Make session management thread-safe.

deanberris · deanberris · commit 5fbc670dada9 · 2013-04-07T01:21:25.000+11:00
diff --git a/http/src/http/server/simple_sessions.cpp b/http/src/http/server/simple_sessions.cpp
@@ -5,17 +5,24 @@
 // http://www.boost.org/LICENSE_1_0.txt)
 
 #include <http/server/simple_sessions.hpp>
+#include <cassert>
 
 namespace network {
 namespace http {
 
 session& simple_sessions::lookup(boost::string_ref session_id) {
-  std::string real_session_id = session_id.empty() ?
-    std::to_string(next_session_id_.fetch_add(1, std::memory_order::memory_order_seq_cst))
-    : static_cast<std::string>(session_id);
+  std::string real_session_id =
+      session_id.empty() ? std::to_string(next_session_id_.fetch_add(
+          1, std::memory_order::memory_order_seq_cst)) :
+      static_cast<std::string>(session_id);
+  assert(real_session_id != "");
+  std::lock_guard<std::mutex> lock_sessions(sessions_mutex_);
   std::pair<session_map_type::iterator, bool> result =
     sessions_.insert(make_pair(std::move(real_session_id), session()));
-  result.first->second.set("id", real_session_id);
+  if (result.second) {
+    result.first->second.set("id", result.first->first);
+    assert(result.first->second["id"] != "");
+  }
   return result.first->second;
 }
 
diff --git a/http/src/http/server/simple_sessions.hpp b/http/src/http/server/simple_sessions.hpp
@@ -11,6 +11,7 @@
 #include <http/server/session.hpp>
 #include <boost/utility/string_ref.hpp>
 #include <atomic>
+#include <thread>
 
 namespace network {
 namespace http {
@@ -25,6 +26,7 @@ struct simple_sessions {
   session &lookup(boost::string_ref session_id);
  private:
   typedef std::unordered_map<std::string, session> session_map_type;
+  std::mutex sessions_mutex_;
   session_map_type sessions_;
   std::atomic_uint_fast64_t next_session_id_;
 };
diff --git a/http/test/server_simple_sessions_test.cpp b/http/test/server_simple_sessions_test.cpp
@@ -6,6 +6,7 @@
 
 #include <gtest/gtest.h>
 #include <http/server/simple_sessions.hpp>
+#include <future>
 
 namespace http = network::http;
 namespace net = network;
@@ -35,4 +36,26 @@ TEST(simple_sessions_test, update) {
   }
 }
 
+TEST(simple_sessions_test, threaded_sessions) {
+  http::simple_sessions simple_sessions;
+  auto f0 = std::async([&]() {
+    http::session &session = simple_sessions.lookup("");
+    return session["id"];
+  });
+  auto f1 = std::async([&]() {
+    http::session &session = simple_sessions.lookup("");
+    return session["id"];
+  });
+  auto f2 = std::async([&]() {
+    http::session &session = simple_sessions.lookup("");
+    return session["id"];
+  });
+  std::string session0 = f0.get(),
+    session1 = f1.get(),
+    session2 = f2.get();
+  EXPECT_NE(session0, session1);
+  EXPECT_NE(session1, session2);
+  EXPECT_NE(session0, session2);
+}
+
 }  // namespace
