Pass callback to get provider options to provider_v26 constructor

Passing a callback allows constructing the options string using
config service after loading the provider but before initializing
the provider. This way it is possible get options which are given
at DBMS startup, in command line or config file.

Author: Daniele Sciascia

include/wsrep/provider.hpp

@@ -29,6 +29,7 @@
 
 #include <cstring>
 
+#include <functional>
 #include <memory>
 #include <string>
 #include <vector>
@@ -50,6 +51,7 @@ namespace wsrep
     class event_service;
     class client_service;
     class connection_monitor_service;
+    class provider_options;
     class stid
     {
     public:
@@ -521,13 +523,13 @@ namespace wsrep
          * Create a new provider.
          *
          * @param provider_spec Provider specification
-         * @param provider_options Initial options to provider
+         * @param provider_options_cb Callback to get initial provider options
          * @param thread_service Optional thread service implementation.
          */
         static std::unique_ptr<provider> make_provider(
-            wsrep::server_state&,
-            const std::string& provider_spec,
-            const std::string& provider_options,
+            wsrep::server_state&, const std::string& provider_spec,
+            const std::function<int(const provider_options&, std::string&)>&
+                provider_options_cb,
             const wsrep::provider::services& services
             = wsrep::provider::services());
 

include/wsrep/provider_options.hpp

@@ -214,7 +214,7 @@ namespace wsrep
             int flags_;
         };
 
-        provider_options(wsrep::provider&);
+        provider_options();
         provider_options(const provider_options&) = delete;
         provider_options& operator=(const provider_options&) = delete;
 
@@ -225,7 +225,7 @@ namespace wsrep
          *
          * @return Provider status code.
          */
-        enum wsrep::provider::status initial_options();
+        enum wsrep::provider::status initial_options(wsrep::provider& provider);
 
         /**
          * Get the option with the given name
@@ -241,7 +241,8 @@ namespace wsrep
          * @return wsrep::provider::error_size_exceeded if memory could
          *         not be allocated for the new value.
          */
-        enum wsrep::provider::status set(const std::string& name,
+        enum wsrep::provider::status set(wsrep::provider& provider,
+                                         const std::string& name,
                                          std::unique_ptr<option_value> value);
 
         /**
@@ -252,10 +253,15 @@ namespace wsrep
                     std::unique_ptr<option_value> value,
                     std::unique_ptr<option_value> default_value, int flags);
 
-        void for_each(const std::function<void(option*)>& fn);
+        /**
+         * Invoke the given function with each provider option
+         * as argument.
+         *
+         * @param fn Function to call for each option
+         */
+        void for_each(const std::function<void(option*)>& fn) const;
 
     private:
-        provider& provider_;
         using options_map = std::map<std::string, std::unique_ptr<option>>;
         options_map options_;
     };

include/wsrep/server_state.hpp

@@ -117,6 +117,7 @@ namespace wsrep
     class server_service;
     class client_service;
     class encryption_service;
+    class provider_options;
 
     /** @class Server Context
      *
@@ -287,17 +288,47 @@ namespace wsrep
          * Load WSRep provider.
          *
          * @param provider WSRep provider library to be loaded.
-         * @param provider_options Provider specific options string
+         * @param provider_options_cb Callback to get provider options.
+         *                            The function to be called must be
+         *                            idempotent.
+         * @param services Application defined services passed to
+         *                 the provider.
+         *
+         * @return Zero on success, non-zero on error.
+         */
+        int load_provider(
+            const std::string& provider,
+            const std::function<int(const provider_options&, std::string&)>&
+                provider_options_cb,
+            const wsrep::provider::services& services
+            = wsrep::provider::services());
+
+        /**
+         * Load WSRep provider.
+         *
+         * @param provider WSRep provider library to be loaded.
+         * @param options Provider specific options string
          *        to be passed for provider during initialization.
          * @param services Application defined services passed to
          *                 the provider.
          *
          * @return Zero on success, non-zero on error.
+         *
+         * @note Provided for backward compatibility.
          */
         int load_provider(const std::string& provider,
-                          const std::string& provider_options,
+                          const std::string& options,
                           const wsrep::provider::services& services
-                          = wsrep::provider::services());
+                          = wsrep::provider::services())
+        {
+            return load_provider(
+                provider,
+                [options](const provider_options&, std::string& option_string) {
+                  option_string.append(options);
+                  return 0;
+                },
+                services);
+        }
 
