Added 'maxUses' parameter to automatically purge instances that have been used more than a specified number of times

Author: mikedaly

README.md

@@ -63,8 +63,14 @@ import createPhantomPool from 'phantom-pool'
 const pool = createPhantomPool({
   max: 10, // default
   min: 2, // default
-  // specifies how long a resource can stay idle in pool before being removed
+  // how long a resource can stay idle in pool before being removed
   idleTimeoutMillis: 30000, // default.
+  // maximum number of times an individual resource can be reused before being destroyed; set to 0 to disable
+  maxUses: 50, // default
+  // function to validate an instance prior to use; see https://github.com/coopernurse/node-pool#createpool
+  validator: () => Promise.resolve(true), // defaults to always resolving true
+  // validate resource before borrowing; required for `maxUses and `validator`
+  testOnBorrow: true // default
   // For all opts, see opts at https://github.com/coopernurse/node-pool#createpool
   phantomArgs: [['--ignore-ssl-errors=true', '--disk-cache=true'], {
     logLevel: 'debug',

src/index.js

@@ -10,23 +10,37 @@ export default ({
   min = 2,
   // specifies how long a resource can stay idle in pool before being removed
   idleTimeoutMillis = 30000,
+  // specifies the maximum number of times a resource can be reused before being destroyed
+  maxUses = 50,
+  testOnBorrow = true,
   phantomArgs = [],
-  validator,
+  validator = () => Promise.resolve(true),
   ...otherConfig
 } = {}) => {
   // TODO: randomly destroy old instances to avoid resource leak?
   const factory = {
-    create: () => phantom.create(...phantomArgs),
+    create: () => phantom.create(...phantomArgs)
+      .then(instance => {
+        instance.useCount = 0
+        return instance
+      }),
     destroy: (instance) => instance.exit(),
-    validate: validator,
+    validate: (instance) => validator(instance)
+      .then(valid => Promise.resolve(valid && (maxUses <= 0 || instance.useCount < maxUses))),
   }
   const config = {
     max,
     min,
     idleTimeoutMillis,
+    testOnBorrow,
     ...otherConfig,
   }
   const pool = genericPool.createPool(factory, config)
+  const genericAcquire = pool.acquire.bind(pool)
+  pool.acquire = () => genericAcquire().then(r => {
+    r.useCount += 1
+    return r
+  })
   pool.use = (fn) => {
     let resource
     return pool.acquire()