Serialization backwards compatiblity w/buffer size

This adds proper server side conditional handling for buffer sizes. In
the original patch in [#2115](#2115)
support was added for sending original user requested buffers.
Compatibility was maintained for clients, but the server path missed
handling the older clients in the deserialization path.

HISTORY.md

@@ -18,7 +18,7 @@
 ## Bug fixes
 
 * Corrected a bug where sparse cells may be incorrectly returned using string dimensions. [#2125](https://github.com/TileDB-Inc/TileDB/pull/2125)
-* Always use original buffer size in serialized read queries serverside. [#2115](https://github.com/TileDB-Inc/TileDB/pull/2115)
+* Always use original buffer size in serialized read queries serverside. [#2115](https://github.com/TileDB-Inc/TileDB/pull/2115) [#2128](https://github.com/TileDB-Inc/TileDB/pull/2128)
 * Fix segfault in serialized queries when partition is unsplittable [#2120](https://github.com/TileDB-Inc/TileDB/pull/2120)
 
 ## API additions

tiledb/sm/serialization/query.cc

@@ -678,7 +678,7 @@ Status query_from_capnp(
       // We use the query_buffer directly in order to get the original buffer
       // sizes This avoid a problem where an incomplete query will change the
       // users buffer size to the smaller results and we end up not being able
-      // to correctly calcuate if the new results can fit into the users buffer
+      // to correctly calculate if the new results can fit into the users buffer
       if (var_size) {
         if (!nullable) {
           existing_offset_buffer = static_cast<uint64_t*>(query_buffer.buffer_);
@@ -707,7 +707,7 @@ Status query_from_capnp(
         }
       }
     } else {
-      // For writes we need to use get_buffer
+      // For writes we need to use get_buffer and clientside
       if (var_size) {
         if (!nullable) {
           RETURN_NOT_OK(query->get_buffer(
@@ -904,12 +904,30 @@ Status query_from_capnp(
         // submit's result size not the original user set buffer size. To work
         // around this we revert the server to always use the full original user
         // requested buffer sizes.
-        attr_state->fixed_len_size =
-            buffer_header.getOriginalFixedLenBufferSizeInBytes();
-        attr_state->var_len_size =
-            buffer_header.getOriginalVarLenBufferSizeInBytes();
-        attr_state->validity_len_size =
-            buffer_header.getOriginalValidityLenBufferSizeInBytes();
+        // We check for > 0 for fallback for clients older than 2.2.5
+        if (buffer_header.getOriginalFixedLenBufferSizeInBytes() > 0) {
+          attr_state->fixed_len_size =
+              buffer_header.getOriginalFixedLenBufferSizeInBytes();
+        } else {
+          attr_state->fixed_len_size =
+              buffer_header.getFixedLenBufferSizeInBytes();
+        }
+
+        if (buffer_header.getOriginalVarLenBufferSizeInBytes() > 0) {
+          attr_state->var_len_size =
+              buffer_header.getOriginalVarLenBufferSizeInBytes();
+        } else {
+          attr_state->var_len_size = buffer_header.getVarLenBufferSizeInBytes();
+        }
+
+        if (buffer_header.getOriginalValidityLenBufferSizeInBytes() > 0) {
+          attr_state->validity_len_size =
+              buffer_header.getOriginalValidityLenBufferSizeInBytes();
+        } else {
+          attr_state->validity_len_size =
+              buffer_header.getValidityLenBufferSizeInBytes();
+        }
+
         attr_state->fixed_len_data.swap(offsets_buff);
         attr_state->var_len_data.swap(varlen_buff);
         attr_state->validity_len_data.swap(validitylen_buff);