introduce a cache control: a way of keeping the cache directory under certain size (should fix #229)

app.js

@@ -153,6 +153,9 @@ redis.on('error', (error) => {
   }
 })
 
+const cacheControl = require('./cacheControl.js')
+cacheControl.removeCacheFiles()
+
 if(config.https_enabled) {
   https.listen(config.ssl_port, config.listen_address, () => console.log(`Teddit running on https://${config.domain}:${config.ssl_port}`))
 }

cacheControl.js

@@ -0,0 +1,58 @@
+module.exports.removeCacheFiles = function() {
+  const fs = require('fs')
+  const config = require('./config')
+  const pics = './static/pics'
+  const flairs = './static/pics/flairs'
+  const icons = './static/pics/icons'
+  const thumbs = './static/pics/thumbs'
+  const vids = './static/vids'
+  let util  = require('util')
+  let spawn = require('child_process').spawn
+  
+  let usage
+  const limit = config.cache_max_size
+  
+  function getUsage() {
+    return new Promise((resolve, reject) => {
+      let size = spawn('du', ['-sBM', './static/'])
+      size.stdout.on('data', function (data) {
+        usage = parseInt(data)
+        resolve(usage)
+      })
+    })
+  }
+
+  function deleteFiles() {
+    return new Promise(async (resolve, reject) => {
+      usage = await getUsage()
+      if(usage > limit) {
+        const { exec } = require('child_process')
+        exec(`cd ${pics} && ls -1btr -Iflairs -Iicons -Ithumbs -I.gitignore | head -50 | xargs rm -f --`)
+        exec(`cd ${flairs} && ls -1btr -I.gitignore | head -50 | xargs rm -f --`)
+        exec(`cd ${icons} && ls -1btr -I.gitignore | head -50 | xargs rm -f --`)
+        exec(`cd ${thumbs} && ls -1btr -I.gitignore | head -50 | xargs rm -f --`)
+        exec(`cd ${vids} && ls -1btr -I.gitignore | head -30 | xargs rm -f --`)
+      }
+      resolve(1)
+    })
+  }
+  
+  async function main() {
+    usage = await getUsage()
+    if(usage > limit) {
+      console.log('Started removeCacheFiles()')
+      while(usage > limit) {
+        await deleteFiles()
+      }
+    }
+  }
+
+  if(config.cache_control) {
+    main()
+    
+    const interval_ms = config.cache_control_interval
+    setInterval(() => {
+      main()
+    }, interval_ms)
+  }
+}

config.js.template

@@ -32,6 +32,9 @@ const config = {
   domain_replacements: process.env.DOMAIN_REPLACEMENTS
     ? (JSON.parse(process.env.DOMAIN_REPLACEMENTS).map(([p, r]) => [new RegExp(p, 'gm'), r]))
     : [], // Replacements for domains in outgoing links. Tuples with regular expressions to match, and replacement values. This is in addition to user-level configuration of privacyDomains.
+  cache_control: process.env.CACHE_CONTROL !== 'true' || true, // If true, teddit will automatically try to keep the size of the cache directory (static) under config.cache_max_size. By default this is set to true.
+  cache_max_size: process.env.CACHE_MAX_SIZE || 3000, // How much can we cache to the disk? Default is 3000 MB (~3 GB). Note: This is not perfectly exact limit.
+  cache_control_interval: process.env.CACHE_CONTROL_INTERVAL || 1000 * 60 * 30, // How often the size of the cache directory (static/) is checked. Default is every 30 minutes.
   post_media_max_heights: {
     /**
     * Sets the max-height value for images and videos in posts.