From 389d5d8c144b252efa20d422fd94adfb559474f8 Mon Sep 17 00:00:00 2001
From: "Brian M. Carlson" <brian.m.carlson@gmail.com>
Date: Wed, 30 Oct 2019 11:33:52 -0500
Subject: [PATCH 1/2] Fix named portal being left open

When code was added to use a random named portal instead of the empty portal to support redshift we didn't update the close messages approprately.  This could result in postgres keeping locks on tables for modification if streaming and table modification was both done within a transaction.  This update fixes the issue by always issuing a close command on the named portal when query is finished.

fixes #56
---
 .eslintrc            |  3 +++
 .travis.yml          |  8 ++++----
 index.js             | 16 ++++++++++++----
 test/transactions.js | 30 ++++++++++++++++++++++++++++++
 4 files changed, 49 insertions(+), 8 deletions(-)
 create mode 100644 test/transactions.js

diff --git a/.eslintrc b/.eslintrc
index 5ce7148e..aa7df694 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -1,5 +1,8 @@
 {
   "extends": ["eslint:recommended"],
+  "parserOptions": {
+    "ecmaVersion": 2017
+  },
   "plugins": ["prettier"],
   "rules": {
     "prettier/prettier": "error",
diff --git a/.travis.yml b/.travis.yml
index b2ef3881..aea6a149 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,14 +2,14 @@ language: node_js
 dist: trusty
 sudo: false
 node_js:
-  - "8"
-  - "10"
-  - "12"
+  - '8'
+  - '10'
+  - '12'
 env:
   - PGUSER=postgres
 services:
   - postgresql
 addons:
-  postgresql: "9.6"
+  postgresql: '9.6'
 before_script:
   - psql -c 'create database travis;' -U postgres | true
diff --git a/index.js b/index.js
index 8136c389..ce8b503b 100644
--- a/index.js
+++ b/index.js
@@ -75,6 +75,15 @@ Cursor.prototype._shiftQueue = function() {
   }
 }
 
+Cursor.prototype._closePortal = function() {
+  // because we opened a named portal to stream results
+  // we need to close the same named portal.  Leaving a named portal
+  // open can lock tables for modification if inside a transaction.
+  // see https://github.com/brianc/node-pg-cursor/issues/56
+  this.connection.close({ type: 'P', name: this._portal })
+  this.connection.sync()
+}
+
 Cursor.prototype.handleRowDescription = function(msg) {
   this._result.addFields(msg.fields)
   this.state = 'idle'
@@ -105,7 +114,7 @@ Cursor.prototype._sendRows = function() {
 
 Cursor.prototype.handleCommandComplete = function(msg) {
   this._result.addCommandComplete(msg)
-  this.connection.sync()
+  this._closePortal()
 }
 
 Cursor.prototype.handlePortalSuspended = function() {
@@ -114,8 +123,8 @@ Cursor.prototype.handlePortalSuspended = function() {
 
 Cursor.prototype.handleReadyForQuery = function() {
   this._sendRows()
-  this.emit('end', this._result)
   this.state = 'done'
+  this.emit('end', this._result)
 }
 
 Cursor.prototype.handleEmptyQuery = function() {
@@ -166,8 +175,7 @@ Cursor.prototype.close = function(cb) {
   if (this.state === 'done') {
     return setImmediate(cb)
   }
-  this.connection.close({ type: 'P' })
-  this.connection.sync()
+  this._closePortal()
   this.state = 'done'
   if (cb) {
     this.connection.once('closeComplete', function() {
diff --git a/test/transactions.js b/test/transactions.js
new file mode 100644
index 00000000..75d32a4a
--- /dev/null
+++ b/test/transactions.js
@@ -0,0 +1,30 @@
+const assert = require('assert')
+const Cursor = require('../')
+const pg = require('pg')
+
+describe('transactions', () => {
+  it('can execute multiple statements in a transaction', async () => {
+    const client = new pg.Client()
+    await client.connect()
+    await client.query('begin')
+    await client.query('CREATE TEMP TABLE foobar(id SERIAL PRIMARY KEY)')
+    const cursor = client.query(new Cursor('SELECT * FROM foobar'))
+    const rows = await new Promise((resolve, reject) => {
+      cursor.read(10, (err, rows) => (err ? reject(err) : resolve(rows)))
+    })
+    assert.equal(rows.length, 0)
+    await client.query('ALTER TABLE foobar ADD COLUMN name TEXT')
+    await client.end()
+  })
+
+  it('can execute multiple statements in a transaction if ending cursor early', async () => {
+    const client = new pg.Client()
+    await client.connect()
+    await client.query('begin')
+    await client.query('CREATE TEMP TABLE foobar(id SERIAL PRIMARY KEY)')
+    const cursor = client.query(new Cursor('SELECT * FROM foobar'))
+    await new Promise(resolve => cursor.close(resolve))
+    await client.query('ALTER TABLE foobar ADD COLUMN name TEXT')
+    await client.end()
+  })
+})

From bd86514c722e803321f4036d1e67139a695cf1bd Mon Sep 17 00:00:00 2001
From: "Brian M. Carlson" <brian.m.carlson@gmail.com>
Date: Wed, 30 Oct 2019 11:43:17 -0500
Subject: [PATCH 2/2] Add another test

---
 test/transactions.js | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/test/transactions.js b/test/transactions.js
index 75d32a4a..37af28c4 100644
--- a/test/transactions.js
+++ b/test/transactions.js
@@ -27,4 +27,17 @@ describe('transactions', () => {
     await client.query('ALTER TABLE foobar ADD COLUMN name TEXT')
     await client.end()
   })
+
+  it.only('can execute multiple statements in a transaction if no data', async () => {
+    const client = new pg.Client()
+    await client.connect()
+    await client.query('begin')
+    // create a cursor that has no data response
+    const createText = 'CREATE TEMP TABLE foobar(id SERIAL PRIMARY KEY)'
+    const cursor = client.query(new Cursor(createText))
+    const err = await new Promise(resolve => cursor.read(100, resolve))
+    assert.ifError(err)
+    await client.query('ALTER TABLE foobar ADD COLUMN name TEXT')
+    await client.end()
+  })
 })