From dc6bfb63dae05beea68c833562deef82fb78d6ab Mon Sep 17 00:00:00 2001
From: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Date: Wed, 24 Jun 2015 14:07:12 +0200
Subject: [PATCH] system_keyspace: Introduce query()

Simple method to get all data from a system table.

Note: Perhaps we should move storage_proxy::query_local() here as well.
---
 db/system_keyspace.cc | 27 +++++++++++++++++++++++++++
 db/system_keyspace.hh | 12 ++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/db/system_keyspace.cc b/db/system_keyspace.cc
index 1c2a8dc305..d37ffa26ee 100644
--- a/db/system_keyspace.cc
+++ b/db/system_keyspace.cc
@@ -21,9 +21,13 @@
  * Copyright 2015 Cloudius Systems
  */
 
+#include <boost/range/algorithm_ext/push_back.hpp>
+#include <boost/range/adaptor/transformed.hpp>
+
 #include "system_keyspace.hh"
 #include "types.hh"
 #include "service/storage_service.hh"
+#include "service/storage_proxy.hh"
 
 namespace db {
 namespace system_keyspace {
@@ -1058,5 +1062,28 @@ load_dc_rack_info()
 #endif
     return result;
 }
+
+future<lw_shared_ptr<query::result_set>>
+query(service::storage_proxy& proxy, const sstring& cf_name) {
+    database& db = proxy.get_db().local();
+    schema_ptr schema = db.find_schema(db::system_keyspace::NAME, cf_name);
+    std::vector<column_id> regular_cols;
+    boost::range::push_back(regular_cols, schema->regular_columns() | boost::adaptors::transformed(std::mem_fn(&column_definition::id)));
+    std::vector<column_id> static_cols;
+    boost::range::push_back(static_cols, schema->static_columns() | boost::adaptors::transformed(std::mem_fn(&column_definition::id)));
+    auto opts = query::partition_slice::option_set::of<
+        query::partition_slice::option::send_partition_key,
+        query::partition_slice::option::send_clustering_key>();
+    query::partition_slice slice{{query::clustering_range::make_open_ended_both_sides()}, static_cols, regular_cols, opts};
+    auto cmd = make_lw_shared<query::read_command>(schema->id(), slice, std::numeric_limits<uint32_t>::max());
+    return proxy.query(cmd, {query::full_partition_range}, db::consistency_level::ONE).then([schema, cmd] (auto&& result) {
+        query::result_set_builder builder{schema};
+        bytes_ostream w(result->buf());
+        query::result_view view(w.linearize());
+        view.consume(cmd->slice, builder);
+        return builder.build();
+    });
+}
+
 } // namespace system_keyspace
 } // namespace db
diff --git a/db/system_keyspace.hh b/db/system_keyspace.hh
index 8c75156ccd..f8ce270fa4 100644
--- a/db/system_keyspace.hh
+++ b/db/system_keyspace.hh
@@ -29,6 +29,13 @@
 #include "legacy_schema_tables.hh"
 #include "utils/UUID.hh"
 #include "gms/inet_address.hh"
+#include "query-result-set.hh"
+
+namespace service {
+
+class storage_proxy;
+
+}
 
 namespace db {
 namespace system_keyspace {
@@ -54,6 +61,11 @@ extern schema_ptr built_indexes(); // TODO (from Cassandra): make private
 std::vector<schema_ptr> all_tables();
 void make(database& db, bool durable);
 
+// Returns all data from given system table.
+// Intended to be used by code which is not performance critical.
+future<lw_shared_ptr<query::result_set>> query(service::storage_proxy& proxy, const sstring& cf_name);
+
+
 // Endpoint Data Center and Rack names
 struct endpoint_dc_rack {
     sstring dc;