Rework thread cancellation, using regular exception (#177)

BREAKS BACK COMPATIBILITY:
  - cancellation error can be caught by `pcall`
  - `canceled` thread status was renamed to `cancelled`

README.md

@@ -25,6 +25,7 @@ Requires C++14 compiler compliance. Tested with GCC 4.9+, clang 3.8 and Visual S
 * [Important notes](#important-notes)
 * [Blocking and nonblocking operations](#blocking-and-nonblocking-operations)
 * [Function's upvalues](#functions-upvalues)
+* [Thread cancellation and pausing](#thread-cancellation-and-pausing)
 * [API Reference](#api-reference)
    * [Thread](#thread)
       * [effil.thread()](#runner--effilthreadfunc)
@@ -45,6 +46,7 @@ Requires C++14 compiler compliance. Tested with GCC 4.9+, clang 3.8 and Visual S
       * [effil.yield()](#effilyield)
       * [effil.sleep()](#effilsleeptime-metric)
       * [effil.hardware_threads()](#effilhardware_threads)
+      * [effil.pcall()](#status---effilpcallfunc)
     * [Table](#table)
       * [effil.table()](#table--effiltabletbl)
       * [__newindex: table[key] = value](#tablekey--value)
@@ -71,6 +73,7 @@ Requires C++14 compiler compliance. Tested with GCC 4.9+, clang 3.8 and Visual S
       * [effil.size()](#size--effilsizeobj)
       * [effil.type()](#effiltype)
 
+
 # How to install
 ### Build from src on Linux and Mac
 1. `git clone --recursive https://github.com/effil/effil effil`
@@ -256,7 +259,7 @@ local worker = effil.thread(function()
     effil.sleep(999) -- worker will hang for 999 seconds
 end)()
 
-worker:cancel(1) -- returns true, cause blocking operation was interrupted and thread was canceled
+worker:cancel(1) -- returns true, cause blocking operation was interrupted and thread was cancelled
 ```
    </p>
 </details>
@@ -269,10 +272,71 @@ Working with function Effil can store function environment (`_ENV`) as well. Con
  * *Lua = 5.1*: function environment is not stored at all (due to limitations of lua_setfenv we cannot use userdata)
  * *Lua > 5.1*: Effil serialize and store function environment only if it's not equal to global environment (`_ENV ~= _G`).
 
+## Thread cancellation and pausing
+The [`effil.thread`](#runner--effilthreadfunc) can be paused and cancelled using corresponding methods of thread object [`thread:cancel()`](#threadcanceltime-metric) and [`thread:pause()`](#threadpausetime-metric).  
+Thread that you try to interrupt can be interrupted in two execution points: explicit and implicit.
+  - Explicit points are [`effil.yield()`](#effilyield)
+      <details>
+      <summary>Example of explicit interruption point</summary>
+      <p>
+
+      ```lua
+      local thread = effil.thread(function()
+         while true do
+            effil.yield()
+         end
+         -- will never reach this line
+      end)()
+      thread:cancel()
+      ```
+
+      </p>
+      </details>
+  - Implicit points are lua debug hook invocation which is set using [lua_sethook](https://www.lua.org/manual/5.3/manual.html#lua_sethook) with LUA_MASKCOUNT.  
+    Implicit points are optional and enabled only if [thread_runner.step](#runnerstep) > 0.
+      <details>
+      <summary>Example of implicit interruption point</summary>
+      <p>
+
+      ```lua
+      local thread_runner = effil.thread(function()
+         while true do
+         end
+         -- will never reach this line
+      end)
+      thread_runner.step = 10
+      thread = thread_runner()
+      thread:cancel()
+      ```
+
+      </p>
+      </details>
+  - Additionally thread can be cancelled (but not paused) in any [blocking or non-blocking waiting operation](#blocking-and-nonblocking-operations).  
+      <details>
+      <summary>Example</summary>
+      <p>
+
+      ```lua
+      local channel = effil.channel()
+      local thread = effil.thread(function()
+         channel:pop() -- thread hangs waiting infinitely
+         -- will never reach this line
+      end)()
+      thread:cancel()
+      ```
+
+      </p>
+      </details>
+
+   **How does cancellation works?**  
+   When you cancel thread it generates lua [`error`](https://lua.org.ru/manual_ru.html#pdf-error) with message `"Effil: thread is cancelled"` when it reaches any interruption point. It means that you can catch this error using [`pcall`](https://lua.org.ru/manual_ru.html#pdf-pcall) but thread will generate new error on next interruption point.  
