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
llvm · Oct 5, 2017 · 17ffd39 · 17ffd39
1 parent b9aa9a5
commit 17ffd39
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Showing 10 changed files with 139 additions and 24 deletions.
diff --git a/lldb/include/lldb/API/SBCommandInterpreter.h b/lldb/include/lldb/API/SBCommandInterpreter.h
@@ -165,6 +165,8 @@ class SBCommandInterpreter {
                        int match_start_point, int max_return_elements,
                        lldb::SBStringList &matches);
 
+  bool WasInterrupted() const;
+
   // Catch commands before they execute by registering a callback that will
   // get called when the command gets executed. This allows GUI or command
   // line interfaces to intercept a command and stop it from happening

diff --git a/lldb/include/lldb/Core/IOHandler.h b/lldb/include/lldb/Core/IOHandler.h
@@ -195,7 +195,7 @@ class IOHandlerDelegate {
   enum class Completion { None, LLDBCommand, Expression };
 
   IOHandlerDelegate(Completion completion = Completion::None)
-      : m_completion(completion), m_io_handler_done(false) {}
+      : m_completion(completion) {}
 
   virtual ~IOHandlerDelegate() = default;
 
@@ -296,7 +296,6 @@ class IOHandlerDelegate {
 
 protected:
   Completion m_completion; // Support for common builtin completions
-  bool m_io_handler_done;
 };
 
 //----------------------------------------------------------------------

diff --git a/lldb/include/lldb/Interpreter/CommandInterpreter.h b/lldb/include/lldb/Interpreter/CommandInterpreter.h
@@ -242,6 +242,8 @@ class CommandInterpreter : public Broadcaster,
                      bool repeat_on_empty_command = true,
                      bool no_context_switching = false);
 
+  bool WasInterrupted() const;
+
   //------------------------------------------------------------------
   /// Execute a list of commands in sequence.
   ///
@@ -522,6 +524,25 @@ class CommandInterpreter : public Broadcaster,
                               StringList &commands_help,
                               CommandObject::CommandMap &command_map);
 
+  // An interruptible wrapper around the stream output
+  void PrintCommandOutput(Stream &stream, llvm::StringRef str);
+
+  // A very simple state machine which models the command handling transitions
+  enum class CommandHandlingState {
+    eIdle,
+    eInProgress,
+    eInterrupted,
+  };
+
+  std::atomic<CommandHandlingState> m_command_state{
+      CommandHandlingState::eIdle};
+
+  int m_iohandler_nesting_level = 0;
+
+  void StartHandlingCommand();
+  void FinishHandlingCommand();
+  bool InterruptCommand();
+
   Debugger &m_debugger; // The debugger session that this interpreter is
                         // associated with
   ExecutionContextRef m_exe_ctx_ref; // The current execution context to use

diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/command_source/.lldb b/lldb/packages/Python/lldbsuite/test/functionalities/command_source/.lldb
@@ -1 +1,2 @@
-script import my
+# one more level of indirection to stress the command interpreter reentrancy
+command source commands.txt
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/command_source/commands.txt b/lldb/packages/Python/lldbsuite/test/functionalities/command_source/commands.txt
@@ -0,0 +1,2 @@
+script import my
+p 1 + 1
diff --git a/lldb/scripts/interface/SBCommandInterpreter.i b/lldb/scripts/interface/SBCommandInterpreter.i
@@ -125,18 +125,18 @@ public:
     {
         eBroadcastBitThreadShouldExit       = (1 << 0),
         eBroadcastBitResetPrompt            = (1 << 1),
-        eBroadcastBitQuitCommandReceived    = (1 << 2),           // User entered quit 
+        eBroadcastBitQuitCommandReceived    = (1 << 2),           // User entered quit
         eBroadcastBitAsynchronousOutputData = (1 << 3),
         eBroadcastBitAsynchronousErrorData  = (1 << 4)
     };
 
     SBCommandInterpreter (const lldb::SBCommandInterpreter &rhs);
-    
+
     ~SBCommandInterpreter ();
 
-    static const char * 
+    static const char *
     GetArgumentTypeAsCString (const lldb::CommandArgumentType arg_type);
-    
+
     static const char *
     GetArgumentDescriptionAsCString (const lldb::CommandArgumentType arg_type);
 
@@ -181,7 +181,7 @@ public:
 
     lldb::SBProcess
     GetProcess ();
-    
+
     lldb::SBDebugger
     GetDebugger ();
 
