Merge ad50a73 into 27bdb2b

services/storehost/spaceMon.go

@@ -0,0 +1,214 @@
+// Copyright (c) 2016 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.
+
+package storehost
+
+import (
+	"os"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/uber-common/bark"
+	"github.com/uber/cherami-server/common"
+	"github.com/uber/cherami-server/common/metrics"
+	"github.com/uber/cherami-server/services/storehost/load"
+)
+
+const (
+	warnThreshold         = 200 * gigaBytes
+	alertThreshold        = 100 * gigaBytes
+	resumeWritesThreshold = 200 * gigaBytes
+)
+
+// monitoring interval
+const spaceMonInterval = 2 * time.Minute
+
+const (
+	kiloBytes = 1024
+	megaBytes = 1024 * kiloBytes
+	gigaBytes = 1024 * megaBytes
+	teraBytes = 1024 * gigaBytes
+)
+
+// StorageMode defines the read write mode of the storage host
+type StorageMode int32
+
+const (
+	// StorageModeReadWrite read/write
+	StorageModeReadWrite StorageMode = iota
+	// StorageModeReadOnly read only
+	StorageModeReadOnly
+)
+
+type (
+	// SpaceMon monitors free-space and switches store to read-only on low-space
+	SpaceMon interface {
+		common.Daemon
+		GetMode() StorageMode
+	}
+
+	// spaceMon implements SpaceMon interface
+	spaceMon struct {
+		sync.RWMutex
+
+		storeHost   *StoreHost // TODO: use this to trigger turning into read only mode
+		logger      bark.Logger
+		m3Client    metrics.Client
+		hostMetrics *load.HostMetrics
+
+		stopCh chan struct{}
+		path   string
+		mode   StorageMode
+	}
+)
+
+// NewSpaceMon returns an instance of SpaceMon.
+func NewSpaceMon(store *StoreHost, m3Client metrics.Client, hostMetrics *load.HostMetrics, logger bark.Logger, path string) SpaceMon {
+
+	return &spaceMon{
+		storeHost:   store,
+		logger:      logger,
+		m3Client:    m3Client,
+		hostMetrics: hostMetrics,
+		path:        path,
+		mode:        StorageModeReadWrite, // default: read-write
+	}
+}
+
+// Start starts the monitoring
+func (s *spaceMon) Start() {
+
+	s.logger.Info("SpaceMon: started")
+	s.stopCh = make(chan struct{})
+	go s.pump()
+}
+
+// Stop stops the monitoring
+func (s *spaceMon) Stop() {
+
+	close(s.stopCh)
+	s.logger.Info("SpaceMon: stopped")
+}
+
+// GetMode returns the read/write mode of storage
+func (s *spaceMon) GetMode() StorageMode {
+
+	s.RLock()
+	defer s.RUnlock()
+
+	return s.mode
+}
+
+func (s *spaceMon) pump() {
+
+	var path = s.path
+
+	// if no path specified, use the current working directory
+	if len(path) <= 0 {
+
+		s.logger.Warn("SpaceMon: monitoring path is empty, trying working directory")
+
+		cwd, err := os.Getwd()
+		if err != nil {
+			s.logger.Error("SpaceMon: os.Getwd() failed", err)
+			return
+		}
+
+		path = cwd
+	}
+
+	log := s.logger.WithField(`path`, path)
+
+	ticker := time.NewTicker(spaceMonInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			// continue below to check free-space, etc
+		case <-s.stopCh:
+			return // done
+		}
+
+		// query available/total space
+		var stat syscall.Statfs_t
+		err := syscall.Statfs(path, &stat)
+		if err != nil {
+			log.WithField(common.TagErr, err).Error("SpaceMon: syscall.Statfs failed", path)
+			continue
+		}
+
+		avail := stat.Bavail * uint64(stat.Bsize)
+		total := stat.Blocks * uint64(stat.Bsize)
+
+		if total <= 0 {
+			log.Error(`SpaceMon: total space unavailable`)
+			continue
+		}
+
+		availMiBs, totalMiBs := avail/megaBytes, total/megaBytes
+		availPercent := 100.0 * float64(avail) / float64(total)
+
+		s.hostMetrics.Set(load.HostMetricFreeDiskSpaceBytes, int64(avail))
+		s.m3Client.UpdateGauge(metrics.SystemResourceScope, metrics.StorageDiskAvailableSpaceMB, int64(availMiBs))
+
+		xlog := log.WithFields(bark.Fields{
+			`avail`:   availMiBs,
+			`total`:   totalMiBs,
+			`percent`: availPercent,
+		})
+
+		s.Lock()
+		defer s.Unlock()
+
+		switch {
+		case s.mode == StorageModeReadOnly:
+
+			// disable read-only, if above resume-writes threshold
+			if avail > resumeWritesThreshold {
+
+				s.storeHost.EnableWrite()
+				s.mode = StorageModeReadWrite
+
+				xlog.Info("SpaceMon: disabling read-only")
+
+			} else {
+
+				xlog.Warn(`SpaceMon: continuing in read-only mode`)
+			}
+
+		case avail < alertThreshold: // enable read-only, if below alert-threshold
+
+			xlog.Error("SpaceMon: available space less than alert-threshold")
+
+			if s.mode != StorageModeReadOnly {
+				s.mode = StorageModeReadOnly
+				s.storeHost.DisableWrite()
+			}
+
+		case avail < warnThreshold: // warn, if below warn-threshold
+			xlog.Warn("SpaceMon: available space less than warn-threshold")
+
+		default:
+			xlog.Debug("SpaceMon: monitoring")
+		}
+	}
+}