internalise snapshots

lib/core.js

@@ -117,11 +117,10 @@ class Update {
 }
 
 class SessionState {
-  constructor (core, storage, blocks, tree, bitfield, treeLength, snapshot, overlay) {
+  constructor (core, storage, blocks, tree, bitfield, treeLength, overlay) {
     this.core = core
 
     this.storage = storage
-    this.storageSnapshot = snapshot || null
 
     this.mutex = new Mutex()
 
@@ -142,7 +141,7 @@ class SessionState {
   }
 
   get isSnapshot () {
-    return this.storageSnapshot !== null
+    return this.storage.snapshotted
   }
 
   get isDefault () {
@@ -161,23 +160,18 @@ class SessionState {
   }
 
   async close () {
-    if (this.storageSnapshot) this.storageSnapshot.destroy()
-
     await this.storage.close()
     await this.mutex.destroy(new Error('Closed'))
   }
 
   snapshot () {
-    const snapshot = this.storage.snapshot()
-
     const s = new SessionState(
       this.core,
-      this.storage,
+      this.storage.snapshot(),
       this.blocks,
       this.tree,
       this.bitfield,
       this.treeLength,
-      snapshot,
       null
     )
 
@@ -193,15 +187,14 @@ class SessionState {
       this.tree.clone(storage),
       this.bitfield,
       this.treeLength,
-      null,
       storage
     )
 
     return s
   }
 
   createReadBatch () {
-    const reader = this.storage.createReadBatch({ snapshot: this.storageSnapshot })
+    const reader = this.storage.createReadBatch()
     return this.overlay === null ? reader : this.overlay.createReadBatch(reader)
   }
 
@@ -218,7 +211,7 @@ class SessionState {
   }
 
   createUpdate () {
-    assert(!this._activeBatch && !this.isSnapshot)
+    assert(!this._activeBatch && !this.storage.snapshotted)
 
     this._activeBatch = this.overlay ? this.overlay.createWriteBatch() : this.storage.createWriteBatch()
     return new Update(this._activeBatch, this.bitfield, this.core.header, this)