@@ -209,10 +209,12 @@ public:
                       int match_start_point,
                       int max_return_elements,
                       lldb::SBStringList &matches);
-    
+
     bool
     IsActive ();
 
+    bool
+    WasInterrupted () const;
 };
 
 } // namespace lldb
diff --git a/lldb/source/API/SBCommandInterpreter.cpp b/lldb/source/API/SBCommandInterpreter.cpp
@@ -161,6 +161,10 @@ bool SBCommandInterpreter::IsActive() {
   return (IsValid() ? m_opaque_ptr->IsActive() : false);
 }
 
+bool SBCommandInterpreter::WasInterrupted() const {
+  return (IsValid() ? m_opaque_ptr->WasInterrupted() : false);
+}
+
 const char *SBCommandInterpreter::GetIOHandlerControlSequence(char ch) {
   return (IsValid()
               ? m_opaque_ptr->GetDebugger()

diff --git a/lldb/source/Commands/CommandObjectTarget.cpp b/lldb/source/Commands/CommandObjectTarget.cpp
@@ -2053,6 +2053,8 @@ class CommandObjectTargetModulesDumpSymtab
               result.GetOutputStream().EOL();
               result.GetOutputStream().EOL();
             }
+            if (m_interpreter.WasInterrupted())
+              break;
             num_dumped++;
             DumpModuleSymtab(
                 m_interpreter, result.GetOutputStream(),
@@ -2081,6 +2083,8 @@ class CommandObjectTargetModulesDumpSymtab
                   result.GetOutputStream().EOL();
                   result.GetOutputStream().EOL();
                 }
+                if (m_interpreter.WasInterrupted())
+                  break;
                 num_dumped++;
                 DumpModuleSymtab(m_interpreter, result.GetOutputStream(),
                                  module, m_options.m_sort_order);
@@ -2146,6 +2150,8 @@ class CommandObjectTargetModulesDumpSections
                                           " modules.\n",
                                           (uint64_t)num_modules);
           for (size_t image_idx = 0; image_idx < num_modules; ++image_idx) {
+            if (m_interpreter.WasInterrupted())
+              break;
             num_dumped++;
             DumpModuleSections(
                 m_interpreter, result.GetOutputStream(),
@@ -2167,6 +2173,8 @@ class CommandObjectTargetModulesDumpSections
               FindModulesByName(target, arg_cstr, module_list, true);
           if (num_matches > 0) {
             for (size_t i = 0; i < num_matches; ++i) {
+              if (m_interpreter.WasInterrupted())
+                break;
               Module *module = module_list.GetModulePointerAtIndex(i);
               if (module) {
                 num_dumped++;
@@ -2239,6 +2247,8 @@ class CommandObjectTargetModulesDumpSymfile
                                           " modules.\n",
                                           (uint64_t)num_modules);
           for (uint32_t image_idx = 0; image_idx < num_modules; ++image_idx) {
+            if (m_interpreter.WasInterrupted())
+              break;
             if (DumpModuleSymbolVendor(
                     result.GetOutputStream(),
                     target_modules.GetModulePointerAtIndexUnlocked(image_idx)))
@@ -2260,6 +2270,8 @@ class CommandObjectTargetModulesDumpSymfile
               FindModulesByName(target, arg_cstr, module_list, true);
           if (num_matches > 0) {
             for (size_t i = 0; i < num_matches; ++i) {
+              if (m_interpreter.WasInterrupted())
+                break;
               Module *module = module_list.GetModulePointerAtIndex(i);
               if (module) {
                 if (DumpModuleSymbolVendor(result.GetOutputStream(), module))
@@ -2327,6 +2339,8 @@ class CommandObjectTargetModulesDumpLineTable
         if (num_modules > 0) {
           uint32_t num_dumped = 0;
           for (uint32_t i = 0; i < num_modules; ++i) {
+            if (m_interpreter.WasInterrupted())
+              break;
             if (DumpCompileUnitLineTable(
                     m_interpreter, result.GetOutputStream(),
                     target_modules.GetModulePointerAtIndexUnlocked(i),

diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
@@ -1170,7 +1170,7 @@ TestPromptFormats (StackFrame *frame)
         return;
 
     StreamString s;
-    const char *prompt_format =         
+    const char *prompt_format =
     "{addr = '${addr}'\n}"
     "{addr-file-or-load = '${addr-file-or-load}'\n}"
     "{current-pc-arrow = '${current-pc-arrow}'\n}"

diff --git 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());
       }