Add persistent server-side address cache

server/status.js

@@ -22,6 +22,133 @@ const {
 const port = 8080
 const fulcrumTimeoutMs = 3000
 
+const fs = require('fs')
+const path = require('path')
+
+const addressCacheDir = '/data/cache/addresses'
+const addressCacheMaxAgeMs = 60000
+const addressRefreshes = new Map()
+
+function ensureAddressCacheDir() {
+  fs.mkdirSync(addressCacheDir, {
+    recursive: true,
+  })
+}
+
+function getAddressCachePath(scripthash) {
+  return path.join(
+    addressCacheDir,
+    `${scripthash}.json`,
+  )
+}
+
+function readAddressCache(scripthash) {
+  try {
+    const cachePath =
+      getAddressCachePath(scripthash)
+
+    const stat = fs.statSync(cachePath)
+
+    const data =
+      JSON.parse(
+        fs.readFileSync(
+          cachePath,
+          'utf8',
+        ),
+      )
+
+    if (
+      !data ||
+      typeof data !== 'object' ||
+      !data.address
+    ) {
+      return null
+    }
+
+    return {
+      data,
+      ageMs: Math.max(
+        0,
+        Date.now() - stat.mtimeMs,
+      ),
+    }
+  } catch {
+    return null
+  }
+}
+
+function writeAddressCache(data) {
+  try {
+    ensureAddressCacheDir()
+
+    const cachePath =
+      getAddressCachePath(
+        data.scripthash,
+      )
+
+    const tempPath =
+      `${cachePath}.${process.pid}.tmp`
+
+    fs.writeFileSync(
+      tempPath,
+      JSON.stringify(data),
+      'utf8',
+    )
+
+    fs.renameSync(
+      tempPath,
+      cachePath,
+    )
+  } catch (error) {
+    console.error(
+      'Failed to write address cache:',
+      error,
+    )
+  }
+}
+
+function refreshAddressCache(
+  address,
+  scripthash,
+) {
+  const existing =
+    addressRefreshes.get(scripthash)
+
+  if (existing) {
+    return existing
+  }
+
+  const refresh =
+    getAddressDataFromFulcrum(
+      address,
+      scripthash,
+    )
+      .then((data) => {
+        writeAddressCache(data)
+        return data
+      })
+      .catch((error) => {
+        console.error(
+          `Failed to refresh address ${address}:`,
+          error,
+        )
+
+        throw error
+      })
+      .finally(() => {
+        addressRefreshes.delete(
+          scripthash,
+        )
+      })
+
+  addressRefreshes.set(
+    scripthash,
+    refresh,
+  )
+
+  return refresh
+}
+
 function queryFulcrum(fulcrumUrl, method, params = []) {
   return new Promise((resolve) => {
     if (!fulcrumUrl) {
@@ -247,23 +374,17 @@ async function getStatus() {
   }
 }
 
-async function getAddressData(address) {
-  let scripthash
-
-  try {
-    scripthash = addressToScripthash(address)
-  } catch (error) {
-    throw new Error(
-      error instanceof Error
-        ? error.message
-        : 'Invalid Bitcoin address',
-    )
-  }
-
-  const fulcrumUrl = process.env.MUNIN_FULCRUM_URL || null
+async function getAddressDataFromFulcrum(
+  address,
+  scripthash,
+) {
+  const fulcrumUrl =
+    process.env.MUNIN_FULCRUM_URL || null
 
   if (!fulcrumUrl) {
-    throw new Error('Fulcrum URL is not configured')
+    throw new Error(
+      'Fulcrum URL is not configured',
+    )
   }
 
   const balance = await queryFulcrum(
@@ -309,12 +430,63 @@ async function getAddressData(address) {
       Number(balance.result?.confirmed || 0),
     unconfirmedBalance:
       Number(balance.result?.unconfirmed || 0),
-    utxos: Array.isArray(utxos.result)
+    utxos:
+      Array.isArray(utxos.result)
         ? utxos.result
         : [],
-    history: Array.isArray(history.result)
+    history:
+      Array.isArray(history.result)
         ? history.result
         : [],
+    lastSynced:
+      new Date().toISOString(),
+  }
+}
+
+async function getAddressData(address) {
+  let scripthash
+
+  try {
+    scripthash =
+      addressToScripthash(address)
+  } catch (error) {
+    throw new Error(
+      error instanceof Error
+        ? error.message
+        : 'Invalid Bitcoin address',
+    )
+  }
+
+  const cached =
+    readAddressCache(scripthash)
+
+  if (cached) {
+    if (
+      cached.ageMs >
+      addressCacheMaxAgeMs
+    ) {
+      refreshAddressCache(
+        address,
+        scripthash,
+      ).catch(() => {})
+    }
+
+    return {
+      ...cached.data,
+      cacheAgeMs:
+        cached.ageMs,
+    }
+  }
+
+  const data =
+    await refreshAddressCache(
+      address,
+      scripthash,
+    )
+
+  return {
+    ...data,
+    cacheAgeMs: 0,
   }
 }
 
@@ -333,6 +505,10 @@ async function getAddressesWithData() {
         unconfirmedBalance: data.unconfirmedBalance,
         utxos: data.utxos,
         history: data.history,
+        lastSynced:
+          data.lastSynced || null,
+        cacheAgeMs:
+          Number(data.cacheAgeMs || 0),
         error: null,
       })
     } catch (error) {
@@ -342,6 +518,8 @@ async function getAddressesWithData() {
         unconfirmedBalance: null,
         utxos: [],
         history: [],
+        lastSynced: null,
+        cacheAgeMs: null,
         error:
           error instanceof Error
             ? error.message