non-throwing, non-allocating exception_wrapper

[folly.git] / folly / ExceptionWrapper.cpp

diff --git a/folly/ExceptionWrapper.cpp b/folly/ExceptionWrapper.cpp
index c6ad16675955544b311ea55a57f8fafa413a3ac1..c1440a57a40a9f67d84d8301ba4babd081560be6 100644 (file)
--- a/folly/ExceptionWrapper.cpp
+++ b/folly/ExceptionWrapper.cpp
@@ -15,50 +15,53 @@
  */
 #include <folly/ExceptionWrapper.h>
 
  */
 #include <folly/ExceptionWrapper.h>
 

-#include <exception>

 #include <iostream>
 
 #include <iostream>
 

+#include <folly/Logging.h>
+

 namespace folly {
 
 namespace folly {
 

-[[noreturn]] void exception_wrapper::throwException() const {
-  if (throwfn_) {
-    throwfn_(*item_);
-  } else if (eptr_) {
-    std::rethrow_exception(eptr_);
+constexpr exception_wrapper::VTable const exception_wrapper::uninit_;
+constexpr exception_wrapper::VTable const exception_wrapper::ExceptionPtr::ops_;
+constexpr exception_wrapper::VTable const exception_wrapper::SharedPtr::ops_;
+
+namespace {
+std::exception const* get_std_exception_(std::exception_ptr eptr) noexcept {
+  try {
+    std::rethrow_exception(eptr);
+  } catch (const std::exception& ex) {
+    return &ex;
+  } catch (...) {
+    return nullptr;

   }
   }

-  std::ios_base::Init ioinit_; // ensure std::cerr is alive
-  std::cerr
-      << "Cannot use `throwException` with an empty folly::exception_wrapper"
-      << std::endl;
-  std::terminate();
+}

 }
 
 }
 

-fbstring exception_wrapper::class_name() const {
-  if (item_) {
-    auto& i = *item_;
-    return demangle(typeid(i));
-  } else if (eptr_ && eobj_) {
-    return demangle(typeid(*eobj_));
-  } else if (eptr_ && etype_) {
-    return demangle(*etype_);
-  } else {
-    return fbstring();
+exception_wrapper::exception_wrapper(std::exception_ptr ptr) noexcept
+    : exception_wrapper{} {
+  if (ptr) {
+    if (auto e = get_std_exception_(ptr)) {
+      LOG(DFATAL)
+          << "Performance error: Please construct exception_wrapper with a "
+             "reference to the std::exception along with the "
+             "std::exception_ptr.";
+      *this = exception_wrapper{std::move(ptr), *e};
+    } else {
+      Unknown uk;
+      *this = exception_wrapper{ptr, uk};
+    }

   }
 }
 
   }
 }
 

-fbstring exception_wrapper::what() const {
-  if (item_) {
-    return exceptionStr(*item_);
-  } else if (eptr_ && eobj_) {
-    return class_name() + ": " + eobj_->what();
-  } else if (eptr_ && etype_) {
-    return class_name();
-  } else {
-    return class_name();
-  }
+[[noreturn]] void exception_wrapper::onNoExceptionError() {
+  std::ios_base::Init ioinit_; // ensure std::cerr is alive
+  std::cerr
+      << "Cannot use `throwException` with an empty folly::exception_wrapper"
+      << std::endl;
+  std::terminate();

 }
 
 }
 

-fbstring exceptionStr(const exception_wrapper& ew) {
+fbstring exceptionStr(exception_wrapper const& ew) {

   return ew.what();
 }
 
   return ew.what();
 }