Add actions job log buffer and profiler (#866)

* add sliding window for actions logs * refactor: fix sliding * remove trim content * only use up to 1mb of memory for logs * update to tail lines in second pass * add better memory usage calculation * increase window size to 5MB * update test * update vers * undo vers change * add incremental memory tracking * use ring buffer * remove unused ctx param * remove manual GC clear * fix cca feedback * extract ring buffer logic to new package * handle log content processing errors and use correct param for maxjobloglines * fix tailing * account for if tailLines exceeds window size * add profiling thats reusable * remove profiler testing * refactor profiler: introduce safeMemoryDelta for accurate memory delta calculations * linter fixes * Update pkg/buffer/buffer.go Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> * use flag for maxJobLogLines * add param passing for context window size * refactor: rename contextWindowSize to contentWindowSize for consistency * fix: use tailLines if bigger but only if <= 5000 * fix: limit tailLines to a maximum of 500 for log content download * Update cmd/github-mcp-server/main.go Co-authored-by: Adam Holt <omgitsads@github.com> * Update cmd/github-mcp-server/main.go Co-authored-by: Adam Holt <omgitsads@github.com> * move profiler to internal/ * update actions test with new profiler location * fix: adjust buffer size limits * make line buffer 1028kb * fix mod path * change test to use same buffer size as normal use * improve test for non-sliding window implementation to not count empty lines * make test memory measurement more accurate * remove impossible conditional --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Co-authored-by: Adam Holt <omgitsads@github.com>
LuluBeatson · Sep 4, 2025 · Jul 26, 2025 · Aug 2, 2025 · Aug 3, 2025 · Aug 5, 2025
commit fc381f899fb85d0015d472df302cb94c6f468ab7
diff --git a/cmd/github-mcp-server/generate_docs.go b/cmd/github-mcp-server/generate_docs.go
@@ -64,7 +64,7 @@ func generateReadmeDocs(readmePath string) error {
 	t, _ := translations.TranslationHelper()
 
 	// Create toolset group with mock clients
-	tsg := github.DefaultToolsetGroup(false, mockGetClient, mockGetGQLClient, mockGetRawClient, t)
+	tsg := github.DefaultToolsetGroup(false, mockGetClient, mockGetGQLClient, mockGetRawClient, t, 5000)
 
 	// Generate toolsets documentation
 	toolsetsDoc := generateToolsetsDoc(tsg)
@@ -302,7 +302,7 @@ func generateRemoteToolsetsDoc() string {
 	t, _ := translations.TranslationHelper()
 
 	// Create toolset group with mock clients
-	tsg := github.DefaultToolsetGroup(false, mockGetClient, mockGetGQLClient, mockGetRawClient, t)
+	tsg := github.DefaultToolsetGroup(false, mockGetClient, mockGetGQLClient, mockGetRawClient, t, 5000)
 
 	// Generate table header
 	buf.WriteString("| Name           | Description                                      | API URL                                               | 1-Click Install (VS Code)                                                                                                                                                                                                 | Read-only Link                                                                                                 | 1-Click Read-only Install (VS Code)                                                                                                                                                                                                 |\n")

diff --git a/cmd/github-mcp-server/main.go b/cmd/github-mcp-server/main.go
@@ -55,6 +55,7 @@ var (
 				ExportTranslations:   viper.GetBool("export-translations"),
 				EnableCommandLogging: viper.GetBool("enable-command-logging"),
 				LogFilePath:          viper.GetString("log-file"),
+				ContentWindowSize:    viper.GetInt("content-window-size"),
 			}
 			return ghmcp.RunStdioServer(stdioServerConfig)
 		},
@@ -75,6 +76,7 @@ func init() {
 	rootCmd.PersistentFlags().Bool("enable-command-logging", false, "When enabled, the server will log all command requests and responses to the log file")
 	rootCmd.PersistentFlags().Bool("export-translations", false, "Save translations to a JSON file")
 	rootCmd.PersistentFlags().String("gh-host", "", "Specify the GitHub hostname (for GitHub Enterprise etc.)")
+	rootCmd.PersistentFlags().Int("content-window-size", 5000, "Specify the content window size")
 
