als-path-tree/lib/memory-monitor.js

A Node.js library for managing a virtual file system structure, offering functionalities for file and directory operations with a shared storage system.

const os = require('os');
const totalMemory = os.totalmem();
const options = require('./options')
class MemoryMonitor {
   static get options() { return options }

   constructor() {
      this.filesWithContent = new Set()
   }

   get freeMemoryPercentage() { return (os.freemem() / totalMemory) * 100 }
   get isMemOk() { return this.freeMemoryPercentage > options.thresholdPercentage }

   add(file) {
      this.filesWithContent.add(file)
      this.clear()
   }
   
   clear(force=false) {
      if (!force && this.isMemOk) return
      const now = Date.now()
      if(this.lastClear && (now - this.lastClear) < 1000) return
      this.lastClear = now
      let count = 0
      for (const file of this.filesWithContent) {
         if(this.isMemOk && !force) break
         const rating = this.calculateRating(file)
         if(file.age > options.maxStoreTime || rating < options.thresholdRating) {
            delete file._buffer
            this.filesWithContent.delete(file)
            count++
         }
      }
      if(count) options.logger.warn(`The memory is full. The content for ${count} files was removed. `)
   }

   calculateRating(file) {
      const { accessCount, lastAccess, size } = options.weights
      return accessCount * file.accessCount + lastAccess * file.age + size * file.meta.size
   }

   remove(...files) {
      files.forEach(file => this.filesWithContent.delete(file))
   }
}

module.exports = MemoryMonitor;