version1/src/js/iotjs/orig/slotbuffer.js

   1 class SlotBuffer{
   2         constructor(){
   3                 this.DEFAULT_SIZE = 128;
   4                 this.array = [];
   5                 this.head=0;
   6                 this.tail=0;
   7                 this.oldestseqn = 0;
   8         }
   9         size(){
  10                 if(this.head>=this.tail){
  11                         return this.head-this.tail;
  12                 }
  13                 return (this.array.length + this.head - this.tail);
  14         }
  15         capacity(){
  16                 return this.array.length-1;
  17         }
  18         resize(newsize){
  19                 if(newsize === (this.array.length-1)){
  20                         return;
  21                 }
  22                 var newarray = [];
  23                 var currsize = this.size();
  24                 var index = this.tail;
  25                 for(let i = 0 ; i<currsize ; i++){
  26                         newarray[i]=this.array[index];
  27                         if((++index) === this.array.length){
  28                                 index = 0;
  29                         }
  30                         this.array = newarray;
  31                         this.tail=0;
  32                         this.head=currsize;
  33                 }
  34         }
  35         incrementHead(){
  36                 this.head++;
  37                 if(this.head >= this.array.length){
  38                         this.head=0;
  39                 }
  40         }
  41         incrementTail(){
  42                 this.tail++;
  43                 if(this.tail >= this.array.length){
  44                         this.tail=0;
  45                 }
  46         }
  47         putSlot(s){
  48                 if(!(s instanceof Slot)){
  49                         throw new Error("Error with arguments. Argument should be a slot object");
  50                 }
  51                 this.array[this.head]=s;
  52                 this.incrementHead();
  53
  54                 if(this.oldestseqn ===0){
  55                         this.oldestseqn = s.getSequenceNumber();
  56                 }
  57
  58                 if(this.head === this.tail){
  59                         this.incrementTail();
  60                         this.oldestseqn++;
  61                 }
  62         }
  63         getSlot(seqnum){
  64                 var diff = (seqnum - this.oldestseqn);
  65                 var index = diff + this.tail;
  66                 if(index >= this.array.length){
  67                         if(this.head >= this.tail){
  68                                 return null;
  69                         }
  70                         index = index - this.array.length;
  71                 }
  72                 if(index >= this.array.length){
  73                         return null;
  74                 }
  75
  76                 if(this.head >= this.tail && index >= this.head){
  77                         return null;
  78                 }
  79
  80                 return this.array[index];
  81         }
  82
  83         getOldestSeqNum(){
  84                 return this.oldestseqn;
  85         }
  86         getNewestSeqNum(){
  87                 return this.oldestseqn + this.size() -1
  88         }
  89 }