Add RecordBatch encoding

CMakeLists.txt

@@ -450,6 +450,7 @@ if(NANOARROW_BUILD_TESTS)
     endforeach()
 
     target_link_libraries(nanoarrow_ipc_files_test nlohmann_json ZLIB::ZLIB)
+    target_link_libraries(nanoarrow_ipc_decoder_test gmock_main)
   endif()
 
   if(NANOARROW_DEVICE)

ci/scripts/bundle.py

@@ -205,6 +205,7 @@ def bundle_nanoarrow_ipc(
             src_dir / "ipc" / "decoder.c",
             src_dir / "ipc" / "encoder.c",
             src_dir / "ipc" / "reader.c",
+            src_dir / "ipc" / "encoder.c",
         ]
     )
     nanoarrow_ipc_c = nanoarrow_ipc_c.replace(

src/nanoarrow/ipc/decoder.c

@@ -1654,9 +1654,16 @@ static ArrowErrorCode ArrowIpcDecoderDecodeArrayViewInternal(
     return EINVAL;
   }
 
+  // RecordBatch messages don't count the root node but decoder->fields does
+  // (decoder->fields[0] is the root field)
+  if (field_i + 1 >= private_data->n_fields) {
+    ArrowErrorSet(error, "cannot decode column %" PRId64 "; there are only %" PRId64,
+                  field_i, private_data->n_fields - 1);
+    return EINVAL;
+  }
+
   ns(RecordBatch_table_t) batch = (ns(RecordBatch_table_t))private_data->last_message;
 
-  // RecordBatch messages don't count the root node but decoder->fields does
   struct ArrowIpcField* root = private_data->fields + field_i + 1;
 
   struct ArrowIpcArraySetter setter;

src/nanoarrow/ipc/decoder_test.cc

@@ -21,6 +21,7 @@
 #include <arrow/c/bridge.h>
 #include <arrow/ipc/api.h>
 #include <arrow/util/key_value_metadata.h>
+#include <gmock/gmock-matchers.h>
 #include <gtest/gtest.h>
 
 // For bswap32()
@@ -763,6 +764,132 @@ TEST_P(ArrowTypeParameterizedTestFixture, NanoarrowIpcArrowArrayRoundtrip) {
   ArrowIpcDecoderReset(&decoder);
 }
 
