top.cc.svn-base

Google浏览器V8内核代码

// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "v8.h"

#include "api.h"
#include "bootstrapper.h"
#include "debug.h"
#include "execution.h"
#include "string-stream.h"
#include "platform.h"

namespace v8 { namespace internal {

ThreadLocalTop Top::thread_local_;
Mutex* Top::break_access_ = OS::CreateMutex();
StackFrame::Id Top::break_frame_id_;
int Top::break_count_;
int Top::break_id_;

NoAllocationStringAllocator* preallocated_message_space = NULL;

Address top_addresses[] = {
#define C(name) reinterpret_cast<Address>(Top::name()),
    TOP_ADDRESS_LIST(C)
#undef C
    NULL
};

Address Top::get_address_from_id(Top::AddressId id) {
  return top_addresses[id];
}

char* Top::Iterate(ObjectVisitor* v, char* thread_storage) {
  ThreadLocalTop* thread = reinterpret_cast<ThreadLocalTop*>(thread_storage);
  Iterate(v, thread);
  return thread_storage + sizeof(ThreadLocalTop);
}


#define VISIT(field) v->VisitPointer(reinterpret_cast<Object**>(&(field)));

void Top::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
  VISIT(thread->pending_exception_);
  VISIT(thread->security_context_);
  VISIT(thread->context_);
  VISIT(thread->scheduled_exception_);

  for (v8::TryCatch* block = thread->try_catch_handler_;
       block != NULL;
       block = block->next_) {
    VISIT(reinterpret_cast<Object*&>(block->exception_));
    VISIT(reinterpret_cast<Object*&>(block->message_));
  }

  // Iterate over pointers on native execution stack.
  for (StackFrameIterator it(thread); !it.done(); it.Advance()) {
    it.frame()->Iterate(v);
  }
}
#undef VISIT


void Top::Iterate(ObjectVisitor* v) {
  ThreadLocalTop* current_t = &thread_local_;
  Iterate(v, current_t);
}


void Top::InitializeThreadLocal() {
  thread_local_.c_entry_fp_ = 0;
  thread_local_.handler_ = 0;
  thread_local_.stack_is_cooked_ = false;
  thread_local_.try_catch_handler_ = NULL;
  thread_local_.security_context_ = NULL;
  thread_local_.context_ = NULL;
  thread_local_.external_caught_exception_ = false;
  thread_local_.failed_access_check_callback_ = NULL;
  clear_pending_exception();
  clear_scheduled_exception();
  thread_local_.save_context_ = NULL;
}


// Create a dummy thread that will wait forever on a semaphore. The only
// purpose for this thread is to have some stack area to save essential data
// into for use by a stacks only core dump (aka minidump).
class PreallocatedMemoryThread: public Thread {
 public:
  PreallocatedMemoryThread() : keep_running_(true) {
    wait_for_ever_semaphore_ = OS::CreateSemaphore(0);
    data_ready_semaphore_ = OS::CreateSemaphore(0);
  }

  // When the thread starts running it will allocate a fixed number of bytes
  // on the stack and publish the location of this memory for others to use.
  void Run() {
    EmbeddedVector<char, 16 * 1024> local_buffer;

    // Initialize the buffer with a known good value.
    OS::StrNCpy(local_buffer, "Trace data was not generated.\n",
                local_buffer.length());

    // Publish the local buffer and signal its availability.
    data_ = &local_buffer[0];
    length_ = sizeof(local_buffer);
    data_ready_semaphore_->Signal();

    while (keep_running_) {
      // This thread will wait here until the end of time.
      wait_for_ever_semaphore_->Wait();
    }

    // Make sure we access the buffer after the wait to remove all possibility
    // of it being optimized away.
    OS::StrNCpy(local_buffer, "PreallocatedMemoryThread shutting down.\n",
                local_buffer.length());
  }

  static char* data() {
    if (data_ready_semaphore_ != NULL) {
      // Initial access is guarded until the data has been published.
      data_ready_semaphore_->Wait();
      delete data_ready_semaphore_;
      data_ready_semaphore_ = NULL;
    }
    return data_;
  }

  static unsigned length() {
    if (data_ready_semaphore_ != NULL) {
      // Initial access is guarded until the data has been published.
      data_ready_semaphore_->Wait();
      delete data_ready_semaphore_;
      data_ready_semaphore_ = NULL;
    }
    return length_;
  }

  static void StartThread() {
    if (the_thread_ != NULL) return;

    the_thread_ = new PreallocatedMemoryThread();
    the_thread_->Start();
  }

  // Stop the PreallocatedMemoryThread and release its resources.
  static void StopThread() {
    if (the_thread_ == NULL) return;

    the_thread_->keep_running_ = false;
    wait_for_ever_semaphore_->Signal();

