Allow to supply an invalidation key to FileSystemBlobStore

spec/file-system-blob-store-spec.coffee

@@ -9,61 +9,71 @@ describe "FileSystemBlobStore", ->
     blobStore = FileSystemBlobStore.load(storageDirectory)
 
   it "is empty when the file doesn't exist", ->
-    expect(blobStore.get("foo")).toBeUndefined()
-    expect(blobStore.get("bar")).toBeUndefined()
+    expect(blobStore.get("foo", "invalidation-key-1")).toBeUndefined()
+    expect(blobStore.get("bar", "invalidation-key-2")).toBeUndefined()
 
   it "allows to read and write buffers from/to memory without persisting them", ->
-    blobStore.set("foo", new Buffer("foo"))
-    blobStore.set("bar", new Buffer("bar"))
+    blobStore.set("foo", "invalidation-key-1", new Buffer("foo"))
+    blobStore.set("bar", "invalidation-key-2", new Buffer("bar"))
 
-    expect(blobStore.get("foo")).toEqual(new Buffer("foo"))
-    expect(blobStore.get("bar")).toEqual(new Buffer("bar"))
+    expect(blobStore.get("foo", "invalidation-key-1")).toEqual(new Buffer("foo"))
+    expect(blobStore.get("bar", "invalidation-key-2")).toEqual(new Buffer("bar"))
+
+    expect(blobStore.get("foo", "unexisting-key")).toBeUndefined()
+    expect(blobStore.get("bar", "unexisting-key")).toBeUndefined()
 
   it "persists buffers when saved and retrieves them on load, giving priority to in-memory ones", ->
-    blobStore.set("foo", new Buffer("foo"))
-    blobStore.set("bar", new Buffer("bar"))
+    blobStore.set("foo", "invalidation-key-1", new Buffer("foo"))
+    blobStore.set("bar", "invalidation-key-2", new Buffer("bar"))
     blobStore.save()
 
     blobStore = FileSystemBlobStore.load(storageDirectory)
 
-    expect(blobStore.get("foo")).toEqual(new Buffer("foo"))
-    expect(blobStore.get("bar")).toEqual(new Buffer("bar"))
+    expect(blobStore.get("foo", "invalidation-key-1")).toEqual(new Buffer("foo"))
+    expect(blobStore.get("bar", "invalidation-key-2")).toEqual(new Buffer("bar"))
+    expect(blobStore.get("foo", "unexisting-key")).toBeUndefined()
+    expect(blobStore.get("bar", "unexisting-key")).toBeUndefined()
 
-    blobStore.set("foo", new Buffer("changed"))
+    blobStore.set("foo", "new-key", new Buffer("changed"))
 
-    expect(blobStore.get("foo")).toEqual(new Buffer("changed"))
+    expect(blobStore.get("foo", "new-key")).toEqual(new Buffer("changed"))
+    expect(blobStore.get("foo", "invalidation-key-1")).toBeUndefined()
 
   it "persists both in-memory and previously stored buffers when saved", ->
-    blobStore.set("foo", new Buffer("foo"))
-    blobStore.set("bar", new Buffer("bar"))
+    blobStore.set("foo", "invalidation-key-1", new Buffer("foo"))
+    blobStore.set("bar", "invalidation-key-2", new Buffer("bar"))
     blobStore.save()
 
     blobStore = FileSystemBlobStore.load(storageDirectory)
-    blobStore.set("bar", new Buffer("changed"))
-    blobStore.set("qux", new Buffer("qux"))
+    blobStore.set("bar", "invalidation-key-3", new Buffer("changed"))
+    blobStore.set("qux", "invalidation-key-4", new Buffer("qux"))
     blobStore.save()
 
     blobStore = FileSystemBlobStore.load(storageDirectory)
 
