add support for transferring data ownership to Bytes via custom delet…

…er (#335)

* add support for transferring data ownership to Bytes via custom deleter

* mention that deleter should be a thread safe

include/zenoh/api/bytes.hxx

@@ -98,6 +98,24 @@ class Bytes : public Owned<::z_owned_bytes_t> {
                            detail::closures::_zenoh_drop_with_context, drop);
     }
 
+    /// @brief Construct by taking ownership of sequence of bytes.
+    /// @tparam Deleter callable with signature void Deleter(uint8_t*).
+    /// @param ptr pointer to data.
+    /// @param len number of bytes to consider.
+    /// @param deleter a thread-safe delete function to be invoked once corresponding ``Bytes`` object and all of its
+    /// clones are destroyed.
+    template <class Deleter>
+    Bytes(uint8_t* ptr, size_t len, Deleter deleter) : Bytes() {
+        static_assert(std::is_invocable_r<void, Deleter, uint8_t*>::value,
+                      "deleter should be callable with the following signature: void deleter(uint8_t* data)");
+        auto d = [p = ptr, del = std::move(deleter)]() mutable { del(p); };
+        using D = decltype(d);
+        using Dval = std::remove_reference_t<D>;
+        using DroppableType = typename detail::closures::Droppable<Dval>;
+        auto drop = DroppableType::into_context(std::forward<D>(d));
+        ::z_bytes_from_buf(interop::as_owned_c_ptr(*this), ptr, len, detail::closures::_zenoh_drop_with_context, drop);
+    }
+
     /// @brief Construct a shallow copy of this data.
     Bytes clone() const {
         Bytes b;

tests/universal/bytes.cxx

@@ -21,7 +21,6 @@
 using namespace zenoh;
 
 void reader_writer() {
-    std::cout << "running reader_writer\n";
     std::vector<uint8_t> data = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
     Bytes::Writer writer;
     writer.write_all(data.data(), 5);
@@ -39,7 +38,6 @@ void reader_writer() {
 }
 
 void reader_seek_tell() {
-    std::cout << "running reader_seek_tell\n";
     std::vector<uint8_t> data = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
     Bytes::Writer writer;
     writer.write_all(data.data(), 5);
@@ -73,7 +71,6 @@ void reader_seek_tell() {
 }
 
 void reader_writer_append() {
-    std::cout << "running reader_writer_append\n";
     std::vector<uint8_t> data = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
     std::vector<uint8_t> data2 = {11, 12, 13, 14};
     Bytes b, b2;
@@ -116,9 +113,28 @@ void from_into() {
     assert(bs2.as_string() == s);
 }
 
+void custom_deleter() {
+    uint8_t* ptr = new uint8_t[10];
+    for (size_t i = 0; i < 10; i++) {
+        ptr[i] = i;
+    }
+
+    bool deleted = false;
+    auto deleter = [&deleted](uint8_t* data) {
+        deleted = true;
+        delete[] data;
+    };
+    {
+        Bytes b(ptr, 10, deleter);
+        assert(b.as_vector() == std::vector<uint8_t>(ptr, ptr + 10));
+    }
+    assert(deleted);
+}
+
 int main(int argc, char** argv) {
     reader_writer();
     reader_seek_tell();
     reader_writer_append();
     from_into();
+    custom_deleter();
 }