// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "include/dart_api.h"
#include "platform/assert.h"
#include "vm/globals.h"
#include "vm/isolate.h"
#include "vm/lockers.h"
#include "vm/thread_barrier.h"
#include "vm/thread_pool.h"
#include "vm/unit_test.h"

namespace dart {

UNIT_TEST_CASE(IsolateCurrent) {
  Dart_Isolate isolate = Dart_CreateIsolate(
      NULL, NULL, bin::isolate_snapshot_buffer, NULL, NULL, NULL);
  EXPECT_EQ(isolate, Dart_CurrentIsolate());
  Dart_ShutdownIsolate();
  EXPECT_EQ(reinterpret_cast<Dart_Isolate>(NULL), Dart_CurrentIsolate());
}


// Test to ensure that an exception is thrown if no isolate creation
// callback has been set by the embedder when an isolate is spawned.
TEST_CASE(IsolateSpawn) {
  const char* kScriptChars =
      "import 'dart:isolate';\n"
      // Ignores printed lines.
      "var _nullPrintClosure = (String line) {};\n"
      "void entry(message) {}\n"
      "int testMain() {\n"
      "  Isolate.spawn(entry, null);\n"
      // TODO(floitsch): the following code is only to bump the event loop
      // so it executes asynchronous microtasks.
      "  var rp = new RawReceivePort();\n"
      "  rp.sendPort.send(null);\n"
      "  rp.handler = (_) { rp.close(); };\n"
      "}\n";

  Dart_Handle test_lib = TestCase::LoadTestScript(kScriptChars, NULL);

  // Setup the internal library's 'internalPrint' function.
  // Necessary because asynchronous errors use "print" to print their
  // stack trace.
  Dart_Handle url = NewString("dart:_internal");
  DART_CHECK_VALID(url);
  Dart_Handle internal_lib = Dart_LookupLibrary(url);
  DART_CHECK_VALID(internal_lib);
  Dart_Handle print = Dart_GetField(test_lib, NewString("_nullPrintClosure"));
  Dart_Handle result = Dart_SetField(internal_lib,
                                     NewString("_printClosure"),
                                     print);

  DART_CHECK_VALID(result);

  // Setup the 'scheduleImmediate' closure.
  url = NewString("dart:isolate");
  DART_CHECK_VALID(url);
  Dart_Handle isolate_lib = Dart_LookupLibrary(url);
  DART_CHECK_VALID(isolate_lib);
  Dart_Handle schedule_immediate_closure =
      Dart_Invoke(isolate_lib, NewString("_getIsolateScheduleImmediateClosure"),
                  0, NULL);
  Dart_Handle args[1];
  args[0] = schedule_immediate_closure;
  url = NewString("dart:async");
  DART_CHECK_VALID(url);
  Dart_Handle async_lib = Dart_LookupLibrary(url);
  DART_CHECK_VALID(async_lib);
  DART_CHECK_VALID(Dart_Invoke(
      async_lib, NewString("_setScheduleImmediateClosure"), 1, args));


  result = Dart_Invoke(test_lib, NewString("testMain"), 0, NULL);
  EXPECT_VALID(result);
  // Run until all ports to isolate are closed.
  result = Dart_RunLoop();
  EXPECT_ERROR(result, "Unsupported operation: Isolate.spawn");
  EXPECT(Dart_ErrorHasException(result));
  Dart_Handle exception_result = Dart_ErrorGetException(result);
  EXPECT_VALID(exception_result);
}


class InterruptChecker : public ThreadPool::Task {
 public:
  static const intptr_t kTaskCount;
  static const intptr_t kIterations;

  InterruptChecker(Isolate* isolate,
                   ThreadBarrier* barrier)
    : isolate_(isolate),
      barrier_(barrier) {
  }

  virtual void Run() {
    Thread::EnterIsolateAsHelper(isolate_);
    // Tell main thread that we are ready.
    barrier_->Sync();
    for (intptr_t i = 0; i < kIterations; ++i) {
      // Busy wait for interrupts.
      while (!isolate_->HasInterruptsScheduled(Isolate::kVMInterrupt)) {
        // Do nothing.
      }
      // Tell main thread that we observed the interrupt.
      barrier_->Sync();
    }
    Thread::ExitIsolateAsHelper();
    barrier_->Exit();
  }

 private:
  Isolate* isolate_;
  ThreadBarrier* barrier_;
};


const intptr_t InterruptChecker::kTaskCount = 5;
const intptr_t InterruptChecker::kIterations = 10;