    // Wait for the thread to terminate.
    the_thread_->Join();

    if (data_ready_semaphore_ != NULL) {
      delete data_ready_semaphore_;
      data_ready_semaphore_ = NULL;
    }

    delete wait_for_ever_semaphore_;
    wait_for_ever_semaphore_ = NULL;

    // Done with the thread entirely.
    delete the_thread_;
    the_thread_ = NULL;
  }

 private:
  // Used to make sure that the thread keeps looping even for spurious wakeups.
  bool keep_running_;

  // The preallocated memory thread singleton.
  static PreallocatedMemoryThread* the_thread_;
  // This semaphore is used by the PreallocatedMemoryThread to wait for ever.
  static Semaphore* wait_for_ever_semaphore_;
  // Semaphore to signal that the data has been initialized.
  static Semaphore* data_ready_semaphore_;

  // Location and size of the preallocated memory block.
  static char* data_;
  static unsigned length_;

  DISALLOW_COPY_AND_ASSIGN(PreallocatedMemoryThread);
};

PreallocatedMemoryThread* PreallocatedMemoryThread::the_thread_ = NULL;
Semaphore* PreallocatedMemoryThread::wait_for_ever_semaphore_ = NULL;
Semaphore* PreallocatedMemoryThread::data_ready_semaphore_ = NULL;
char* PreallocatedMemoryThread::data_ = NULL;
unsigned PreallocatedMemoryThread::length_ = 0;

static bool initialized = false;

void Top::Initialize() {
  CHECK(!initialized);

  InitializeThreadLocal();

  break_frame_id_ = StackFrame::NO_ID;
  break_count_ = 0;
  break_id_ = 0;

  // Only preallocate on the first initialization.
  if (FLAG_preallocate_message_memory && (preallocated_message_space == NULL)) {
    // Start the thread which will set aside some memory.
    PreallocatedMemoryThread::StartThread();
    preallocated_message_space =
        new NoAllocationStringAllocator(PreallocatedMemoryThread::data(),
                                        PreallocatedMemoryThread::length());
    PreallocatedStorage::Init(PreallocatedMemoryThread::length() / 4);
  }
  initialized = true;
}


void Top::TearDown() {
  if (initialized) {
    // Remove the external reference to the preallocated stack memory.
    if (preallocated_message_space != NULL) {
      delete preallocated_message_space;
      preallocated_message_space = NULL;
    }

    PreallocatedMemoryThread::StopThread();
    initialized = false;
  }
}


void Top::RegisterTryCatchHandler(v8::TryCatch* that) {
  thread_local_.try_catch_handler_ = that;
}


void Top::UnregisterTryCatchHandler(v8::TryCatch* that) {
  ASSERT(thread_local_.try_catch_handler_ == that);
  thread_local_.try_catch_handler_ = that->next_;
}


void Top::new_break(StackFrame::Id break_frame_id) {
  ExecutionAccess access;
  break_frame_id_ = break_frame_id;
  break_id_ = ++break_count_;
}


void Top::set_break(StackFrame::Id break_frame_id, int break_id) {
  ExecutionAccess access;
  break_frame_id_ = break_frame_id;
  break_id_ = break_id;
}


bool Top::check_break(int break_id) {
  ExecutionAccess access;
  return break_id == break_id_;
}


bool Top::is_break() {
  ExecutionAccess access;
  return break_id_ != 0;
}


StackFrame::Id Top::break_frame_id() {
  ExecutionAccess access;
  return break_frame_id_;
}


int Top::break_id() {
  ExecutionAccess access;
  return break_id_;
}


void Top::MarkCompactPrologue() {
  MarkCompactPrologue(&thread_local_);
}


void Top::MarkCompactPrologue(char* data) {
  MarkCompactPrologue(reinterpret_cast<ThreadLocalTop*>(data));
}


void Top::MarkCompactPrologue(ThreadLocalTop* thread) {
  StackFrame::CookFramesForThread(thread);
}


void Top::MarkCompactEpilogue(char* data) {
  MarkCompactEpilogue(reinterpret_cast<ThreadLocalTop*>(data));
}


void Top::MarkCompactEpilogue() {
  MarkCompactEpilogue(&thread_local_);
}


void Top::MarkCompactEpilogue(ThreadLocalTop* thread) {
  StackFrame::UncookFramesForThread(thread);
}


static int stack_trace_nesting_level = 0;
static StringStream* incomplete_message = NULL;