+   If you want to catch your own error but pass cancellation error you can use [effil.pcall()](#status---effilpcallfunc).  
+   Status of cancelled thread will be equal to `cancelled` only if it finished with cancellation error. It means that if you catch cancellation error thread may finished with `completed` status or `failed` status if there will be some another error.
+
 # API Reference
 
 ## Thread
-`effil.thread` is the way to create a thread. Threads can be stopped, paused, resumed and canceled.
+`effil.thread` is the way to create a thread. Threads can be stopped, paused, resumed and cancelled.
 All operation with threads can be synchronous (with optional timeout) or asynchronous.
 Each thread runs with its own lua state.
 
@@ -309,7 +373,7 @@ Thread handle provides API for interaction with thread.
 Returns thread status.
 
 **output**:
-- `status` - string values describes status of thread. Possible values are: `"running", "paused", "canceled", "completed" and "failed"`.
+- `status` - string values describes status of thread. Possible values are: `"running", "paused", "cancelled", "completed" and "failed"`.
 - `err` - error message, if any. This value is specified only if thread status == `"failed"`.
 - `stacktrace` - stacktrace of failed thread. This value is specified only if thread status == `"failed"`.
 
@@ -360,9 +424,20 @@ Suspend current thread.
 
 ### `effil.hardware_threads()`
 Returns the number of concurrent threads supported by implementation.
-Basically forwards value from [std::thread::hardware_concurrency](https://en.cppreference.com/w/cpp/thread/thread/hardware_concurrency).
+Basically forwards value from [std::thread::hardware_concurrency](https://en.cppreference.com/w/cpp/thread/thread/hardware_concurrency).  
 **output**: number of concurrent hardware threads.
 
+### `status, ... = effil.pcall(func, ...)`
+Works exactly the same way as standard [pcall](https://www.lua.org/manual/5.3/manual.html#pdf-pcall) except that it will not catch thread cancellation error caused by [thread:cancel()](#threadcanceltime-metric) call.  
+
+**input:**
+  - func - function to call
+  - ... - arguments to pass to functions  
+
+**output:**
+  - status - `true` if no error occurred, `false` otherwise
+  - ... - in case of error return one additional result with message of error, otherwise return function call results
+
 ## Table
 `effil.table` is a way to exchange data between effil threads. It behaves almost like standard lua tables.
 All operations with shared table are thread safe. **Shared table stores** primitive types (number, boolean, string), function, table, light userdata and effil based userdata. **Shared table doesn't store** lua threads (coroutines) or arbitrary userdata. See examples of shared table usage [here](#examples)

src/cpp/channel.cpp

@@ -52,7 +52,7 @@ bool Channel::push(const sol::variadic_args& args) {
 
 StoredArray Channel::pop(const sol::optional<int>& duration,
                           const sol::optional<std::string>& period) {
-    this_thread::interruptionPoint();
+    this_thread::cancellationPoint();
     std::unique_lock<std::mutex> lock(ctx_->lock_);
     {
         this_thread::ScopedSetInterruptable interruptable(this);
@@ -70,7 +70,7 @@ StoredArray Channel::pop(const sol::optional<int>& duration,
             else { // No time limit
                 ctx_->cv_.wait(lock);
             }
-            this_thread::interruptionPoint();
+            this_thread::cancellationPoint();
         }
     }
 

src/cpp/lua-module.cpp

@@ -1,8 +1,9 @@
-#include "threading.h"
+#include "thread.h"
+#include "this-thread.h"
+#include "thread-runner.h"
 #include "shared-table.h"
 #include "garbage-collector.h"
 #include "channel.h"
-#include "thread_runner.h"
 
 #include <lua.hpp>
 
@@ -100,6 +101,7 @@ int luaopen_effil(lua_State* L) {
         "thread_id",    this_thread::threadId,
         "sleep",        this_thread::sleep,
         "yield",        this_thread::yield,
+        "pcall",        this_thread::pcall,
         "table",        createTable,
         "rawset",       SharedTable::luaRawSet,
         "rawget",       SharedTable::luaRawGet,
@@ -115,7 +117,6 @@ int luaopen_effil(lua_State* L) {
