Make FixtureLogObserver thread-safe

We can log for different threads (main, map, workers, etc) so
we need to lock before adding the messages on the list.

This was causing few tests to randomly crash.

2 files changed, 11 insertions, 1 deletions

diff --git a/test/fixtures/fixture_log_observer.cpp b/test/fixtures/fixture_log_observer.cpp
index f28bbdcd25..a6e89e2e79 100644
--- a/test/fixtures/fixture_log_observer.cpp
+++ b/test/fixtures/fixture_log_observer.cpp
@@ -31,16 +31,22 @@ bool FixtureLog::Observer::onRecord(EventSeverity severity,
                                     Event event,
                                     int64_t code,
                                     const std::string& msg) {
+    std::lock_guard<std::mutex> lock(messagesMutex);
+
     messages.emplace_back(severity, event, code, msg);
 
     return true;
 }
 
 bool FixtureLog::Observer::empty() const {
+    std::lock_guard<std::mutex> lock(messagesMutex);
+
     return messages.empty();
 }
 
 size_t FixtureLog::Observer::count(const Message& message) const {
+    std::lock_guard<std::mutex> lock(messagesMutex);
+
     size_t message_count = 0;
     for (const auto& msg : messages) {
         if (msg == message) {
@@ -70,6 +76,8 @@ FixtureLog::~FixtureLog() {
 }
 
 std::vector<FixtureLog::Message> FixtureLogObserver::unchecked() const {
+    std::lock_guard<std::mutex> lock(messagesMutex);
+
     std::vector<Message> unchecked_messages;
     for (const auto& msg : messages) {
         if (!msg.checked) {
diff --git a/test/fixtures/fixture_log_observer.hpp b/test/fixtures/fixture_log_observer.hpp
index f28bb552ae..f2ccb5cb58 100644
--- a/test/fixtures/fixture_log_observer.hpp
+++ b/test/fixtures/fixture_log_observer.hpp
@@ -5,6 +5,7 @@
 
 #include <vector>
 #include <cstdarg>
+#include <mutex>
 #include <iostream>
 
 namespace mbgl {
@@ -42,9 +43,10 @@ public:
         size_t count(const Message& message) const;
         std::vector<Message> unchecked() const;
 
-    public:
+    private:
         FixtureLog* log;
         std::vector<Message> messages;
+        mutable std::mutex messagesMutex;
     };
 
     FixtureLog();