Handle<String> Top::StackTrace() {
  if (stack_trace_nesting_level == 0) {
    stack_trace_nesting_level++;
    HeapStringAllocator allocator;
    StringStream::ClearMentionedObjectCache();
    StringStream accumulator(&allocator);
    incomplete_message = &accumulator;
    PrintStack(&accumulator);
    Handle<String> stack_trace = accumulator.ToString();
    incomplete_message = NULL;
    stack_trace_nesting_level = 0;
    return stack_trace;
  } else if (stack_trace_nesting_level == 1) {
    stack_trace_nesting_level++;
    OS::PrintError(
      "\n\nAttempt to print stack while printing stack (double fault)\n");
    OS::PrintError(
      "If you are lucky you may find a partial stack dump on stdout.\n\n");
    incomplete_message->OutputToStdOut();
    return Factory::empty_symbol();
  } else {
    OS::Abort();
    // Unreachable
    return Factory::empty_symbol();
  }
}


void Top::PrintStack() {
  if (stack_trace_nesting_level == 0) {
    stack_trace_nesting_level++;

    StringAllocator* allocator;
    if (preallocated_message_space == NULL) {
      allocator = new HeapStringAllocator();
    } else {
      allocator = preallocated_message_space;
    }

    NativeAllocationChecker allocation_checker(
      !FLAG_preallocate_message_memory ?
      NativeAllocationChecker::ALLOW :
      NativeAllocationChecker::DISALLOW);

    StringStream::ClearMentionedObjectCache();
    StringStream accumulator(allocator);
    incomplete_message = &accumulator;
    PrintStack(&accumulator);
    accumulator.OutputToStdOut();
    accumulator.Log();
    incomplete_message = NULL;
    stack_trace_nesting_level = 0;
    if (preallocated_message_space == NULL) {
      // Remove the HeapStringAllocator created above.
      delete allocator;
    }
  } else if (stack_trace_nesting_level == 1) {
    stack_trace_nesting_level++;
    OS::PrintError(
      "\n\nAttempt to print stack while printing stack (double fault)\n");
    OS::PrintError(
      "If you are lucky you may find a partial stack dump on stdout.\n\n");
    incomplete_message->OutputToStdOut();
  }
}


static void PrintFrames(StringStream* accumulator,
                        StackFrame::PrintMode mode) {
  StackFrameIterator it;
  for (int i = 0; !it.done(); it.Advance()) {
    it.frame()->Print(accumulator, mode, i++);
  }
}


void Top::PrintStack(StringStream* accumulator) {
  // The MentionedObjectCache is not GC-proof at the moment.
  AssertNoAllocation nogc;
  ASSERT(StringStream::IsMentionedObjectCacheClear());

  // Avoid printing anything if there are no frames.
  if (c_entry_fp(GetCurrentThread()) == 0) return;

  accumulator->Add(
      "\n==== Stack trace ============================================\n\n");
  PrintFrames(accumulator, StackFrame::OVERVIEW);

  accumulator->Add(
      "\n==== Details ================================================\n\n");
  PrintFrames(accumulator, StackFrame::DETAILS);

  accumulator->PrintMentionedObjectCache();
  accumulator->Add("=====================\n\n");
}


void Top::SetFailedAccessCheckCallback(v8::FailedAccessCheckCallback callback) {
  ASSERT(thread_local_.failed_access_check_callback_ == NULL);
  thread_local_.failed_access_check_callback_ = callback;
}


void Top::ReportFailedAccessCheck(JSObject* receiver, v8::AccessType type) {
  if (!thread_local_.failed_access_check_callback_) return;

  ASSERT(receiver->IsAccessCheckNeeded());
  ASSERT(Top::security_context());