         "hardware_threads", std::thread::hardware_concurrency,
         sol::meta_function::index, luaIndex
     );
-
     sol::stack::push(lua, type);
     sol::stack::pop<sol::object>(lua);
     sol::stack::push(lua, EffilApiMarker());

src/cpp/notifier.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <this_thread.h>
+#include <this-thread.h>
 #include <lua-helpers.h>
 
 #include <mutex>
@@ -29,20 +29,20 @@ public:
     }
 
     void wait() {
-        this_thread::interruptionPoint();
+        this_thread::cancellationPoint();
 
         this_thread::ScopedSetInterruptable interruptable(this);
 
         std::unique_lock<std::mutex> lock(mutex_);
         while (!notified_) {
             cv_.wait(lock);
-            this_thread::interruptionPoint();
+            this_thread::cancellationPoint();
         }
     }
 
     template <typename T>
     bool waitFor(T period) {
-        this_thread::interruptionPoint();
+        this_thread::cancellationPoint();
 
         if (period == std::chrono::seconds(0) || notified_)
             return notified_;
@@ -54,7 +54,7 @@ public:
         while (!timer.isFinished() &&
                cv_.wait_for(lock, timer.left()) != std::cv_status::timeout &&
                !notified_) {
-            this_thread::interruptionPoint();
+            this_thread::cancellationPoint();
         }
         return notified_;
     }

src/cpp/stored-object.cpp

@@ -1,10 +1,10 @@
 #include "stored-object.h"
 #include "channel.h"
-#include "threading.h"
+#include "thread.h"
 #include "shared-table.h"
 #include "function.h"
 #include "utils.h"
-#include "thread_runner.h"
+#include "thread-runner.h"
 
 #include <map>
 #include <vector>

src/cpp/this-thread.cpp

@@ -0,0 +1,83 @@
+#include "this-thread.h"
+
+#include "thread-handle.h"
+#include "notifier.h"
+
+namespace effil {
+namespace this_thread {
+
+ScopedSetInterruptable::ScopedSetInterruptable(IInterruptable* notifier) {
+    if (const auto thisThread = ThreadHandle::getThis()) {
+        thisThread->setNotifier(notifier);
+    }
+}
+
+ScopedSetInterruptable::~ScopedSetInterruptable() {
+    if (const auto thisThread = ThreadHandle::getThis()) {
+        thisThread->setNotifier(nullptr);
+    }
+}
+
+void cancellationPoint() {
+    const auto thisThread = ThreadHandle::getThis();
+    if (thisThread && thisThread->command() == ThreadHandle::Command::Cancel) {
+        thisThread->changeStatus(ThreadHandle::Status::Cancelled);
+        throw ThreadCancelException();
+    }
+}
+
+std::string threadId() {
+    std::stringstream ss;
+    ss << std::this_thread::get_id();
+    return ss.str();
+}
+
+void yield() {
+    if (const auto thisThread = ThreadHandle::getThis()) {
+        thisThread->performInterruptionPointThrow();
+    }
+    std::this_thread::yield();
+}
+
+void sleep(const sol::stack_object& duration, const sol::stack_object& metric) {
+    if (duration.valid()) {
+        REQUIRE(duration.get_type() == sol::type::number)
+                << "bad argument #1 to 'effil.sleep' (number expected, got "
+                << luaTypename(duration) << ")";
+
+        if (metric.valid())
+        {
+            REQUIRE(metric.get_type() == sol::type::string)
+                    << "bad argument #2 to 'effil.sleep' (string expected, got "
+                    << luaTypename(metric) << ")";
+        }
+        try {
+            Notifier notifier;
+            notifier.waitFor(fromLuaTime(duration.as<int>(),
+                                         metric.as<sol::optional<std::string>>()));
+        } RETHROW_WITH_PREFIX("effil.sleep");
+    }
+    else {
+        yield();
+    }
+}
+
+int pcall(lua_State* L)
+{
+    int status;
+    luaL_checkany(L, 1);
+    status = lua_pcall(L, lua_gettop(L) - 1, LUA_MULTRET, 0);
+
+    const auto thisThread = ThreadHandle::getThis();
+    if (thisThread && thisThread->command() == ThreadHandle::Command::Cancel) {
+        lua_pushstring(L, ThreadCancelException::message);
+        lua_error(L);
+    }
+
+    lua_pushboolean(L, (status == 0));
+    lua_insert(L, 1);
+    return lua_gettop(L);  /* return status + all results */
+}
+
+} // namespace this_thread
+} // namespace effil