-    expect(blobStore.get("foo")).toEqual(new Buffer("foo"))
-    expect(blobStore.get("bar")).toEqual(new Buffer("changed"))
-    expect(blobStore.get("qux")).toEqual(new Buffer("qux"))
+    expect(blobStore.get("foo", "invalidation-key-1")).toEqual(new Buffer("foo"))
+    expect(blobStore.get("bar", "invalidation-key-3")).toEqual(new Buffer("changed"))
+    expect(blobStore.get("qux", "invalidation-key-4")).toEqual(new Buffer("qux"))
+    expect(blobStore.get("foo", "unexisting-key")).toBeUndefined()
+    expect(blobStore.get("bar", "invalidation-key-2")).toBeUndefined()
+    expect(blobStore.get("qux", "unexisting-key")).toBeUndefined()
 
   it "allows to delete keys from both memory and stored buffers", ->
-    blobStore.set("a", new Buffer("a"))
-    blobStore.set("b", new Buffer("b"))
+    blobStore.set("a", "invalidation-key-1", new Buffer("a"))
+    blobStore.set("b", "invalidation-key-2", new Buffer("b"))
     blobStore.save()
 
     blobStore = FileSystemBlobStore.load(storageDirectory)
 
-    blobStore.set("b", new Buffer("b"))
-    blobStore.set("c", new Buffer("c"))
+    blobStore.set("b", "invalidation-key-3", new Buffer("b"))
+    blobStore.set("c", "invalidation-key-4", new Buffer("c"))
     blobStore.delete("b")
     blobStore.delete("c")
     blobStore.save()
 
     blobStore = FileSystemBlobStore.load(storageDirectory)
 
-    expect(blobStore.get("a")).toEqual(new Buffer("a"))
-    expect(blobStore.get("b")).toBeUndefined()
-    expect(blobStore.get("c")).toBeUndefined()
+    expect(blobStore.get("a", "invalidation-key-1")).toEqual(new Buffer("a"))
+    expect(blobStore.get("b", "invalidation-key-2")).toBeUndefined()
+    expect(blobStore.get("b", "invalidation-key-3")).toBeUndefined()
+    expect(blobStore.get("c", "invalidation-key-4")).toBeUndefined()

src/file-system-blob-store.js

@@ -13,8 +13,10 @@ class FileSystemBlobStore {
 
   constructor (directory) {
     this.inMemoryBlobs = new Map()
+    this.invalidationKeys = {}
     this.blobFilename = path.join(directory, 'BLOB')
     this.blobMapFilename = path.join(directory, 'MAP')
+    this.invalidationKeysFilename = path.join(directory, 'INVKEYS')
     this.lockFilename = path.join(directory, 'LOCK')
     this.storedBlob = new Buffer(0)
     this.storedBlobMap = {}
@@ -27,14 +29,19 @@ class FileSystemBlobStore {
     if (!fs.existsSync(this.blobFilename)) {
       return
     }
+    if (!fs.existsSync(this.invalidationKeysFilename)) {
+      return
+    }
     this.storedBlob = fs.readFileSync(this.blobFilename)
     this.storedBlobMap = JSON.parse(fs.readFileSync(this.blobMapFilename))
+    this.invalidationKeys = JSON.parse(fs.readFileSync(this.invalidationKeysFilename))
   }
 
   save () {
     let dump = this.getDump()
     let blobToStore = Buffer.concat(dump[0])
     let mapToStore = JSON.stringify(dump[1])
+    let invalidationKeysToStore = JSON.stringify(this.invalidationKeys)
 
     let acquiredLock = false
     try {
@@ -43,6 +50,7 @@ class FileSystemBlobStore {
 
       fs.writeFileSync(this.blobFilename, blobToStore)
       fs.writeFileSync(this.blobMapFilename, mapToStore)
+      fs.writeFileSync(this.invalidationKeysFilename, invalidationKeysToStore)
     } catch (error) {
       // Swallow the exception silently only if we fail to acquire the lock.
       if (error.code !== 'EEXIST') {
@@ -55,15 +63,20 @@ class FileSystemBlobStore {
     }
   }
 
-  has (key) {
-    return this.inMemoryBlobs.hasOwnProperty(key) || this.storedBlobMap.hasOwnProperty(key)
+  has (key, invalidationKey) {
+    let containsKey = this.inMemoryBlobs.has(key) || this.storedBlobMap.hasOwnProperty(key)
+    let isValid = this.invalidationKeys[key] === invalidationKey
+    return containsKey && isValid
   }
 
-  get (key) {
-    return this.getFromMemory(key) || this.getFromStorage(key)
+  get (key, invalidationKey) {
+    if (this.has(key, invalidationKey)) {
+      return this.getFromMemory(key) || this.getFromStorage(key)
+    }
   }
 
-  set (key, buffer) {
+  set (key, invalidationKey, buffer) {
+    this.invalidationKeys[key] = invalidationKey
     return this.inMemoryBlobs.set(key, buffer)
   }