| 1 | /** |
| 2 | * The pure parts of request timing and D1 read consistency for the site: |
| 3 | * the `g1t_d1` cookie, which session each service call asks for, which |
| 4 | * calls may write, and the `Server-Timing` header. perf.server.ts holds |
| 5 | * the per-request state; docs/PERFORMANCE.md explains the whole. |
| 6 | */ |
| 7 | |
| 8 | /** The cookie that carries D1 bookmarks between a person's requests. */ |
| 9 | export const D1_COOKIE = "g1t_d1"; |
| 10 | |
| 11 | /** |
| 12 | * How long after a write the services a request did not get a bookmark |
| 13 | * from read their primary. A write can reach a service the site did not |
| 14 | * call itself (work writing to repos, say), whose bookmark the site never |
| 15 | * sees; D1 replicas trail the primary by well under a second, so 30 |
| 16 | * seconds covers that with room to spare. |
| 17 | */ |
| 18 | export const PRIMARY_WINDOW_SECONDS = 30; |
| 19 | |
| 20 | /** How long the bookmarks are kept: far longer than any replica trails. */ |
| 21 | export const D1_COOKIE_MAX_AGE = 300; |
| 22 | |
| 23 | /** |
| 24 | * The services whose RPCs open a D1 session (crates/kit/src/d1.rs and |
| 25 | * @g1t/contracts d1.ts), by the name the site gives their binding. |
| 26 | */ |
| 27 | export const SESSION_SERVICES = new Set(["identity", "repos", "work", "search", "billing", "projects", "deployments"]); |
| 28 | |
| 29 | /** What the site remembers from a person's last writes. */ |
| 30 | export type Bookmarks = { |
| 31 | /** Unix seconds of the last request that may have written, if recent. */ |
| 32 | at: number | null; |
| 33 | /** The latest bookmark each service returned after it. */ |
| 34 | services: Record<string, string>; |
| 35 | }; |
| 36 | |
| 37 | const BOOKMARK = /^[0-9A-Za-z-]{1,256}$/; |
| 38 | const SERVICE = /^[a-z]{1,32}$/; |
| 39 | |
| 40 | /** Reads the `g1t_d1` cookie; anything malformed is dropped. */ |
| 41 | export function readBookmarks(cookieHeader: string | null): Bookmarks { |
| 42 | const empty: Bookmarks = { at: null, services: {} }; |
| 43 | if (!cookieHeader) return empty; |
| 44 | const match = new RegExp(`(?:^|;\\s*)${D1_COOKIE}=([^;]*)`).exec(cookieHeader); |
| 45 | if (!match) return empty; |
| 46 | const found: Bookmarks = { at: null, services: {} }; |
| 47 | for (const entry of match[1].split("~")) { |
| 48 | const colon = entry.indexOf(":"); |
| 49 | if (colon < 1) continue; |
| 50 | const key = entry.slice(0, colon); |
| 51 | const value = entry.slice(colon + 1); |
| 52 | if (key === "at") { |
| 53 | const at = Number(value); |
| 54 | if (Number.isSafeInteger(at) && at > 0) found.at = at; |
| 55 | } else if (SERVICE.test(key) && SESSION_SERVICES.has(key) && BOOKMARK.test(value)) { |
| 56 | found.services[key] = value; |
| 57 | } |
| 58 | } |
| 59 | return found; |
| 60 | } |
| 61 | |
| 62 | /** The `g1t_d1` cookie's value. */ |
| 63 | export function writeBookmarks(bookmarks: Bookmarks): string { |
| 64 | const entries = bookmarks.at ? [`at:${bookmarks.at}`] : []; |
| 65 | for (const [service, bookmark] of Object.entries(bookmarks.services).sort()) { |
| 66 | if (SESSION_SERVICES.has(service) && BOOKMARK.test(bookmark)) entries.push(`${service}:${bookmark}`); |
| 67 | } |
| 68 | return entries.join("~"); |
| 69 | } |
| 70 | |
| 71 | /** The `Set-Cookie` value for `bookmarks`. */ |
| 72 | export function bookmarkCookie(bookmarks: Bookmarks, secure: boolean): string { |
| 73 | return `${D1_COOKIE}=${writeBookmarks(bookmarks)}; Path=/; HttpOnly;${secure ? " Secure;" : ""} SameSite=Lax; Max-Age=${D1_COOKIE_MAX_AGE}`; |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * What a call to `service` sends as `x-d1-bookmark`, or null for none |
| 78 | * (that service reads its primary, as before sessions): |
| 79 | * |
| 80 | * - A request that writes (any method but GET and HEAD) starts every |
| 81 | * session on the primary, so what it checks before writing is current. |
| 82 | * - Within `PRIMARY_WINDOW_SECONDS` of the person's last write, the |
| 83 | * primary, for every service: that write may have reached a service |
