sstables: : remove unnecessary throws

Throws are translated to passing the exceptions directly.

sstables/sstables.cc

@@ -551,7 +551,7 @@ inline void write(sstable_version_types v, file_writer& out, const summary& s) {
 future<summary_entry&> sstable::read_summary_entry(size_t i) {
     // The last one is the boundary marker
     if (i >= (_components->summary.entries.size())) {
-        throw std::out_of_range(format("Invalid Summary index: {:d}", i));
+        return make_exception_future<summary_entry&>(std::out_of_range(format("Invalid Summary index: {:d}", i)));
     }
 
     return make_ready_future<summary_entry&>(_components->summary.entries[i]);
@@ -624,7 +624,7 @@ future<> parse(const schema& s, sstable_version_types v, random_access_reader& i
     uint32_t length = *len;
 
     if (length == 0) {
-        throw malformed_sstable_exception("Estimated histogram with zero size found. Can't continue!");
+        co_await coroutine::return_exception(malformed_sstable_exception("Estimated histogram with zero size found. Can't continue!"));
     }
 
     // Arrays are potentially pre-initialized by the estimated_histogram constructor.
@@ -694,7 +694,7 @@ future<> parse(const schema& s, sstable_version_types v, random_access_reader& i
     co_await parse(s, v, in, sh.max_bin_size, a);
     auto length = a.elements.size();
     if (length > sh.max_bin_size) {
-        throw malformed_sstable_exception("Streaming histogram with more entries than allowed. Can't continue!");
+        co_await coroutine::return_exception(malformed_sstable_exception("Streaming histogram with more entries than allowed. Can't continue!"));
     }
 
     // Find bad histogram which had incorrect elements merged due to use of
@@ -800,7 +800,7 @@ future<> sstable::read_toc() noexcept {
             // but if we so much as read a whole page from it, there is definitely something fishy
             // going on - and this simplifies the code.
             if (size >= 4096) {
-                throw malformed_sstable_exception("SSTable TOC too big: " + to_sstring(size) + " bytes", filename(component_type::TOC));
+                return make_exception_future<>(malformed_sstable_exception("SSTable TOC too big: " + to_sstring(size) + " bytes", filename(component_type::TOC)));
             }
 
             std::string_view buf(bufptr.get(), size);
@@ -821,18 +821,20 @@ future<> sstable::read_toc() noexcept {
                 }
             }
             if (!_recognized_components.size()) {
-                throw malformed_sstable_exception("Empty TOC", filename(component_type::TOC));
+                return make_exception_future<>(malformed_sstable_exception("Empty TOC", filename(component_type::TOC)));
             }
+            return make_ready_future<>();
         });
     }).then_wrapped([this] (future<> f) {
         try {
             f.get();
         } catch (std::system_error& e) {
             if (e.code() == std::error_code(ENOENT, std::system_category())) {
-                throw malformed_sstable_exception(filename(component_type::TOC) + ": file not found");
+                return make_exception_future<>(malformed_sstable_exception(filename(component_type::TOC) + ": file not found"));
             }
-            throw;
+            return make_exception_future<>(e);
         }
+        return make_ready_future<>();
     });
 
 }
@@ -1004,12 +1006,13 @@ future<> sstable::read_simple(T& component, const io_priority_class& pc) {
             f.get();
         } catch (std::system_error& e) {
             if (e.code() == std::error_code(ENOENT, std::system_category())) {
-                throw malformed_sstable_exception(file_path + ": file not found");
+                return make_exception_future<>(malformed_sstable_exception(file_path + ": file not found"));
             }
-            throw;
+            return make_exception_future<>(e);
         } catch (malformed_sstable_exception &e) {
-            throw malformed_sstable_exception(e.what(), file_path);
+            return make_exception_future<>(malformed_sstable_exception(e.what(), file_path));
         }
+        return make_ready_future<>();
     });
 }
 
@@ -1309,12 +1312,12 @@ future<> sstable::update_info_for_opened_data() {
                         } catch (const std::system_error& ex) {
                             // ignore summary that isn't present in disk but was previously generated by read_summary().
                             if (ex.code().value() == ENOENT && c == component_type::Summary && _components->summary.memory_footprint()) {
-                                return uint64_t(0);
+                                return make_ready_future<uint64_t>(0);
                             }
-                            throw;
+                            return make_exception_future<uint64_t>(ex);
                         }
                     }
-                    return f.get0().allocated_size;
+                    return make_ready_future<uint64_t>(f.get0().allocated_size);
                 });
             }).then([this] (uint64_t bytes) {
                 _bytes_on_disk += bytes;
@@ -1981,7 +1984,7 @@ future<> sstable::check_create_links_replay(const sstring& dst_dir, int64_t dst_
                     if (!same) {
                         auto msg = format("Error while linking SSTable: {} to {}: File exists", src, dst);
                         sstlog.error("{}", msg);
-                        throw malformed_sstable_exception(msg, _dir);
+                        return make_exception_future<>(malformed_sstable_exception(msg, _dir));
                     }
                     return make_ready_future<>();
                 });
@@ -2565,7 +2568,7 @@ future<> sstable::mutate_sstable_level(uint32_t new_level) {
 
     auto& p = entry->second;
     if (!p) {
-        throw std::runtime_error("Statistics is malformed");
+        return make_exception_future<>(std::runtime_error("Statistics is malformed"));
     }
     stats_metadata& s = *static_cast<stats_metadata *>(p.get());
     if (s.sstable_level == new_level) {