Implement interactive command interruption

The core of this change is the new CommandInterpreter::m_command_state,
which models the state transitions for interactive commands, including
an "interrupted" state transition.

In general, command interruption requires cooperation from the code
executing the command, which needs to poll for interruption requests
through CommandInterpreter::WasInterrupted().

CommandInterpreter::PrintCommandOutput() implements an optionally
interruptible printing of the command output, which for large outputs 
was likely the longest blocking part.
(ex. target modules dump symtab on a complex binary could take 10+ minutes)

Differential Revision: https://reviews.llvm.org/D37923

llvm-svn: 315037

1 files changed, 84 insertions, 14 deletions

diff --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index 5efc6d1db27..8dc5637b6e4 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -546,7 +546,7 @@ void CommandInterpreter::LoadCommandDictionary() {
       char buffer[1024];
       int num_printed =
           snprintf(buffer, 1024, "%s %s", break_regexes[i][1], "-o");
-      assert(num_printed < 1024);
+      lldbassert(num_printed < 1024);
       UNUSED_IF_ASSERT_DISABLED(num_printed);
       success =
           tbreak_regex_cmd_ap->AddRegexCommand(break_regexes[i][0], buffer);
@@ -891,8 +891,8 @@ bool CommandInterpreter::AddCommand(llvm::StringRef name,
                                     const lldb::CommandObjectSP &cmd_sp,
                                     bool can_replace) {
   if (cmd_sp.get())
-    assert((this == &cmd_sp->GetCommandInterpreter()) &&
-           "tried to add a CommandObject from a different interpreter");
+    lldbassert((this == &cmd_sp->GetCommandInterpreter()) &&
+               "tried to add a CommandObject from a different interpreter");
 
   if (name.empty())
     return false;
@@ -913,8 +913,8 @@ bool CommandInterpreter::AddUserCommand(llvm::StringRef name,
                                         const lldb::CommandObjectSP &cmd_sp,
                                         bool can_replace) {
   if (cmd_sp.get())
-    assert((this == &cmd_sp->GetCommandInterpreter()) &&
-           "tried to add a CommandObject from a different interpreter");
+    lldbassert((this == &cmd_sp->GetCommandInterpreter()) &&
+               "tried to add a CommandObject from a different interpreter");
 
   if (!name.empty()) {
     // do not allow replacement of internal commands
@@ -1062,8 +1062,8 @@ CommandInterpreter::AddAlias(llvm::StringRef alias_name,
                              lldb::CommandObjectSP &command_obj_sp,
                              llvm::StringRef args_string) {
   if (command_obj_sp.get())
-    assert((this == &command_obj_sp->GetCommandInterpreter()) &&
-           "tried to add a CommandObject from a different interpreter");
+    lldbassert((this == &command_obj_sp->GetCommandInterpreter()) &&
+               "tried to add a CommandObject from a different interpreter");
 
   std::unique_ptr<CommandAlias> command_alias_up(
       new CommandAlias(*this, command_obj_sp, args_string, alias_name));
@@ -1541,6 +1541,12 @@ bool CommandInterpreter::HandleCommand(const char *command_line,
   if (!no_context_switching)
     UpdateExecutionContext(override_context);
 
+  if (WasInterrupted()) {
+    result.AppendError("interrupted");
+    result.SetStatus(eReturnStatusFailed);
+    return false;
+  }
+
   bool add_to_history;
   if (lazy_add_to_history == eLazyBoolCalculate)
     add_to_history = (m_command_source_depth == 0);
@@ -1839,7 +1845,7 @@ int CommandInterpreter::HandleCompletion(
   matches.Clear();
 
   // Only max_return_elements == -1 is supported at present:
-  assert(max_return_elements == -1);
+  lldbassert(max_return_elements == -1);
   bool word_complete;
   num_command_matches = HandleCompletionMatches(
       parsed_line, cursor_index, cursor_char_position, match_start_point,
@@ -2210,7 +2216,7 @@ void CommandInterpreter::HandleCommands(const StringList &commands,
     m_debugger.SetAsyncExecution(false);
   }
 
-  for (size_t idx = 0; idx < num_lines; idx++) {
+  for (size_t idx = 0; idx < num_lines && !WasInterrupted(); idx++) {
     const char *cmd = commands.GetStringAtIndex(idx);
     if (cmd[0] == '\0')
       continue;
@@ -2677,8 +2683,67 @@ size_t CommandInterpreter::GetProcessOutput() {
   return total_bytes;
 }
 
