From 855d8daa41f96c37bcbbd047e28a50bc28ff45d6 Mon Sep 17 00:00:00 2001
From: Thomas Buckley-Houston <tom@tombh.co.uk>
Date: Thu, 2 Aug 2018 19:26:09 +0800
Subject: [PATCH] Use thread-safe map for HTTP requests

This fixes a race condition when may parallel requests are made to the
HTTP service
---
 interfacer/src/browsh/comms.go           |  2 +-
 interfacer/src/browsh/raw_text_server.go | 42 +++++++++++++++++++++---
 interfacer/src/browsh/version.go         |  2 +-
 3 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/interfacer/src/browsh/comms.go b/interfacer/src/browsh/comms.go
index 46c10bb..494af08 100644
--- a/interfacer/src/browsh/comms.go
+++ b/interfacer/src/browsh/comms.go
@@ -96,7 +96,7 @@ func handleRawFrameTextCommands(parts []string) {
 		}
 		if incoming.RequestID != "" {
 			Log("Raw text for " + incoming.RequestID)
-			rawTextRequests[incoming.RequestID] = incoming.RawJSON
+			rawTextRequests.store(incoming.RequestID, incoming.RawJSON)
 		} else {
 			Log("Raw text but no associated request ID")
 		}
diff --git a/interfacer/src/browsh/raw_text_server.go b/interfacer/src/browsh/raw_text_server.go
index 1aab195..a2b3d4c 100644
--- a/interfacer/src/browsh/raw_text_server.go
+++ b/interfacer/src/browsh/raw_text_server.go
@@ -2,6 +2,7 @@ package browsh
 
 import (
 	"crypto/rand"
+	"sync"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -20,7 +21,37 @@ import (
 
 // In order to communicate between the incoming HTTP request and the websocket request to the
 // real browser to render the webpage, we keep track of requests in a map.
-var rawTextRequests = make(map[string]string)
+var rawTextRequests = newRequestsMap()
+
+type threadSafeRequestsMap struct {
+	sync.RWMutex
+	internal map[string]string
+}
+
+func newRequestsMap() *threadSafeRequestsMap {
+	return &threadSafeRequestsMap{
+		internal: make(map[string]string),
+	}
+}
+
+func (m *threadSafeRequestsMap) load(key string) (value string, ok bool) {
+	m.RLock()
+	result, ok := m.internal[key]
+	m.RUnlock()
+	return result, ok
+}
+
+func (m *threadSafeRequestsMap) store(key string, value string) {
+	m.Lock()
+	m.internal[key] = value
+	m.Unlock()
+}
+
+func (m *threadSafeRequestsMap) remove(key string) {
+	m.Lock()
+	delete(m.internal, key)
+	m.Unlock()
+}
 
 type rawTextResponse struct {
 	PageloadDuration int    `json:"page_load_duration"`
@@ -136,7 +167,7 @@ func handleHTTPServerRequest(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	rawTextRequestID := pseudoUUID()
-	rawTextRequests[rawTextRequestID+"-start"] = start
+	rawTextRequests.store(rawTextRequestID+"-start", start)
 	mode := getRawTextMode(r)
 	sendMessageToWebExtension(
 		"/raw_text_request," + rawTextRequestID + "," +
@@ -211,16 +242,17 @@ func waitForResponse(rawTextRequestID string, w http.ResponseWriter) {
 	var totalTime, pageLoad, parsing string
 	var ok bool
 	for {
-		if rawTextRequestResponse, ok = rawTextRequests[rawTextRequestID]; ok {
+		if rawTextRequestResponse, ok = rawTextRequests.load(rawTextRequestID); ok {
 			jsonResponse = unpackResponse(rawTextRequestResponse)
-			totalTime = getTotalTiming(rawTextRequests[rawTextRequestID+"-start"])
+			requestStart, _ := rawTextRequests.load(rawTextRequestID+"-start")
+			totalTime = getTotalTiming(requestStart)
 			pageLoad = fmt.Sprintf("%d", jsonResponse.PageloadDuration)
 			parsing = fmt.Sprintf("%d", jsonResponse.ParsingDuration)
 			w.Header().Set("X-Browsh-Duration-Total", totalTime)
 			w.Header().Set("X-Browsh-Duration-Pageload", pageLoad)
 			w.Header().Set("X-Browsh-Duration-Parsing", parsing)
 			io.WriteString(w, jsonResponse.Text)
-			delete(rawTextRequests, rawTextRequestID)
+			rawTextRequests.remove(rawTextRequestID)
 			break
 		}
 		time.Sleep(1 * time.Millisecond)
diff --git a/interfacer/src/browsh/version.go b/interfacer/src/browsh/version.go
index 8b02007..53537e8 100644
--- a/interfacer/src/browsh/version.go
+++ b/interfacer/src/browsh/version.go
@@ -1,3 +1,3 @@
 package browsh
 
-var browshVersion = "1.4.11"
+var browshVersion = "1.4.12"