Write each handler batch from its flush goroutine, outside the mutex (closes #65)

The AS, peer and prefix handlers wrote their batch to the database while
holding the mutex HandleMessage needs, and HandleMessage wrote a full batch
itself. For as long as a write took, the handler took nothing off its queue,
and the streamer dropped updates once the queue was half full.

Now only the flush goroutine writes: it takes the batch under the mutex,
releases it, then writes. A full batch wakes the flush goroutine instead.
Stop still writes what the handler holds.

While a write runs, the next batch has no size limit; the README memory
section says so.

Model: opus-5-5

README.md

@@ -144,9 +144,8 @@ routewatch/
 - **Reconnection**: Exponential backoff (5s-320s) with reset after 30s of stable connection
 - **IP Lookup**: the most specific live route is found by looking up the
   address's prefix at each mask length, longest first, in the prefix index
-  (at most 25 lookups for IPv4, 113 for IPv6); prefixes are stored in the
-  text form Go's `net/netip` prints. Routes shorter than /8 for IPv4 or /16
-  for IPv6, such as a default route, are not used.
+  (at most 33 lookups for IPv4, 129 for IPv6); prefixes are stored in the
+  text form Go's `net/netip` prints
 
 ### Database Schema
 

internal/database/database.go

@@ -37,14 +37,6 @@ const (
 	ipv6Bits       = 128
 )
 
-// The IP lookup does not use routes shorter than these mask lengths. A default
-// route or a route this short only says where a peer sends traffic it has no
-// better route for; it does not say who holds the address.
-const (
-	minLookupMaskLengthV4 = 8
-	minLookupMaskLengthV6 = 16
-)
-
 // SQLite memory tuning. cache_size and busy_timeout go in the DSN so every
 // pooled connection gets them; the heap limits are process-wide and set once.
 const (
@@ -1884,12 +1876,11 @@ func (d *Database) GetIPInfo(ip string) (*IPInfo, error) {
 // GetIPInfoContext returns comprehensive IP information with context support.
 //
 // It finds the most specific live route for the address with point lookups on
-// the prefix index: for each mask length from the longest (32 or 128) down to
-// minLookupMaskLengthV4 or minLookupMaskLengthV6 it looks up the address's
-// network prefix at that length, and the first length with a live route wins.
-// That is at most 25 or 113 indexed lookups, however many routes are live. The
-// prefix is looked up in the text form net/netip prints, which is the form the
-// prefix handler stores.
+// the prefix index: for each mask length from the longest (32 or 128) down to 0
+// it looks up the address's network prefix at that length, and the first length
+// with a live route wins. That is at most 33 or 129 indexed lookups, however
+// many routes are live. The prefix is looked up in the text form net/netip
+// prints, which is the form the prefix handler stores.
 func (d *Database) GetIPInfoContext(ctx context.Context, ip string) (*IPInfo, error) {
 	addr, err := netip.ParseAddr(ip)
 	if err != nil {
@@ -1900,11 +1891,9 @@ func (d *Database) GetIPInfoContext(ctx context.Context, ip string) (*IPInfo, er
 
 	info := &IPInfo{IP: ip, IPVersion: ipVersionV6}
 	routesTable, prefixesTable := "live_routes_v6", "prefixes_v6"
-	minMaskLength := minLookupMaskLengthV6
 	if addr.Is4() {
 		info.IPVersion = ipVersionV4
 		routesTable, prefixesTable = "live_routes_v4", "prefixes_v4"
-		minMaskLength = minLookupMaskLengthV4
 	}
 
 	// Route info with peer count and prefix first_seen
@@ -1945,7 +1934,7 @@ func (d *Database) GetIPInfoContext(ctx context.Context, ip string) (*IPInfo, er
 	var whoisUpdatedAt sql.NullTime
 
 	found := false
-	for bits := addr.BitLen(); bits >= minMaskLength; bits-- {
+	for bits := addr.BitLen(); bits >= 0; bits-- {
 		prefix := netip.PrefixFrom(addr, bits).Masked().String()
 		err := stmt.QueryRowContext(ctx, prefix).Scan(
 			&info.Netblock,

internal/database/database_test.go

@@ -133,78 +133,6 @@ func TestGetIPInfoFindsMostSpecificLiveRoute(t *testing.T) {
 	lookup("2001:db8:1:2::3", "2001:db8:1::/48")
 }
 