+struct ArrowArrayViewEqualTo {
+  const struct ArrowArrayView* expected;
+
+  using is_gtest_matcher = void;
+
+  bool MatchAndExplain(const struct ArrowArrayView* actual, std::ostream* os) const {
+    return MatchAndExplain({}, actual, expected, os);
+  }
+
+  static bool MatchAndExplain(std::vector<int> field_path,
+                              const struct ArrowArrayView* actual,
+                              const struct ArrowArrayView* expected, std::ostream* os) {
+    auto prefixed = [&]() -> std::ostream& {
+      if (!field_path.empty()) {
+        for (int i : field_path) {
+          *os << "." << i;
+        }
+        *os << ":";
+      }
+      return *os;
+    };
+
+    NANOARROW_DCHECK(actual->offset == 0);
+    NANOARROW_DCHECK(expected->offset == 0);
+
+    if (actual->length != expected->length) {
+      prefixed() << "expected length=" << expected->length << "\n";
+      prefixed() << "  actual length=" << actual->length << "\n";
+      return false;
+    }
+
+    auto null_count = [](const struct ArrowArrayView* a) {
+      return a->null_count != -1 ? a->null_count : ArrowArrayViewComputeNullCount(a);
+    };
+    if (null_count(actual) != null_count(expected)) {
+      prefixed() << "expected null_count=" << null_count(expected) << "\n";
+      prefixed() << "  actual null_count=" << null_count(actual) << "\n";
+      return false;
+    }
+
+    for (int64_t i = 0; actual->layout.buffer_type[i] != NANOARROW_BUFFER_TYPE_NONE &&
+                        i < NANOARROW_MAX_FIXED_BUFFERS;
+         ++i) {
+      auto a_buf = actual->buffer_views[i];
+      auto e_buf = expected->buffer_views[i];
+      if (a_buf.size_bytes != e_buf.size_bytes) {
+        prefixed() << "expected buffer[" << i << "].size=" << e_buf.size_bytes << "\n";
+        prefixed() << "  actual buffer[" << i << "].size=" << a_buf.size_bytes << "\n";
+        return false;
+      }
+      if (memcmp(a_buf.data.data, e_buf.data.data, a_buf.size_bytes) != 0) {
+        prefixed() << "expected buffer[" << i << "]'s data to match\n";
+        return false;
+      }
+    }
+
+    field_path.push_back(0);
+    for (int64_t i = 0; i < actual->n_children; ++i) {
+      field_path.back() = i;
+      if (!MatchAndExplain(field_path, actual->children[i], expected->children[i], os)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  void DescribeTo(std::ostream* os) const { *os << "is equivalent to the array view"; }
+  void DescribeNegationTo(std::ostream* os) const {
+    *os << "is not equivalent to the array view";
+  }
+};
+
+TEST_P(ArrowTypeParameterizedTestFixture, NanoarrowIpcNanoarrowArrayRoundtrip) {
+  struct ArrowError error;
+  nanoarrow::UniqueSchema schema;
+  ASSERT_TRUE(
+      arrow::ExportSchema(arrow::Schema({arrow::field("", GetParam())}), schema.get())
+          .ok());
+
+  // now make one empty struct array with this schema and another with all zeroes
+  nanoarrow::UniqueArray empty_array, zero_array;
+  for (auto* array : {empty_array.get(), zero_array.get()}) {
+    ASSERT_EQ(ArrowArrayInitFromSchema(array, schema.get(), nullptr), NANOARROW_OK);
+    ASSERT_EQ(ArrowArrayStartAppending(array), NANOARROW_OK);
+    if (array == zero_array.get()) {
+      ASSERT_EQ(ArrowArrayAppendEmpty(array, 5), NANOARROW_OK);
+    }
+    ASSERT_EQ(ArrowArrayFinishBuildingDefault(array, nullptr), NANOARROW_OK);
+
+    nanoarrow::UniqueArrayView array_view;
+    ASSERT_EQ(ArrowArrayViewInitFromSchema(array_view.get(), schema.get(), &error),
+              NANOARROW_OK);
+    ASSERT_EQ(ArrowArrayViewSetArray(array_view.get(), array, &error), NANOARROW_OK)
+        << error.message;
+
+    nanoarrow::ipc::UniqueEncoder encoder;
+    EXPECT_EQ(ArrowIpcEncoderInit(encoder.get()), NANOARROW_OK);
+
+    nanoarrow::UniqueBuffer buffer, body_buffer;
+    ArrowIpcEncoderBuildContiguousBodyBuffer(encoder.get(), body_buffer.get());
+    EXPECT_EQ(ArrowIpcEncoderEncodeRecordBatch(encoder.get(), array_view.get(), &error),
+              NANOARROW_OK)
+        << error.message;
+    EXPECT_EQ(
+        ArrowIpcEncoderFinalizeBuffer(encoder.get(), /*encapsulate=*/true, buffer.get()),
+        NANOARROW_OK);
+
+    nanoarrow::ipc::UniqueDecoder decoder;
+    ArrowIpcDecoderInit(decoder.get());
+    EXPECT_EQ(ArrowIpcDecoderSetSchema(decoder.get(), schema.get(), &error), NANOARROW_OK)
+        << error.message;
+    EXPECT_EQ(ArrowIpcDecoderDecodeHeader(decoder.get(),
+                                          {buffer->data, buffer->size_bytes}, &error),
+              NANOARROW_OK)
+        << error.message;
+
+    struct ArrowArrayView* roundtripped;
+    ASSERT_EQ(ArrowIpcDecoderDecodeArrayView(decoder.get(),
+                                             {body_buffer->data, body_buffer->size_bytes},
+                                             -1, &roundtripped, nullptr),
+              NANOARROW_OK);
+
+    EXPECT_THAT(roundtripped, ArrowArrayViewEqualTo{array_view.get()});
+  }
+}
+
 INSTANTIATE_TEST_SUITE_P(
     NanoarrowIpcTest, ArrowTypeParameterizedTestFixture,
     ::testing::Values(

src/nanoarrow/ipc/encoder.c

@@ -52,6 +52,9 @@ ArrowErrorCode ArrowIpcEncoderInit(struct ArrowIpcEncoder* encoder) {
   encoder->private_data = ArrowMalloc(sizeof(struct ArrowIpcEncoderPrivate));
   struct ArrowIpcEncoderPrivate* private =
       (struct ArrowIpcEncoderPrivate*)encoder->private_data;
+  if (private == NULL) {
+    return ENOMEM;
+  }
   if (flatcc_builder_init(&private->builder) == -1) {
     ArrowFree(private);
     return ESPIPE;
@@ -65,10 +68,12 @@ void ArrowIpcEncoderReset(struct ArrowIpcEncoder* encoder) {
   NANOARROW_DCHECK(encoder != NULL && encoder->private_data != NULL);
   struct ArrowIpcEncoderPrivate* private =
       (struct ArrowIpcEncoderPrivate*)encoder->private_data;
-  flatcc_builder_clear(&private->builder);
-  ArrowBufferReset(&private->nodes);
-  ArrowBufferReset(&private->buffers);
-  ArrowFree(private);
+  if (private != NULL) {
+    flatcc_builder_clear(&private->builder);
+    ArrowBufferReset(&private->nodes);
+    ArrowBufferReset(&private->buffers);
+    ArrowFree(private);
+  }
   memset(encoder, 0, sizeof(struct ArrowIpcEncoder));
 }
 
