Segment: Rework append_samples() so it can handle large input

Before, adding large blocks of samples didn't work if they
would fill the current chunk, fill a new one and still have
data left to add. Using an iterative approach fixes this and
also makes the function more elegant.

diff --git a/pv/data/segment.cpp b/pv/data/segment.cpp
index 433e7536bbf9cd973c3a2a5af4fec2666d12de1c..905b79274efeb6ee5ddebd7045348c5da85d9db3 100644 (file)
--- a/pv/data/segment.cpp
+++ b/pv/data/segment.cpp
@@ -135,35 +135,38 @@ void Segment::append_samples(void* data, uint64_t samples)
 {
        lock_guard<recursive_mutex> lock(mutex_);
 
-       if (unused_samples_ >= samples) {
-               // All samples fit into the current chunk
-               memcpy(current_chunk_ + (used_samples_ * unit_size_),
-                       data, (samples * unit_size_));
-               used_samples_ += samples;
-               unused_samples_ -= samples;
-       } else {
-               // Only a part of the samples fit, split data up between chunks
-               memcpy(current_chunk_ + (used_samples_ * unit_size_),
-                       data, (unused_samples_ * unit_size_));
-               const uint64_t remaining_samples = samples - unused_samples_;
-
-               // If we're out of memory, this will throw std::bad_alloc
-               current_chunk_ = new uint8_t[chunk_size_];
-               data_chunks_.push_back(current_chunk_);
-               memcpy(current_chunk_, (uint8_t*)data + (unused_samples_ * unit_size_),
-                       (remaining_samples * unit_size_));
-
-               used_samples_ = remaining_samples;
-               unused_samples_ = (chunk_size_ / unit_size_) - remaining_samples;
-       }
-
-       if (unused_samples_ == 0) {
-               // If we're out of memory, this will throw std::bad_alloc
-               current_chunk_ = new uint8_t[chunk_size_];
-               data_chunks_.push_back(current_chunk_);
-               used_samples_ = 0;
-               unused_samples_ = chunk_size_ / unit_size_;
-       }
+       const uint8_t* data_byte_ptr = (uint8_t*)data;
+       uint64_t remaining_samples = samples;
+       uint64_t data_offset = 0;
+
+       do {
+               uint64_t copy_count = 0;
+
+               if (remaining_samples <= unused_samples_) {
+                       // All samples fit into the current chunk
+                       copy_count = remaining_samples;
+               } else {
+                       // Only a part of the samples fit, fill up current chunk
+                       copy_count = unused_samples_;
+               }
+
+               const uint8_t* dest = &(current_chunk_[used_samples_ * unit_size_]);
+               const uint8_t* src = &(data_byte_ptr[data_offset]);
+               memcpy((void*)dest, (void*)src, (copy_count * unit_size_));
+
+               used_samples_ += copy_count;
+               unused_samples_ -= copy_count;
+               remaining_samples -= copy_count;
+               data_offset += (copy_count * unit_size_);
+
+               if (unused_samples_ == 0) {
+                       // If we're out of memory, this will throw std::bad_alloc
+                       current_chunk_ = new uint8_t[chunk_size_];
+                       data_chunks_.push_back(current_chunk_);
+                       used_samples_ = 0;
+                       unused_samples_ = chunk_size_ / unit_size_;
+               }
+       } while (remaining_samples > 0);
 
        sample_count_ += samples;
 }