Implement common class for RamBuffer

core-buffer/src/RamBuffer.cpp

@@ -0,0 +1,66 @@
+#include <sys/mman.h>
+#include <bits/fcntl-linux.h>
+#include <cstring>
+#include <stdexcept>
+#include <unistd.h>
+#include "RamBuffer.hpp"
+#include "buffer_config.hpp"
+
+using namespace std;
+using namespace buffer_config;
+
+RamBuffer::RamBuffer(
+        const string &detector_name,
+        const size_t n_modules,
+        const int module_n,
+        const size_t n_slots) :
+        detector_name_(detector_name),
+        module_n_(module_n),
+        n_slots_(n_slots),
+        image_size_(MODULE_N_BYTES * n_modules),
+        buffer_size_((sizeof(ModuleFrame) + image_size_) * n_slots)
+{
+    shm_fd_ = shm_open(detector_name_.c_str(), O_RDWR | O_CREAT, 0777);
+    if (shm_fd_ < 0) {
+        throw runtime_error(strerror(errno));
+    }
+
+    if ((ftruncate(shm_fd_, buffer_size_)) == -1) {
+        throw runtime_error(strerror(errno));
+    }
+
+    // TODO: Test with MAP_HUGETLB
+    buffer_ = mmap(NULL, buffer_size_, PROT_WRITE, MAP_SHARED, shm_fd_, 0);
+    if (buffer_ == MAP_FAILED) {
+        throw runtime_error(strerror(errno));
+    }
+
+    meta_buffer_ = (ModuleFrame *) buffer_;
+    // Image buffer start right after metadata buffer.
+    image_buffer_ = (char *) (meta_buffer_ + n_slots);
+}
+
+RamBuffer::~RamBuffer()
+{
+    munmap(buffer_, buffer_size_);
+    close(shm_fd_);
+    shm_unlink(detector_name_.c_str());
+
+}
+
+void RamBuffer::write_frame(
+        const ModuleFrame &metadata,
+        const char *data)
+{
+    size_t slot_n = metadata.pulse_id % n_slots_;
+
+    ModuleFrame *meta = meta_buffer_ + slot_n;
+    *meta = metadata;
+
+    char *frame = image_buffer_ +
+                  (image_size_ * slot_n) +
+                  (MODULE_N_BYTES * module_n_);
+
+    memcpy(frame, data, MODULE_N_BYTES);
+}
+