[battor agent] Add option to log serial communication

tools/battor_agent/battor_connection_impl.cc

Index: tools/battor_agent/battor_connection_impl.cc
diff --git a/tools/battor_agent/battor_connection_impl.cc b/tools/battor_agent/battor_connection_impl.cc
index cce643a6e18e4a75a115896bc3257b84c1176ce8..6433eed0e4d6ec5078fb3ec46e7def75a4f240b6 100644
--- a/tools/battor_agent/battor_connection_impl.cc
+++ b/tools/battor_agent/battor_connection_impl.cc
@@ -6,18 +6,25 @@
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/thread_task_runner_handle.h"
 #include "device/serial/buffer.h"
 #include "device/serial/serial_io_handler.h"
 #include "net/base/io_buffer.h"
+#include "tools/battor_agent/serial_utils.h"
 
+using std::endl;
 using std::vector;
 
 namespace battor {
 
 namespace {
 
+// The command line switch used to specify a file to which serial communication
+// is logged.
+const char kSerialLogPathSwitch[] = "battor-serial-log";
+
 // Serial configuration parameters for the BattOr.
 const uint32_t kBattOrBitrate = 2000000;
 const device::serial::DataBits kBattOrDataBits =
@@ -58,7 +65,16 @@ BattOrConnectionImpl::BattOrConnectionImpl(
     : BattOrConnection(listener),
       path_(path),
       file_thread_task_runner_(file_thread_task_runner),
-      ui_thread_task_runner_(ui_thread_task_runner) {}
+      ui_thread_task_runner_(ui_thread_task_runner) {
+  std::string serial_log_path =
+      base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          kSerialLogPathSwitch);
+  if (!serial_log_path.empty()) {
+    serial_log_.open(serial_log_path.c_str(),
+                     std::fstream::out | std::fstream::trunc);
+    serial_log_ << std::boolalpha;
+  }
+}
 
 BattOrConnectionImpl::~BattOrConnectionImpl() {}
 
@@ -78,11 +94,16 @@ void BattOrConnectionImpl::Open() {
   options.cts_flow_control = kBattOrCtsFlowControl;
   options.has_cts_flow_control = kBattOrHasCtsFlowControl;
 
+  serial_log_ << "Opening serial connection." << endl << endl;
   io_handler_->Open(path_, options,
                     base::Bind(&BattOrConnectionImpl::OnOpened, AsWeakPtr()));
 }
 
 void BattOrConnectionImpl::OnOpened(bool success) {
+  serial_log_ << "Serial connection open finished with success: " << success
+              << "." << endl
+              << endl;
+
   if (!success)
     Close();
 
@@ -92,6 +113,7 @@ void BattOrConnectionImpl::OnOpened(bool success) {
 }
 
 void BattOrConnectionImpl::Close() {
+  serial_log_ << "Serial connection closed." << endl << endl;
   io_handler_ = nullptr;
 }
 
@@ -119,6 +141,9 @@ void BattOrConnectionImpl::SendBytes(BattOrMessageType type,
 
   data.push_back(BATTOR_CONTROL_BYTE_END);
 
+  serial_log_ << "Bytes sent: " << CharVectorToString(data) << "." << endl
+              << endl;
+
   pending_write_length_ = data.size();
   io_handler_->Write(base::WrapUnique(new device::SendBuffer(
       data, base::Bind(&BattOrConnectionImpl::OnBytesSent, AsWeakPtr()))));
@@ -134,7 +159,13 @@ void BattOrConnectionImpl::ReadMessage(BattOrMessageType type) {
   std::unique_ptr<vector<char>> bytes(new vector<char>());
   bytes->reserve(max_bytes_to_read);
 
+  serial_log_
+      << "Checking if a complete message is in the 'already read' buffer."
+      << endl
+      << endl;
+
   if (ParseMessage(&parsed_type, bytes.get())) {
+    serial_log_ << "Complete message found." << endl << endl;
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE,
         base::Bind(&Listener::OnMessageRead, base::Unretained(listener_), true,
@@ -142,6 +173,7 @@ void BattOrConnectionImpl::ReadMessage(BattOrMessageType type) {
     return;
   }
 
