feat: Handle stdin closure and shut down the tailer.

.github/workflows/automerge.yml

@@ -17,20 +17,21 @@ jobs:
   enable-automerge:
     if: github.event.pull_request.user.login == 'dependabot[bot]' && contains(github.event.pull_request.labels.*.name, 'dependencies')
     runs-on: ubuntu-latest
+    # https://github.com/orgs/community/discussions/24686
     permissions:
-      # enable-automerge is a graphql query, not REST, so isn't documented,
-      # except in a mention in
-      # https://github.blog/changelog/2021-02-04-pull-request-auto-merge-is-now-generally-available/
-      # which says "can only be enabled by users with permissino to merge"; the
-      # REST documentation says you need contents: write to perform a merge.
-      # https://github.community/t/what-permission-does-a-github-action-need-to-call-graphql-enablepullrequestautomerge/197708
-      # says this is it
       contents: write
+      pull-requests: write
     steps:
-      # Enable auto-merge *before* issuing an approval.
-      - uses: alexwilson/enable-github-automerge-action@main
-        with:
-          github-token: "${{ secrets.GITHUB_TOKEN }}"
+      - run: |
+          gh api graphql -f pullRequestId="${{ github.event.pull_request.node_id }}" -f query='
+          mutation EnablePullRequestAutoMerge($pullRequestId: ID!) {
+            enablePullRequestAutoMerge(input: {pullRequestId: $pullRequestId}) {
+              clientMutationId
+            }
+          }
+          '
+        env:
+          GH_TOKEN: ${{ github.token }}
 
   wait-on-checks:
     needs: enable-automerge

cmd/mtail/main.go

@@ -182,7 +182,7 @@ func main() {
 	}
 	if *staleLogGcTickInterval > 0 {
 		staleLogGcWaker := waker.NewTimed(ctx, *staleLogGcTickInterval)
-		opts = append(opts, mtail.StaleLogGcWaker(staleLogGcWaker))
+		opts = append(opts, mtail.GcWaker(staleLogGcWaker))
 	}
 	if *pollInterval > 0 {
 		logStreamPollWaker := waker.NewTimed(ctx, *pollInterval)

internal/mtail/basic_tail_integration_test.go

@@ -17,11 +17,11 @@ import (
 func TestBasicTail(t *testing.T) {
 	testutil.SkipIfShort(t)
 	if testing.Verbose() {
-		testutil.SetFlag(t, "vmodule", "tail=2,log_watcher=2")
+		testutil.SetFlag(t, "vmodule", "tail=2,filestream=2")
 	}
 	logDir := testutil.TestTempDir(t)
 
-	m, stopM := mtail.TestStartServer(t, 1, mtail.LogPathPatterns(logDir+"/*"), mtail.ProgramPath("../../examples/linecount.mtail"))
+	m, stopM := mtail.TestStartServer(t, 1, 1, mtail.LogPathPatterns(logDir+"/*"), mtail.ProgramPath("../../examples/linecount.mtail"))
 	defer stopM()
 
 	logFile := filepath.Join(logDir, "log")
@@ -31,12 +31,13 @@ func TestBasicTail(t *testing.T) {
 
 	f := testutil.TestOpenFile(t, logFile)
 	defer f.Close()
-	m.PollWatched(1) // Force sync to EOF
+	m.AwakenPatternPollers(1, 1) // Find `logFile`
+	m.AwakenLogStreams(1, 1)     // Force a sync to EOF
 
 	for i := 1; i <= 3; i++ {
 		testutil.WriteString(t, f, fmt.Sprintf("%d\n", i))
 	}
-	m.PollWatched(1) // Expect to read 3 lines here.
+	m.AwakenLogStreams(1, 1) // Expect to read 3 lines here.
 
 	var wg sync.WaitGroup
 	wg.Add(2)
@@ -57,7 +58,7 @@ func TestNewLogDoesNotMatchIsIgnored(t *testing.T) {
 
