3 files changed, 13 insertions, 0 deletions

diff --git a/src/tracking/change_tracker.cc b/src/tracking/change_tracker.cc
index 1b554aa..ca07214 100644
--- a/src/tracking/change_tracker.cc
+++ b/src/tracking/change_tracker.cc
@@ -82,6 +82,8 @@ bool ChangeTracker::track(const std::string& file_path) {
 		boost::filesystem::canonical(file_path).string()
 	};
 
+	std::unique_lock<std::mutex> guard(this->write_mutex_);
+
 	auto result = this->children_.emplace(
 		full_file_path,
 		std::make_unique<boost::process::child>(
@@ -92,6 +94,8 @@ bool ChangeTracker::track(const std::string& file_path) {
 		)
 	);
 
+	guard.unlock();
+
 	if ( std::get<EMPLACE_SUCCESS>(result) ) {
 		boost::filesystem::ifstream file(
 			std::get<FILE_NAME>(*result.first)
diff --git a/src/tracking/change_tracker.h b/src/tracking/change_tracker.h
index 24251e5..e694b56 100644
--- a/src/tracking/change_tracker.h
+++ b/src/tracking/change_tracker.h
@@ -2,6 +2,7 @@
 #define CHANGE_SRC_TRACKING_CHANGE_TRACKER_H_
 
 #include <unordered_map>
+#include <mutex>
 
 #include <boost/process.hpp>
 
@@ -22,6 +23,7 @@ class ChangeTracker {
 	private:
 		const std::string      diff_cmd_;
 		utility::Logger* const logger_;
+		std::mutex             write_mutex_;
 
 		std::unordered_map<
 			std::string, std::unique_ptr<boost::process::child>
diff --git a/src/utility/logger.h b/src/utility/logger.h
index e21f6fd..30a6b44 100644
--- a/src/utility/logger.h
+++ b/src/utility/logger.h
@@ -1,6 +1,8 @@
 #ifndef CHANGE_SRC_LOGGER_H_
 #define CHANGE_SRC_LOGGER_H_
 
+#include <mutex>
+
 #include <ext/stdio_filebuf.h>
 
 #include <boost/process.hpp>
@@ -14,6 +16,8 @@ class Logger {
 			stream_(&this->buffer_) { }
 
 		void append(const std::string& msg) {
+			std::lock_guard<std::mutex> guard(this->write_mutex_);
+
 			this->stream_ << msg << std::endl;
 		}
 
@@ -25,6 +29,8 @@ class Logger {
 		// flag.
 		//
 		void forward(boost::process::pistream& stream) {
+			std::lock_guard<std::mutex> guard(this->write_mutex_);
+
 			this->stream_ << std::string(
 				(std::istreambuf_iterator<char>(stream)),
 				(std::istreambuf_iterator<char>())
@@ -34,6 +40,7 @@ class Logger {
 	private:
 		__gnu_cxx::stdio_filebuf<char> buffer_;
 		std::ostream                   stream_;
+		std::mutex                     write_mutex_;
 
 };