rpc: Add thread_get_io_channels RPC

Add an new JSON RPC thread_get_io_channels to retrieve IO channels
of the threads. IO channel don't have its own name and so get the
name of the corresponding IO device instead.

Signed-off-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Change-Id: Id8fbb328ffba09e1eace35994cdbf36b24832b82
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/887
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

doc/jsonrpc.md

@@ -663,6 +663,50 @@ Example response:
 }
 ~~~
 
+## thread_get_io_channels {#rpc_thread_get_io_channels}
+
+Retrieve current IO channels of all the threads.
+
+### Parameters
+
+This method has no parameters.
+
+### Response
+
+The response is an array of objects containing IO channels of all the threads.
+
+### Example
+
+Example request:
+~~~
+{
+  "jsonrpc": "2.0",
+  "method": "thread_get_io_channels",
+  "id": 1
+}
+~~~
+
+Example response:
+~~~
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": {
+    "tick_rate": 2500000000,
+    "threads": [
+      {
+        "name": "app_thread",
+        "io_channels": [
+          {
+            "name": "nvmf_tgt",
+            "ref": 1
+          }
+        ]
+      }
+    ]
+  }
+}
+~~~
 # Block Device Abstraction Layer {#jsonrpc_components_bdev}
 
 ## bdev_set_options {#rpc_bdev_set_options}

module/event/rpc/app_rpc.c

@@ -284,6 +284,49 @@ spdk_rpc_thread_get_pollers(struct spdk_jsonrpc_request *request,
 
 SPDK_RPC_REGISTER("thread_get_pollers", spdk_rpc_thread_get_pollers, SPDK_RPC_RUNTIME)
 
+static void
+rpc_get_io_channel(struct spdk_io_channel *ch, struct spdk_json_write_ctx *w)
+{
+	spdk_json_write_object_begin(w);
+	spdk_json_write_named_string(w, "name", spdk_io_device_get_name(ch->dev));
+	spdk_json_write_named_uint32(w, "ref", ch->ref);
+	spdk_json_write_object_end(w);
+}
+
+static void
+rpc_thread_get_io_channels(void *arg)
+{
+	struct rpc_get_stats_ctx *ctx = arg;
+	struct spdk_thread *thread = spdk_get_thread();
+	struct spdk_io_channel *ch;
+
+	spdk_json_write_object_begin(ctx->w);
+	spdk_json_write_named_string(ctx->w, "name", spdk_thread_get_name(thread));
+
+	spdk_json_write_named_array_begin(ctx->w, "io_channels");
+	TAILQ_FOREACH(ch, &thread->io_channels, tailq) {
+		rpc_get_io_channel(ch, ctx->w);
+	}
+	spdk_json_write_array_end(ctx->w);
+
+	spdk_json_write_object_end(ctx->w);
+}
+
+static void
+spdk_rpc_thread_get_io_channels(struct spdk_jsonrpc_request *request,
+				const struct spdk_json_val *params)
+{
+	if (params) {
+		spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS,
+						 "'thread_get_io_channels' requires no arguments");
+		return;
+	}
+
+	rpc_thread_get_stats_for_each(request, rpc_thread_get_io_channels);
+}
+
+SPDK_RPC_REGISTER("thread_get_io_channels", spdk_rpc_thread_get_io_channels, SPDK_RPC_RUNTIME);
+
 static void
 rpc_framework_get_reactors_done(void *arg1, void *arg2)
 {

scripts/rpc.py

@@ -2290,6 +2290,13 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
         'thread_get_pollers', help='Display current pollers of all the threads')
     p.set_defaults(func=thread_get_pollers)
 
+    def thread_get_io_channels(args):
+        print_dict(rpc.app.thread_get_io_channels(args.client))
+
+    p = subparsers.add_parser(
+        'thread_get_io_channels', help='Display current IO channels of all the threads')
+    p.set_defaults(func=thread_get_io_channels)
+
     def env_dpdk_get_mem_stats(args):
         print_dict(rpc.env_dpdk.env_dpdk_get_mem_stats(args.client))
 

scripts/rpc/app.py

@@ -67,3 +67,12 @@ def thread_get_pollers(client):
         Current pollers.
     """
     return client.call('thread_get_pollers')
+
+
+def thread_get_io_channels(client):
+    """Query current IO channels.
+
+    Returns:
+        Current IO channels.
+    """
+    return client.call('thread_get_io_channels')