1 files changed, 78 insertions, 0 deletions
diff --git a/src/mongo/util/concurrency/race.h b/src/mongo/util/concurrency/race.h
new file mode 100644
index 00000000000..71bf7fde5dd
--- /dev/null
+++ b/src/mongo/util/concurrency/race.h
@@ -0,0 +1,78 @@
+#pragma once
+
+#include "../goodies.h" // printStackTrace
+#include "mutexdebugger.h"
+#include "mongo/util/stacktrace.h"
+
+namespace mongo {
+
+    namespace race {
+
+#ifdef _WIN32
+    typedef unsigned threadId_t;
+#else
+    typedef pthread_t threadId_t;
+#endif
+
+#if defined(_DEBUG)
+
+        class Block { 
+            volatile int n;
+            unsigned ncalls;
+            const string file;
+            const unsigned line;
+            void fail() { 
+                log() << "\n\n\nrace: synchronization (race condition) failure\ncurrent locks this thread (" << getThreadName() << "):\n"
+                    << mutexDebugger.currentlyLocked() << endl;
+                printStackTrace();
+                ::abort();
+            }
+            void enter() { 
+                if( ++n != 1 ) fail();
+                ncalls++;
+                if( ncalls < 100 ) {
+                    sleepmillis(0);
+                }
+                else {
+                    RARELY {
+                        sleepmillis(0);
+                        if( ncalls < 128 * 20 ) {
+                            OCCASIONALLY { 
+                                sleepmillis(3);
+                            }
+                        }
+                    }
+                }
+            }
+            void leave() {
+                if( --n != 0 ) fail();
+            }
+        public:
+            Block(string f, unsigned l) : n(0), ncalls(0), file(f), line(l) { }
+            ~Block() { 
+                if( ncalls > 1000000 ) { 
+                    // just so we know if we are slowing things down
+                    log() << "race::Block lots of calls " << file << ' ' << line << " n:" << ncalls << endl;
+                }
+            }
+            class Within { 
+                Block& _s;
+            public:
+                Within(Block& s) : _s(s) { _s.enter(); }
+                ~Within() { _s.leave(); }
+            };
+        };
+ 
+        /* in a rwlock situation this will fail, so not appropriate for things like that. */
+# define RACECHECK \
+        static race::Block __cp(__FILE__, __LINE__); \
+        race::Block::Within __ck(__cp);
+
+#else
+        /* !_DEBUG */
+# define RACECHECK
+
+#endif
+
+    }
+}