+void CommandInterpreter::StartHandlingCommand() {
+  auto idle_state = CommandHandlingState::eIdle;
+  if (m_command_state.compare_exchange_strong(
+          idle_state, CommandHandlingState::eInProgress))
+    lldbassert(m_iohandler_nesting_level == 0);
+  else
+    lldbassert(m_iohandler_nesting_level > 0);
+  ++m_iohandler_nesting_level;
+}
+
+void CommandInterpreter::FinishHandlingCommand() {
+  lldbassert(m_iohandler_nesting_level > 0);
+  if (--m_iohandler_nesting_level == 0) {
+    auto prev_state = m_command_state.exchange(CommandHandlingState::eIdle);
+    lldbassert(prev_state != CommandHandlingState::eIdle);
+  }
+}
+
+bool CommandInterpreter::InterruptCommand() {
+  auto in_progress = CommandHandlingState::eInProgress;
+  return m_command_state.compare_exchange_strong(
+      in_progress, CommandHandlingState::eInterrupted);
+}
+
+bool CommandInterpreter::WasInterrupted() const {
+  bool was_interrupted =
+      (m_command_state == CommandHandlingState::eInterrupted);
+  lldbassert(!was_interrupted || m_iohandler_nesting_level > 0);
+  return was_interrupted;
+}
+
+void CommandInterpreter::PrintCommandOutput(Stream &stream,
+                                            llvm::StringRef str) {
+  // Split the output into lines and poll for interrupt requests
+  const char *data = str.data();
+  size_t size = str.size();
+  while (size > 0 && !WasInterrupted()) {
+    size_t chunk_size = 0;
+    for (; chunk_size < size; ++chunk_size) {
+      lldbassert(data[chunk_size] != '\0');
+      if (data[chunk_size] == '\n') {
+        ++chunk_size;
+        break;
+      }
+    }
+    chunk_size = stream.Write(data, chunk_size);
+    lldbassert(size >= chunk_size);
+    data += chunk_size;
+    size -= chunk_size;
+  }
+  if (size > 0) {
+    stream.Printf("\n... Interrupted.\n");
+  }
+}
+
 void CommandInterpreter::IOHandlerInputComplete(IOHandler &io_handler,
                                                 std::string &line) {
+    // If we were interrupted, bail out...
+    if (WasInterrupted())
+      return;
+
   const bool is_interactive = io_handler.GetIsInteractive();
   if (is_interactive == false) {
     // When we are not interactive, don't execute blank lines. This will happen
@@ -2700,6 +2765,8 @@ void CommandInterpreter::IOHandlerInputComplete(IOHandler &io_handler,
                                                line.c_str());
   }
 
+  StartHandlingCommand();
+
   lldb_private::CommandReturnObject result;
   HandleCommand(line.c_str(), eLazyBoolCalculate, result);
 
@@ -2710,18 +2777,18 @@ void CommandInterpreter::IOHandlerInputComplete(IOHandler &io_handler,
 
     if (!result.GetImmediateOutputStream()) {
       llvm::StringRef output = result.GetOutputData();
-      if (!output.empty())
-        io_handler.GetOutputStreamFile()->PutCString(output);
+      PrintCommandOutput(*io_handler.GetOutputStreamFile(), output);
     }
 
     // Now emit the command error text from the command we just executed
     if (!result.GetImmediateErrorStream()) {
       llvm::StringRef error = result.GetErrorData();
-      if (!error.empty())
-        io_handler.GetErrorStreamFile()->PutCString(error);
+      PrintCommandOutput(*io_handler.GetErrorStreamFile(), error);
     }
   }
 
+  FinishHandlingCommand();
+
   switch (result.GetStatus()) {
   case eReturnStatusInvalid:
   case eReturnStatusSuccessFinishNoResult:
@@ -2777,6 +2844,9 @@ bool CommandInterpreter::IOHandlerInterrupt(IOHandler &io_handler) {
   ExecutionContext exe_ctx(GetExecutionContext());
   Process *process = exe_ctx.GetProcessPtr();
 
+  if (InterruptCommand())
+    return true;
+
   if (process) {
     StateType state = process->GetState();
     if (StateIsRunningState(state)) {
@@ -2998,7 +3068,7 @@ CommandInterpreter::ResolveCommandImpl(std::string &command_line,
         result.AppendRawError(error_msg.GetString());
       } else {
         // We didn't have only one match, otherwise we wouldn't get here.
-        assert(num_matches == 0);
+        lldbassert(num_matches == 0);
         result.AppendErrorWithFormat("'%s' is not a valid command.\n",
                                      next_word.c_str());
       }