Support both versions

Level · Jun 18, 2024 · 0874891 · 0874891
1 parent cb4b436
commit 0874891
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Showing 2 changed files with 62 additions and 16 deletions.
diff --git a/index.js b/index.js
@@ -3,7 +3,9 @@
 const { Readable } = require('readable-stream')
 
 const kIterator = Symbol('iterator')
+const kPromises = Symbol('promises')
 const kNextv = Symbol('nextv')
+const kNextvLegacy = Symbol('nextvLegacy')
 const kDestroy = Symbol('destroy')
 
 class LevelReadStream extends Readable {
@@ -17,8 +19,15 @@ class LevelReadStream extends Readable {
 
     this[kIterator] = db[method](rest)
     this[kNextv] = this[kNextv].bind(this)
+    this[kNextvLegacy] = this[kNextvLegacy].bind(this)
     this[kDestroy] = this.destroy.bind(this)
 
+    // Detect abstract-level 2 by the presence of hooks. Version 2 doesn't
+    // support callbacks anymore. Version 1 does also support promises but
+    // that would be slower because it works by wrapping the callback API.
+    // TODO: test against memory-level once it has upgraded.
+    this[kPromises] = db.hooks !== undefined
+
     // NOTE: use autoDestroy option when it lands in readable-stream
     this.once('end', this.destroy.bind(this, null, null))
   }
@@ -29,10 +38,28 @@ class LevelReadStream extends Readable {
 
   _read (size) {
     if (this.destroyed) return
-    this[kIterator].nextv(size).then(
-      this[kNextv],
-      this[kDestroy]
-    )
+
+    if (this[kPromises]) {
+      this[kIterator].nextv(size).then(
+        this[kNextv],
+        this[kDestroy]
+      )
+    } else {
+      this[kIterator].nextv(size, this[kNextvLegacy])
+    }
+  }
+
+  [kNextvLegacy] (err, items) {
+    if (this.destroyed) return
+    if (err) return this.destroy(err)
+
+    if (items.length === 0) {
+      this.push(null)
+    } else {
+      for (const item of items) {
+        this.push(item)
+      }
+    }
   }
 
   [kNextv] (items) {
@@ -48,10 +75,16 @@ class LevelReadStream extends Readable {
   }
 
   _destroy (err, callback) {
-    this[kIterator].close().then(
-      err ? () => callback(err) : callback,
-      callback
-    )
+    if (this[kPromises]) {
+      this[kIterator].close().then(
+        err ? () => callback(err) : callback,
+        callback
+      )
+    } else {
+      this[kIterator].close(function (err2) {
+        callback(err || err2)
+      })
+    }
   }
 }
 
@@ -60,6 +93,19 @@ class EntryStream extends LevelReadStream {
     super(db, 'iterator', { ...options, keys: true, values: true })
   }
 
+  [kNextvLegacy] (err, entries) {
+    if (this.destroyed) return
+    if (err) return this.destroy(err)
+
+    if (entries.length === 0) {
+      this.push(null)
+    } else {
+      for (const [key, value] of entries) {
+        this.push({ key, value })
+      }
+    }
+  }
+
   [kNextv] (entries) {
     if (this.destroyed) return
 

diff --git a/test.js b/test.js
@@ -135,7 +135,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     })
   })
 
-  test.skip(name + ': destroy() during iterator.nextv', function (t) {
+  test(name + ': destroy() during iterator.nextv', function (t) {
     const stream = new Ctor(db)
     const order = monitor(stream, function () {
       t.same(order, ['_close', 'close'], 'event order')
@@ -149,7 +149,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.resume()
   })
 
-  test.skip(name + ': destroy(err) during iterator.nextv', function (t) {
+  test(name + ': destroy(err) during iterator.nextv', function (t) {
     const stream = new Ctor(db)
     const order = monitor(stream, function () {
       t.same(order, ['_close', 'error: user', 'close'], 'event order')
@@ -163,7 +163,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.resume()
   })
 
-  test.skip(name + ': destroy(err, callback) during iterator.nextv', function (t) {
+  test(name + ': destroy(err, callback) during iterator.nextv', function (t) {
     const stream = new Ctor(db)
 
     const order = monitor(stream, function () {
@@ -181,7 +181,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.resume()
   })
 
-  test.skip(name + ': destroy(null, callback) during iterator.nextv', function (t) {
+  test(name + ': destroy(null, callback) during iterator.nextv', function (t) {
     const stream = new Ctor(db)
 
     const order = monitor(stream, function () {
@@ -199,7 +199,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.resume()
   })
 
-  test.skip(name + ': destroy during iterator.nextv 1', function (t) {
+  test(name + ': destroy during iterator.nextv 1', function (t) {
     const stream = new Ctor(db)
     const iterator = db[kLastIterator]
     const nextv = iterator.nextv.bind(iterator)
@@ -214,7 +214,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.on('close', t.end.bind(t))
   })
 
-  test.skip(name + ': destroy during iterator.nextv 2', function (t) {
+  test(name + ': destroy during iterator.nextv 2', function (t) {
     const stream = new Ctor(db)
     const iterator = db[kLastIterator]
     const nextv = iterator.nextv.bind(iterator)
@@ -232,7 +232,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.on('close', t.end.bind(t))
   })
 
-  test.skip(name + ': destroy after iterator.nextv 1', function (t) {
+  test(name + ': destroy after iterator.nextv 1', function (t) {
     const stream = new Ctor(db)
     const iterator = db[kLastIterator]
     const nextv = iterator.nextv.bind(iterator)
@@ -249,7 +249,7 @@ for (const Ctor of [EntryStream, KeyStream, ValueStream]) {
     stream.on('close', t.end.bind(t))
   })
 
-  test.skip(name + ': destroy after iterator.nextv 2', function (t) {
+  test(name + ': destroy after iterator.nextv 2', function (t) {
     const stream = new Ctor(db)
     const iterator = db[kLastIterator]
     const nextv = iterator.nextv.bind(iterator)