From 0d5495e997ecdb56f6a6d5a2407200376d3f828e Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Sat, 3 Oct 2020 13:25:56 +0300
Subject: [PATCH] [#70] object manager: Implement an example object garbage
 collector

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 pkg/services/object_manager/gc/gc.go   | 148 +++++++++++++++++++++++++
 pkg/services/object_manager/gc/opts.go |  42 +++++++
 2 files changed, 190 insertions(+)
 create mode 100644 pkg/services/object_manager/gc/gc.go
 create mode 100644 pkg/services/object_manager/gc/opts.go

diff --git a/pkg/services/object_manager/gc/gc.go b/pkg/services/object_manager/gc/gc.go
new file mode 100644
index 00000000..69290a96
--- /dev/null
+++ b/pkg/services/object_manager/gc/gc.go
@@ -0,0 +1,148 @@
+package gc
+
+import (
+	"context"
+	"time"
+
+	"github.com/mr-tron/base58"
+	"github.com/nspcc-dev/neofs-api-go/pkg/container"
+	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+	"go.uber.org/zap"
+)
+
+// GC represents an object garbage collector.
+type GC struct {
+	*cfg
+
+	timer *time.Timer
+
+	queue chan *object.Address
+}
+
+// Option represents GC constructor option.
+type Option func(*cfg)
+
+type cfg struct {
+	sleepInterval, workInterval time.Duration
+
+	queueCap uint32
+
+	log *logger.Logger
+
+	remover Remover
+}
+
+// Remover is an interface of the component that stores objects.
+type Remover interface {
+	// Delete removes (or marks to remove) object from physical storage.
+	Delete(*object.Address) error
+}
+
+func defaultCfg() *cfg {
+	return &cfg{
+		sleepInterval: 5 * time.Second,
+		workInterval:  5 * time.Second,
+		queueCap:      10,
+		log:           zap.L(),
+	}
+}
+
+// New creates, initializes and returns GC instance.
+func New(opts ...Option) *GC {
+	cfg := defaultCfg()
+
+	for i := range opts {
+		opts[i](cfg)
+	}
+
+	cfg.log = cfg.log.With(zap.String("component", "Object GC"))
+
+	return &GC{
+		cfg: cfg,
+	}
+}
+
+func (gc *GC) Run(ctx context.Context) {
+	defer func() {
+		close(gc.queue)
+		gc.timer.Stop()
+		gc.log.Info("routine stopped")
+	}()
+
+	gc.log.Info("process routine",
+		zap.Uint32("queue capacity", gc.queueCap),
+		zap.Duration("sleep interval", gc.sleepInterval),
+		zap.Duration("working interval", gc.workInterval),
+	)
+
+	gc.queue = make(chan *object.Address, gc.queueCap)
+	gc.timer = time.NewTimer(gc.sleepInterval)
+
+	for {
+		select {
+		case <-ctx.Done():
+			gc.log.Warn("context is done",
+				zap.String("error", ctx.Err().Error()),
+			)
+
+			return
+		case _, ok := <-gc.timer.C:
+			if !ok {
+				gc.log.Warn("timer is stopped")
+
+				return
+			}
+
+			abort := time.After(gc.workInterval)
+
+		loop:
+			for {
+				select {
+				case <-ctx.Done():
+					gc.log.Warn("context is done",
+						zap.String("error", ctx.Err().Error()),
+					)
+
+					return
+				case <-abort:
+					break loop
+				case addr, ok := <-gc.queue:
+					if !ok {
+						gc.log.Warn("queue channel is closed")
+					} else if err := gc.remover.Delete(addr); err != nil {
+						gc.log.Error("could not remove object",
+							zap.String("error", err.Error()),
+						)
+					} else {
+						gc.log.Info("object removed",
+							zap.String("CID", stringifyCID(addr.GetContainerID())),
+							zap.String("ID", stringifyID(addr.GetObjectID())),
+						)
+					}
+				}
+			}
+
+			gc.timer.Reset(gc.sleepInterval)
+		}
+	}
+}
+
+func stringifyID(addr *object.ID) string {
+	return base58.Encode(addr.ToV2().GetValue())
+}
+
+func stringifyCID(addr *container.ID) string {
+	return base58.Encode(addr.ToV2().GetValue())
+}
+
+// DeleteObjects adds list of adresses to delete queue.
+func (gc *GC) DeleteObjects(list ...*object.Address) {
+	for i := range list {
+		select {
+		case gc.queue <- list[i]:
+		default:
+			gc.log.Info("queue for deletion is full")
+		}
+	}
+}
diff --git a/pkg/services/object_manager/gc/opts.go b/pkg/services/object_manager/gc/opts.go
new file mode 100644
index 00000000..fa159cf7
--- /dev/null
+++ b/pkg/services/object_manager/gc/opts.go
@@ -0,0 +1,42 @@
+package gc
+
+import (
+	"time"
+
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+)
+
+// WithRemover returns option to set object remover.
+func WithRemover(v Remover) Option {
+	return func(c *cfg) {
+		c.remover = v
+	}
+}
+
+// WithLogger returns option to set logging component.
+func WithLogger(v *logger.Logger) Option {
+	return func(c *cfg) {
+		c.log = v
+	}
+}
+
+// WithQueueCapacity returns option to set delete queue capacity.
+func WithQueueCapacity(v uint32) Option {
+	return func(c *cfg) {
+		c.queueCap = v
+	}
+}
+
+// WithWorkingInterval returns option to set working interval of GC.
+func WithWorkingInterval(v time.Duration) Option {
+	return func(c *cfg) {
+		c.workInterval = v
+	}
+}
+
+// WithSleepInteval returns option to set sleep interval of GC.
+func WithSleepInterval(v time.Duration) Option {
+	return func(c *cfg) {
+		c.sleepInterval = v
+	}
+}