 	// Start mtail
 	logFilepath := filepath.Join(workdir, "log")
-	m, stopM := mtail.TestStartServer(t, 0, mtail.LogPathPatterns(logFilepath))
+	m, stopM := mtail.TestStartServer(t, 1, 0, mtail.LogPathPatterns(logFilepath))
 	defer stopM()
 
 	logCountCheck := m.ExpectExpvarDeltaWithDeadline("log_count", 0)
@@ -68,7 +69,7 @@ func TestNewLogDoesNotMatchIsIgnored(t *testing.T) {
 	logFile, err := os.Create(newLogFilepath)
 	testutil.FatalIfErr(t, err)
 	defer logFile.Close()
-	m.PollWatched(0) // No streams so don't wait for any.
+	// No streams so don't wait for any.
 
 	logCountCheck()
 }

internal/mtail/examples_integration_test.go

@@ -92,7 +92,7 @@ func TestExamplePrograms(t *testing.T) {
 		t.Run(fmt.Sprintf("%s on %s", tc.programfile, tc.logfile),
 			testutil.TimeoutTest(exampleTimeout, func(t *testing.T) { //nolint:thelper
 				ctx, cancel := context.WithCancel(context.Background())
-				waker, _ := waker.NewTest(ctx, 0) // oneshot means we should never need to wake the stream
+				waker, _ := waker.NewTest(ctx, 0, "waker") // oneshot means we should never need to wake the stream
 				store := metrics.NewStore()
 				programFile := filepath.Join("../..", tc.programfile)
 				mtail, err := mtail.New(ctx, store, mtail.ProgramPath(programFile), mtail.LogPathPatterns(tc.logfile), mtail.OneShot, mtail.OmitMetricSource, mtail.DumpAstTypes, mtail.DumpBytecode, mtail.LogPatternPollWaker(waker), mtail.LogstreamPollWaker(waker))
@@ -155,7 +155,7 @@ func BenchmarkProgram(b *testing.B) {
 			logFile := filepath.Join(logDir, "test.log")
 			log := testutil.TestOpenFile(b, logFile)
 			ctx, cancel := context.WithCancel(context.Background())
-			waker, awaken := waker.NewTest(ctx, 1)
+			waker, awaken := waker.NewTest(ctx, 1, "streams")
 			store := metrics.NewStore()
 			programFile := filepath.Join("../..", bm.programfile)
 			mtail, err := mtail.New(ctx, store, mtail.ProgramPath(programFile), mtail.LogPathPatterns(log.Name()), mtail.LogstreamPollWaker(waker))
@@ -176,7 +176,7 @@ func BenchmarkProgram(b *testing.B) {
 				count, err := io.Copy(log, l)
 				testutil.FatalIfErr(b, err)
 				total += count
-				awaken(1)
+				awaken(1, 1)
 			}
 			cancel()
 			wg.Wait()

internal/mtail/examples_integration_unix_test.go

@@ -149,7 +149,7 @@ func TestFileSocketStreamComparison(t *testing.T) {
 						defer wg.Done()
 						source, err := os.OpenFile(tc.logfile, os.O_RDONLY, 0)
 						testutil.FatalIfErr(t, err)
-						s, err := net.DialUnix(scheme, nil, &net.UnixAddr{sockName, scheme})
+						s, err := net.DialUnix(scheme, nil, &net.UnixAddr{Name: sockName, Net: scheme})
 						testutil.FatalIfErr(t, err)
 						n, err := io.Copy(s, source)
 						testutil.FatalIfErr(t, err)

internal/mtail/log_deletion_integration_unix_test.go

@@ -25,18 +25,20 @@ func TestLogDeletion(t *testing.T) {
 	logFile := testutil.TestOpenFile(t, logFilepath)
 	defer logFile.Close()
 
-	m, stopM := mtail.TestStartServer(t, 1, mtail.LogPathPatterns(logFilepath))
+	m, stopM := mtail.TestStartServer(t, 1, 1, mtail.LogPathPatterns(logFilepath))
 	defer stopM()
 
 	logCloseCheck := m.ExpectMapExpvarDeltaWithDeadline("log_closes_total", logFilepath, 1)
 	logCountCheck := m.ExpectExpvarDeltaWithDeadline("log_count", -1)
 
