Merge seastar upstream

* seastar 2b55789...5b7252d (3):
  > Merge "rpc: serialize large messages into fragmented memory" from Gleb
  > Merge "Print backtrace on SIGSEGV and SIGABRT" from Tomasz
  > test_runner: avoid nested optionals

Includes patch from Gleb to adapt to seastar changes.

bytes_ostream.hh

@@ -174,7 +174,7 @@ public:
         value_type* ptr;
         // makes the place_holder looks like a stream
         seastar::simple_output_stream get_stream() {
-            return seastar::simple_output_stream{reinterpret_cast<char*>(ptr)};
+            return seastar::simple_output_stream(reinterpret_cast<char*>(ptr), sizeof(T));
         }
     };
 

db/commitlog/commitlog_entry.cc

@@ -73,7 +73,7 @@ void commitlog_entry_writer::compute_size() {
 }
 
 void commitlog_entry_writer::write(data_output& out) const {
-    seastar::simple_output_stream str(out.reserve(size()));
+    seastar::simple_output_stream str(out.reserve(size()), size());
     ser::serialize(str, get_entry());
 }
 

serializer.hh

@@ -101,14 +101,11 @@ inline void skip(Input& v, boost::type<T>) {
 template<typename T>
 size_type get_sizeof(const T& obj);
 
-template<typename T>
-void set_size(seastar::simple_output_stream& os, const T& obj);
-
 template<typename T>
 void set_size(seastar::measuring_output_stream& os, const T& obj);
 
-template<typename T>
-void set_size(bytes_ostream& os, const T& obj);
+template<typename Stream, typename T>
+void set_size(Stream& os, const T& obj);
 
 template<typename Buffer, typename T>
 Buffer serialize_to_buffer(const T& v, size_t head_space = 0);

serializer_impl.hh

@@ -24,18 +24,13 @@
 #include "serializer.hh"
 namespace ser {
 
-template<typename T>
-void set_size(seastar::simple_output_stream& os, const T& obj) {
-    serialize(os, get_sizeof(obj));
-}
-
 template<typename T>
 void set_size(seastar::measuring_output_stream& os, const T& obj) {
     serialize(os, uint32_t(0));
 }
 
-template<typename T>
-void set_size(bytes_ostream& os, const T& obj) {
+template<typename Stream, typename T>
+void set_size(Stream& os, const T& obj) {
     serialize(os, get_sizeof(obj));
 }
 
@@ -260,9 +255,9 @@ struct serializer<std::map<K, V>> {
 
 template<typename Iterator>
 class deserialized_bytes_proxy {
-    seastar::memory_stream<Iterator> _stream;
+    seastar::memory_input_stream<Iterator> _stream;
 public:
-    explicit deserialized_bytes_proxy(seastar::memory_stream<Iterator> stream)
+    explicit deserialized_bytes_proxy(seastar::memory_input_stream<Iterator> stream)
         : _stream(std::move(stream)) { }
 
     [[gnu::always_inline]]
@@ -440,7 +435,7 @@ Buffer serialize_to_buffer(const T& v, size_t head_space) {
     seastar::measuring_output_stream measure;
     ser::serialize(measure, v);
     Buffer ret(typename Buffer::initialized_later(), measure.size() + head_space);
-    seastar::simple_output_stream out(reinterpret_cast<char*>(ret.begin()), head_space);
+    seastar::simple_output_stream out(reinterpret_cast<char*>(ret.begin()), ret.size(), head_space);
     ser::serialize(out, v);
     return ret;
 }

utils/input_stream.hh

@@ -26,6 +26,6 @@
 
 namespace utils {
 
-using input_stream = seastar::memory_stream<bytes_ostream::fragment_iterator>;
+using input_stream = seastar::memory_input_stream<bytes_ostream::fragment_iterator>;
 
 }