fix memory leak when using scopes with recursive timers (#227)

src/scope/context.js

@@ -23,9 +23,12 @@ class Context {
   }
 
   link (parent) {
-    this.unlink()
+    const oldParent = this._parent
+
     this._parent = parent
     this._parent.attach(this)
+
+    oldParent && oldParent.detach(this)
   }
 
   unlink () {

src/scope/context_execution.js

@@ -7,6 +7,7 @@ class ContextExecution {
     this._active = null
     this._count = 0
     this._set = []
+    this._executed = false
 
     if (context) {
       context.retain()
@@ -43,14 +44,17 @@ class ContextExecution {
 
     this._set.splice(index, 1)
     this._active = this._set[this._set.length - 1] || null
-  }
 
-  exit () {
-    if (this._context && !this._active) {
+    if (this._executed) {
       this._bypass()
     }
   }
 
+  exit () {
+    this._executed = true
+    this._bypass()
+  }
+
   attach (child) {
     this._children.add(child)
     this.retain()
@@ -76,7 +80,9 @@ class ContextExecution {
   }
 
   _bypass () {
-    this._children.forEach(child => child.link(this._context.parent()))
+    if (this._context && !this._active) {
+      this._children.forEach(child => child.link(this._context.parent()))
+    }
   }
 }
 

test/leak/scope_manager.js

@@ -1,6 +1,6 @@
 'use strict'
 
-require('../..').init()
+const tracer = require('../..').init()
 
 const test = require('tape')
 const profile = require('../profile')
@@ -12,3 +12,17 @@ test('ScopeManager should destroy executions even if their context is already de
     Promise.resolve().then(done)
   }
 })
+
+test('ScopeManager should not leak when using scopes with recursive timers', t => {
+  profile(t, operation)
+
+  function operation (done) {
+    const active = tracer.scopeManager().active()
+
+    active && active.close()
+
+    tracer.scopeManager().activate({})
+
+    done()
+  }
+})