-	m.PollWatched(1) // Force sync to EOF
+	m.AwakenPatternPollers(1, 1)
+	m.AwakenLogStreams(1, 1) // Force read to EOF
+
 	glog.Info("remove")
 	testutil.FatalIfErr(t, os.Remove(logFilepath))
 
-	m.PollWatched(0) // one pass to stop
+	m.AwakenLogStreams(1, 0) // run stream to observe it's missing
 	logCloseCheck()
-	m.PollWatched(0) // one pass to remove completed stream
+	m.AwakenGcPoller(1, 1)
 	logCountCheck()
 }

internal/mtail/log_glob_integration_test.go

@@ -45,7 +45,7 @@ func TestGlobBeforeStart(t *testing.T) {
 		testutil.WriteString(t, log, "\n")
 		log.Close()
 	}
-	m, stopM := mtail.TestStartServer(t, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")))
+	m, stopM := mtail.TestStartServer(t, 0, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")))
 	stopM()
 
 	if r := m.GetExpvar("log_count"); r.(*expvar.Int).Value() != count {
@@ -75,10 +75,10 @@ func TestGlobAfterStart(t *testing.T) {
 			false,
 		},
 	}
-	m, stopM := mtail.TestStartServer(t, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")))
+	m, stopM := mtail.TestStartServer(t, 1, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")))
 	defer stopM()
 
-	m.PollWatched(0) // Force sync to EOF
+	m.AwakenPatternPollers(1, 1)
 
 	var count int64
 	for _, tt := range globTests {
@@ -90,9 +90,8 @@ func TestGlobAfterStart(t *testing.T) {
 	for _, tt := range globTests {
 		log := testutil.TestOpenFile(t, tt.name)
 		defer log.Close()
-		m.PollWatched(0) // Force sync to EOF
+		m.AwakenPatternPollers(1, 1)
 	}
-	// m.PollWatched(2)
 	logCountCheck()
 }
 
@@ -142,7 +141,7 @@ func TestGlobIgnoreFolder(t *testing.T) {
 		testutil.WriteString(t, log, "\n")
 	}
 
-	m, stopM := mtail.TestStartServer(t, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")), mtail.IgnoreRegexPattern("\\.gz"))
+	m, stopM := mtail.TestStartServer(t, 0, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")), mtail.IgnoreRegexPattern("\\.gz"))
 
 	stopM()
 
@@ -184,7 +183,7 @@ func TestFilenameRegexIgnore(t *testing.T) {
 		testutil.WriteString(t, log, "\n")
 	}
 
-	m, stopM := mtail.TestStartServer(t, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")), mtail.IgnoreRegexPattern("\\.gz"))
+	m, stopM := mtail.TestStartServer(t, 0, 0, mtail.LogPathPatterns(filepath.Join(workdir, "log*")), mtail.IgnoreRegexPattern("\\.gz"))
 
 	stopM()
 
@@ -207,7 +206,7 @@ func TestGlobRelativeAfterStart(t *testing.T) {
 	// Move to logdir to make relative paths
 	testutil.Chdir(t, logDir)
 
-	m, stopM := mtail.TestStartServer(t, 1, mtail.ProgramPath(progDir), mtail.LogPathPatterns("log.*"))
+	m, stopM := mtail.TestStartServer(t, 1, 0, mtail.ProgramPath(progDir), mtail.LogPathPatterns("log.*"))
 	defer stopM()
 
 	{
@@ -217,9 +216,11 @@ func TestGlobRelativeAfterStart(t *testing.T) {
 		f := testutil.TestOpenFile(t, logFile)
 		defer f.Close()
 