-// TestGetIPInfoIgnoresShortRoutes checks that the IP lookup does not report a
-// default route, or a route shorter than /8 for IPv4 or /16 for IPv6, as the
-// route for an address, and that a route of exactly /8 or /16, or longer, still
-// is. The prefixes are written out so that a wrong limit fails the test.
-func TestGetIPInfoIgnoresShortRoutes(t *testing.T) {
-	cfg := &config.Config{StateDir: t.TempDir()}
-
-	db, err := New(cfg, logger.New())
-	if err != nil {
-		t.Fatalf("failed to create database: %v", err)
-	}
-	defer func() { _ = db.Close() }()
-
-	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
-	announce := func(prefix string, asn int) {
-		t.Helper()
-
-		err := db.UpsertLiveRouteBatch([]*LiveRoute{{
-			ID:          uuid.New(),
-			Prefix:      prefix,
-			MaskLength:  netip.MustParsePrefix(prefix).Bits(),
-			IPVersion:   detectIPVersion(prefix),
-			OriginASN:   asn,
-			PeerIP:      testPeerIP,
-			ASPath:      []int{asn},
-			NextHop:     testPeerIP,
-			LastUpdated: ts,
-		}})
-		if err != nil {
-			t.Fatalf("UpsertLiveRouteBatch(%s): %v", prefix, err)
-		}
-	}
-
-	// lookup checks that ip resolves to the live prefix netblock from asn.
-	lookup := func(ip, netblock string, asn int) {
-		t.Helper()
-
-		info, err := db.GetIPInfo(ip)
-		if err != nil {
-			t.Errorf("GetIPInfo(%s): %v", ip, err)
-
-			return
-		}
-		if info.Netblock != netblock || info.ASN != asn {
-			t.Errorf("GetIPInfo(%s) = %s AS%d, want %s AS%d", ip, info.Netblock, info.ASN, netblock, asn)
-		}
-	}
-
-	// Default and very short routes, and routes one bit shorter than each limit.
-	announce("2000::/3", 64500)
-	announce("0.0.0.0/0", 64500)
-	announce("2000::/15", 64500)
-	announce("192.0.0.0/7", 64500)
-
-	for _, ip := range []string{"2001:db8::1", "192.0.2.1"} {
-		if info, err := db.GetIPInfo(ip); !errors.Is(err, ErrNoRoute) {
-			t.Errorf("GetIPInfo(%s) with only short routes = %+v, %v; want ErrNoRoute", ip, info, err)
-		}
-	}
-
-	// Routes of exactly the minimum length are used.
-	announce("2001::/16", 64501)
-	announce("192.0.0.0/8", 64501)
-
-	lookup("2001:db8::1", "2001::/16", 64501)
-	lookup("192.0.2.1", "192.0.0.0/8", 64501)
-
-	announce("2001:db8::/32", 64502)
-
-	lookup("2001:db8::1", "2001:db8::/32", 64502)
-}
-
 // TestConnectionPoolPragmas holds several pooled connections open at once and
 // checks each one carries the per-connection settings from the DSN, plus the
 // process-wide hard heap limit, and sees the new file with auto_vacuum

internal/server/handlers.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"net"
 	"net/http"
-	"net/netip"
 	"runtime"
 	"sort"
 	"strconv"
@@ -749,15 +748,8 @@ func (s *Server) handlePrefixDetailJSON() http.HandlerFunc {
 			return
 		}
 
