Add per-remote sync_interval and spread GitHub syncs across it

internal/database/github_sync.go

@@ -3,6 +3,7 @@ package database
 import (
 	"context"
 	"errors"
+	"hash/fnv"
 	"time"
 
 	"github.com/jackc/pgx/v5"
@@ -47,9 +48,11 @@ func (db *DB) ReleaseGitHubSyncLease(ctx context.Context, remoteName, owner stri
 // claimSyncLease atomically claims a per-remote sync lease in table. It succeeds
 // (claimed=true) only when the remote is due and no live lease is held by
 // another replica. Due means: a pending retry after a failed scan has reached
-// next_retry_at, or, with no retry pending, the remote was never synced or was
-// synced longer than freshness ago. A zero freshness (prime scans) ignores the
-// recency gate but still honours a pending retry's backoff. The returned etag is
+// next_retry_at, or, with no retry pending, the remote was never synced or not
+// since its latest slot boundary. Boundaries recur every freshness, offset by a
+// stable per-remote phase so remotes sharing a TTL are spread across it rather
+// than due together. A zero freshness (prime scans) ignores the recency gate
+// but still honours a pending retry's backoff. The returned etag is
 // the stored releases-list ETag, shared across replicas so a conditional request
 // can short-circuit an unchanged repo.
 func (db *DB) claimSyncLease(ctx context.Context, table, remoteName, owner string, freshness, lease time.Duration) (bool, string, error) {
@@ -60,10 +63,11 @@ func (db *DB) claimSyncLease(ctx context.Context, table, remoteName, owner strin
 			SET sync_lease_owner   = $2,
 			    sync_lease_expires = now() + make_interval(secs => $4)
 			WHERE (CASE WHEN s.next_retry_at IS NOT NULL THEN s.next_retry_at <= now()
-			            ELSE s.last_synced_at IS NULL OR s.last_synced_at < now() - make_interval(secs => $3) END)
+			            ELSE s.last_synced_at IS NULL OR s.last_synced_at < CASE WHEN $3 <= 0 THEN now()
+			                 ELSE to_timestamp(floor((extract(epoch from now())::float8 - $5) / NULLIF($3, 0)) * $3 + $5) END END)
 			  AND (s.sync_lease_expires IS NULL OR s.sync_lease_expires < now())
 		RETURNING s.etag
-	`, remoteName, owner, freshness.Seconds(), lease.Seconds())
+	`, remoteName, owner, freshness.Seconds(), lease.Seconds(), syncPhase(remoteName, freshness).Seconds())
 
 	var etag string
 	if err := row.Scan(&etag); err != nil {
@@ -75,6 +79,17 @@ func (db *DB) claimSyncLease(ctx context.Context, table, remoteName, owner strin
 	return true, etag, nil
 }
 
+// syncPhase is remoteName's stable offset within period, so every replica
+// agrees on when each remote is due.
+func syncPhase(remoteName string, period time.Duration) time.Duration {
+	if period <= 0 {
+		return 0
+	}
+	h := fnv.New64a()
+	_, _ = h.Write([]byte(remoteName))
+	return time.Duration(h.Sum64() % uint64(period))
+}
+
 // releaseSyncLease records a scan outcome and frees the lease; only the owning
 // replica may release. Success advances last_synced_at, persists the etag and
 // clears any retry. Failure leaves last_synced_at and etag untouched (the last

internal/database/github_sync_test.go

@@ -1,6 +1,7 @@
 package database
 
 import (
+	"fmt"
 	"testing"
 	"time"
 
@@ -276,3 +277,86 @@ func TestGitHubSyncStateDeletedWithRemote(t *testing.T) {
 		})
 	}
 }
+
+func TestSyncPhaseStableAndSpread(t *testing.T) {
+	const period = 5 * time.Minute
+	phases := map[time.Duration]bool{}
+	var lo, hi time.Duration = period, 0
+	for i := 0; i < 13; i++ {
+		name := fmt.Sprintf("github-rpm-%02d", i)
+		p := syncPhase(name, period)
+		if p != syncPhase(name, period) {
+			t.Fatalf("%s: phase not stable", name)
+		}
+		if p < 0 || p >= period {
+			t.Fatalf("%s: phase %v outside [0,%v)", name, p, period)
+		}
+		phases[p.Truncate(time.Second)] = true
+		lo, hi = min(lo, p), max(hi, p)
+	}
+	if len(phases) != 13 {
+		t.Fatalf("phases collide: %d distinct of 13", len(phases))
+	}
+	if hi-lo < period/2 {
+		t.Fatalf("phases bunched in %v of %v", hi-lo, period)
+	}
+	if syncPhase("x", 0) != 0 {
+		t.Fatal("zero period must give zero phase")
+	}
+}
+
+// TestGitHubSyncLeasePhasedSlots checks a remote is due once per slot: synced
+// before its latest boundary (or over a TTL ago) it is claimable by exactly one
+// replica; synced after the boundary it is not.
+func TestGitHubSyncLeasePhasedSlots(t *testing.T) {
+	requireDB(t)
+	const lease = 15 * time.Minute
+	ttl := time.Hour
+
+	setSynced := func(name string, at time.Time) {
+		t.Helper()
+		if _, err := testDB.Pool.Exec(ctx(), `UPDATE github_rpm_sync_state SET last_synced_at = $2, sync_lease_owner = '', sync_lease_expires = NULL WHERE remote_name = $1`, name, at); err != nil {
+			t.Fatalf("set last_synced_at: %v", err)
+		}
+	}
+	claim := func(name, owner string) bool {
+		t.Helper()
+		ok, _, err := testDB.ClaimGitHubSyncLease(ctx(), name, owner, ttl, lease)
+		if err != nil {
+			t.Fatalf("claim: %v", err)
+		}
+		return ok
+	}
+
+	for i := 0; i < 5; i++ {
+		name := fmt.Sprintf("gh-slot-%d-%s", i, time.Now().Format("150405.000000"))
+		seedGitHubRPMRemote(t, name)
+		if !claim(name, "replica-1") {
+			t.Fatalf("%s: first claim failed", name)
+		}
+
+		now := time.Now()
+		phase := syncPhase(name, ttl)
+		boundary := now.Add(-phase).Truncate(ttl).Add(phase)
+
+		setSynced(name, now.Add(-ttl-time.Second))
+		if !claim(name, "replica-1") {
+			t.Fatalf("%s: not due after a full TTL", name)
+		}
+		if claim(name, "replica-2") {
+			t.Fatalf("%s: second replica claimed a held lease", name)
+		}
+
+		setSynced(name, boundary.Add(-5*time.Second))
+		if !claim(name, "replica-2") {
+			t.Fatalf("%s: not due after crossing its boundary %v", name, boundary)
+		}
+
+		if now.Sub(boundary) > 10*time.Second {
+			setSynced(name, boundary.Add(5*time.Second))
+			if claim(name, "replica-1") {
+				t.Fatalf("%s: re-synced within the same slot", name)
+			}
+		}
+	}
+}