// Test and document usage of Isolate::HasInterruptsScheduled.
//
// Go through a number of rounds of scheduling interrupts and waiting until all
// unsynchronized busy-waiting tasks observe it (in the current implementation,
// the exact latency depends on cache coherence). Synchronization is then used
// to ensure that the response to the interrupt, i.e., starting a new round,
// happens *after* the interrupt is observed. Without this synchronization, the
// compiler and/or CPU could reorder operations to make the tasks observe the
// round update *before* the interrupt is set.
TEST_CASE(StackLimitInterrupts) {
  Isolate* isolate = Thread::Current()->isolate();
  ThreadBarrier barrier(InterruptChecker::kTaskCount + 1,
                        isolate->heap()->barrier(),
                        isolate->heap()->barrier_done());
  // Start all tasks. They will busy-wait until interrupted in the first round.
  for (intptr_t task = 0; task < InterruptChecker::kTaskCount; task++) {
    Dart::thread_pool()->Run(new InterruptChecker(isolate, &barrier));
  }
  // Wait for all tasks to get ready for the first round.
  barrier.Sync();
  for (intptr_t i = 0; i < InterruptChecker::kIterations; ++i) {
    isolate->ScheduleInterrupts(Isolate::kVMInterrupt);
    // Wait for all tasks to observe the interrupt.
    barrier.Sync();
    // Continue with next round.
    uword interrupts = isolate->GetAndClearInterrupts();
    EXPECT((interrupts & Isolate::kVMInterrupt) != 0);
  }
  barrier.Exit();
}


class IsolateTestHelper {
 public:
  static uword GetStackLimit(Isolate* isolate) {
    return isolate->stack_limit_;
  }
  static uword GetSavedStackLimit(Isolate* isolate) {
    return isolate->saved_stack_limit_;
  }
  static uword GetDeferredInterruptsMask(Isolate* isolate) {
    return isolate->deferred_interrupts_mask_;
  }
  static uword GetDeferredInterrupts(Isolate* isolate) {
    return isolate->deferred_interrupts_;
  }
};


TEST_CASE(NoOOBMessageScope) {
  // EXPECT_EQ is picky about type agreement for its arguments.
  const uword kZero = 0;
  const uword kMessageInterrupt = Isolate::kMessageInterrupt;
  const uword kVMInterrupt = Isolate::kVMInterrupt;
  uword stack_limit;
  uword interrupt_bits;

  // Initially no interrupts are scheduled or deferred.
  Isolate* isolate = Thread::Current()->isolate();
  EXPECT_EQ(IsolateTestHelper::GetStackLimit(isolate),
            IsolateTestHelper::GetSavedStackLimit(isolate));
  EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterruptsMask(isolate));
  EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterrupts(isolate));

  {
    // Defer message interrupts.
    NoOOBMessageScope no_msg_scope(Thread::Current());
    EXPECT_EQ(IsolateTestHelper::GetStackLimit(isolate),
              IsolateTestHelper::GetSavedStackLimit(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterruptsMask(isolate));
    EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterrupts(isolate));

    // Schedule a message, it is deferred.
    isolate->ScheduleInterrupts(Isolate::kMessageInterrupt);
    EXPECT_EQ(IsolateTestHelper::GetStackLimit(isolate),
              IsolateTestHelper::GetSavedStackLimit(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterruptsMask(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterrupts(isolate));

    // Schedule a vm interrupt, it is not deferred.
    isolate->ScheduleInterrupts(Isolate::kVMInterrupt);
    stack_limit = IsolateTestHelper::GetStackLimit(isolate);
    EXPECT_NE(stack_limit, IsolateTestHelper::GetSavedStackLimit(isolate));
    EXPECT((stack_limit & Isolate::kVMInterrupt) != 0);
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterruptsMask(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterrupts(isolate));

    // Clear the vm interrupt.  Message is still deferred.
    interrupt_bits = isolate->GetAndClearInterrupts();
    EXPECT_EQ(kVMInterrupt, interrupt_bits);
    EXPECT_EQ(IsolateTestHelper::GetStackLimit(isolate),
              IsolateTestHelper::GetSavedStackLimit(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterruptsMask(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterrupts(isolate));
  }

  // Restore message interrupts.  Message is now pending.
  stack_limit = IsolateTestHelper::GetStackLimit(isolate);
  EXPECT_NE(stack_limit, IsolateTestHelper::GetSavedStackLimit(isolate));
  EXPECT((stack_limit & Isolate::kMessageInterrupt) != 0);
  EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterruptsMask(isolate));
  EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterrupts(isolate));

  {
    // Defer message interrupts, again.  The pending interrupt is deferred.
    NoOOBMessageScope no_msg_scope(Thread::Current());
    EXPECT_EQ(IsolateTestHelper::GetStackLimit(isolate),
              IsolateTestHelper::GetSavedStackLimit(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterruptsMask(isolate));
    EXPECT_EQ(kMessageInterrupt,
              IsolateTestHelper::GetDeferredInterrupts(isolate));
  }

  // Restore, then clear interrupts.  The world is as it was.
  interrupt_bits = isolate->GetAndClearInterrupts();
  EXPECT_EQ(kMessageInterrupt, interrupt_bits);
  EXPECT_EQ(IsolateTestHelper::GetStackLimit(isolate),
            IsolateTestHelper::GetSavedStackLimit(isolate));
  EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterruptsMask(isolate));
  EXPECT_EQ(kZero, IsolateTestHelper::GetDeferredInterrupts(isolate));
}

}  // namespace dart