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[tsan] Workaround uninstrumented library code #114

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Merged
merged 1 commit into from
Sep 24, 2020
Merged

[tsan] Workaround uninstrumented library code #114

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54 changes: 47 additions & 7 deletions include/indexstore/IndexStoreCXX.h
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/Mutex.h"
#include <ctime>

namespace indexstore {
Expand Down Expand Up @@ -203,6 +204,29 @@ class IndexStore {
typedef std::function<void(UnitEventNotification)> UnitEventHandler;
typedef std::function<void(indexstore_unit_event_notification_t)> RawUnitEventHandler;

private:
struct EventHandlerContext {
RawUnitEventHandler handler;
#if __has_feature(thread_sanitizer)
std::unique_ptr<llvm::sys::Mutex> eventHandlerMutex;
#endif

EventHandlerContext(RawUnitEventHandler handler) : handler(std::move(handler)) {
#if __has_feature(thread_sanitizer)
eventHandlerMutex = std::make_unique<llvm::sys::Mutex>();
#endif
}

~EventHandlerContext() {
#if __has_feature(thread_sanitizer)
// See comment in event_handler_finalizer.
assert(!eventHandlerMutex);
#endif
}
};

public:

void setUnitEventHandler(UnitEventHandler handler) {
auto localLib = std::weak_ptr<IndexStoreLibrary>(library);
if (!handler) {
Expand All @@ -212,7 +236,7 @@ class IndexStore {

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wc++14-extensions"
auto fnPtr = new RawUnitEventHandler([handler, localLib=std::move(localLib)](
auto fnPtr = new EventHandlerContext([handler, localLib=std::move(localLib)](
indexstore_unit_event_notification_t evt_note) {
if (auto lib = localLib.lock()) {
handler(UnitEventNotification(evt_note, lib));
Expand All @@ -223,13 +247,29 @@ class IndexStore {
}

private:
static void event_handler(void *ctx, indexstore_unit_event_notification_t evt) {
auto fnPtr = (RawUnitEventHandler*)ctx;
(*fnPtr)(evt);
static void event_handler(void *ctx_, indexstore_unit_event_notification_t evt) {
auto ctx = (EventHandlerContext*)ctx_;

#if __has_feature(thread_sanitizer)
// See comment in event_handler_finalizer.
llvm::sys::ScopedLock L(*ctx->eventHandlerMutex);
#endif

(ctx->handler)(evt);
}
static void event_handler_finalizer(void *ctx) {
auto fnPtr = (RawUnitEventHandler*)ctx;
delete fnPtr;
static void event_handler_finalizer(void *ctx_) {
auto ctx = (EventHandlerContext*)ctx_;

#if __has_feature(thread_sanitizer)
// We need to convince TSan that the event handler callback never overlaps the
// destructor of the context. We use `eventHandlerMutex` to ensure TSan can
// see the synchronization, and we need to move the mutex out of the context
// so that it can be held during `delete` below.
auto mutexPtr = std::move(ctx->eventHandlerMutex);
llvm::sys::ScopedLock L(*mutexPtr);
#endif

delete ctx;
}

public:
Expand Down