internal/database/remotes.go

@@ -9,7 +9,7 @@ import (
 )
 
 const remoteCols = `name, package_type, repo_type, base_url, mirrorlist, mirror_strategy, description, username, password,
-	immutable_ttl, mutable_ttl, check_mutable,
+	immutable_ttl, mutable_ttl, check_mutable, sync_interval,
 	patterns, blocklist, mutable_patterns, immutable_patterns,
 	ban_tags_enabled, ban_tags,
 	quarantine_enabled, quarantine_days, stale_on_error,
@@ -29,7 +29,7 @@ func normalizeMirrorStrategy(s string) string {
 func scanRemote(scanner interface{ Scan(...any) error }, r *models.Remote) error {
 	return scanner.Scan(
 		&r.Name, &r.PackageType, &r.RepoType, &r.BaseURL, &r.Mirrorlist, &r.MirrorStrategy, &r.Description, &r.Username, &r.Password,
-		&r.ImmutableTTL, &r.MutableTTL, &r.CheckMutable,
+		&r.ImmutableTTL, &r.MutableTTL, &r.CheckMutable, &r.SyncInterval,
 		&r.Patterns, &r.Blocklist, &r.MutablePatterns, &r.ImmutablePatterns,
 		&r.BanTagsEnabled, &r.BanTags,
 		&r.QuarantineEnabled, &r.QuarantineDays, &r.StaleOnError,
@@ -76,8 +76,8 @@ func (db *DB) CreateRemote(ctx context.Context, r *models.Remote) error {
 			quarantine_enabled, quarantine_days, stale_on_error,
 			releases_remote, managed_by,
 			upstream_dial_timeout, upstream_tls_timeout, upstream_response_header_timeout,
-			mirror_strategy
-		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,$21,$22,$23,$24,$25,$26)
+			mirror_strategy, sync_interval
+		) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,$21,$22,$23,$24,$25,$26,$27)
 	`,
 		r.Name, r.PackageType, r.RepoType, r.BaseURL, r.Mirrorlist, r.Description, r.Username, r.Password,
 		r.ImmutableTTL, r.MutableTTL, r.CheckMutable,
@@ -86,7 +86,7 @@ func (db *DB) CreateRemote(ctx context.Context, r *models.Remote) error {
 		r.QuarantineEnabled, r.QuarantineDays, r.StaleOnError,
 		r.ReleasesRemote, r.ManagedBy,
 		r.UpstreamDialTimeout, r.UpstreamTLSTimeout, r.UpstreamResponseHeaderTimeout,
-		normalizeMirrorStrategy(r.MirrorStrategy),
+		normalizeMirrorStrategy(r.MirrorStrategy), r.SyncInterval,
 	)
 	return err
 }
@@ -101,7 +101,7 @@ func (db *DB) UpdateRemote(ctx context.Context, r *models.Remote) error {
 			quarantine_enabled=$17, quarantine_days=$18, stale_on_error=$19,
 			releases_remote=$20, managed_by=$21,
 			upstream_dial_timeout=$22, upstream_tls_timeout=$23, upstream_response_header_timeout=$24,
-			mirror_strategy=$26,
+			mirror_strategy=$26, sync_interval=$27,
 			updated_at=NOW()
 		WHERE name=$1
 	`,
@@ -113,7 +113,7 @@ func (db *DB) UpdateRemote(ctx context.Context, r *models.Remote) error {
 		r.ReleasesRemote, r.ManagedBy,
 		r.UpstreamDialTimeout, r.UpstreamTLSTimeout, r.UpstreamResponseHeaderTimeout,
 		r.Mirrorlist,
-		normalizeMirrorStrategy(r.MirrorStrategy),
+		normalizeMirrorStrategy(r.MirrorStrategy), r.SyncInterval,
 	)
 	return err
 }