src/cpp/this-thread.h

@@ -14,12 +14,12 @@ public:
     ScopedSetInterruptable(IInterruptable* notifier);
     ~ScopedSetInterruptable();
 };
-void interruptionPoint();
 
-// Lua API
+void cancellationPoint();
 std::string threadId();
 void yield();
 void sleep(const sol::stack_object& duration, const sol::stack_object& metric);
+int pcall(lua_State* L);
 
 } // namespace this_thread
 } // namespace effil

src/cpp/thread-handle.cpp

@@ -0,0 +1,82 @@
+#include "thread-handle.h"
+
+namespace effil {
+
+// Thread specific pointer to current thread
+static thread_local ThreadHandle* thisThreadHandle = nullptr;
+static const sol::optional<std::chrono::milliseconds> NO_TIMEOUT;
+
+ThreadHandle::ThreadHandle()
+        : status_(Status::Running)
+        , command_(Command::Run)
+        , currNotifier_(nullptr)
+        , lua_(std::make_unique<sol::state>())
+{
+    luaL_openlibs(*lua_);
+}
+
+void ThreadHandle::putCommand(Command cmd) {
+    std::unique_lock<std::mutex> lock(stateLock_);
+    if (isFinishStatus(status_) || command() == Command::Cancel)
+        return;
+
+    command_ = cmd;
+    statusNotifier_.reset();
+    commandNotifier_.notify();
+}
+
+void ThreadHandle::changeStatus(Status stat) {
+    std::unique_lock<std::mutex> lock(stateLock_);
+    status_ = stat;
+    commandNotifier_.reset();
+    statusNotifier_.notify();
+    if (isFinishStatus(stat))
+        completionNotifier_.notify();
+}
+
+void ThreadHandle::performInterruptionPointImpl(const std::function<void(void)>& cancelClbk) {
+    switch (command()) {
+        case Command::Run:
+            break;
+        case Command::Cancel:
+            cancelClbk();
+            break;
+        case Command::Pause: {
+            changeStatus(Status::Paused);
+            Command cmd;
+            do {
+                cmd = waitForCommandChange(NO_TIMEOUT);
+            } while(cmd != Command::Run && cmd != Command::Cancel);
+            if (cmd == Command::Run) {
+                changeStatus(Status::Running);
+            } else {
+                cancelClbk();
+            }
+            break;
+        }
+    }
+}
+
+void ThreadHandle::performInterruptionPoint(lua_State* L) {
+    performInterruptionPointImpl([L](){
+        lua_pushstring(L, ThreadCancelException::message);
+        lua_error(L);
+    });
+}
+
+void ThreadHandle::performInterruptionPointThrow() {
+    performInterruptionPointImpl([](){
+        throw ThreadCancelException();
+    });
+}
+
+ThreadHandle* ThreadHandle::getThis() {
+    return thisThreadHandle;
+}
+
+void ThreadHandle::setThis(ThreadHandle* handle) {
+    assert(handle);
+    thisThreadHandle = handle;
+}
+
+} // namespace effil

src/cpp/thread-handle.h

@@ -1,19 +1,31 @@
 #pragma once
 
 #include "lua-helpers.h"
-#include "function.h"
 #include "notifier.h"
+#include "gc-data.h"
 
 #include <sol.hpp>
 
 namespace effil {
 
+class ThreadCancelException : public std::runtime_error
+{
+public:
+    static constexpr auto message = "Effil: thread is cancelled";
+
+    ThreadCancelException()
+        : std::runtime_error(message)
+    {}
+};
+
+class Thread;
+
 class ThreadHandle : public GCData {
 public:
     enum class Status {
         Running,
         Paused,
-        Canceled,
+        Cancelled,
         Completed,
         Failed
     };
@@ -29,6 +41,14 @@ public:
     Command command() const { return command_; }
     void putCommand(Command cmd);
     void changeStatus(Status stat);
+    void performInterruptionPoint(lua_State* L);
+    void performInterruptionPointThrow();
+
+    static ThreadHandle* getThis();
+
+    static bool isFinishStatus(Status stat) {
+        return stat == Status::Cancelled || stat == Status::Completed || stat == Status::Failed;
+    }
 
     template <typename T>
     Status waitForStatusChange(const sol::optional<T>& time) {
@@ -90,38 +110,11 @@ private:
     StoredArray result_;
     IInterruptable* currNotifier_;
     std::unique_ptr<sol::state> lua_;
+
+    void performInterruptionPointImpl(const std::function<void(void)>& cancelClbk);
+
+    static void setThis(ThreadHandle* handle);
+    friend class Thread;
 };
 
-class Thread : public GCObject<ThreadHandle> {
+} // namespace effil
