mirror of
https://github.com/bilawalsidhu/gods-eye-view.git
synced 2026-11-04 18:34:02 +00:00
Sameh Khamis
c42b072e99
Uses a full SHA-256 of the sorted instance list, so reordering the same instances for failover keeps the cache. Adds the installation-cache repoint test (tagged, reordered, repointed, untagged, unconfigured) and the changelog and current-state notes.
214 lines
8.0 KiB
JavaScript
214 lines
8.0 KiB
JavaScript
import path from 'node:path';
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import { createHash } from 'node:crypto';
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// ---------------------------------------------------------------------------
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// Overpass API proxy constants and cache state
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// ---------------------------------------------------------------------------
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/** Stable application identity for operator-configured Overpass instances. */
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const OVERPASS_USER_AGENT =
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'gods-eye-view/0.1 (+https://github.com/bilawalsidhu/gods-eye-view)';
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/** Parse only operator-supplied HTTP(S) endpoints; private instances are allowed. */
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function parseOverpassUpstreams(raw) {
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const endpoints = [];
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for (const token of String(raw || '').split(',')) {
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try {
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const url = new URL(token.trim());
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if (
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!['http:', 'https:'].includes(url.protocol) ||
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!url.hostname ||
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url.hash
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)
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continue;
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if (!endpoints.includes(url.href)) endpoints.push(url.href);
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} catch {
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// Invalid configuration never becomes an upstream or appears in logs.
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}
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}
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return endpoints.slice(0, 8);
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}
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let upstreamMemo = { raw: null, endpoints: [], tag: 'none' };
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/**
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* Short, stable identifier for the configured upstream set. Cached responses
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* carry it so an answer produced by a different instance is not served after
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* the operator repoints `OVERPASS_UPSTREAMS` — the disk cache outlives the
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* configuration change by 7 days, a month for boundary queries, and forever on
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* the serve-stale path. It is a hash, never the URLs, and it is only ever
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* compared on read: it is not sent to clients and does not appear in errors.
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*/
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function upstreamTag(endpoints) {
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if (!endpoints.length) return 'none';
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// Sorted, so reordering the same instances for failover keeps the cache.
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return createHash('sha256')
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.update([...endpoints].sort().join('\n'))
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.digest('hex');
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}
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/** Resolve after environment loading. Public Overpass instances are not used by default. */
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function resolveOverpassUpstreams() {
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readUpstreamMemo();
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return [...upstreamMemo.endpoints];
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}
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/** The configured-upstream tag stored alongside, and checked against, cache entries. */
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function resolveOverpassUpstreamTag() {
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return readUpstreamMemo().tag;
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}
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let reportedForeignCache = false;
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/**
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* Was this cached entry produced by the upstream set configured now?
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*
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* With nothing configured there is no instance to contradict, and serving
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* last-good data at any age is the point of the cache (the proxy's
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* not-configured path depends on it), so any entry is accepted. Once an
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* operator does configure an instance, only its own answers are served: an
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* entry with no tag, or one from a different instance, is refused rather than
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* matched on the query alone. Shared by both caches fed by these upstreams.
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*/
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function cachedByConfiguredUpstream(entry) {
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const tag = resolveOverpassUpstreamTag();
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if (tag === 'none' || entry?.upstreams === tag) return true;
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if (!reportedForeignCache) {
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reportedForeignCache = true;
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console.warn(
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'[Overpass] ignoring cached responses produced by a different OVERPASS_UPSTREAMS; they will be refetched from the configured instance.',
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);
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}
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return false;
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}
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function readUpstreamMemo() {
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const raw = process.env.OVERPASS_UPSTREAMS || '';
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if (upstreamMemo.raw !== raw) {
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const endpoints = parseOverpassUpstreams(raw);
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upstreamMemo = { raw, endpoints, tag: upstreamTag(endpoints) };
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}
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return upstreamMemo;
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}
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/**
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* TTL for FRESH cached Overpass responses (ms). Road geometry is static for
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* months — the original 45 s TTL forced a public-mirror round-trip on nearly
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* every viewport revisit and left nothing to serve when the mirrors 502
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* (field-test 2026-07-17: all three mirrors down during US morning peak =
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* "traffic takes forever to load"). 24 h in memory; the disk layer below
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* keeps 7 days and also survives dev-server restarts.
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*/
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const OVERPASS_CACHE_MS = 86_400_000;
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/** Disk-cache TTL for Overpass responses (ms) — 7 days. */
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const OVERPASS_DISK_TTL_MS = 7 * 86_400_000;
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/**
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* Disk-cache TTL for BOUNDARY-class queries (is_in / admin-relation pivots) — 30
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* days. Admin boundaries change ≈never, and their pivots are the most expensive
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* queries the app issues (multi-MB coastline geometry, 10–25 s on public mirrors —
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* field test 2026-07-23: outline latency + the Sicily miss). Keeping them a month
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* means each boundary is fetched roughly once per machine, ever.