+  serial_log_ << "No complete message found." << endl << endl;
   BeginReadBytes(max_bytes_to_read - already_read_buffer_.size());
 }
 
@@ -156,6 +188,10 @@ scoped_refptr<device::SerialIoHandler> BattOrConnectionImpl::CreateIoHandler() {
 }
 
 void BattOrConnectionImpl::BeginReadBytes(size_t max_bytes_to_read) {
+  serial_log_ << "Starting read of up to " << max_bytes_to_read << " bytes."
+              << endl
+              << endl;
+
   pending_read_buffer_ =
       make_scoped_refptr(new net::IOBuffer(max_bytes_to_read));
 
@@ -169,13 +205,27 @@ void BattOrConnectionImpl::BeginReadBytes(size_t max_bytes_to_read) {
 
 void BattOrConnectionImpl::OnBytesRead(int bytes_read,
                                        device::serial::ReceiveError error) {
-  if (bytes_read == 0 || error != device::serial::ReceiveError::NONE) {
+  if (error != device::serial::ReceiveError::NONE) {
+    serial_log_ << "Read failed with error: " << error << "." << endl << endl;
+    EndReadBytes(false, BATTOR_MESSAGE_TYPE_CONTROL, nullptr);
+    return;
+  }
+
+  if (bytes_read == 0) {
     // If we didn't have a message before, and we weren't able to read any
     // additional bytes, then there's no valid message available.
+    serial_log_ << "Read failed due to no bytes being read." << endl << endl;
     EndReadBytes(false, BATTOR_MESSAGE_TYPE_CONTROL, nullptr);
     return;
   }
 
+  serial_log_ << bytes_read << " more bytes read: "
+              << CharVectorToString(
+                     vector<char>(pending_read_buffer_->data(),
+                                  pending_read_buffer_->data() + bytes_read))
+              << "." << endl
+              << endl;
+
   already_read_buffer_.insert(already_read_buffer_.end(),
                               pending_read_buffer_->data(),
                               pending_read_buffer_->data() + bytes_read);
@@ -185,14 +235,18 @@ void BattOrConnectionImpl::OnBytesRead(int bytes_read,
   bytes->reserve(GetMaxBytesForMessageType(pending_read_message_type_));
 
   if (!ParseMessage(&type, bytes.get())) {
-    // Even after reading the max number of bytes, we still don't have a valid
-    // message.
+    serial_log_ << "Read failed due to having no complete message after max "
+                   "read length."
+                << endl
+                << endl;

[nednguyen, 2016/05/12 15:44:29]

Let create a Log(const string& message) method instead of copy & paste the
format. In the future, we may add things like timestamp, etc...

     EndReadBytes(false, BATTOR_MESSAGE_TYPE_CONTROL, nullptr);
     return;
   }
 
   if (type != pending_read_message_type_) {
-    // We received a complete message, but it wasn't the type we were expecting.
+    serial_log_ << "Read failed due to receiving a message of the wrong type."
+                << endl
+                << endl;
     EndReadBytes(false, BATTOR_MESSAGE_TYPE_CONTROL, nullptr);
     return;
   }
@@ -200,10 +254,12 @@ void BattOrConnectionImpl::OnBytesRead(int bytes_read,
   EndReadBytes(true, type, std::move(bytes));
 }
 
-void BattOrConnectionImpl::EndReadBytes(
-    bool success,
-    BattOrMessageType type,
-    std::unique_ptr<std::vector<char>> bytes) {
+void BattOrConnectionImpl::EndReadBytes(bool success,
+                                        BattOrMessageType type,
+                                        std::unique_ptr<vector<char>> bytes) {
+  serial_log_ << "Read finished with success: " << success << "." << endl
+              << endl;
+
   pending_read_buffer_ = nullptr;
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,