-public:
-    static void exportAPI(sol::state_view& lua);
-
-    StoredArray status(const sol::this_state& state);
-    StoredArray wait(const sol::this_state& state,
-                     const sol::optional<int>& duration,
-                     const sol::optional<std::string>& period);
-    StoredArray get(const sol::optional<int>& duration,
-                   const sol::optional<std::string>& period);
-    bool cancel(const sol::this_state& state,
-                const sol::optional<int>& duration,
-                const sol::optional<std::string>& period);
-    bool pause(const sol::this_state&,
-               const sol::optional<int>& duration,
-               const sol::optional<std::string>& period);
-    void resume();
-
-private:
-    Thread() = default;
-    void initialize(
-        const std::string& path,
-        const std::string& cpath,
-        int step,
-        const sol::function& function,
-        const sol::variadic_args& args);
-    friend class GC;
-
-private:
-    static void runThread(Thread, Function, effil::StoredArray);
-};
-
-} // effil

src/cpp/thread-runner.cpp

@@ -1,4 +1,4 @@
-#include "thread_runner.h"
+#include "thread-runner.h"
 
 namespace effil {
 

src/cpp/thread-runner.h

@@ -1,4 +1,4 @@
-#include "threading.h"
+#include "thread.h"
 #include "gc-data.h"
 #include "gc-object.h"
 

src/cpp/thread.cpp

@@ -1,5 +1,6 @@
-#include "threading.h"
+#include "thread.h"
 
+#include "thread-handle.h"
 #include "stored-object.h"
 #include "notifier.h"
 #include "spin-mutex.h"
@@ -15,27 +16,14 @@ using Command = ThreadHandle::Command;
 
 namespace {
 
-const sol::optional<std::chrono::milliseconds> NO_TIMEOUT;
-
-// Thread specific pointer to current thread
-static thread_local ThreadHandle* thisThreadHandle = nullptr;
-
-// Doesn't inherit std::exception
-// to prevent from catching this exception third party lua C++ libs
-class LuaHookStopException {};
-
-bool isFinishStatus(Status stat) {
-    return stat == Status::Canceled || stat == Status::Completed || stat == Status::Failed;
-}
-
 std::string statusToString(Status status) {
     switch (status) {
         case Status::Running:
             return "running";
         case Status::Paused:
             return "paused";
-        case Status::Canceled:
+        case Status::Cancelled:
-            return "canceled";
+            return "cancelled";
         case Status::Completed:
             return "completed";
         case Status::Failed:
@@ -48,131 +36,26 @@ std::string statusToString(Status status) {
 int luaErrorHandler(lua_State* state) {
     luaL_traceback(state, state, nullptr, 1);
     const auto stacktrace = sol::stack::pop<std::string>(state);
-    thisThreadHandle->result().emplace_back(createStoredObject(stacktrace));
+    ThreadHandle::getThis()->result().emplace_back(createStoredObject(stacktrace));
     return 1;
 }
 
 const lua_CFunction luaErrorHandlerPtr = luaErrorHandler;
 
-void luaHook(lua_State*, lua_Debug*) {
+void luaHook(lua_State* L, lua_Debug*) {
-    assert(thisThreadHandle);
+    if (const auto thisThread = ThreadHandle::getThis()) {
-    switch (thisThreadHandle->command()) {
+        thisThread->performInterruptionPoint(L);
-        case Command::Run:
-            break;
-        case Command::Cancel:
-            thisThreadHandle->changeStatus(Status::Canceled);
-            throw LuaHookStopException();
-        case Command::Pause: {
-            thisThreadHandle->changeStatus(Status::Paused);
-            Command cmd;
-            do {
-                cmd = thisThreadHandle->waitForCommandChange(NO_TIMEOUT);
-            } while(cmd != Command::Run && cmd != Command::Cancel);
-            if (cmd == Command::Run) {
-                thisThreadHandle->changeStatus(Status::Running);
-            } else {
-                thisThreadHandle->changeStatus(Status::Canceled);
-                throw LuaHookStopException();
-            }
-            break;
-        }
     }
 }
 
 } // namespace
 
-namespace this_thread {
+void Thread::runThread(
-
+    Thread thread,
-ScopedSetInterruptable::ScopedSetInterruptable(IInterruptable* notifier) {
+    Function function,
-    if (thisThreadHandle) {
