Expose length of valid data in segment chunk

[pulseview.git] / pv / data / segment.cpp

diff --git a/pv/data/segment.cpp b/pv/data/segment.cpp
index 9b18c6499a1b32cf03362dc67e835f410acb9159..ef555292a61a902fbea973298008f0c0bbcd89d3 100644 (file)
--- a/pv/data/segment.cpp
+++ b/pv/data/segment.cpp
@@ -24,6 +24,9 @@
 #include <cstdlib>
 #include <cstring>
 
+#include <QDebug>
+
+using std::bad_alloc;
 using std::lock_guard;
 using std::min;
 using std::recursive_mutex;
@@ -51,7 +54,7 @@ Segment::Segment(uint32_t segment_id, uint64_t samplerate, unsigned int unit_siz
        chunk_size_ = min(MaxChunkSize, (MaxChunkSize / unit_size_) * unit_size_);
 
        // Create the initial chunk
-       current_chunk_ = new uint8_t[chunk_size_];
+       current_chunk_ = new uint8_t[chunk_size_ + 7];  /* FIXME +7 is workaround for #1284 */
        data_chunks_.push_back(current_chunk_);
        used_samples_ = 0;
        unused_samples_ = chunk_size_ / unit_size_;
@@ -116,15 +119,17 @@ void Segment::free_unused_memory()
                return;
        }
 
-       // No more data will come in, so re-create the last chunk accordingly
-       uint8_t* resized_chunk = new uint8_t[used_samples_ * unit_size_];
-       memcpy(resized_chunk, current_chunk_, used_samples_ * unit_size_);
+       if (current_chunk_) {
+               // No more data will come in, so re-create the last chunk accordingly
+               uint8_t* resized_chunk = new uint8_t[used_samples_ * unit_size_ + 7];  /* FIXME +7 is workaround for #1284 */
+               memcpy(resized_chunk, current_chunk_, used_samples_ * unit_size_);
 
-       delete[] current_chunk_;
-       current_chunk_ = resized_chunk;
+               delete[] current_chunk_;
+               current_chunk_ = resized_chunk;
 
-       data_chunks_.pop_back();
-       data_chunks_.push_back(resized_chunk);
+               data_chunks_.pop_back();
+               data_chunks_.push_back(resized_chunk);
+       }
 }
 
 void Segment::append_single_sample(void *data)
@@ -139,7 +144,7 @@ void Segment::append_single_sample(void *data)
        unused_samples_--;
 
        if (unused_samples_ == 0) {
-               current_chunk_ = new uint8_t[chunk_size_];
+               current_chunk_ = new uint8_t[chunk_size_ + 7];  /* FIXME +7 is workaround for #1284 */
                data_chunks_.push_back(current_chunk_);
                used_samples_ = 0;
                unused_samples_ = chunk_size_ / unit_size_;
@@ -177,8 +182,26 @@ void Segment::append_samples(void* data, uint64_t samples)
                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_];
+                       try {
+                               // If we're out of memory, allocating a chunk will throw
+                               // std::bad_alloc. To give the application some usable memory
+                               // to work with in case chunk allocation fails, we allocate
+                               // extra memory and throw it away if it all succeeded.
+                               // This way, memory allocation will fail early enough to let
+                               // PV remain alive. Otherwise, PV will crash in a random
+                               // memory-allocating part of the application.
+                               current_chunk_ = new uint8_t[chunk_size_ + 7];  /* FIXME +7 is workaround for #1284 */
+
+                               const int dummy_size = 2 * chunk_size_;
+                               auto dummy_chunk = new uint8_t[dummy_size];
+                               memset(dummy_chunk, 0xFF, dummy_size);
+                               delete[] dummy_chunk;
+                       } catch (bad_alloc&) {
+                               delete[] current_chunk_;  // The new may have succeeded
+                               current_chunk_ = nullptr;
+                               throw;
+                       }
+
                        data_chunks_.push_back(current_chunk_);
                        used_samples_ = 0;
                        unused_samples_ = chunk_size_ / unit_size_;
@@ -219,9 +242,9 @@ void Segment::get_raw_samples(uint64_t start, uint64_t count,
        }
 }
 
-SegmentRawDataIterator* Segment::begin_raw_sample_iteration(uint64_t start)
+SegmentDataIterator* Segment::begin_sample_iteration(uint64_t start)
 {
-       SegmentRawDataIterator* it = new SegmentRawDataIterator;
+       SegmentDataIterator* it = new SegmentDataIterator;
 
        assert(start < sample_count_);
 
@@ -231,17 +254,12 @@ SegmentRawDataIterator* Segment::begin_raw_sample_iteration(uint64_t start)
        it->chunk_num = (start * unit_size_) / chunk_size_;
        it->chunk_offs = (start * unit_size_) % chunk_size_;
        it->chunk = data_chunks_[it->chunk_num];
-       it->value = it->chunk + it->chunk_offs;
 
        return it;
 }
 
-void Segment::continue_raw_sample_iteration(SegmentRawDataIterator* it, uint64_t increase)
+void Segment::continue_sample_iteration(SegmentDataIterator* it, uint64_t increase)
 {
-       // Fail gracefully if we are asked to deliver data we don't have
-       if (it->sample_index > sample_count_)
-               return;
-
        it->sample_index += increase;
        it->chunk_offs += (increase * unit_size_);
 
@@ -250,11 +268,9 @@ void Segment::continue_raw_sample_iteration(SegmentRawDataIterator* it, uint64_t
                it->chunk_offs -= chunk_size_;
                it->chunk = data_chunks_[it->chunk_num];
        }
-
-       it->value = it->chunk + it->chunk_offs;
 }
 
-void Segment::end_raw_sample_iteration(SegmentRawDataIterator* it)
+void Segment::end_sample_iteration(SegmentDataIterator* it)
 {
        delete it;
 
@@ -266,5 +282,20 @@ void Segment::end_raw_sample_iteration(SegmentRawDataIterator* it)
        }
 }
 
+uint8_t* Segment::get_iterator_value(SegmentDataIterator* it)
+{
+       assert(it->sample_index <= (sample_count_ - 1));
+
+       return (it->chunk + it->chunk_offs);
+}
+
+uint64_t Segment::get_iterator_valid_length(SegmentDataIterator* it)
+{
+       assert(it->sample_index <= (sample_count_ - 1));
+
+       return ((chunk_size_ - it->chunk_offs) / unit_size_);
+}
+
+
 } // namespace data
 } // namespace pv