wr.Host.Hostname, err)
fmt.Println(logLine)
if logWriter != nil {
logWriter.Write(logLine, true)
}
}
// favicon.ico insert
if _, err := br.Exec(); err != nil {
dbErrors++
logLine := fmt.Sprintf("DB_ERROR: %s icon_insert: %v", wr.Host.Hostname, err)
fmt.Println(logLine)
if logWriter != nil {
logWriter.Write(logLine, true)
}
}
// link_rel icon inserts
for range wr.Result.Icons {
if _, err := br.Exec(); err != nil {
dbErrors++
logLine := fmt.Sprintf("DB_ERROR: %s icon_insert: %v", wr.Host.Hostname, err)
fmt.Println(logLine)
if logWriter != nil {
logWriter.Write(logLine, true)
}
}
}
}
br.Close()
return dbErrors
}
func nilIfEmpty(s string) *string {
if s == "" {
return nil
}
return &s
}