+    effil::StoredArray arguments)
-        thisThreadHandle->setNotifier(notifier);
-    }
-}
-
-ScopedSetInterruptable::~ScopedSetInterruptable() {
-    if (thisThreadHandle) {
-        thisThreadHandle->setNotifier(nullptr);
-    }
-}
-
-void interruptionPoint() {
-    if (thisThreadHandle && thisThreadHandle->command() == Command::Cancel)
-    {
-        thisThreadHandle->changeStatus(Status::Canceled);
-        throw LuaHookStopException();
-    }
-}
-
-std::string threadId() {
-    std::stringstream ss;
-    ss << std::this_thread::get_id();
-    return ss.str();
-}
-
-void yield() {
-    luaHook(nullptr, nullptr);
-    std::this_thread::yield();
-}
-
-void sleep(const sol::stack_object& duration, const sol::stack_object& metric) {
-    if (duration.valid()) {
-        REQUIRE(duration.get_type() == sol::type::number)
-                << "bad argument #1 to 'effil.sleep' (number expected, got "
-                << luaTypename(duration) << ")";
-
-        if (metric.valid())
-        {
-            REQUIRE(metric.get_type() == sol::type::string)
-                    << "bad argument #2 to 'effil.sleep' (string expected, got "
-                    << luaTypename(metric) << ")";
-        }
-        try {
-            Notifier notifier;
-            notifier.waitFor(fromLuaTime(duration.as<int>(),
-                                         metric.as<sol::optional<std::string>>()));
-        } RETHROW_WITH_PREFIX("effil.sleep");
-    }
-    else {
-        yield();
-    }
-}
-
-} // namespace this_thread
-
-ThreadHandle::ThreadHandle()
-        : status_(Status::Running)
-        , command_(Command::Run)
-        , currNotifier_(nullptr)
-        , lua_(std::make_unique<sol::state>())
 {
-    luaL_openlibs(*lua_);
+    ThreadHandle::setThis(thread.ctx_.get());
-}
-
-void ThreadHandle::putCommand(Command cmd) {
-    std::unique_lock<std::mutex> lock(stateLock_);
-    if (isFinishStatus(status_))
-        return;
-
-    command_ = cmd;
-    statusNotifier_.reset();
-    commandNotifier_.notify();
-}
-
-void ThreadHandle::changeStatus(Status stat) {
-    std::unique_lock<std::mutex> lock(stateLock_);
-    status_ = stat;
-    commandNotifier_.reset();
-    statusNotifier_.notify();
-    if (isFinishStatus(stat))
-        completionNotifier_.notify();
-}
-
-void Thread::runThread(Thread thread,
-               Function function,
-               effil::StoredArray arguments) {
-    thisThreadHandle = thread.ctx_.get();
-    assert(thisThreadHandle != nullptr);
-
     try {
         {
             ScopeGuard reportComplete([thread, &arguments](){
@@ -193,7 +76,7 @@ void Thread::runThread(Thread thread,
 
             sol::protected_function_result result = userFuncObj(std::move(arguments));
             if (!result.valid()) {
-                if (thread.ctx_->status() == Status::Canceled)
+                if (thread.ctx_->status() == Status::Cancelled)
                     return;
 
                 sol::error err = result;
@@ -213,15 +96,18 @@ void Thread::runThread(Thread thread,
             }
         }
         thread.ctx_->changeStatus(Status::Completed);
-    } catch (const LuaHookStopException&) {
-        thread.ctx_->changeStatus(Status::Canceled);
     } catch (const std::exception& err) {
-        DEBUG("thread") << "Failed with msg: " << err.what() << std::endl;
+        if (thread.ctx_->command() == Command::Cancel && strcmp(err.what(), ThreadCancelException::message) == 0) {
-        auto& returns = thread.ctx_->result();
+            thread.ctx_->changeStatus(Status::Cancelled);
-        returns.insert(returns.begin(),
+        } else {
-                { createStoredObject("failed"),
+            DEBUG("thread") << "Failed with msg: " << err.what() << std::endl;
-                  createStoredObject(err.what()) });
+            auto& returns = thread.ctx_->result();
-        thread.ctx_->changeStatus(Status::Failed);
+            returns.insert(returns.begin(), {
+                createStoredObject("failed"),
+                createStoredObject(err.what())
+            });
+            thread.ctx_->changeStatus(Status::Failed);
+        }
     }
 }
 
@@ -319,7 +205,7 @@ bool Thread::cancel(const sol::this_state&,
