From 38e562bdd6f96b57d7a1130d4a041659190ea547 Mon Sep 17 00:00:00 2001
From: Josh Harvey <josh@lamassu.is>
Date: Tue, 31 May 2016 19:13:35 +0300
Subject: [PATCH] improve incoming tx status updating

---
 lib/plugins.js              |  7 +----
 lib/postgresql_interface.js | 54 ++++++++++++++++++++++++++++++-------
 lib/routes.js               |  5 +++-
 3 files changed, 49 insertions(+), 17 deletions(-)

diff --git a/lib/plugins.js b/lib/plugins.js
index 01eb2439..7aa31741 100644
--- a/lib/plugins.js
+++ b/lib/plugins.js
@@ -406,12 +406,7 @@ function processTxStatus (tx) {
         return resolve()  // Resolve on error because we ignore errors
       }
 
-      var status = res.status
-      if (tx.status === status) return resolve()
-
-      const confirm = (status === 'instant' && tx.status !== 'confirmed') ||
-        (status === 'confirmed' && tx.status !== 'instant')
-      db.updateTxStatus(tx, status, confirm).then(resolve).catch(reject)
+      db.updateTxStatus(tx, res.status).then(resolve).catch(reject)
     })
   })
 }
diff --git a/lib/postgresql_interface.js b/lib/postgresql_interface.js
index d03ff676..bd2137a1 100644
--- a/lib/postgresql_interface.js
+++ b/lib/postgresql_interface.js
@@ -1,3 +1,4 @@
+// @flow weak
 'use strict'
 
 const BigNumber = require('bignumber.js')
@@ -302,18 +303,51 @@ exports.fetchUnnotifiedTxs = function fetchUnnotifiedTxs (age, waitPeriod) {
   .then(rows => normalizeTxs(rows))
 }
 
-exports.updateTxStatus = function updateTxStatus (tx, status, confirm) {
-  const sql = confirm
-  ? 'UPDATE cash_out_txs SET status=$1, confirmation_time=now() WHERE session_id=$2'
-  : 'UPDATE cash_out_txs SET status=$1 WHERE session_id=$2'
+function ratchetStatus (oldStatus, newStatus) {
+  const statusOrder = ['notSeen', 'published', 'rejected',
+    'authorized', 'instant', 'confirmed']
 
-  const values = [status, tx.sessionId]
+  if (oldStatus === newStatus) return oldStatus
+  if (newStatus === 'insufficientFunds') return newStatus
 
-  return db.none(sql, values)
-  .then(() => {
-    const sql2 = 'insert into cash_out_actions (session_id, action) values ($1, $2)'
-    return db.none(sql2, [tx.sessionId, status])
-  })
+  const idx = Math.max(statusOrder.indexOf(oldStatus), statusOrder.indexOf(newStatus))
+  return statusOrder[idx]
+}
+
+exports.updateTxStatus = function updateTxStatus (tx, status) {
+  const TransactionMode = pgp.txMode.TransactionMode
+  const isolationLevel = pgp.txMode.isolationLevel
+  const tmSRD = new TransactionMode({tiLevel: isolationLevel.serializable})
+
+  function transaction (t) {
+    const sql = 'select status, confirmation_time from cash_out_txs where session_id=$1'
+    return t.one(sql, [tx.sessionId])
+    .then(row => {
+      const newStatus = ratchetStatus(row.status, status)
+      if (row.status === newStatus) return
+
+      const setConfirmationTime = !row.confirmation_time &&
+        (newStatus === 'instant' || newStatus === 'confirmed')
+
+      const sql2 = setConfirmationTime
+      ? 'UPDATE cash_out_txs SET status=$1, confirmation_time=now() WHERE session_id=$2'
+      : 'UPDATE cash_out_txs SET status=$1 WHERE session_id=$2'
+
+      const values2 = [newStatus, tx.sessionId]
+
+      return t.none(sql2, values2)
+      .then(() => {
+        const sql3 = 'insert into cash_out_actions (session_id, action) values ($1, $2)'
+        return t.none(sql3, [tx.sessionId, newStatus])
+      })
+    })
+  }
+
+  transaction.txMode = tmSRD
+
+  // Note: don't worry about retrying failed transaction here
+  // It will be tried again on the next status check
+  return db.tx(transaction)
 }
 
 exports.updateRedeem = function updateRedeem (session) {
diff --git a/lib/routes.js b/lib/routes.js
index 6e4f9d0b..14714570 100644
--- a/lib/routes.js
+++ b/lib/routes.js
@@ -210,7 +210,10 @@ function pair (req, res) {
     getFingerprint(req),
     name,
     function (err) {
-      if (err) return res.send(500).json({ err: err.message })
+      if (err) {
+        logger.error(err)
+        return res.json({err: err.message})
+      }
 
       res.json({success: true})
     }