disable zero copy partial write combined with multibuffering (#1163)

ecal/core/src/io/ecal_memfile.cpp

@@ -314,15 +314,15 @@ namespace eCAL
     }
   }
 
-  size_t CMemoryFile::WritePayload(CPayloadWriter& payload_, const size_t len_, const size_t offset_)
+  size_t CMemoryFile::WritePayload(CPayloadWriter& payload_, const size_t len_, const size_t offset_, bool force_full_write_ /*= false*/)
   {
     if (!m_created) return(0);
 
     void* wbuf(nullptr);
     if (GetWriteAddress(wbuf, len_ + offset_) != 0u)
     {
       // (re)write complete buffer
-      if (!m_payload_initialized)
+      if (!m_payload_initialized || force_full_write_)
       {
         bool const success = payload_.Write(static_cast<char*>(wbuf) + offset_, len_);
         if (!success)

ecal/core/src/io/ecal_memfile.h

@@ -147,13 +147,14 @@ namespace eCAL
     /**
      * @brief Apply payload on the memory file.
      *
-     * @param payload_  The payload.
-     * @param len_      The number of bytes to write.
-     * @param offset_   The offset for writing the data.
+     * @param payload_            The payload.
+     * @param len_                The number of bytes to write.
+     * @param offset_             The offset for writing the data.
+     * @param force_full_write_   Force full write action.
      *
-     * @return          Number of bytes access (len if succeeded otherwise zero).
+     * @return          Number of bytes accessed (len if succeeded otherwise zero).
     **/
-    size_t WritePayload(CPayloadWriter& payload_, size_t len_, size_t offset_);
+    size_t WritePayload(CPayloadWriter& payload_, size_t len_, size_t offset_, bool force_full_write_ = false);
 
     /**
      * @brief Maximum data size of the whole memory file.

ecal/core/src/io/ecal_memfile_sync.cpp

@@ -129,7 +129,7 @@ namespace eCAL
     return false;
   }
 
-  bool CSyncMemoryFile::Write(CPayloadWriter& payload_, const SWriterAttr& data_)
+  bool CSyncMemoryFile::Write(CPayloadWriter& payload_, const SWriterAttr& data_, bool force_full_write_/* = false*/)
   {
     if (!m_created)
     {
@@ -197,7 +197,7 @@ namespace eCAL
     // write the buffer
     if (data_.len > 0)
     {
-      written &= m_memfile.WritePayload(payload_, data_.len, wbytes) > 0;
+      written &= m_memfile.WritePayload(payload_, data_.len, wbytes, force_full_write_) > 0;
     }
     // release write access
     m_memfile.ReleaseWriteAccess();

ecal/core/src/io/ecal_memfile_sync.h

@@ -53,7 +53,7 @@ namespace eCAL
     bool Disconnect(const std::string& process_id_);
 
     bool CheckSize(size_t size_);
-    bool Write(CPayloadWriter& payload_, const SWriterAttr& data_);
+    bool Write(CPayloadWriter& payload_, const SWriterAttr& data_, bool force_full_write_ = false);
 
     std::string GetName() const;
     size_t GetSize() const;

ecal/core/src/readwrite/ecal_writer_shm.cpp

@@ -103,12 +103,17 @@ namespace eCAL
 
   bool CDataWriterSHM::SetBufferCount(size_t buffer_count_)
   {
+    // no need to adapt anything
+    if (m_memory_file_vec.size() == buffer_count_) return true;
+
+    // buffer count zero not allowed
     if (buffer_count_ < 1)
     {
       Logging::Log(log_level_error, m_topic_name + "::CDataWriterSHM::SetBufferCount minimal number of memory files is 1 !");
       return false;
     }
 
+    // retrieve the memory file size of existing files
     size_t memory_file_size(0);
     if (!m_memory_file_vec.empty())
     {
@@ -119,37 +124,14 @@ namespace eCAL
       memory_file_size = m_memory_file_attr.min_size;
     }
 
-    // ----------------------------------------------------------------------
-    // REMOVE ME IN ECAL6
-    // ----------------------------------------------------------------------
-    // recreate memory buffer list to stay compatible to older versions
-    // for the case that we have ONE existing buffer
-    // and that single buffer is communicated with an older shm datareader
-    // in this case we need to invalidate (destroy) the existing buffer
-    // and the old datareader will get blind (fail safe)
-    // otherwise it would still receive every n-th write
-    // this state change will lead to some lost samples
-    if ((m_memory_file_vec.size() == 1) && (m_memory_file_vec.size() < buffer_count_))
-    {
-      m_memory_file_vec.clear();
-    }
-    // ----------------------------------------------------------------------
-    // REMOVE ME IN ECAL6
-    // ----------------------------------------------------------------------
-
-    // increase buffer count
+    // recreate memory file vector
+    m_memory_file_vec.clear();
     while (m_memory_file_vec.size() < buffer_count_)
     {
       auto sync_memfile = std::make_shared<CSyncMemoryFile>(m_memfile_base_name, memory_file_size, m_memory_file_attr);
       m_memory_file_vec.push_back(sync_memfile);
     }
 
-    // decrease buffer count
-    while (m_memory_file_vec.size() > buffer_count_)
-    {
-      m_memory_file_vec.pop_back();
-    }
-
     return true;
   }
 
@@ -185,7 +167,8 @@ namespace eCAL
     if (!m_created) return false;
 
     // write content
-    const bool sent = m_memory_file_vec[m_write_idx]->Write(payload_, attr_);
+    const bool force_full_write(m_memory_file_vec.size() > 1);
+    const bool sent = m_memory_file_vec[m_write_idx]->Write(payload_, attr_, force_full_write);
 
     // and increment file index
     m_write_idx++;

testing/ecal/pubsub_test/CMakeLists.txt

@@ -23,6 +23,7 @@ find_package(GTest REQUIRED)
 
 set(pubsub_test_src
   src/pubsub_gettopics.cpp
+  src/pubsub_multibuffer
   src/pubsub_test.cpp
   src/pubsub_receive_test.cpp
 )