         using provider_factory_func =
             std::function<decltype(wsrep::provider::make_provider)>;

src/config_service_v1.cpp

@@ -19,6 +19,7 @@
 
 #include "config_service_v1.hpp"
 #include "service_helpers.hpp"
+#include "v26/wsrep_api.h"
 #include "v26/wsrep_config_service.h"
 #include "wsrep/logger.hpp"
 #include "wsrep/provider_options.hpp"
@@ -150,7 +151,7 @@ static void config_service_v1_deinit(void* dlh)
 int wsrep::config_service_v1_fetch(wsrep::provider& provider,
                                    wsrep::provider_options* options)
 {
-    struct wsrep_st* wsrep = (struct wsrep_st*)provider.native();
+    struct wsrep_st* wsrep = static_cast<struct wsrep_st*>(provider.native());
     if (wsrep == nullptr)
     {
         // Not a provider which was loaded via wsrep-API
@@ -179,3 +180,70 @@ int wsrep::config_service_v1_fetch(wsrep::provider& provider,
 
     return 0;
 }
+
+namespace wsrep_config_service_v2
+{
+    wsrep_config_service_v2_t service{ 0 };
+
+    wsrep_status_t service_callback(const wsrep_parameter* p, void* context)
+    {
+        return wsrep_config_service_v1::service_callback(p, context);
+    }
+} // namespace wsrep_config_service_v2
+
+static int config_service_v2_probe(void* dlh)
+{
+    typedef int (*init_fn)(wsrep_config_service_v2_t*);
+    typedef void (*deinit_fn)();
+    return wsrep_impl::service_probe<init_fn>(
+               dlh, WSREP_CONFIG_SERVICE_INIT_FUNC_V2, "config service v2")
+           || wsrep_impl::service_probe<deinit_fn>(
+               dlh, WSREP_CONFIG_SERVICE_DEINIT_FUNC_V2, "config service v2");
+}
+
+static int config_service_v2_init(void* dlh)
+{
+    typedef int (*init_fn)(wsrep_config_service_v2_t*);
+    return wsrep_impl::service_init<init_fn>(
+        dlh, WSREP_CONFIG_SERVICE_INIT_FUNC_V2,
+        &wsrep_config_service_v2::service, "config service v2");
+}
+
+static void config_service_v2_deinit(void* dlh)
+{
+    typedef int (*deinit_fn)();
+    wsrep_impl::service_deinit<deinit_fn>(
+        dlh, WSREP_CONFIG_SERVICE_DEINIT_FUNC_V2, "config service v2");
+}
+
+int wsrep::config_service_v2_fetch(struct wsrep_st* wsrep,
+                                   wsrep::provider_options* options)
+{
+    if (wsrep == nullptr)
+    {
+        // Not a provider which was loaded via wsrep-API
+        return 0;
+    }
+    if (config_service_v2_probe(wsrep->dlh))
+    {
+        wsrep::log_info() << "Provider does not support config service v2";
+        return 1;
+    }
+    if (config_service_v2_init(wsrep->dlh))
+    {
+        wsrep::log_warning() << "Failed to initialize config service v2";
+        return 1;
+    }
+
+    wsrep_status_t ret = wsrep_config_service_v2::service.get_parameters(
+        wsrep, &wsrep_config_service_v2::service_callback, options);
+
+    config_service_v2_deinit(wsrep->dlh);
+
+    if (ret != WSREP_OK)
+    {
+        return 1;
+    }
+
+    return 0;
+}

src/config_service_v1.hpp

@@ -20,11 +20,15 @@
 #ifndef WSREP_CONFIG_SERVICE_V1_HPP
 #define WSREP_CONFIG_SERVICE_V1_HPP
 
+struct wsrep_st;
+
 namespace wsrep
 {
     class provider;
     class provider_options;
     int config_service_v1_fetch(provider& provider, provider_options* opts);
+    int config_service_v1_fetch(struct wsrep_st* wsrep, provider_options* opts);
+    int config_service_v2_fetch(struct wsrep_st* wsrep, provider_options* opts);
 } // namespace wsrep
 
 #endif // WSREP_CONFIG_SERVICE_V1_HPP

src/provider.cpp

@@ -19,6 +19,7 @@
 
 #include "wsrep/provider.hpp"
 #include "wsrep/logger.hpp"
+#include "wsrep/provider_options.hpp"
 
 #include "wsrep_provider_v26.hpp"
 