 	// Bind flag to viper
 	_ = viper.BindPFlag("toolsets", rootCmd.PersistentFlags().Lookup("toolsets"))
@@ -84,6 +86,7 @@ func init() {
 	_ = viper.BindPFlag("enable-command-logging", rootCmd.PersistentFlags().Lookup("enable-command-logging"))
 	_ = viper.BindPFlag("export-translations", rootCmd.PersistentFlags().Lookup("export-translations"))
 	_ = viper.BindPFlag("host", rootCmd.PersistentFlags().Lookup("gh-host"))
+	_ = viper.BindPFlag("content-window-size", rootCmd.PersistentFlags().Lookup("content-window-size"))
 
 	// Add subcommands
 	rootCmd.AddCommand(stdioCmd)

diff --git a/internal/ghmcp/server.go b/internal/ghmcp/server.go
@@ -47,6 +47,9 @@ type MCPServerConfig struct {
 
 	// Translator provides translated text for the server tooling
 	Translator translations.TranslationHelperFunc
+
+	// Content window size
+	ContentWindowSize int
 }
 
 const stdioServerLogPrefix = "stdioserver"
@@ -132,7 +135,7 @@ func NewMCPServer(cfg MCPServerConfig) (*server.MCPServer, error) {
 	}
 
 	// Create default toolsets
-	tsg := github.DefaultToolsetGroup(cfg.ReadOnly, getClient, getGQLClient, getRawClient, cfg.Translator)
+	tsg := github.DefaultToolsetGroup(cfg.ReadOnly, getClient, getGQLClient, getRawClient, cfg.Translator, cfg.ContentWindowSize)
 	err = tsg.EnableToolsets(enabledToolsets)
 
 	if err != nil {
@@ -180,6 +183,9 @@ type StdioServerConfig struct {
 
 	// Path to the log file if not stderr
 	LogFilePath string
+
+	// Content window size
+	ContentWindowSize int
 }
 
 // RunStdioServer is not concurrent safe.
@@ -191,13 +197,14 @@ func RunStdioServer(cfg StdioServerConfig) error {
 	t, dumpTranslations := translations.TranslationHelper()
 
 	ghServer, err := NewMCPServer(MCPServerConfig{
-		Version:         cfg.Version,
-		Host:            cfg.Host,
-		Token:           cfg.Token,
-		EnabledToolsets: cfg.EnabledToolsets,
-		DynamicToolsets: cfg.DynamicToolsets,
-		ReadOnly:        cfg.ReadOnly,
-		Translator:      t,
+		Version:           cfg.Version,
+		Host:              cfg.Host,
+		Token:             cfg.Token,
+		EnabledToolsets:   cfg.EnabledToolsets,
+		DynamicToolsets:   cfg.DynamicToolsets,
+		ReadOnly:          cfg.ReadOnly,
+		Translator:        t,
+		ContentWindowSize: cfg.ContentWindowSize,
 	})
 	if err != nil {
 		return fmt.Errorf("failed to create MCP server: %w", err)

