refactor to have no context.Context in server mapreduce aggregate structs

2 files changed, 44 insertions, 38 deletions

diff --git a/internal/mapr/server/aggregate.go b/internal/mapr/server/aggregate.go
index 1028943..cd59b63 100644
--- a/internal/mapr/server/aggregate.go
+++ b/internal/mapr/server/aggregate.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/mimecast/dtail/internal"
 	"github.com/mimecast/dtail/internal/config"
 	"github.com/mimecast/dtail/internal/io/line"
 	"github.com/mimecast/dtail/internal/io/logger"
@@ -15,6 +16,7 @@ import (
 
 // Aggregate is for aggregating mapreduce data on the DTail server side.
 type Aggregate struct {
+	done *internal.Done
 	// Log lines to process (parsing MAPREDUCE lines).
 	Lines chan line.Line
 	// Hostname of the current server (used to populate $hostname field).
@@ -23,12 +25,12 @@ type Aggregate struct {
 	serialize chan struct{}
 	// Signals to flush data.
 	flush chan struct{}
+	// Signals that data has been flushed
+	flushed chan struct{}
 	// The mapr query
 	query *mapr.Query
 	// The mapr log format parser
 	parser *logformat.Parser
-	cancel context.CancelFunc
-	ctx    context.Context
 }
 
 // NewAggregate return a new server side aggregator.
@@ -64,56 +66,63 @@ func NewAggregate(queryStr string) (*Aggregate, error) {
 		}
 	}
 
-	ctx, cancel := context.WithCancel(context.Background())
-
 	a := Aggregate{
+		done:      internal.NewDone(),
 		Lines:     make(chan line.Line, 100),
 		serialize: make(chan struct{}),
 		flush:     make(chan struct{}),
+		flushed:   make(chan struct{}),
 		hostname:  s[0],
 		query:     query,
 		parser:    logParser,
-		ctx:       ctx,
-		cancel:    cancel,
 	}
 
 	return &a, nil
 }
 
+func (a *Aggregate) Shutdown() {
+	a.Flush()
+	a.done.Shutdown()
+}
+
 // Start an aggregation.
 func (a *Aggregate) Start(ctx context.Context, maprLines chan<- string) {
-	defer a.cancel()
 
-	fieldsCh := a.linesToFields(ctx)
+	myCtx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	go func() {
+		select {
+		case <-myCtx.Done():
+			a.done.Shutdown()
+		case <-a.done.Done():
+			cancel()
+		}
+	}()
+
+	fieldsCh := a.makeFields(myCtx)
 
 	// Add fields (e.g. via 'set' clause)
 	if len(a.query.Set) > 0 {
-		fieldsCh = a.addMoreFields(ctx, fieldsCh)
+		fieldsCh = a.addFields(myCtx, fieldsCh)
 	}
 
-	go a.fieldsToMaprLines(ctx, fieldsCh, maprLines)
-	a.periodicAggregateTimer(ctx)
+	go a.aggregateTimer(myCtx)
+	a.makeMaprLines(myCtx, fieldsCh, maprLines)
 }
 
-// Cancel the aggregation.
-func (a *Aggregate) Cancel() {
-	a.cancel()
-}
-
-func (a *Aggregate) periodicAggregateTimer(ctx context.Context) {
+func (a *Aggregate) aggregateTimer(ctx context.Context) {
 	for {
 		select {
 		case <-time.After(a.query.Interval):
 			a.Serialize(ctx)
 		case <-ctx.Done():
 			return
-		case <-a.ctx.Done():
-			return
 		}
 	}
 }
 