@@ -422,3 +427,139 @@ ArrowErrorCode ArrowIpcEncoderEncodeSchema(struct ArrowIpcEncoder* encoder,
   FLATCC_RETURN_UNLESS_0(Message_bodyLength_add(builder, 0));
   return ns(Message_end_as_root(builder)) ? NANOARROW_OK : ENOMEM;
 }
+
+static ArrowErrorCode ArrowIpcEncoderBuildContiguousBodyBufferCallback(
+    struct ArrowBufferView buffer_view, struct ArrowIpcEncoder* encoder, int64_t* offset,
+    int64_t* length, struct ArrowError* error) {
+  struct ArrowIpcEncoderPrivate* private =
+      (struct ArrowIpcEncoderPrivate*)encoder->private_data;
+  struct ArrowBuffer* body_buffer = (struct ArrowBuffer*)encoder->encode_buffer_state;
+
+  int compressed_buffer_header =
+      encoder->codec != NANOARROW_IPC_COMPRESSION_TYPE_NONE ? sizeof(int64_t) : 0;
+  int64_t old_size = body_buffer->size_bytes;
+  int64_t buffer_begin = _ArrowRoundUpToMultipleOf8(old_size);
+  int64_t buffer_end = buffer_begin + compressed_buffer_header + buffer_view.size_bytes;
+  int64_t new_size = _ArrowRoundUpToMultipleOf8(buffer_end);
+
+  // reserve all the memory we'll need now
+  NANOARROW_RETURN_NOT_OK(ArrowBufferReserve(body_buffer, new_size - old_size));
+
+  // zero padding up to the start of the buffer
+  NANOARROW_RETURN_NOT_OK(ArrowBufferAppendFill(body_buffer, 0, buffer_begin - old_size));
+
+  // store offset and length of the buffer
+  *offset = buffer_begin;
+  *length = buffer_view.size_bytes;
+
+  if (compressed_buffer_header) {
+    // Signal that the buffer is not compressed; eventually we will set this to the
+    // decompressed length of an actually compressed buffer.
+    NANOARROW_RETURN_NOT_OK(ArrowBufferAppendInt64(body_buffer, -1));
+  }
+  NANOARROW_RETURN_NOT_OK(
+      ArrowBufferAppend(body_buffer, buffer_view.data.data, buffer_view.size_bytes));
+
+  // zero padding after writing the buffer
+  NANOARROW_DCHECK(body_buffer->size_bytes == buffer_end);
+  NANOARROW_RETURN_NOT_OK(ArrowBufferAppendFill(body_buffer, 0, new_size - buffer_end));
+
+  encoder->body_length = body_buffer->size_bytes;
+  return NANOARROW_OK;
+}
+
+void ArrowIpcEncoderBuildContiguousBodyBuffer(struct ArrowIpcEncoder* encoder,
+                                              struct ArrowBuffer* body_buffer) {
+  NANOARROW_DCHECK(encoder != NULL && encoder->private_data != NULL &&
+                   body_buffer != NULL);
+  struct ArrowIpcEncoderPrivate* private =
+      (struct ArrowIpcEncoderPrivate*)encoder->private_data;
+  encoder->encode_buffer = &ArrowIpcEncoderBuildContiguousBodyBufferCallback;
+  encoder->encode_buffer_state = body_buffer;
+}
+
+static ArrowErrorCode ArrowIpcEncoderEncodeRecordBatchImpl(
+    struct ArrowIpcEncoder* encoder, const struct ArrowArrayView* array_view,
+    struct ArrowBuffer* buffers, struct ArrowBuffer* nodes, struct ArrowError* error) {
+  if (array_view->offset != 0) {
+    ArrowErrorSet(error, "Cannot encode arrays with nonzero offset");
+    return ENOTSUP;
+  }
+
+  for (int64_t c = 0; c < array_view->n_children; ++c) {
+    const struct ArrowArrayView* child = array_view->children[c];
+
+    struct ns(FieldNode) node = {child->length, child->null_count};
+    NANOARROW_RETURN_NOT_OK(ArrowBufferAppend(nodes, &node, sizeof(node)));
+
+    for (int64_t b = 0; b < child->array->n_buffers; ++b) {
+      struct ns(Buffer) buffer;
+      NANOARROW_RETURN_NOT_OK(encoder->encode_buffer(
+          child->buffer_views[b], encoder, &buffer.offset, &buffer.length, error));