     ctx_->putCommand(Command::Cancel);
     ctx_->interrupt();
     Status status = ctx_->waitForStatusChange(toOptionalTime(duration, period));
-    return isFinishStatus(status);
+    return ThreadHandle::isFinishStatus(status);
 }
 
 bool Thread::pause(const sol::this_state&,

src/cpp/thread.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include "lua-helpers.h"
+#include "function.h"
+#include "thread-handle.h"
+
+#include <sol.hpp>
+
+namespace effil {
+
+class Thread : public GCObject<ThreadHandle> {
+public:
+    static void exportAPI(sol::state_view& lua);
+
+    StoredArray status(const sol::this_state& state);
+    StoredArray wait(const sol::this_state& state,
+                     const sol::optional<int>& duration,
+                     const sol::optional<std::string>& period);
+    StoredArray get(const sol::optional<int>& duration,
+                   const sol::optional<std::string>& period);
+    bool cancel(const sol::this_state& state,
+                const sol::optional<int>& duration,
+                const sol::optional<std::string>& period);
+    bool pause(const sol::this_state&,
+               const sol::optional<int>& duration,
+               const sol::optional<std::string>& period);
+    void resume();
+
+private:
+    Thread() = default;
+    void initialize(
+        const std::string& path,
+        const std::string& cpath,
+        int step,
+        const sol::function& function,
+        const sol::variadic_args& args);
+    friend class GC;
+
+private:
+    static void runThread(Thread, Function, effil::StoredArray);
+};
+
+} // effil

src/cpp/utils.h

@@ -23,10 +23,10 @@ int luaopen_effil(lua_State* L);
 
 namespace effil {
 
-class Exception : public sol::error {
+class Exception : public std::runtime_error {
 public:
     Exception() noexcept
-            : sol::error("") {}
+        : std::runtime_error("") {}
 
     template <typename T>
     Exception& operator<<(const T& value) {

tests/lua/thread-interrupt.lua

@@ -16,7 +16,7 @@ local function interruption_test(worker)
     local start_time = os.time()
     thr:cancel(1)
 
-    test.equal(thr:status(), "canceled")
+    test.equal(thr:status(), "cancelled")
     test.almost_equal(os.time(), start_time, 1)
     state.stop = true
 end

tests/lua/thread-stress.lua

@@ -6,7 +6,7 @@ test.thread_stress.time = function ()
     local function check_time(real_time, use_time, metric)
         local start_time = os.time()
         effil.sleep(use_time, metric)
-        test.almost_equal(os.time(), start_time + real_time, 1)
+        test.almost_equal(os.time(), start_time + real_time, 2)
     end
     check_time(4, 4, nil) -- seconds by default
     check_time(4, 4, 's')

tests/lua/thread.lua

@@ -124,7 +124,7 @@ test.thread.cancel = function ()
     )()
 
     test.is_true(thread:cancel())
-    test.equal(thread:status(), "canceled")
+    test.equal(thread:status(), "cancelled")
 end
 
 test.thread.async_cancel = function ()
@@ -140,7 +140,7 @@ test.thread.async_cancel = function ()
     thread:cancel(0)
 
     test.is_true(wait(2, function() return thread:status() ~= 'running' end))
-    test.equal(thread:status(), 'canceled')
+    test.equal(thread:status(), 'cancelled')
 end
 
 test.thread.pause_resume_cancel = function ()
@@ -156,7 +156,7 @@ test.thread.pause_resume_cancel = function ()
     test.is_true(wait(2, function() return data.value > 100 end))
     test.is_true(thread:pause())
     test.equal(thread:status(), "paused")
-
+    
     local savedValue = data.value
     sleep(1)
     test.equal(data.value, savedValue)
@@ -209,7 +209,7 @@ test.thread.async_pause_resume_cancel = function ()
     test.is_true(wait(5, function() return (data.value - savedValue) > 100 end))
 
     thread:cancel(0)
-    test.is_true(wait(5, function() return thread:status() == "canceled" end))
+    test.is_true(wait(5, function() return thread:status() == "cancelled" end))
     thread:wait()
 end
 
@@ -314,6 +314,30 @@ test.this_thread.functions = function ()
     test.not_equal(share["child.id"], effil.thread_id())
 end
 
+test.this_thread.cancel_with_yield = function ()
+    local ctx = effil.table()
+    local spec = effil.thread(function()
