correcting issue facebook#4797

hphp/runtime/base/execution-context.h

@@ -626,7 +626,7 @@ struct ExecutionContext {
   // destroying the context, so C++ order of destruction is not an issue.
   req::hash_map<const ObjectData*,ArrayNoDtor> dynPropTable;
   VarEnv* m_globalVarEnv;
-  req::hash_map<const StringData*,Unit*,string_data_hash,string_data_same>
+  req::hash_map<const StringData*,std::pair<Unit*,time_t>,string_data_hash,string_data_same>
     m_evaledFiles;
   req::vector<const StringData*> m_evaledFilesOrder;
   req::vector<Unit*> m_createdFuncs;

hphp/runtime/base/unit-cache.cpp

@@ -483,9 +483,9 @@ Unit* lookupUnit(StringData* path, const char* currentDir, bool* initial_opt) {
 
   // Check if this file has already been included.
   auto it = eContext->m_evaledFiles.find(spath.get());
-  if (it != end(eContext->m_evaledFiles)) {
-    initial = false;
-    return it->second;
+  if (it != end(eContext->m_evaledFiles) && it->second.second >= s.st_mtime) {
+        initial = false;
+        return it->second.first;
   }
 
   // This file hasn't been included yet, so we need to parse the file
@@ -499,10 +499,10 @@ Unit* lookupUnit(StringData* path, const char* currentDir, bool* initial_opt) {
     // if parsing was successful, update the mappings for spath and
     // rpath (if it exists).
     eContext->m_evaledFilesOrder.push_back(cunit.unit->filepath());
-    eContext->m_evaledFiles[spath.get()] = cunit.unit;
+    eContext->m_evaledFiles[spath.get()] =  std::make_pair(cunit.unit,time(NULL));
     spath.get()->incRefCount();
     if (!cunit.unit->filepath()->same(spath.get())) {
-      eContext->m_evaledFiles[cunit.unit->filepath()] = cunit.unit;
+      eContext->m_evaledFiles[cunit.unit->filepath()] = std::make_pair(cunit.unit,time(NULL));
     }
     if (g_system_profiler) {
       g_system_profiler->fileLoadCallBack(path->toCppString());

hphp/runtime/debugger/debugger_hook_handler.cpp

@@ -77,7 +77,7 @@ void proxySetBreakPoints(DebuggerProxy* proxy) {
     auto fileName = bp->m_file;
     if (!fileName.empty()) {
       for (auto& kv : g_context->m_evaledFiles) {
-        auto const unit = kv.second;
+        auto const unit = kv.second.first;
         if (!BreakPointInfo::MatchFile(fileName,
                             unit->filepath()->toCppString())) {
           continue;

hphp/runtime/ext/xdebug/hook.cpp

@@ -110,7 +110,7 @@ static const Unit* find_unit(String filename) {
   // Search the given filename in the list of evaled files. We translate each
   // unit's filename to a canonical format, which is slow, but necessary.
   for (auto& kv : g_context->m_evaledFiles) {
-    auto const unit = kv.second;
+    auto const unit = kv.second.first;
     String ufilename(const_cast<StringData*>(unit->filepath()));
     if (filename == File::TranslatePath(ufilename)) {
       return unit;

hphp/test/slow/include/included_twice_different.php

@@ -0,0 +1,11 @@
+<?php
+
+file_put_contents('foo.php', "<?php \n\$i=1;\n");
+include 'foo.php';
+echo $i;
+sleep(2); // just to make sure that timestamp is different 
+file_put_contents('foo.php', "<?php \n\$i=2;\n");
+include 'foo.php';
+echo $i;
+
+?>

hphp/test/slow/include/included_twice_different.php.expect

@@ -0,0 +1 @@
+12