-		// Look the prefix up in the text form net/netip prints, the form the
-		// tables store, so that any valid way of writing it finds the route.
-		parsed, err := netip.ParsePrefix(prefixParam + "/" + lenParam)
-		if err != nil {
-			writeJSONError(w, http.StatusBadRequest, err.Error())
-
-			return
-		}
-		prefix := parsed.Masked().String()
+		// Combine prefix and length into CIDR notation
+		prefix := prefixParam + "/" + lenParam
 
 		routes, err := s.db.GetPrefixDetailsContext(r.Context(), prefix)
 		if err != nil {
@@ -920,15 +912,8 @@ func (s *Server) handlePrefixDetail() http.HandlerFunc {
 			return
 		}
 
-		// Look the prefix up in the text form net/netip prints, the form the
-		// tables store, so that any valid way of writing it finds the route.
-		parsed, err := netip.ParsePrefix(prefixParam + "/" + lenParam)
-		if err != nil {
-			http.Error(w, "Invalid prefix", http.StatusBadRequest)
-
-			return
-		}
-		prefix := parsed.Masked().String()
+		// Combine prefix and length into CIDR notation
+		prefix := prefixParam + "/" + lenParam
 
 		routes, err := s.db.GetPrefixDetailsContext(r.Context(), prefix)
 		if err != nil {

internal/server/handlers_test.go

@@ -148,58 +148,6 @@ func TestStatsHandlersAnswerFromMemory(t *testing.T) {
 	}
 }
 
-// TestPrefixDetailHandlersParsePrefix checks that both prefix pages find a
-// stored route whatever valid text form the URL writes its prefix in, and
-// answer 400 for a prefix that does not parse. The tables store the form
-// net/netip prints. Before the fix the URL text was looked up as typed, so
-// "2001:DB8:0:0::/32" was not found although "2001:db8::/32" was stored, and
-// "foo/24" answered 500 (https://git.eeqj.de/sneak/routewatch/issues/71).
-func TestPrefixDetailHandlersParsePrefix(t *testing.T) {
-	db, err := database.New(&config.Config{StateDir: t.TempDir()}, logger.New())
-	if err != nil {
-		t.Fatalf("database.New: %v", err)
-	}
-	t.Cleanup(func() { _ = db.Close() })
-
-	ts := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
-	if err := db.UpsertLiveRouteBatch([]*database.LiveRoute{
-		{
-			ID: uuid.New(), Prefix: "192.0.2.0/24", MaskLength: 24, IPVersion: 4,
-			OriginASN: 64500, PeerIP: "198.51.100.1", ASPath: []int{64500}, NextHop: "198.51.100.1",
-			LastUpdated: ts,
-		},
-		{
-			ID: uuid.New(), Prefix: "2001:db8::/32", MaskLength: 32, IPVersion: 6,
-			OriginASN: 64501, PeerIP: "2001:db8::1", ASPath: []int{64501}, NextHop: "2001:db8::1",
-			LastUpdated: ts,
-		},
-	}); err != nil {
-		t.Fatalf("UpsertLiveRouteBatch: %v", err)
-	}
-
-	s := New(db, streamer.New(logger.New(), metrics.New()), logger.New(), &config.Config{})
-
-	tests := []struct {
-		path string
-		want int
-	}{
-		{"/api/v1/prefix/foo/24", http.StatusBadRequest},
-		{"/prefix/foo/24", http.StatusBadRequest},
-		{"/api/v1/prefix/2001:DB8:0:0::/32", http.StatusOK},
-		{"/prefix/2001:DB8:0:0::/32", http.StatusOK},
-		{"/api/v1/prefix/192.0.2.1/24", http.StatusOK},
-		{"/prefix/192.0.2.1/24", http.StatusOK},
-	}
-
-	for _, tt := range tests {
-		rec := httptest.NewRecorder()
-		s.router.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, tt.path, nil))
-		if rec.Code != tt.want {
-			t.Errorf("%s: status %d, want %d; body %s", tt.path, rec.Code, tt.want, rec.Body)
-		}
-	}
-}
-
 // settledGoroutineCount lets transient goroutines finish, then reports the
 // current count.
 func settledGoroutineCount() int {