| 84 | * through another one, whose bookmark the site never saw. |
| 85 | * - Otherwise the bookmark that service returned after that write: never |
| 86 | * older than what they did, however far a replica trails. |
| 87 | * - Otherwise the nearest copy. |
| 88 | */ |
| 89 | export function sessionFor(service: string, bookmarks: Bookmarks, writing: boolean, nowSeconds: number): string | null { |
| 90 | if (!SESSION_SERVICES.has(service)) return null; |
| 91 | if (writing) return "first-primary"; |
| 92 | if (bookmarks.at && nowSeconds - bookmarks.at < PRIMARY_WINDOW_SECONDS) return "first-primary"; |
| 93 | return bookmarks.services[service] ?? "first-unconstrained"; |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Methods that only read. Anything not listed is taken to write, so a new |
| 98 | * method errs towards a cookie and a primary read, never a stale page. |
| 99 | * `get`, `list`, `queue` and `pulls_for_repos` were missing: every project |
| 100 | * page called `get` (repos, projects), so every one set the cookie, was |
| 101 | * never kept in the public cache, and sent the next 30 s of the person's |
| 102 | * reads to the primary. `stars`, `about` and `public_links` (2026-10-08) |
| 103 | * did the same to every project page and Explore for 13 hours. `tags`, |
| 104 | * `commit_checks` and `shortcuts` (every overview), and the Files page's |
| 105 | * `last_commits`, `languages`, `contributors` and `license`, still made a |
| 106 | * signed-in view count as a write until 2026-10-08: the cookie, 30 s of |
| 107 | * primary reads, and no sidebar cache after every overview. |
| 108 | */ |
| 109 | const READS = new Set( |
| 110 | ( |
| 111 | "account active_agents all_ids get list queue pulls_for_repos blame blob branches by_author by_repo catalog check_invite check_limit " + |
| 112 | "check_workspace_deletion check_workspace_rename collaborator_permission compare counts deleted deliveries " + |
| 113 | "dependencies domains entitlements entity explore features git_access graph has_feature invoices ledger limit " + |
| 114 | "limit_requests links log logs managed_pulls memories_by_id memory_context my_repo_invitations " + |
| 115 | "outside_collaborators overview path_by_id prices profile profile_workspaces public_namespaces read_session " + |
| 116 | "readable ready_issues references registration repo_access resolve resolve_branch resolve_path resolve_slug " + |
| 117 | "routes run run_context run_cost runner_groups runner_settings runners runs scorecards search search_memories " + |
| 118 | "settings statement statement_entries status status_by_id suggest tree usage usage_meters user_by_username " + |
| 119 | "user_for_session usernames waiting_workspaces workflows workspace workspace_invites github_enabled " + |
| 120 | "stars about public_links branch_drift tags last_commits languages contributors license releases release " + |
| 121 | "stargazers starred commit_checks shortcuts" |
| 122 | ).split(" "), |
| 123 | ); |
| 124 | |
| 125 | /** |
| 126 | * Whether a response sets the `g1t_d1` cookie. A signed-out GET never |
| 127 | * does, whatever it called: nobody signed out can write anything their |
| 128 | * next page must read, and a cookie keeps the page out of the public |
| 129 | * cache. Signing in on a GET (GitHub) starts a session, so it does. |
| 130 | */ |
| 131 | export function setsBookmark(request: { writing: boolean; wrote: boolean; hasSession: boolean; signedIn: boolean }): boolean { |
| 132 | if (request.writing || request.signedIn) return true; |
| 133 | return request.wrote && request.hasSession; |
| 134 | } |
| 135 | |
| 136 | /** Whether an RPC to `method` may write. */ |
| 137 | export function mayWrite(method: string): boolean { |
| 138 | if (READS.has(method)) return false; |
| 139 | return !(method.startsWith("get_") || method.startsWith("list_")); |
| 140 | } |
| 141 | |
| 142 | /** The method name of an RPC URL (`https://service/rpc/<method>`). */ |
| 143 | export function rpcMethodOf(input: string): string { |
| 144 | const at = input.indexOf("/rpc/"); |
