event: Move RPC server initialization to init

I'm not sure whether this should go into lib/init or to lib/rpc
directly, but I've chosen lib/init for now.

This is to support applications that want to run the SPDK JSON
RPC server, but aren't using the SPDK application framework.

Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Change-Id: I79ca39aa0ca6e1a3a6905b0bf73e6cc99b086e55
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/6644
Reviewed-by: Tom Nabarro <tom.nabarro@outlook.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot

include/spdk/event.h

@@ -44,6 +44,7 @@
 #include "spdk/stdinc.h"
 
 #include "spdk/cpuset.h"
+#include "spdk/init.h"
 #include "spdk/queue.h"
 #include "spdk/log.h"
 #include "spdk/thread.h"
@@ -82,8 +83,6 @@ typedef void (*spdk_app_shutdown_cb)(void);
  */
 typedef void (*spdk_sighandler_t)(int signal);
 
-#define SPDK_DEFAULT_RPC_ADDR "/var/tmp/spdk.sock"
-
 /**
  * \brief Event framework initialization options
  */

include/spdk/init.h

@@ -45,6 +45,23 @@
 extern "C" {
 #endif
 
+#define SPDK_DEFAULT_RPC_ADDR "/var/tmp/spdk.sock"
+
+/**
+ * Create the SPDK JSON-RPC server and listen at the provided address. The RPC server is optional and is
+ * independent of subsystem initialization. The RPC server can be started and stopped at any time.
+ *
+ * \param listen_addr Path to a unix domain socket to listen on
+ *
+ * \return Negated errno on failure. 0 on success.
+ */
+int spdk_rpc_initialize(const char *listen_addr);
+
+/**
+ * Shut down the SPDK JSON-RPC target
+ */
+void spdk_rpc_finish(void);
+
 typedef void (*spdk_subsystem_init_fn)(int rc, void *ctx);
 
 /**

include/spdk_internal/event.h

@@ -170,9 +170,6 @@ void spdk_app_json_config_load(const char *json_config_file, const char *rpc_add
 			       spdk_app_init_fn cb_fn, void *cb_arg,
 			       bool stop_on_error);
 
-int spdk_rpc_initialize(const char *listen_addr);
-void spdk_rpc_finish(void);
-
 struct spdk_governor_capabilities {
 	bool freq_change;
 	bool freq_getset;

lib/event/Makefile

@@ -40,7 +40,7 @@ SO_MINOR := 0
 CFLAGS += $(ENV_CFLAGS)
 
 LIBNAME = event
-C_SRCS = app.c reactor.c rpc.c json_config.c log_rpc.c \
+C_SRCS = app.c reactor.c json_config.c log_rpc.c \
 	 app_rpc.c scheduler_static.c
 
 # Do not compile schedulers and governors based on DPDK env

lib/event/spdk_event.map

@@ -26,8 +26,6 @@
 	spdk_for_each_reactor;
 	spdk_reactor_set_interrupt_mode;
 	spdk_app_json_config_load;
-	spdk_rpc_initialize;
-	spdk_rpc_finish;
 
 	local: *;
 };

lib/init/Makefile

@@ -37,7 +37,7 @@ include $(SPDK_ROOT_DIR)/mk/spdk.common.mk
 SO_VER := 1
 SO_MINOR := 0
 
-C_SRCS = subsystem.c subsystem_rpc.c
+C_SRCS = subsystem.c subsystem_rpc.c rpc.c
 LIBNAME = init
 
 SPDK_MAP_FILE = $(abspath $(CURDIR)/spdk_init.map)

lib/init/rpc.c

@@ -34,12 +34,11 @@
 #include "spdk/stdinc.h"
 
 #include "spdk/env.h"
+#include "spdk/init.h"
 #include "spdk/thread.h"
 #include "spdk/log.h"
 #include "spdk/rpc.h"
 
-#include "spdk_internal/event.h"
-
 #define RPC_SELECT_INTERVAL	4000 /* 4ms */
 
 static struct spdk_poller *g_rpc_poller = NULL;

lib/init/spdk_init.map

@@ -9,5 +9,8 @@
 	spdk_subsystem_init_next;
 	spdk_subsystem_fini_next;
 
+	spdk_rpc_initialize;
+	spdk_rpc_finish;
+
 	local: *;
 };