+        while not ctx.stop do
+           -- Just waiting
+        end
+        ctx.done = true
+        while true do
+            effil.yield()
+        end
+        ctx.after_yield = true
+    end)
+    spec.step = 0
+    local thr = spec()
+
+    test.is_false(thr:cancel(1))
+    ctx.stop = true
+
+    test.is_true(thr:cancel())
+    test.equal(thr:status(), "cancelled")
+    test.is_true(ctx.done)
+    test.is_nil(ctx.after_yield)
+end
+
 test.this_thread.pause_with_yield = function ()
     local share = effil.table({stop = false})
     local spec = effil.thread(function (share)
@@ -352,12 +376,12 @@ local function call_pause(thr)
     return true
 end
 
--- Regress test to check hanging when invoke pause on canceled thread
+-- Regress test to check hanging when invoke pause on cancelled thread
-test.this_thread.pause_on_canceled_thread = function ()
+test.this_thread.pause_on_cancelled_thread = function ()
     local worker_thread = effil.thread(worker)({ need_to_stop = false})
     effil.sleep(1, 's')
     worker_thread:cancel()
-    test.equal(worker_thread:wait(2, "s"), "canceled")
+    test.equal(worker_thread:wait(2, "s"), "cancelled")
     test.is_true(effil.thread(call_pause)(worker_thread):get(5, "s"))
 end
 
@@ -406,3 +430,108 @@ test.thread.traceback = function()
 end
 
 end -- LUA_VERSION > 51
+
+test.thread.cancel_thread_with_pcall = function()
+    local steps = effil.table{step1 = false, step2 = false}
+    local pcall_results = effil.table{}
+
+    local thr = effil.thread(
+        function()
+            pcall_results.ret, pcall_results.msg = pcall(function()
+                while true do
+                    effil.yield()
+                end
+            end)
+
+            steps.step1 = true
+            effil.yield()
+            steps.step2 = true -- should never reach
+        end
+    )()
+
+    test.is_true(thr:cancel())
+    test.equal(thr:wait(), "cancelled")
+    test.is_true(steps.step1)
+    test.is_false(steps.step2)
+    test.is_false(pcall_results.ret)
+    test.equal(pcall_results.msg, "Effil: thread is cancelled")
+end
+
+test.thread.cancel_thread_with_pcall_not_cancelled = function()
+    local thr = effil.thread(
+        function()
+            pcall(function()
+                while true do
+                    effil.yield()
+                end
+            end)
+        end
+    )()
+    test.is_true(thr:cancel())
+    test.equal(thr:wait(), "completed")
+end
+
+test.thread.cancel_thread_with_pcall_and_another_error = function()
+    local msg = 'some text'
+    local thr = effil.thread(
+        function()
+            pcall(function()
+                while true do
+                    effil.yield()
+                end
+            end)
+            error(msg)
+        end
+    )()
+    test.is_true(thr:cancel())
+    local status, message = thr:wait()
+    test.equal(status, "failed")
+    test.is_not_nil(string.find(message, ".+: " .. msg))
+end
+
+if not jit then
+
+test.thread.cancel_thread_with_pcall_without_yield = function()
+    local thr = effil.thread(
+        function()
+            while true do
+                -- pass
+            end
+        end
+    )
+    thr = thr()
+    test.is_true(thr:cancel())
+    test.equal(thr:wait(), "cancelled")
+end
+
+end
+
+test.thread.check_effil_pcall_success = function()
+    local inp1, inp2, inp3 = 1, "str", {}
+    local res, ret1, ret2, ret3 = effil.pcall(function(...) return ... end, inp1, inp2, inp3)
+    test.is_true(res)
+    test.equal(ret1, inp1)
+    test.equal(ret2, inp2)
+    test.equal(ret3, inp3)
+end
+
+test.thread.check_effil_pcall_fail = function()
+    local err = "some text"
+    local res, msg = effil.pcall(function(err) error(err) end, err)
+    test.is_false(res)
+    test.is_not_nil(string.find(msg, ".+: " .. err))
+end
+
+test.thread.check_effil_pcall_with_cancel_thread = function()
+    local thr = effil.thread(
+        function()
+            effil.pcall(function()
+                while true do
+                    effil.yield()
+                end
+            end)
+        end
+    )()
+    test.is_true(thr:cancel())
+    test.equal(thr:wait(), "cancelled")
+end