platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/resolver/resolve_batch.go

@@ -0,0 +1,115 @@
+package resolver
+
+type ResolveBatchInput struct {
+	ToResolve    []string
+	Workers      int
+	Now          int
+	StaleKeepSec int
+}
+
+type ResolveBatchResult struct {
+	DNSStats                DNSMetrics
+	ResolvedNowDNS          int
+	ResolvedNowStale        int
+	UnresolvedAfterAttempts int
+	StaleHitsDelta          int
+}
+
+func ExecuteResolveBatch(
+	in ResolveBatchInput,
+	resolved map[string][]string,
+	domainCache *DomainCacheState,
+	cacheSourceForHost func(string) DomainCacheSource,
+	resolveHost func(string) ([]string, DNSMetrics),
+	logf func(string, ...any),
+) ResolveBatchResult {
+	out := ResolveBatchResult{}
+	if len(in.ToResolve) == 0 || resolveHost == nil || domainCache == nil {
+		return out
+	}
+
+	workers := in.Workers
+	if workers < 1 {
+		workers = 1
+	}
+	if workers > 500 {
+		workers = 500
+	}
+	resolveSource := cacheSourceForHost
+	if resolveSource == nil {
+		resolveSource = func(string) DomainCacheSource { return DomainCacheSourceDirect }
+	}
+
+	type result struct {
+		host  string
+		ips   []string
+		stats DNSMetrics
+	}
+
+	jobs := make(chan string, len(in.ToResolve))
+	results := make(chan result, len(in.ToResolve))
+
+	for i := 0; i < workers; i++ {
+		go func() {
+			for host := range jobs {
+				ips, stats := resolveHost(host)
+				results <- result{host: host, ips: ips, stats: stats}
+			}
+		}()
+	}
+
+	for _, host := range in.ToResolve {
+		jobs <- host
+	}
+	close(jobs)
+
+	for i := 0; i < len(in.ToResolve); i++ {
+		r := <-results
+		out.DNSStats.Merge(r.stats)
+		hostErrors := r.stats.TotalErrors()
+		if hostErrors > 0 && logf != nil {
+			logf("resolve errors for %s: total=%d nxdomain=%d timeout=%d temporary=%d other=%d", r.host, hostErrors, r.stats.NXDomain, r.stats.Timeout, r.stats.Temporary, r.stats.Other)
+		}
+		if len(r.ips) > 0 {
+			if resolved != nil {
+				resolved[r.host] = r.ips
+			}
+			out.ResolvedNowDNS++
+			source := resolveSource(r.host)
+			domainCache.Set(r.host, source, r.ips, in.Now)
+			if logf != nil {
+				logf("%s -> %v", r.host, r.ips)
+			}
+			continue
+		}
+
+		staleApplied := false
+		if hostErrors > 0 {
+			source := resolveSource(r.host)
+			domainCache.SetErrorWithStats(r.host, source, r.stats, in.Now)
+			if in.StaleKeepSec > 0 && ShouldUseStaleOnError(r.stats) {
+				if staleIPs, staleAge, ok := domainCache.GetStale(r.host, source, in.Now, in.StaleKeepSec); ok {
+					out.StaleHitsDelta++
+					out.ResolvedNowStale++
+					staleApplied = true
+					if resolved != nil {
+						resolved[r.host] = staleIPs
+					}
+					if logf != nil {
+						logf("cache stale-keep (error)[age=%ds]: %s -> %v", staleAge, r.host, staleIPs)
+					}
+				}
+			}
+		}
+		if !staleApplied {
+			out.UnresolvedAfterAttempts++
+		}
+		if logf != nil && resolved != nil {
+			if _, ok := resolved[r.host]; !ok {
+				logf("%s: no IPs", r.host)
+			}
+		}
+	}
+
+	return out
+}