diff --git a/internal/profiler/profiler.go b/internal/profiler/profiler.go
@@ -0,0 +1,215 @@
+package profiler
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"runtime"
+	"strconv"
+	"time"
+
+	"log/slog"
+	"math"
+)
+
+// Profile represents performance metrics for an operation
+type Profile struct {
+	Operation    string        `json:"operation"`
+	Duration     time.Duration `json:"duration_ns"`
+	MemoryBefore uint64        `json:"memory_before_bytes"`
+	MemoryAfter  uint64        `json:"memory_after_bytes"`
+	MemoryDelta  int64         `json:"memory_delta_bytes"`
+	LinesCount   int           `json:"lines_count,omitempty"`
+	BytesCount   int64         `json:"bytes_count,omitempty"`
+	Timestamp    time.Time     `json:"timestamp"`
+}
+
+// String returns a human-readable representation of the profile
+func (p *Profile) String() string {
+	return fmt.Sprintf("[%s] %s: duration=%v, memory_delta=%+dB, lines=%d, bytes=%d",
+		p.Timestamp.Format("15:04:05.000"),
+		p.Operation,
+		p.Duration,
+		p.MemoryDelta,
+		p.LinesCount,
+		p.BytesCount,
+	)
+}
+
+func safeMemoryDelta(after, before uint64) int64 {
+	if after > math.MaxInt64 || before > math.MaxInt64 {
+		if after >= before {
+			diff := after - before
+			if diff > math.MaxInt64 {
+				return math.MaxInt64
+			}
+			return int64(diff)
+		}
+		diff := before - after
+		if diff > math.MaxInt64 {
+			return -math.MaxInt64
+		}
+		return -int64(diff)
+	}
+
+	return int64(after) - int64(before)
+}
+
+// Profiler provides minimal performance profiling capabilities
+type Profiler struct {
+	logger  *slog.Logger
+	enabled bool
+}
+
+// New creates a new Profiler instance
+func New(logger *slog.Logger, enabled bool) *Profiler {
+	return &Profiler{
+		logger:  logger,
+		enabled: enabled,
+	}
+}
+
+// ProfileFunc profiles a function execution
+func (p *Profiler) ProfileFunc(ctx context.Context, operation string, fn func() error) (*Profile, error) {
+	if !p.enabled {
+		return nil, fn()
+	}
+
+	profile := &Profile{
+		Operation: operation,
+		Timestamp: time.Now(),
+	}
+
+	var memBefore runtime.MemStats
+	runtime.ReadMemStats(&memBefore)
+	profile.MemoryBefore = memBefore.Alloc
+
+	start := time.Now()
+	err := fn()
+	profile.Duration = time.Since(start)
+
+	var memAfter runtime.MemStats
+	runtime.ReadMemStats(&memAfter)
+	profile.MemoryAfter = memAfter.Alloc
+	profile.MemoryDelta = safeMemoryDelta(memAfter.Alloc, memBefore.Alloc)
+
+	if p.logger != nil {
+		p.logger.InfoContext(ctx, "Performance profile", "profile", profile.String())
+	}
+
+	return profile, err
+}
+
+// ProfileFuncWithMetrics profiles a function execution and captures additional metrics
+func (p *Profiler) ProfileFuncWithMetrics(ctx context.Context, operation string, fn func() (int, int64, error)) (*Profile, error) {
+	if !p.enabled {
+		_, _, err := fn()
+		return nil, err
+	}
+
+	profile := &Profile{
+		Operation: operation,
+		Timestamp: time.Now(),
+	}
+
+	var memBefore runtime.MemStats
+	runtime.ReadMemStats(&memBefore)
+	profile.MemoryBefore = memBefore.Alloc
+
+	start := time.Now()
+	lines, bytes, err := fn()
+	profile.Duration = time.Since(start)
+	profile.LinesCount = lines
+	profile.BytesCount = bytes
+
+	var memAfter runtime.MemStats
+	runtime.ReadMemStats(&memAfter)
+	profile.MemoryAfter = memAfter.Alloc
+	profile.MemoryDelta = safeMemoryDelta(memAfter.Alloc, memBefore.Alloc)
+
+	if p.logger != nil {
+		p.logger.InfoContext(ctx, "Performance profile", "profile", profile.String())
+	}
+
+	return profile, err
+}
+
+// Start begins timing an operation and returns a function to complete the profiling
+func (p *Profiler) Start(ctx context.Context, operation string) func(lines int, bytes int64) *Profile {
+	if !p.enabled {
+		return func(int, int64) *Profile { return nil }
+	}
+
+	profile := &Profile{
+		Operation: operation,
+		Timestamp: time.Now(),
+	}
+
+	var memBefore runtime.MemStats
+	runtime.ReadMemStats(&memBefore)
+	profile.MemoryBefore = memBefore.Alloc
+
+	start := time.Now()
+
+	return func(lines int, bytes int64) *Profile {
