Testing garbage collection with `lmdb-store` using `cache` option

gc-test.js

// node --expose-gc gc-test.js
// CACHE=1 node --expose-gc gc-test.js
const { open } = require("lmdb-store")
const ptop = require("process-top")()

let rootDb
function getRootDb() {
  if (!rootDb) {
    rootDb = open({
      name: `root`,
      path: process.cwd() + `/.data`,
      cache: Boolean(process.env.CACHE),
    })
  }
  return rootDb
}

async function fillDb(db, len) {
  let promise
  for (let i = 0; i < len; i++) {
    promise = db.put(i, { foo: new Array(1000).join(String(i)), i })
    if (i % 100 === 0) {
      await new Promise(resolve => setTimeout(resolve, 5))
    }
  }
  return promise
}

function reportMemory() {
  const used = ptop.memory().heapUsed / (1024 * 1024)
  const total = ptop.memory().heapTotal / (1024 * 1024)
  console.log(`heap: ${used.toFixed(2)} MB / ${total.toFixed(2)} MB`)
}

async function run() {
  const db = getRootDb()

  await fillDb(db, 10000)

  db.getKeys().forEach((key) => {
    const value = db.get(key)
    if (value.i % 1000 === 0) {
      reportMemory()
    }
  })

  console.log(``)
  console.log(`after loop:`)
  reportMemory()

  global.gc()
  console.log(`after forced gc:`)
  reportMemory()
}

run()