Add message history to TreeNode

backend/src/Model/Message.ts

@@ -1,3 +1,5 @@
 export interface Message {
   value?: any | undefined
+  length: number
+  received: Date
 }

backend/src/Model/RingBuffer.ts

@@ -0,0 +1,60 @@
+interface Lengthwise {
+  length: number
+}
+
+export class RingBuffer<T extends Lengthwise> {
+  private capacity: number
+  private maxItems: number
+  private usage: number = 0
+  private items: (any)[] = []
+  private start: number = 0
+  private end: number = 0
+
+  constructor(capacity: number, maxItems = Infinity) {
+    this.capacity = capacity
+    this.maxItems = maxItems
+  }
+
+  public toArray() {
+    return this.items.slice(this.start, this.end)
+  }
+
+  public add(item: T) {
+    const size = item.length
+    this.enforceCapacityConstraints(size)
+    this.usage += size
+    this.items[this.end] = item
+    this.end += 1
+  }
+
+  private enforceCapacityConstraints(addedItemSize: number) {
+    const remainingSize = this.capacity - (this.usage + addedItemSize)
+    if (remainingSize < 0) {
+      this.freeSomeSpace(Math.abs(remainingSize))
+    }
+    while ((this.end - this.start) >= this.maxItems) {
+      this.dropFirst()
+    }
+  }
+
+  private freeSpace(): number {
+    return this.capacity - this.usage
+  }
+
+  private isEmpty(): boolean {
+    return this.usage === 0
+  }
+
+  private freeSomeSpace(requiredSpace: number) {
+    while (this.freeSpace() < requiredSpace && !this.isEmpty()) {
+      this.dropFirst()
+    }
+  }
+
+  private dropFirst() {
+    const freedSpace = this.items[this.start].length
+    this.usage -= freedSpace
+    delete this.items[this.start]
+    this.start += 1
+  }
+}

backend/src/Model/TreeNode.ts

@@ -1,9 +1,10 @@
-import { Edge, Message } from './'
+import { Edge, Message, RingBuffer } from './'
 import { EventDispatcher } from '../../../events'
 
 export class TreeNode {
   public sourceEdge?: Edge
   public message?: Message
+  public messageHistory = new RingBuffer<Message>(3000, 100)
   public edges: {[s: string]: Edge} = {}
   public collapsed = false
   public messages: number = 0
@@ -21,7 +22,7 @@ export class TreeNode {
       sourceEdge.target = this
     }
 
-    this.setMessage(message)
+    message && this.setMessage(message)
     this.onMerge.subscribe(() => {
       this.cachedLeafes = undefined
       this.cachedLeafMessageCount = undefined
@@ -35,8 +36,9 @@ export class TreeNode {
     })
   }
 
-  public setMessage(value: any) {
-    this.message = value
+  public setMessage(message: Message) {
+    this.messageHistory.add(message)
+    this.message = message
     this.messages += 1
   }
 

backend/src/Model/TreeNodeFactory.ts

@@ -1,7 +1,11 @@
-import { Edge, Message, Tree, TreeNode } from './'
+import { Edge, Tree, TreeNode } from './'
+
+interface HasLength {
+  length: number
+}
 
 export abstract class TreeNodeFactory {
-  public static fromEdgesAndValue(edgeNames: string[], value: any): TreeNode {
+  public static fromEdgesAndValue<T extends HasLength>(edgeNames: string[], value: T): TreeNode {
     let currentNode: TreeNode = new Tree()
     for (const edgeName of edgeNames) {
       const edge = new Edge(edgeName)
@@ -11,7 +15,11 @@ export abstract class TreeNodeFactory {
       currentNode = newNode
     }
 
-    currentNode.setMessage({ value })
+    currentNode.setMessage({
+      value,
+      length: value.length,
+      received: new Date(),
+    })
     return currentNode
   }
 }

backend/src/Model/index.ts

@@ -4,3 +4,4 @@ export { Message } from './Message'
 export { TreeNodeFactory } from './TreeNodeFactory'
 export { Tree } from './Tree'
 export { Hashable } from './Hashable'
+export * from './RingBuffer'

backend/src/Model/spec/RingBuffer.spec.ts

@@ -0,0 +1,46 @@
+import { RingBuffer } from '../'
+import { expect } from 'chai'
+import 'mocha'
+
+describe('RingBuffer', () => {
+  it('should add a new value', () => {
+    const b = new RingBuffer(30)
+    b.add('hello')
+    expect(b.toArray()[0]).to.eq('hello')
+  })
+
+  it('should add a new value after the first', () => {
+    const b = new RingBuffer(30)
+    b.add('hello')
+    b.add('world')
+    expect(b.toArray()[1]).to.eq('world')
+  })
+
+  it('should remove old values if buffer size is reached', () => {
+    const b = new RingBuffer(6)
+    b.add('hello')
+    b.add('world')
+    expect(b.toArray()[0]).to.eq('world')
+  })
+
+  it('items bigger then the buffer should be stored anyway', () => {
+    const b = new RingBuffer(3)
+    b.add('hello')
+    expect(b.toArray()[0]).to.eq('hello')
+    b.add('world')
+    expect(b.toArray()[0]).to.eq('world')
+  })
+
+  it('max item count should be respected', () => {
+    const b = new RingBuffer(100, 3)
+    b.add('a')
+    b.add('b')
+    b.add('c')
+    b.add('d')
+    b.add('e')
+    expect(b.toArray().length).to.eq(3)
+    expect(b.toArray()[0]).to.eq('c')
+    expect(b.toArray()[1]).to.eq('d')
+    expect(b.toArray()[2]).to.eq('e')
+  })
+})