Improve performance of console output watcher; work directly with bytes rather than string conversions

remote/types.go

@@ -1,6 +1,7 @@
 package remote
 
 import (
+	"bytes"
 	"regexp"
 	"strings"
 
@@ -85,37 +86,38 @@ type SftpAuthResponse struct {
 type OutputLineMatcher struct {
 	// The raw string to match against. This may or may not be prefixed with
 	// regex: which indicates we want to match against the regex expression.
-	raw string
+	raw []byte
 	reg *regexp.Regexp
 }
 
-// Matches determines if a given string "s" matches the given line.
+// Matches determines if the provided byte string matches the given regex or
-func (olm *OutputLineMatcher) Matches(s string) bool {
+// raw string provided to the matcher.
+func (olm *OutputLineMatcher) Matches(s []byte) bool {
 	if olm.reg == nil {
-		return strings.Contains(s, olm.raw)
+		return bytes.Contains(s, olm.raw)
 	}
-
+	return olm.reg.Match(s)
-	return olm.reg.MatchString(s)
 }
 
 // String returns the matcher's raw comparison string.
 func (olm *OutputLineMatcher) String() string {
-	return olm.raw
+	return string(olm.raw)
 }
 
 // UnmarshalJSON unmarshals the startup lines into individual structs for easier
 // matching abilities.
 func (olm *OutputLineMatcher) UnmarshalJSON(data []byte) error {
-	if err := json.Unmarshal(data, &olm.raw); err != nil {
+	var r string
+	if err := json.Unmarshal(data, &r); err != nil {
 		return err
 	}
 
-	if strings.HasPrefix(olm.raw, "regex:") && len(olm.raw) > 6 {
+	olm.raw = []byte(r)
-		r, err := regexp.Compile(strings.TrimPrefix(olm.raw, "regex:"))
+	if bytes.HasPrefix(olm.raw, []byte("regex:")) && len(olm.raw) > 6 {
+		r, err := regexp.Compile(strings.TrimPrefix(string(olm.raw), "regex:"))
 		if err != nil {
-			log.WithField("error", err).WithField("raw", olm.raw).Warn("failed to compile output line marked as being regex")
+			log.WithField("error", err).WithField("raw", string(olm.raw)).Warn("failed to compile output line marked as being regex")
 		}
-
 		olm.reg = r
 	}
 

server/listeners.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"bytes"
 	"regexp"
 	"strconv"
 	"sync"
@@ -50,6 +51,11 @@ func (dsl *diskSpaceLimiter) Trigger() {
 	})
 }
 
+// processConsoleOutputEvent handles output from a server's Docker container
+// and runs through different limiting logic to ensure that spam console output
+// does not cause negative effects to the system. This will also monitor the
+// output lines to determine if the server is started yet, and if the output is
+// not being throttled, will send the data over to the websocket.
 func (s *Server) processConsoleOutputEvent(v []byte) {
 	t := s.Throttler()
 	err := t.Increment(func() {
@@ -81,13 +87,15 @@ func (s *Server) processConsoleOutputEvent(v []byte) {
 		}
 	}
 
+	// Always process the console output, but do this in a seperate thread since we
+	// don't really care about side-effects from this call, and don't want it to block
+	// the console sending logic.
+	go s.onConsoleOutput(v)
+
 	// If we are not throttled, go ahead and output the data.
 	if !t.Throttled() {
 		s.Sink(LogSink).Push(v)
 	}
-
-	// Also pass the data along to the console output channel.
-	s.onConsoleOutput(string(v))
 }
 
 // StartEventListeners adds all the internal event listeners we want to use for a server. These listeners can only be
@@ -153,27 +161,34 @@ var stripAnsiRegex = regexp.MustCompile("[\u001B\u009B][[\\]()#;?]*(?:(?:(?:[a-z
 
 // Custom listener for console output events that will check if the given line
 // of output matches one that should mark the server as started or not.
-func (s *Server) onConsoleOutput(data string) {
+func (s *Server) onConsoleOutput(data []byte) {
-	// Get the server's process configuration.
+	if s.Environment.State() != environment.ProcessStartingState && !s.IsRunning() {
+		return
+	}
+
 	processConfiguration := s.ProcessConfiguration()
 
+	// Make a copy of the data provided since it is by reference, otherwise you'll
+	// potentially introduce a race condition by modifying the value.
+	v := make([]byte, len(data))
+	copy(v, data)
+
 	// Check if the server is currently starting.
 	if s.Environment.State() == environment.ProcessStartingState {
 		// Check if we should strip ansi color codes.
 		if processConfiguration.Startup.StripAnsi {
-			// Strip ansi color codes from the data string.
+			v = stripAnsiRegex.ReplaceAll(v, []byte(""))
-			data = stripAnsiRegex.ReplaceAllString(data, "")
 		}
 
 		// Iterate over all the done lines.
 		for _, l := range processConfiguration.Startup.Done {
-			if !l.Matches(data) {
+			if !l.Matches(v) {
 				continue
 			}
 
 			s.Log().WithFields(log.Fields{
 				"match":   l.String(),
-				"against": strconv.QuoteToASCII(data),
+				"against": strconv.QuoteToASCII(string(v)),
 			}).Debug("detected server in running state based on console line output")
 
 			// If the specific line of output is one that would mark the server as started,
@@ -190,7 +205,7 @@ func (s *Server) onConsoleOutput(data string) {
 	if s.IsRunning() {
 		stop := processConfiguration.Stop
 
-		if stop.Type == remote.ProcessStopCommand && data == stop.Value {
+		if stop.Type == remote.ProcessStopCommand && bytes.Equal(v, []byte(stop.Value)) {
 			s.Environment.SetState(environment.ProcessOfflineState)
 		}
 	}

server/sink_test.go

@@ -83,7 +83,7 @@ func TestSink(t *testing.T) {
 		g.It("does not panic if a nil channel is provided", func() {
 			ch := make([]chan []byte, 1)
 
-			defer func () {
+			defer func() {
 				if r := recover(); r != nil {
 					g.Fail("removing a nil channel should not cause a panic")
 				}