+      NANOARROW_RETURN_NOT_OK(ArrowBufferAppend(buffers, &buffer, sizeof(buffer)));
+    }
+
+    NANOARROW_RETURN_NOT_OK(
+        ArrowIpcEncoderEncodeRecordBatchImpl(encoder, child, buffers, nodes, error));
+  }
+  return NANOARROW_OK;
+}
+
+ArrowErrorCode ArrowIpcEncoderEncodeRecordBatch(struct ArrowIpcEncoder* encoder,
+                                                const struct ArrowArrayView* array_view,
+                                                struct ArrowError* error) {
+  NANOARROW_DCHECK(encoder != NULL && encoder->private_data != NULL && schema != NULL);
+
+  if (array_view->null_count != 0 && ArrowArrayViewComputeNullCount(array_view) != 0) {
+    ArrowErrorSet(error,
+                  "RecordBatches cannot be constructed from arrays with top level nulls");
+    return EINVAL;
+  }
+
+  if (array_view->storage_type != NANOARROW_TYPE_STRUCT) {
+    ArrowErrorSet(
+        error,
+        "RecordBatches cannot be constructed from arrays of type other than struct");
+    return EINVAL;
+  }
+
+  if (!encoder->encode_buffer) {
+    ArrowErrorSet(error, "No encode_buffer behavior provided when encoding RecordBatch");
+    return EINVAL;
+  }
+
+  struct ArrowIpcEncoderPrivate* private =
+      (struct ArrowIpcEncoderPrivate*)encoder->private_data;
+
+  flatcc_builder_t* builder = &private->builder;
+
+  FLATCC_RETURN_UNLESS_0(Message_start_as_root(builder));
+  FLATCC_RETURN_UNLESS_0(Message_version_add(builder, ns(MetadataVersion_V5)));
+
+  encoder->body_length = 0;
+
+  FLATCC_RETURN_UNLESS_0(Message_header_RecordBatch_start(builder));
+  if (encoder->codec != NANOARROW_IPC_COMPRESSION_TYPE_NONE) {
+    FLATCC_RETURN_UNLESS_0(RecordBatch_compression_start(builder));
+    FLATCC_RETURN_UNLESS_0(BodyCompression_codec_add(builder, encoder->codec));
+    FLATCC_RETURN_UNLESS_0(RecordBatch_compression_end(builder));
+  }
+  FLATCC_RETURN_UNLESS_0(RecordBatch_length_add(builder, array_view->length));
+
+  ArrowBufferResize(&private->buffers, 0, 0);
+  ArrowBufferResize(&private->nodes, 0, 0);
+  NANOARROW_RETURN_NOT_OK(ArrowIpcEncoderEncodeRecordBatchImpl(
+      encoder, array_view, &private->buffers, &private->nodes, error));
+
+  FLATCC_RETURN_UNLESS_0(RecordBatch_nodes_create(  //
+      builder, (struct ns(FieldNode)*)private->nodes.data,
+      private->nodes.size_bytes / sizeof(struct ns(FieldNode))));
+  FLATCC_RETURN_UNLESS_0(RecordBatch_buffers_create(  //
+      builder, (struct ns(Buffer)*)private->buffers.data,
+      private->buffers.size_bytes / sizeof(struct ns(Buffer))));
+
+  FLATCC_RETURN_UNLESS_0(Message_header_RecordBatch_end(builder));
+
+  FLATCC_RETURN_UNLESS_0(Message_bodyLength_add(builder, encoder->body_length));
+  return ns(Message_end_as_root(builder)) ? NANOARROW_OK : ENOMEM;
+}

src/nanoarrow/ipc/ipc_hpp_test.cc

@@ -31,6 +31,18 @@ TEST(NanoarrowIpcHppTest, NanoarrowIpcHppTestUniqueDecoder) {
   EXPECT_EQ(decoder->private_data, nullptr);
 }
 
+TEST(NanoarrowIpcHppTest, NanoarrowIpcHppTestUniqueEncoder) {
+  nanoarrow::ipc::UniqueEncoder encoder;
+
+  EXPECT_EQ(encoder->private_data, nullptr);
+  ASSERT_EQ(ArrowIpcEncoderInit(encoder.get()), NANOARROW_OK);
+  EXPECT_NE(encoder->private_data, nullptr);
+
+  nanoarrow::ipc::UniqueEncoder encoder2 = std::move(encoder);
+  EXPECT_NE(encoder2->private_data, nullptr);
+  EXPECT_EQ(encoder->private_data, nullptr);
+}
+
 TEST(NanoarrowIpcHppTest, NanoarrowIpcHppTestUniqueInputStream) {
   nanoarrow::ipc::UniqueInputStream input;
   nanoarrow::UniqueBuffer buf;