-		m.PollWatched(1) // Force sync to EOF
+		m.AwakenPatternPollers(1, 1)
+		m.AwakenLogStreams(0, 1) // Force read to EOF
+
 		testutil.WriteString(t, f, "line 1\n")
-		m.PollWatched(1)
+		m.AwakenLogStreams(1, 1)
 
 		logCountCheck()
 	}
@@ -232,9 +233,11 @@ func TestGlobRelativeAfterStart(t *testing.T) {
 		f := testutil.TestOpenFile(t, logFile)
 		defer f.Close()
 
-		m.PollWatched(2)
+		m.AwakenPatternPollers(1, 1)
+		m.AwakenLogStreams(1, 2) // Force read to EOF
+
 		testutil.WriteString(t, f, "line 1\n")
-		m.PollWatched(2)
+		m.AwakenLogStreams(2, 2)
 
 		logCountCheck()
 	}
@@ -245,9 +248,11 @@ func TestGlobRelativeAfterStart(t *testing.T) {
 		f := testutil.TestOpenFile(t, logFile)
 		defer f.Close()
 
-		m.PollWatched(2)
+		m.AwakenPatternPollers(1, 1)
+		m.AwakenLogStreams(2, 2) // Force read to EOF
+
 		testutil.WriteString(t, f, "line 2\n")
-		m.PollWatched(2)
+		m.AwakenLogStreams(2, 2)
 
 		logCountCheck()
 	}

internal/mtail/log_rotation_integration_test.go

@@ -15,7 +15,7 @@ import (
 	"github.com/google/mtail/internal/testutil"
 )
 
-func TestLogSoftLinkChange(t *testing.T) {
+func TestLogRotationBySoftLinkChange(t *testing.T) {
 	testutil.SkipIfShort(t)
 
 	for _, tc := range []bool{false, true} {
@@ -29,7 +29,7 @@ func TestLogSoftLinkChange(t *testing.T) {
 
 			logFilepath := filepath.Join(workdir, "log")
 
-			m, stopM := mtail.TestStartServer(t, 1, mtail.LogPathPatterns(logFilepath))
+			m, stopM := mtail.TestStartServer(t, 1, 1, mtail.LogPathPatterns(logFilepath))
 			defer stopM()
 
 			logCountCheck := m.ExpectExpvarDeltaWithDeadline("log_count", 1)
@@ -40,33 +40,42 @@ func TestLogSoftLinkChange(t *testing.T) {
 
 			testutil.FatalIfErr(t, os.Symlink(logFilepath+".true1", logFilepath))
 			glog.Info("symlinked")
-			m.PollWatched(1)
+			m.AwakenPatternPollers(1, 1)
+			m.AwakenLogStreams(1, 1)
 
 			inputLines := []string{"hi1", "hi2", "hi3"}
 			for _, x := range inputLines {
 				testutil.WriteString(t, trueLog1, x+"\n")
 			}
-			m.PollWatched(1)
+			m.AwakenPatternPollers(1, 1)
+			m.AwakenLogStreams(1, 1)
 
 			trueLog2 := testutil.TestOpenFile(t, logFilepath+".true2")
 			defer trueLog2.Close()
-			m.PollWatched(1)
+			m.AwakenPatternPollers(1, 1)
+			m.AwakenLogStreams(1, 1)
+			m.AwakenGcPoller(1, 1)
 			logClosedCheck := m.ExpectMapExpvarDeltaWithDeadline("log_closes_total", logFilepath, 1)
 			logCompletedCheck := m.ExpectExpvarDeltaWithDeadline("log_count", -1)
 			testutil.FatalIfErr(t, os.Remove(logFilepath))
 			if tc {
-				m.PollWatched(0)    // simulate race condition with this poll.
-				logClosedCheck()    // sync when filestream closes fd
-				m.PollWatched(0)    // invoke the GC
-				logCompletedCheck() // sync to when the logstream is removed from tailer
+				// Simulate a race where we poll for a pattern and remove the
+				// existing stream.
+				m.AwakenPatternPollers(1, 1) // simulate race condition with this poll.
+				m.AwakenLogStreams(1, 0)
+				logClosedCheck() // barrier until filestream closes fd
+				m.AwakenGcPoller(1, 1)
+				logCompletedCheck() // barrier until the logstream is removed from tailer
 			}
 			testutil.FatalIfErr(t, os.Symlink(logFilepath+".true2", logFilepath))
-			m.PollWatched(1)
+			m.AwakenPatternPollers(1, 1)
+			m.AwakenLogStreams(0, 1)
 