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*/
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const OVERPASS_BOUNDARY_DISK_TTL_MS = 30 * 86_400_000;
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/** Disk-cache directory for Overpass responses. */
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const OVERPASS_DISK_DIR = path.join(process.cwd(), '.gev-cache', 'overpass');
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/** Per-upstream fetch timeout (ms). */
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const OVERPASS_TIMEOUT_MS = 22000;
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/** Max entries in the Overpass response cache (LRU-like, oldest evicted first). */
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const OVERPASS_CACHE_MAX_ENTRIES = 120;
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// --- Abuse guards shared by the Overpass + route proxies --------------------
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/** Max accepted POST body for the Overpass proxy (Overpass QL queries are tiny). */
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const OVERPASS_MAX_BODY_BYTES = 24 * 1024;
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// 24 KB
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/**
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* Hard cap on a single Overpass upstream response we will buffer into memory.
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* 32 MB (was 12 MB): a dense island/state admin boundary at full `out geom`
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* fidelity — Sicilia's Mediterranean coastline — can exceed 12 MB, and clipping
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* it read as a permanent "transient" failure (field test 2026-07-23, Sicily
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* never traced). The buffered payload is SIMPLIFIED server-side before it is
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* cached or sent (simplifyOverpassPayloadBody), so the raised cap does not
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* raise what clients receive or what the disk stores.
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*/
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const OVERPASS_MAX_RESPONSE_BYTES = 32 * 1024 * 1024;
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// 32 MB
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/** Only payloads at least this large go through geometry simplification. */
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const OVERPASS_SIMPLIFY_MIN_BYTES = 1_500_000;
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/** Only per-element geometry arrays with at least this many points are simplified. */
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const OVERPASS_SIMPLIFY_MIN_POINTS = 1200;
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/**
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* Douglas-Peucker tolerance (degrees, ≈44 m of latitude). Region/state boundary
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* rings are drawn at regional camera scale and the client simplifies again for
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* draw, so ~44 m fidelity is invisible; building footprints never reach the
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* point threshold above and pass through untouched.
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*/
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const OVERPASS_SIMPLIFY_TOLERANCE_DEG = 0.0004;
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/** Max concurrent in-flight upstream Overpass fetches across all distinct queries. */
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const OVERPASS_MAX_CONCURRENT = 6;
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/** Server-side timeout ceiling (seconds) we allow inside an Overpass QL query. */
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const OVERPASS_MAX_QL_TIMEOUT = 30;
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/** Max `around:` radius (m) — every app caller uses <= 1800 m. */
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const OVERPASS_MAX_AROUND_M = 50000;
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/** Max bbox span (degrees) — app bboxes are small viewport tiles. */
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const OVERPASS_MAX_BBOX_DEG = 12;
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/**
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* Every Overpass element-type specifier, including the combined shortcuts
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* (nwr/nw/nr/wr) and `rel`. Shared by the selector + area-element-deny regexes so
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* they can't drift (a missing shortcut like `wr` was an area-scan bypass).
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*/
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const OVERPASS_ELEMENT_TYPES = 'node|way|relation|nwr|nw|nr|wr|rel';
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/** Element-selector (incl. `area`) whose statements must be individually bounded. */
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const OVERPASS_SELECTOR_RE = new RegExp(
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`\\b(?:${OVERPASS_ELEMENT_TYPES}|area)\\b`,
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);
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/** An element selector bounded BY an area — the country-scan abuse shape. */
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const OVERPASS_AREA_ELEMENT_RE = new RegExp(
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`\\b(?:${OVERPASS_ELEMENT_TYPES})\\s*\\(\\s*area\\b`,
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'i',
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);
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/** A single bbox 4-tuple `(s,w,n,e)` (non-global so it does not advance lastIndex). */
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const OVERPASS_BBOX_RE =
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/\(\s*-?\d+(?:\.\d+)?\s*,\s*-?\d+(?:\.\d+)?\s*,\s*-?\d+(?:\.\d+)?\s*,\s*-?\d+(?:\.\d+)?\s*\)/;
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export {
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OVERPASS_BOUNDARY_DISK_TTL_MS,
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OVERPASS_DISK_TTL_MS,
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OVERPASS_DISK_DIR,
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OVERPASS_CACHE_MS,
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OVERPASS_CACHE_MAX_ENTRIES,
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OVERPASS_MAX_BODY_BYTES,
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OVERPASS_MAX_CONCURRENT,
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OVERPASS_MAX_AROUND_M,
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OVERPASS_MAX_BBOX_DEG,
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OVERPASS_AREA_ELEMENT_RE,
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OVERPASS_SELECTOR_RE,
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OVERPASS_BBOX_RE,
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OVERPASS_MAX_QL_TIMEOUT,
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OVERPASS_SIMPLIFY_MIN_BYTES,
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OVERPASS_SIMPLIFY_MIN_POINTS,
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OVERPASS_SIMPLIFY_TOLERANCE_DEG,
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OVERPASS_MAX_RESPONSE_BYTES,
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parseOverpassUpstreams,
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resolveOverpassUpstreams,
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resolveOverpassUpstreamTag,
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cachedByConfiguredUpstream,
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OVERPASS_USER_AGENT,
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OVERPASS_TIMEOUT_MS,
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};
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