-func (a *Aggregate) linesToFields(ctx context.Context) <-chan map[string]string {
+func (a *Aggregate) makeFields(ctx context.Context) <-chan map[string]string {
 	ch := make(chan map[string]string)
 
 	go func() {
@@ -144,8 +153,6 @@ func (a *Aggregate) linesToFields(ctx context.Context) <-chan map[string]string
 				}
 			case <-ctx.Done():
 				return
-			case <-a.ctx.Done():
-				return
 			}
 		}
 	}()
@@ -153,14 +160,14 @@ func (a *Aggregate) linesToFields(ctx context.Context) <-chan map[string]string
 	return ch
 }
 
-func (a *Aggregate) addMoreFields(ctx context.Context, fieldsCh <-chan map[string]string) <-chan map[string]string {
+func (a *Aggregate) addFields(ctx context.Context, fieldsCh <-chan map[string]string) <-chan map[string]string {
 	ch := make(chan map[string]string)
 
 	go func() {
 		defer close(ch)
 
 		for {
-			// fieldsCh will be closed via 'linesToFields' if ctx is done
+			// fieldsCh will be closed via 'makeFields' if ctx is done
 			fields, ok := <-fieldsCh
 			if !ok {
 				return
@@ -179,7 +186,7 @@ func (a *Aggregate) addMoreFields(ctx context.Context, fieldsCh <-chan map[strin
 	return ch
 }
 
-func (a *Aggregate) fieldsToMaprLines(ctx context.Context, fieldsCh <-chan map[string]string, maprLines chan<- string) {
+func (a *Aggregate) makeMaprLines(ctx context.Context, fieldsCh <-chan map[string]string, maprLines chan<- string) {
 	group := mapr.NewGroupSet()
 
 	serialize := func() {
@@ -200,18 +207,10 @@ func (a *Aggregate) fieldsToMaprLines(ctx context.Context, fieldsCh <-chan map[s
 		case <-a.serialize:
 			serialize()
 		case <-a.flush:
-			logger.Info("Flushing mapreduce result")
 			serialize()
-			a.flush <- struct{}{}
-			logger.Info("Done flushing mapreduce result")
+			a.flushed <- struct{}{}
 		case <-ctx.Done():
 			return
-		case <-a.ctx.Done():
-			logger.Info("Flushing mapreduce result")
-			serialize()
-			a.flush <- struct{}{}
-			logger.Info("Done flushing mapreduce result")
-			return
 		}
 	}
 }
@@ -254,6 +253,8 @@ func (a *Aggregate) aggregate(group *mapr.GroupSet, fields map[string]string) {
 func (a *Aggregate) Serialize(ctx context.Context) {
 	select {
 	case a.serialize <- struct{}{}:
+	case <-time.After(time.Minute):
+		logger.Warn("Starting to serialize mapredice data takes over a minute")
 	case <-ctx.Done():
 	}
 }
@@ -261,15 +262,20 @@ func (a *Aggregate) Serialize(ctx context.Context) {
 // Flush all data.
 func (a *Aggregate) Flush() {
 	select {
-	case <-a.ctx.Done():
-		return
 	case a.flush <- struct{}{}:
+		logger.Info("Flushing mapreduce data")
 	case <-time.After(time.Minute):
+		logger.Warn("Starting to flush mapreduce data takes over a minute")
+		return
+	case <-a.done.Done():
 		return
 	}
 
 	select {
-	case <-a.flush:
+	case <-a.flushed:
+		logger.Info("Done flushing")
 	case <-time.After(time.Minute):
+		logger.Warn("Waiting for data to be flushed takes over a minute")
+	case <-a.done.Done():
 	}
 }
diff --git a/internal/server/handlers/serverhandler.go b/internal/server/handlers/serverhandler.go
index 5af3ebb..164a280 100644
--- a/internal/server/handlers/serverhandler.go
+++ b/internal/server/handlers/serverhandler.go
@@ -266,7 +266,7 @@ func (h *ServerHandler) handleUserCommand(ctx context.Context, argc int, args []
 			if h.aggregate == nil {
 				return
 			}
-			h.aggregate.Cancel()
+			h.aggregate.Shutdown()
 		}
 	}