@@ -27,29 +28,36 @@
 #include <memory>
 
 std::unique_ptr<wsrep::provider> wsrep::provider::make_provider(
-    wsrep::server_state& server_state,
-    const std::string& provider_spec,
-    const std::string& provider_options,
+    wsrep::server_state& server_state, const std::string& provider_spec,
+    const std::function<int(const provider_options&, std::string&)>&
+        provider_options_cb,
     const wsrep::provider::services& services)
 {
     try
     {
         return std::unique_ptr<wsrep::provider>(new wsrep::wsrep_provider_v26(
-            server_state, provider_options, provider_spec, services));
+            server_state, provider_spec, provider_options_cb,
+            services));
     }
     catch (const wsrep::runtime_error& e)
     {
+        provider_options options;
+        std::string options_string;
         wsrep::log_error() << "Failed to create a new provider '"
                            << provider_spec << "'"
-                           << " with options '" << provider_options
+                           << " with options '"
+                           << provider_options_cb(options, options_string)
                            << "': " << e.what();
     }
     catch (...)
     {
+        provider_options options;
+        std::string options_string;
         wsrep::log_error() << "Caught unknown exception when trying to "
                            << "create a new provider '"
                            << provider_spec << "'"
-                           << " with options '" << provider_options;
+                           << " with options '"
+                           << provider_options_cb(options, options_string);
     }
     return 0;
 }

src/provider_options.cpp

@@ -18,6 +18,7 @@
  */
 
 #include "wsrep/provider_options.hpp"
+#include "wsrep/provider.hpp"
 #include "config_service_v1.hpp"
 #include "wsrep/logger.hpp"
 
@@ -92,16 +93,16 @@ void wsrep::provider_options::option::update_value(
 
 wsrep::provider_options::option::~option() {}
 
-wsrep::provider_options::provider_options(wsrep::provider& provider)
-    : provider_(provider)
-    , options_()
+wsrep::provider_options::provider_options()
+    : options_()
 {
 }
 
-enum wsrep::provider::status wsrep::provider_options::initial_options()
+enum wsrep::provider::status
+wsrep::provider_options::initial_options(wsrep::provider& provider)
 {
     options_.clear();
-    if (config_service_v1_fetch(provider_, this))
+    if (config_service_v1_fetch(provider, this))
     {
         return wsrep::provider::error_not_implemented;
     }
@@ -123,7 +124,7 @@ wsrep::provider_options::get_option(const std::string& name) const
 }
 
 enum wsrep::provider::status wsrep::provider_options::set(
-    const std::string& name,
+    wsrep::provider& provider, const std::string& name,
     std::unique_ptr<wsrep::provider_options::option_value> value)
 {
     auto option(options_.find(name));
@@ -132,7 +133,7 @@ enum wsrep::provider::status wsrep::provider_options::set(
         return not_found_error;
     }
     provider_options_sep sep;
-    auto ret(provider_.options(std::string(option->second->real_name())
+    auto ret(provider.options(std::string(option->second->real_name())
                                + sep.key_value + value->as_string()
                                + sep.param));
     if (ret == provider::success)
@@ -160,9 +161,10 @@ enum wsrep::provider::status wsrep::provider_options::set_default(
     return wsrep::provider::success;
 }
 
-void wsrep::provider_options::for_each(const std::function<void(option*)>& fn)
+void wsrep::provider_options::for_each(
+    const std::function<void(option*)>& fn) const
 {
-    std::for_each(
-        options_.begin(), options_.end(),
-        [&fn](const options_map::value_type& opt) { fn(opt.second.get()); });
+    std::for_each(options_.begin(), options_.end(),
+                  [&fn](const options_map::value_type& opt)
+                  { fn(opt.second.get()); });
 }

src/server_state.cpp

@@ -499,13 +499,15 @@ static int apply_toi(wsrep::provider& provider,
 //////////////////////////////////////////////////////////////////////////////
 
 int wsrep::server_state::load_provider(
-    const std::string& provider_spec, const std::string& provider_options,
+    const std::string& provider_spec,
+    const std::function<int(const provider_options&, std::string&)>&
+        provider_options_cb,
     const wsrep::provider::services& services)
 {
     wsrep::log_info() << "Loading provider " << provider_spec
                       << " initial position: " << initial_position_;
-    provider_
-        = provider_factory_(*this, provider_spec, provider_options, services);
+    provider_ = provider_factory_(*this, provider_spec, provider_options_cb,
+                                  services);
     return (provider_ ? 0 : 1);
 }