From 59a5edd9eb78a93faa6505984260de4fa11c1147 Mon Sep 17 00:00:00 2001
From: Andrej Babic <andrej.babic@psi.ch>
Date: Mon, 27 Apr 2020 16:05:21 +0200
Subject: [PATCH] Add naive buffer implementation

---
 core-buffer/include/SFWriter.hpp      |  3 ++
 core-buffer/include/buffer_config.hpp |  3 ++
 core-buffer/src/SFWriter.cpp          | 53 ++++++++++++++++++---------
 3 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/core-buffer/include/SFWriter.hpp b/core-buffer/include/SFWriter.hpp
index b8fd593..5ea6900 100644
--- a/core-buffer/include/SFWriter.hpp
+++ b/core-buffer/include/SFWriter.hpp
@@ -20,6 +20,9 @@ class SFWriter {
     H5::DataSet daq_rec_dataset_;
     H5::DataSet n_received_packets_dataset_;
 
+    std::unique_ptr<char[]> image_buffer_;
+    size_t image_buffer_count_;
+
 public:
     SFWriter(
             const std::string& output_file,
diff --git a/core-buffer/include/buffer_config.hpp b/core-buffer/include/buffer_config.hpp
index f5bec4a..c43e1e5 100644
--- a/core-buffer/include/buffer_config.hpp
+++ b/core-buffer/include/buffer_config.hpp
@@ -29,6 +29,9 @@ namespace core_buffer {
     const size_t BUFFER_RB_SIZE = 1000;
 
     const int WRITER_ZMQ_IO_THREADS = 16;
+
+    // How many frames to buffer before flushing to file.
+    const size_t WRITER_BUFFER_SIZE = 100;
 }
 
 #endif //BUFFERCONFIG_HPP
diff --git a/core-buffer/src/SFWriter.cpp b/core-buffer/src/SFWriter.cpp
index 2ab8328..1f9f12c 100644
--- a/core-buffer/src/SFWriter.cpp
+++ b/core-buffer/src/SFWriter.cpp
@@ -15,7 +15,8 @@ SFWriter::SFWriter(
         const size_t n_modules) :
         n_frames_(n_frames),
         n_modules_(n_modules),
-        current_write_index_(0)
+        current_write_index_(0),
+        image_buffer_count_(0)
 {
     file_ = H5::H5File(output_file, H5F_ACC_TRUNC);
 
@@ -57,6 +58,10 @@ SFWriter::SFWriter(
             "n_received_packets",
             H5::PredType::NATIVE_UINT16,
             metadata_dataspace);
+
+    image_buffer_ = make_unique<char[]>(
+            n_modules_ * MODULE_N_BYTES * WRITER_BUFFER_SIZE);
+    image_buffer_count_ = 0;
 }
 
 SFWriter::~SFWriter()
@@ -95,24 +100,36 @@ void SFWriter::write(shared_ptr<DetectorFrame> metadata, char* data) {
 //            buffer_space,
 //            disk_space);
 
-    hsize_t offset[] = {current_write_index_, 0, 0};
+    if (image_buffer_count_ < WRITER_BUFFER_SIZE) {
+        char* buffer = image_buffer_.get();
 
-    if( H5DOwrite_chunk(
-            image_dataset_.getId(),
-            H5P_DEFAULT,
-            0,
-            offset,
-            MODULE_N_BYTES * n_modules_,
-            data))
-    {
-        stringstream error_message;
-        using namespace date;
-        error_message << "[" << std::chrono::system_clock::now() << "]";
-        error_message << "Error while writing data to file at offset ";
-        error_message << current_write_index_ << "." << endl;
+        memcpy(
+                (buffer + image_buffer_count_),
+                data,
+                MODULE_N_BYTES * n_modules_);
 
-        throw runtime_error(error_message.str());
+        image_buffer_count_++;
+    } else {
+        hsize_t offset[] = {current_write_index_, 0, 0};
+
+        if( H5DOwrite_chunk(
+                image_dataset_.getId(),
+                H5P_DEFAULT,
+                0,
+                offset,
+                MODULE_N_BYTES * n_modules_ * WRITER_BUFFER_SIZE,
+                image_buffer_.get()))
+        {
+            stringstream error_message;
+            using namespace date;
+            error_message << "[" << std::chrono::system_clock::now() << "]";
+            error_message << "Error while writing data to file at offset ";
+            error_message << current_write_index_ << "." << endl;
+
+            throw runtime_error(error_message.str());
+        }
+
+        current_write_index_ += WRITER_BUFFER_SIZE;
+        image_buffer_count_ = 0;
     }
-
-    current_write_index_++;
 }