[Lldb-commits] [PATCH] D112169: [lldb] [Communication] Add a WriteAll() method that resumes writing

[Michał Górny via Phabricator via lldb-commits]

mgorny updated this revision to Diff 381063.
mgorny added a comment.

clang-format


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112169/new/

https://reviews.llvm.org/D112169

Files:
  lldb/include/lldb/Core/Communication.h
  lldb/source/Core/Communication.cpp
  lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp


Index: lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -101,7 +101,7 @@
   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
   ConnectionStatus status = eConnectionStatusSuccess;
   char ch = '+';
-  const size_t bytes_written = Write(&ch, 1, status, nullptr);
+  const size_t bytes_written = WriteAll(&ch, 1, status, nullptr);
   LLDB_LOGF(log, "<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
   m_history.AddPacket(ch, GDBRemotePacket::ePacketTypeSend, bytes_written);
   return bytes_written;
@@ -111,7 +111,7 @@
   Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PACKETS));
   ConnectionStatus status = eConnectionStatusSuccess;
   char ch = '-';
-  const size_t bytes_written = Write(&ch, 1, status, nullptr);
+  const size_t bytes_written = WriteAll(&ch, 1, status, nullptr);
   LLDB_LOGF(log, "<%4" PRIu64 "> send packet: %c", (uint64_t)bytes_written, ch);
   m_history.AddPacket(ch, GDBRemotePacket::ePacketTypeSend, bytes_written);
   return bytes_written;
@@ -137,7 +137,7 @@
     ConnectionStatus status = eConnectionStatusSuccess;
     const char *packet_data = packet.data();
     const size_t packet_length = packet.size();
-    size_t bytes_written = Write(packet_data, packet_length, status, nullptr);
+    size_t bytes_written = WriteAll(packet_data, packet_length, status, nullptr);
     if (log) {
       size_t binary_start_offset = 0;
       if (strncmp(packet_data, "$vFile:pwrite:", strlen("$vFile:pwrite:")) ==
Index: lldb/source/Core/Communication.cpp
===================================================================
--- lldb/source/Core/Communication.cpp
+++ lldb/source/Core/Communication.cpp
@@ -26,6 +26,7 @@
 #include <chrono>
 #include <cstring>
 #include <memory>
+#include <thread>
 
 #include <cerrno>
 #include <cinttypes>
@@ -189,6 +190,23 @@
   return 0;
 }
 
+size_t Communication::WriteAll(const void *src, size_t src_len,
+                               ConnectionStatus &status, Status *error_ptr) {
+  size_t total_written = 0;
+  while (1) {
+    size_t written = Write(static_cast<const char *>(src) + total_written,
+                           src_len - total_written, status, error_ptr);
+    total_written += written;
+    if (status != eConnectionStatusSuccess || total_written >= src_len)
+      break;
+    // sleep a short while to avoid wasting CPU cycles while we are unlikely
+    // to be able to write again immediately
+    // FIXME: improve this to use select()
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  }
+  return total_written;
+}
+
 bool Communication::StartReadThread(Status *error_ptr) {
   if (error_ptr)
     error_ptr->Clear();
Index: lldb/include/lldb/Core/Communication.h
===================================================================
--- lldb/include/lldb/Core/Communication.h
+++ lldb/include/lldb/Core/Communication.h
@@ -209,6 +209,22 @@
   size_t Write(const void *src, size_t src_len, lldb::ConnectionStatus &status,
                Status *error_ptr);
 
+  /// Repeatedly attempt writing until either \a src_len bytes are written
+  /// or a permanent failure occurs.
+  ///
+  /// \param[in] src
+  ///     A source buffer that must be at least \a src_len bytes
+  ///     long.
+  ///
+  /// \param[in] src_len
+  ///     The number of bytes to attempt to write, and also the
+  ///     number of bytes are currently available in \a src.
+  ///
+  /// \return
+  ///     The number of bytes actually Written.
+  size_t WriteAll(const void *src, size_t src_len,
+                  lldb::ConnectionStatus &status, Status *error_ptr);
+
   /// Sets the connection that it to be used by this class.
   ///
   /// By making a communication class that uses different connections it


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