TUN-4356: Set AUTOMAXPROCS to the CPU limit when running in a Linux container

vendor/go.uber.org/automaxprocs/internal/cgroups/cgroups.go

@@ -0,0 +1,117 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+// +build linux
+
+package cgroups
+
+const (
+	// _cgroupFSType is the Linux CGroup file system type used in
+	// `/proc/$PID/mountinfo`.
+	_cgroupFSType = "cgroup"
+	// _cgroupSubsysCPU is the CPU CGroup subsystem.
+	_cgroupSubsysCPU = "cpu"
+	// _cgroupSubsysCPUAcct is the CPU accounting CGroup subsystem.
+	_cgroupSubsysCPUAcct = "cpuacct"
+	// _cgroupSubsysCPUSet is the CPUSet CGroup subsystem.
+	_cgroupSubsysCPUSet = "cpuset"
+	// _cgroupSubsysMemory is the Memory CGroup subsystem.
+	_cgroupSubsysMemory = "memory"
+
+	// _cgroupCPUCFSQuotaUsParam is the file name for the CGroup CFS quota
+	// parameter.
+	_cgroupCPUCFSQuotaUsParam = "cpu.cfs_quota_us"
+	// _cgroupCPUCFSPeriodUsParam is the file name for the CGroup CFS period
+	// parameter.
+	_cgroupCPUCFSPeriodUsParam = "cpu.cfs_period_us"
+)
+
+const (
+	_procPathCGroup    = "/proc/self/cgroup"
+	_procPathMountInfo = "/proc/self/mountinfo"
+)
+
+// CGroups is a map that associates each CGroup with its subsystem name.
+type CGroups map[string]*CGroup
+
+// NewCGroups returns a new *CGroups from given `mountinfo` and `cgroup` files
+// under for some process under `/proc` file system (see also proc(5) for more
+// information).
+func NewCGroups(procPathMountInfo, procPathCGroup string) (CGroups, error) {
+	cgroupSubsystems, err := parseCGroupSubsystems(procPathCGroup)
+	if err != nil {
+		return nil, err
+	}
+
+	cgroups := make(CGroups)
+	newMountPoint := func(mp *MountPoint) error {
+		if mp.FSType != _cgroupFSType {
+			return nil
+		}
+
+		for _, opt := range mp.SuperOptions {
+			subsys, exists := cgroupSubsystems[opt]
+			if !exists {
+				continue
+			}
+
+			cgroupPath, err := mp.Translate(subsys.Name)
+			if err != nil {
+				return err
+			}
+			cgroups[opt] = NewCGroup(cgroupPath)
+		}
+
+		return nil
+	}
+
+	if err := parseMountInfo(procPathMountInfo, newMountPoint); err != nil {
+		return nil, err
+	}
+	return cgroups, nil
+}
+
+// NewCGroupsForCurrentProcess returns a new *CGroups instance for the current
+// process.
+func NewCGroupsForCurrentProcess() (CGroups, error) {
+	return NewCGroups(_procPathMountInfo, _procPathCGroup)
+}
+
+// CPUQuota returns the CPU quota applied with the CPU cgroup controller.
+// It is a result of `cpu.cfs_quota_us / cpu.cfs_period_us`. If the value of
+// `cpu.cfs_quota_us` was not set (-1), the method returns `(-1, nil)`.
+func (cg CGroups) CPUQuota() (float64, bool, error) {
+	cpuCGroup, exists := cg[_cgroupSubsysCPU]
+	if !exists {
+		return -1, false, nil
+	}
+
+	cfsQuotaUs, err := cpuCGroup.readInt(_cgroupCPUCFSQuotaUsParam)
+	if defined := cfsQuotaUs > 0; err != nil || !defined {
+		return -1, defined, err
+	}
+
+	cfsPeriodUs, err := cpuCGroup.readInt(_cgroupCPUCFSPeriodUsParam)
+	if err != nil {
+		return -1, false, err
+	}
+
+	return float64(cfsQuotaUs) / float64(cfsPeriodUs), true, nil
+}