| 145 | return at < 0 ? "" : input.slice(at + 5).split(/[?#]/)[0]; |
| 146 | } |
| 147 | |
| 148 | /** One service's calls during a request. */ |
| 149 | export type ServiceTiming = { |
| 150 | calls: number; |
| 151 | /** Summed wall time of its calls, from here. */ |
| 152 | wallMs: number; |
| 153 | /** Summed time its own `server-timing: svc;dur` reported. */ |
| 154 | serviceMs: number; |
| 155 | /** |
| 156 | * Of that, summed time it reported waiting on its database |
| 157 | * (`db;dur`, crates/kit/src/d1.rs `Timing`) and in how many round trips. |
| 158 | * Absent for services that do not time them. |
| 159 | */ |
| 160 | dbMs?: number; |
| 161 | dbTrips?: number; |
| 162 | }; |
| 163 | |
| 164 | /** The `svc;dur=N` a service reports, or null. */ |
| 165 | export function serviceDuration(header: string | null): number | null { |
| 166 | if (!header) return null; |
| 167 | const match = /(?:^|,)\s*svc;dur=([0-9.]+)/.exec(header); |
| 168 | return match ? Number(match[1]) : null; |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * The `db;dur=N;desc="T round trips, …"` a service reports: its summed |
| 173 | * database time and round trips, or null. |
| 174 | */ |
| 175 | export function databaseTime(header: string | null): { ms: number; trips: number } | null { |
| 176 | if (!header) return null; |
| 177 | const match = /(?:^|,)\s*db;dur=([0-9.]+)(?:;desc="(\d+) round trips?)?/.exec(header); |
| 178 | return match ? { ms: Number(match[1]), trips: Number(match[2] ?? 0) } : null; |
| 179 | } |
| 180 | |
| 181 | /** Total time covered by overlapping [start, end] intervals. */ |
| 182 | export function coveredMs(intervals: [number, number][]): number { |
| 183 | const sorted = [...intervals].sort((a, b) => a[0] - b[0]); |
| 184 | let total = 0; |
| 185 | let end = -Infinity; |
| 186 | let start = -Infinity; |
| 187 | for (const [from, to] of sorted) { |
| 188 | if (from > end) { |
| 189 | if (end > start) total += end - start; |
| 190 | start = from; |
| 191 | end = to; |
| 192 | } else if (to > end) { |
| 193 | end = to; |
| 194 | } |
| 195 | } |
| 196 | if (end > start) total += end - start; |
| 197 | return total; |
| 198 | } |
| 199 | |
| 200 | /** A Server-Timing metric name: a token, so `/` and spaces become `.`. */ |
| 201 | export function metricName(name: string): string { |
| 202 | return name.replace(/^routes\//, "").replace(/[^A-Za-z0-9_.-]+/g, "."); |
| 203 | } |
| 204 | |
| 205 | /** |
| 206 | * The `Server-Timing` header for a request: the whole, the loaders, the |
| 207 | * time spent waiting on services (overlap counted once), then each |
| 208 | * service. DevTools shows them in this order under Network → Timing. |
| 209 | */ |
| 210 | export function serverTiming(input: { |
| 211 | totalMs: number; |
| 212 | loaders: { id: string; ms: number; kind: "loader" | "action" }[]; |
| 213 | rpcMs: number; |
| 214 | services: Record<string, ServiceTiming>; |
| 215 | sessions: string; |
| 216 | }): string { |
| 217 | const parts = [`total;dur=${input.totalMs};desc="web to first byte"`]; |
| 218 | for (const loader of input.loaders) { |
| 219 | parts.push(`${loader.kind}.${metricName(loader.id)};dur=${loader.ms}`); |
| 220 | } |
| 221 | const calls = Object.values(input.services).reduce((sum, timing) => sum + timing.calls, 0); |
| 222 | if (calls > 0) parts.push(`rpc;dur=${input.rpcMs};desc="${calls} service calls, overlap counted once"`); |
| 223 | const ranked = Object.entries(input.services).sort((a, b) => b[1].wallMs - a[1].wallMs); |
| 224 | for (const [name, timing] of ranked) { |
| 225 | const db = timing.dbTrips ? `, db ${timing.dbMs ?? 0}ms in ${timing.dbTrips} round trip${timing.dbTrips === 1 ? "" : "s"}` : ""; |
| 226 | const inside = timing.serviceMs > 0 ? `, ${timing.serviceMs}ms inside${db}` : ""; |
| 227 | parts.push(`${metricName(name)};dur=${timing.wallMs};desc="${timing.calls} call${timing.calls === 1 ? "" : "s"}${inside}"`); |
| 228 | } |
| 229 | if (input.sessions) parts.push(`d1;desc="${input.sessions}"`); |
| 230 | return parts.join(", "); |
| 231 | } |