Bind underlying connections in pool to same domain as pool

fixes mysqljs#1242

Changes.md

@@ -8,6 +8,7 @@ you spot any mistakes.
 
 * Add `POOL_CLOSED` code to "Pool is closed." error
 * Add `POOL_CONNLIMIT` code to "No connections available." error #1332
+* Bind underlying connections in pool to same domain as pool #1242
 * Bind underlying socket to same domain as connection #1243
 * Fix edge cases constructing long stack traces #1387
 * Fix Query stream to emit close after ending #1349 #1350

lib/PoolConnection.js

@@ -1,5 +1,6 @@
-var inherits = require('util').inherits;
+var inherits   = require('util').inherits;
 var Connection = require('./Connection');
+var Events     = require('events');
 
 module.exports = PoolConnection;
 inherits(PoolConnection, Connection);
@@ -8,6 +9,17 @@ function PoolConnection(pool, options) {
   Connection.call(this, options);
   this._pool  = pool;
 
+  // Bind connection to pool domain
+  if (Events.usingDomains) {
+    if (this.domain) {
+      this.domain.remove(this);
+    }
+
+    if (pool.domain) {
+      pool.domain.add(this);
+    }
+  }
+
   // When a fatal error occurs the connection's protocol ends, which will cause
   // the connection to end as well, thus we only need to watch for the end event
   // and we will be notified of disconnects.

test/unit/pool/test-connection-domain.js

@@ -0,0 +1,58 @@
+var after  = require('after');
+var assert = require('assert');
+var common = require('../../common');
+var domain = null;
+
+try {
+  domain = require('domain');
+} catch (e) {
+  common.skipTest('node ' + process.version + ' does not support domains');
+}
+
+var d0 = domain.create();
+var d1 = domain.create();
+
+var server = common.createFakeServer();
+
+var pool = null;
+var done = after(2, function () {
+  pool.end(function (err) {
+    assert.ifError(err);
+    server.destroy();
+  });
+});
+
+server.listen(common.fakeServerPort, function (err) {
+  assert.ifError(err);
+
+  var released = false;
+  var timer    = setInterval(function () {
+    if (!released) return;
+    clearInterval(timer);
+
+    assert.ok(!domain.active, 'no current domain');
+    pool.getConnection(function (err, conn) {
+      assert.ifError(err);
+      assert.equal(domain.active, d0, 'current domain is d0');
+      assert.equal(conn.domain, d0, 'connection domain is d0');
+      conn.release();
+      done();
+    });
+  }, 200);
+
+  d0.run(function () {
+    pool = common.createPool({port: common.fakeServerPort, connectionLimit: 1});
+    assert.equal(pool.domain, d0, 'pool belongs to d0');
+
+    d1.run(function () {
+      pool.getConnection(function (err, conn) {
+        assert.ifError(err);
+        assert.equal(domain.active, d1, 'current domain is d1');
+        assert.equal(conn.domain, d0, 'connection domain is d0');
+        conn.release();
+        released = true;
+        done();
+      });
+    });
+  });
+});

test/unit/pool/test-connection-no-domain.js

@@ -0,0 +1,55 @@
+var after  = require('after');
+var assert = require('assert');
+var common = require('../../common');
+var domain = null;
+
+try {
+  domain = require('domain');
+} catch (e) {
+  common.skipTest('node ' + process.version + ' does not support domains');
+}
+
+var d0 = domain.create();
+
+var server = common.createFakeServer();
+
+var pool = null;
+var done = after(2, function () {
+  pool.end(function (err) {
+    assert.ifError(err);
+    server.destroy();
+  });
+});
+
+server.listen(common.fakeServerPort, function (err) {
+  assert.ifError(err);
+
+  var released = false;
+  var timer    = setInterval(function () {
+    if (!released) return;
+    clearInterval(timer);
+
+    assert.ok(!domain.active, 'no current domain');
+    pool.getConnection(function (err, conn) {
+      assert.ifError(err);
+      assert.ok(!domain.active, 'no current domain');
+      assert.equal(conn.domain, null, 'connection is not bound to domain');
+      conn.release();
+      done();
+    });
+  }, 200);
+
+  pool = common.createPool({port: common.fakeServerPort, connectionLimit: 1});
+  assert.equal(pool.domain, null, 'pool is not bound to domain');
+
+  d0.run(function () {
+    pool.getConnection(function (err, conn) {
+      assert.ifError(err);
+      assert.equal(domain.active, d0, 'current domain is d0');
+      assert.equal(conn.domain, null, 'connection is not bound to domain');
+      conn.release();
+      released = true;
+      done();
+    });
+  });
+});