+		profile.Duration = time.Since(start)
+		profile.LinesCount = lines
+		profile.BytesCount = bytes
+
+		var memAfter runtime.MemStats
+		runtime.ReadMemStats(&memAfter)
+		profile.MemoryAfter = memAfter.Alloc
+		profile.MemoryDelta = safeMemoryDelta(memAfter.Alloc, memBefore.Alloc)
+
+		if p.logger != nil {
+			p.logger.InfoContext(ctx, "Performance profile", "profile", profile.String())
+		}
+
+		return profile
+	}
+}
+
+var globalProfiler *Profiler
+
+// IsProfilingEnabled checks if profiling is enabled via environment variables
+func IsProfilingEnabled() bool {
+	if enabled, err := strconv.ParseBool(os.Getenv("GITHUB_MCP_PROFILING_ENABLED")); err == nil {
+		return enabled
+	}
+	return false
+}
+
+// Init initializes the global profiler
+func Init(logger *slog.Logger, enabled bool) {
+	globalProfiler = New(logger, enabled)
+}
+
+// InitFromEnv initializes the global profiler using environment variables
+func InitFromEnv(logger *slog.Logger) {
+	globalProfiler = New(logger, IsProfilingEnabled())
+}
+
+// ProfileFunc profiles a function using the global profiler
+func ProfileFunc(ctx context.Context, operation string, fn func() error) (*Profile, error) {
+	if globalProfiler == nil {
+		return nil, fn()
+	}
+	return globalProfiler.ProfileFunc(ctx, operation, fn)
+}
+
+// ProfileFuncWithMetrics profiles a function with metrics using the global profiler
+func ProfileFuncWithMetrics(ctx context.Context, operation string, fn func() (int, int64, error)) (*Profile, error) {
+	if globalProfiler == nil {
+		_, _, err := fn()
+		return nil, err
+	}
+	return globalProfiler.ProfileFuncWithMetrics(ctx, operation, fn)
+}
+
+// Start begins timing using the global profiler
+func Start(ctx context.Context, operation string) func(int, int64) *Profile {
+	if globalProfiler == nil {
+		return func(int, int64) *Profile { return nil }
+	}
+	return globalProfiler.Start(ctx, operation)
+}
diff --git a/pkg/buffer/buffer.go b/pkg/buffer/buffer.go
@@ -0,0 +1,69 @@
+package buffer
+
+import (
+	"bufio"
+	"fmt"
+	"net/http"
+	"strings"
+)
+
+// ProcessResponseAsRingBufferToEnd reads the body of an HTTP response line by line,
+// storing only the last maxJobLogLines lines using a ring buffer (sliding window).
+// This efficiently retains the most recent lines, overwriting older ones as needed.
+//
+// Parameters:
+//
+//	httpResp:        The HTTP response whose body will be read.
+//	maxJobLogLines:  The maximum number of log lines to retain.
+//
+// Returns:
+//
+//	string:          The concatenated log lines (up to maxJobLogLines), separated by newlines.
+//	int:             The total number of lines read from the response.
+//	*http.Response:  The original HTTP response.
+//	error:           Any error encountered during reading.
+//
+// The function uses a ring buffer to efficiently store only the last maxJobLogLines lines.
+// If the response contains more lines than maxJobLogLines, only the most recent lines are kept.
+func ProcessResponseAsRingBufferToEnd(httpResp *http.Response, maxJobLogLines int) (string, int, *http.Response, error) {
+	lines := make([]string, maxJobLogLines)
+	validLines := make([]bool, maxJobLogLines)
+	totalLines := 0
+	writeIndex := 0
+
+	scanner := bufio.NewScanner(httpResp.Body)
+	scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		totalLines++
+
+		lines[writeIndex] = line
+		validLines[writeIndex] = true
+		writeIndex = (writeIndex + 1) % maxJobLogLines
+	}
+
+	if err := scanner.Err(); err != nil {
+		return "", 0, httpResp, fmt.Errorf("failed to read log content: %w", err)
+	}
+
+	var result []string
+	linesInBuffer := totalLines
+	if linesInBuffer > maxJobLogLines {
+		linesInBuffer = maxJobLogLines
+	}
+
+	startIndex := 0
+	if totalLines > maxJobLogLines {
+		startIndex = writeIndex
+	}
+
+	for i := 0; i < linesInBuffer; i++ {
+		idx := (startIndex + i) % maxJobLogLines
+		if validLines[idx] {
+			result = append(result, lines[idx])
+		}
+	}
+
+	return strings.Join(result, "\n"), totalLines, httpResp, nil
+}