feat(swagger): agent, add definitions for cpu pinning endpoints (#4072)

* feat(swagger): agent, add cpu pinning endpoints

Those endpoints will be used during restore
to optionally unpin agent from cpus for
its duration.

* feat(cpuset): add function for checking pinned cpus

This function will in the agent's endpoint
getting cpus to which agent is pinned.

v3/pkg/util/cpuset/cpuset_linux.go

@@ -53,6 +53,31 @@ func schedSetAffinityToMany(pids []int, set *unix.CPUSet) (err error) {
 	return
 }
 
+// SchedGetAffinity gets a union of CPUs used by this process threads.
+func SchedGetAffinity() ([]int, error) {
+	pids, err := osTasks(os.Getpid())
+	if err != nil {
+		return nil, errors.Wrap(err, "get tasks")
+	}
+
+	union := make(map[int]struct{})
+	for _, pid := range pids {
+		var cpus unix.CPUSet
+		if err := unix.SchedGetaffinity(pid, &cpus); err != nil {
+			return nil, errors.Wrap(err, "get affinity")
+		}
+		for _, cpu := range cpulist(&cpus) {
+			union[cpu] = struct{}{}
+		}
+	}
+
+	var out []int
+	for cpu := range union {
+		out = append(out, cpu)
+	}
+	return out, nil
+}
+
 func cpuset(cpus []int) *unix.CPUSet {
 	set := &unix.CPUSet{}
 	set.Zero()

v3/swagger/agent.json

@@ -843,6 +843,74 @@
         "security": []
       }
     },
+    "/pin_cpu": {
+      "get": {
+        "description": "Get CPUs to which agent is pinned",
+        "summary": "Get CPUs to which agent is pinned",
+        "operationId": "GetCpu",
+        "produces": [
+          "application/json"
+        ],
+        "responses": {
+          "200": {
+            "description": "CPUs to which agent is pinned",
+            "schema": {
+              "$ref": "#/definitions/Cpus"
+            }
+          },
+          "default": {
+            "description": "Server error",
+            "schema": {
+              "$ref": "#/definitions/ErrorResponse"
+            }
+          }
+        }
+      },
+      "post": {
+        "description": "Pin agent to CPUs according to start-up logic",
+        "summary": "Pin agent to CPUs according to start-up logic",
+        "operationId": "PinCpu",
+        "produces": [
+          "application/json"
+        ],
+        "responses": {
+          "200": {
+            "description": "Empty object",
+            "schema": {
+              "type": "object"
+            }
+          },
+          "default": {
+            "description": "Server error",
+            "schema": {
+              "$ref": "#/definitions/ErrorResponse"
+            }
+          }
+        }
+      },
+      "delete": {
+        "description": "Unpin agent from CPUs",
+        "summary": "Unpin agent from CPUs",
+        "operationId": "UnpinCpu",
+        "produces": [
+          "application/json"
+        ],
+        "responses": {
+          "200": {
+            "description": "Empty object",
+            "schema": {
+              "type": "object"
+            }
+          },
+          "default": {
+            "description": "Server error",
+            "schema": {
+              "$ref": "#/definitions/ErrorResponse"
+            }
+          }
+        }
+      }
+    },
     "/terminate": {
       "post": {
         "description": "Reload agent config",
@@ -901,6 +969,18 @@
     }
   },
   "definitions": {
+    "Cpus": {
+      "type": "object",
+      "properties": {
+        "cpu": {
+          "description": "List of cpus",
+          "type": "array",
+          "items": {
+            "type": "integer"
+          }
+        }
+      }
+    },
     "Bandwidth": {
       "title": "bandwidth rate",
       "description": "Rate at witch to rate limit bandwidth",