 			for _, x := range inputLines {
 				testutil.WriteString(t, trueLog2, x+"\n")
 			}
-			m.PollWatched(1)
+			m.AwakenPatternPollers(1, 1)
+			m.AwakenLogStreams(1, 1)
 
 			var wg sync.WaitGroup
 			wg.Add(2)

internal/mtail/log_rotation_integration_unix_test.go

@@ -17,11 +17,12 @@ import (
 	"github.com/google/mtail/internal/testutil"
 )
 
-// TestLogRotation is a unix-specific test because on Windows, files cannot be removed
-// or renamed while there is an open read handle on them. Instead, log rotation would
-// have to be implemented by copying and then truncating the original file. That test
-// case is already covered by TestLogTruncation.
-func TestLogRotation(t *testing.T) {
+// TestLogRotationByRename is a unix-specific test because on Windows, files
+// cannot be removed or renamed while there is an open read handle on
+// them. Instead, log rotation would have to be implemented by copying and then
+// truncating the original file. That test case is already covered by
+// TestLogTruncation.
+func TestLogRotationByRename(t *testing.T) {
 	testutil.SkipIfShort(t)
 
 	for _, tc := range []bool{false, true} {
@@ -45,34 +46,38 @@ func TestLogRotation(t *testing.T) {
 			f := testutil.TestOpenFile(t, logFile)
 			defer f.Close()
 
-			m, stopM := mtail.TestStartServer(t, 1, mtail.ProgramPath(progDir), mtail.LogPathPatterns(logDir+"/log"))
+			m, stopM := mtail.TestStartServer(t, 1, 1, mtail.ProgramPath(progDir), mtail.LogPathPatterns(logDir+"/log"))
 			defer stopM()
 
 			logOpensTotalCheck := m.ExpectMapExpvarDeltaWithDeadline("log_opens_total", logFile, 1)
 			logLinesTotalCheck := m.ExpectMapExpvarDeltaWithDeadline("log_lines_total", logFile, 3)
 
 			testutil.WriteString(t, f, "line 1\n")
-			m.PollWatched(1)
+			m.AwakenLogStreams(1, 1)
 
 			testutil.WriteString(t, f, "line 2\n")
-			m.PollWatched(1)
+			m.AwakenLogStreams(1, 1)
 
 			logClosedCheck := m.ExpectMapExpvarDeltaWithDeadline("log_closes_total", logFile, 1)
 			logCompletedCheck := m.ExpectExpvarDeltaWithDeadline("log_count", -1)
 			glog.Info("rename")
 			err = os.Rename(logFile, logFile+".1")
 			testutil.FatalIfErr(t, err)
 			if tc {
-				m.PollWatched(0)    // simulate race condition with this poll.
-				logClosedCheck()    // sync when filestream closes fd
-				m.PollWatched(0)    // invoke the GC
-				logCompletedCheck() // sync to when the logstream is removed from tailer
+				// Simulate a race where we poll for a pattern and remove the
+				// existing stream.
+				m.AwakenPatternPollers(1, 1) // simulate race condition with this poll.
+				m.AwakenLogStreams(1, 0)
+				logClosedCheck() // barrier until filestream closes fd
+				m.AwakenGcPoller(1, 1)
+				logCompletedCheck() // barrier until the logstream is removed from tailer
 			}
 			glog.Info("create")
 			f = testutil.TestOpenFile(t, logFile)
-			m.PollWatched(1)
+			m.AwakenPatternPollers(1, 1)
+			m.AwakenLogStreams(0, 1)
 			testutil.WriteString(t, f, "line 1\n")
-			m.PollWatched(1)
+			m.AwakenLogStreams(1, 1)
 
 			var wg sync.WaitGroup
 			wg.Add(2)