support deleting plus ghosting

lib/index.js

@@ -76,25 +76,37 @@ function initGC(peer, config) {
   function cleanup(cb) {
     assertDBExists(peer)
     assertGoalsExists(peer)
-    debug('cleanup goalless started')
+    debug('cleanup-per-purpose started')
+
     const done = multicb({ pluck: 1 })
     let waiting = false
     for (const rec of peer.db.records()) {
       if (!rec.msg) continue
-      const purpose = peer.goals.getRecordPurpose(rec)
+      const { id: msgID, msg } = rec
+      const [purpose, details] = peer.goals.getMsgPurpose(msgID, msg)
       if (purpose === 'none') {
-        peer.db.del(rec.id, done())
+        peer.db.del(msgID, done())
+        waiting = true
+      } else if (purpose === 'ghost') {
+        const { tangleID, span } = details
+        const cb = done()
+        // TODO: Could one msg be a ghostable in MANY tangles? Or just one?
+        peer.db.ghosts.add({ tangleID, msgID, span }, (err) => {
+          // prettier-ignore
+          if (err) return cb(new Error('gc failed to add ghost', { cause: err }))
+          peer.db.del(msgID, cb)
+        })
         waiting = true
       } else if (purpose === 'trail') {
-        peer.db.erase(rec.id, done())
+        peer.db.erase(msgID, done())
         waiting = true
       }
     }
     /** @param {Error=} err */
     function whenEnded(err) {
       // prettier-ignore
-      if (err) debug('cleanup goalless ended with an error %s', err.message ?? err)
+      if (err) debug('cleanup-per-purpose ended with an error %s', err.message ?? err)
-        else debug('cleanup goalless ended')
+      else debug('cleanup-per-purpose ended')
       cb()
     }
     if (waiting) done(whenEnded)

package.json

@@ -35,6 +35,7 @@
     "ppppp-db": "github:staltz/ppppp-db",
     "ppppp-goals": "github:staltz/ppppp-goals",
     "ppppp-keypair": "github:staltz/ppppp-keypair",
+    "ppppp-record": "github:staltz/ppppp-record",
     "prettier": "^2.6.2",
     "pretty-quick": "^3.1.3",
     "rimraf": "^4.4.0",

test/record-ghosts.test.js

@@ -0,0 +1,99 @@
+const test = require('node:test')
+const assert = require('node:assert')
+const p = require('node:util').promisify
+const { createPeer } = require('./util')
+
+function getFields(msgs) {
+  return msgs
+    .map((msg) => msg.data?.update)
+    .filter((x) => !!x)
+    .map((x) => x.age ?? x.name)
+}
+
+function isErased(msg) {
+  return !msg.data
+}
+
+function isDeleted(msg) {
+  return !msg
+}
+
+function isPresent(msg) {
+  return !!msg.data.update
+}
+
+test('record ghosts', async (t) => {
+  const alice = createPeer({
+    name: 'alice',
+    gc: { maxLogBytes: 100 * 1024 * 1024 },
+    record: { ghostSpan: 2 },
+  })
+
+  await alice.db.loaded()
+
+  // Alice creates her own account
+  const aliceID = await p(alice.db.account.create)({
+    domain: 'account',
+    _nonce: 'alice',
+  })
+
+  // Alice constructs a record
+  await p(alice.record.load)(aliceID)
+  await p(alice.record.update)('profile', { name: 'alice' })
+  await p(alice.record.update)('profile', { age: 24 })
+  await p(alice.record.update)('profile', { name: 'Alice' })
+  await p(alice.record.update)('profile', { age: 25 })
+  await p(alice.record.update)('profile', { name: 'ALICE' })
+  const recordID = alice.record.getFeedID('profile')
+
+  let mootID
+  let msgID1
+  let msgID2
+  let msgID3
+  let msgID4
+  let msgID5
+  for (const rec of alice.db.records()) {
+    if (rec.msg.metadata.dataSize === 0) mootID = rec.id
+    if (rec.msg.data?.update?.name === 'alice') msgID1 = rec.id
+    if (rec.msg.data?.update?.age === 24) msgID2 = rec.id
+    if (rec.msg.data?.update?.name === 'Alice') msgID3 = rec.id
+    if (rec.msg.data?.update?.age === 25) msgID4 = rec.id
+    if (rec.msg.data?.update?.name === 'ALICE') msgID5 = rec.id
+  }
+
+  // Assert situation before GC
+  assert.deepEqual(
+    getFields([...alice.db.msgs()]),
+    ['alice', 24, 'Alice', 25, 'ALICE'],
+    'has all record msgs'
+  )
+  assert.ok(isErased(alice.db.get(mootID)), 'moot by def erased')
+  assert.ok(isPresent(alice.db.get(msgID1)), 'msg1 exists')
+  assert.ok(isPresent(alice.db.get(msgID2)), 'msg2 exists')
+  assert.ok(isPresent(alice.db.get(msgID3)), 'msg3 exists')
+  assert.ok(isPresent(alice.db.get(msgID4)), 'msg4 exists')
+  assert.ok(isPresent(alice.db.get(msgID5)), 'msg5 exists')
+
+  // Perform garbage collection
+  alice.goals.set(aliceID, 'all')
+  alice.goals.set(recordID, 'record')
+  await p(alice.gc.forceImmediately)()
+
+  // Assert situation after GC
+  assert.deepEqual(
+    getFields([...alice.db.msgs()]),
+    [25, 'ALICE'],
+    'alice has only field root msgs'
+  )
+
+  assert.ok(isErased(alice.db.get(mootID)), 'moot by def erased')
+  assert.ok(isDeleted(alice.db.get(msgID1)), 'msg1 deleted')
+  assert.ok(isDeleted(alice.db.get(msgID2)), 'msg2 deleted') // ghost!
+  assert.ok(isErased(alice.db.get(msgID3)), 'msg3 erased')
+  assert.ok(isPresent(alice.db.get(msgID4)), 'msg4 exists')
+  assert.ok(isPresent(alice.db.get(msgID5)), 'msg5 exists')
+
+  assert.deepEqual(alice.db.ghosts.get(recordID), [msgID2])
+
+  await p(alice.close)(true)
+})

test/util.js

@@ -18,6 +18,7 @@ function createPeer(opts) {
     .use(require('secret-stack/plugins/net'))
     .use(require('secret-handshake-ext/secret-stack'))
     .use(require('ppppp-db'))
+    .use(require('ppppp-record'))
     .use(require('ppppp-goals'))
     .use(require('ssb-box'))
     .use(require('../lib'))