Add "limit" support on "ls" command.

Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>

etcd/Client.hpp

@@ -157,6 +157,15 @@ namespace etcd
     pplx::task<Response> ls(std::string const & key);
 
 
+    /**
+     * Gets a directory listing of the directory identified by the key.
+     * @param key is the key to be listed
+     * @param limit is the size limit of results to be listed, we don't use default parameters
+     *        to ensure backwards binary compatibility.
+     */
+    pplx::task<Response> ls(std::string const & key, size_t const limit);
+
+
     /**
      * Removes a directory node. Fails if the parent directory dos not exists or not a directory.
      * @param key is the directory to be created to be listed

etcd/v3/Action.hpp

@@ -32,6 +32,7 @@ namespace etcdv3
     int old_revision;
     int64_t lease_id;
     int ttl;
+    int limit;
     std::string key;
     std::string value;
     std::string old_value;

src/Client.cpp

@@ -339,6 +339,18 @@ pplx::task<etcd::Response> etcd::Client::ls(std::string const & key)
   etcdv3::ActionParameters params;
   params.key.assign(key);
   params.withPrefix = true;
+  params.limit = 0;  // default no limit.
+  params.kv_stub = stub_.get();
+  std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
+  return Response::create(call);
+}
+
+pplx::task<etcd::Response> etcd::Client::ls(std::string const & key, size_t const limit)
+{
+  etcdv3::ActionParameters params;
+  params.key.assign(key);
+  params.withPrefix = true;
+  params.limit = limit;
   params.kv_stub = stub_.get();
   std::shared_ptr<etcdv3::AsyncGetAction> call(new etcdv3::AsyncGetAction(params));
   return Response::create(call);

src/v3/AsyncGetAction.cpp

@@ -8,6 +8,7 @@ etcdv3::AsyncGetAction::AsyncGetAction(etcdv3::ActionParameters param)
 {
   RangeRequest get_request;
   get_request.set_key(parameters.key);
+  get_request.set_limit(param.limit);
   if(parameters.withPrefix)
   {
     std::string range_end(parameters.key); 

src/v3/AsyncRangeResponse.cpp

@@ -6,7 +6,7 @@ void etcdv3::AsyncRangeResponse::ParseResponse(RangeResponse& resp, bool prefix)
 {
   action = etcdv3::GET_ACTION;
   index = resp.header().revision();
-  if(resp.kvs_size() == 0)
+  if(resp.kvs_size() == 0 && !prefix)
   {
     error_code=100;
     error_message="Key not found";