flamegraph: remove external tool path and document native generation

8 files changed, 20 insertions, 238 deletions

diff --git a/AGENTS.md b/AGENTS.md
index 71fec53..36d2bb1 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -45,7 +45,7 @@ Generator source code:
 
 - **Entry point**: `cmd/ior/main.go` - Linux-only BPF-based I/O syscall tracer
 - **Core packages**: `/internal/event/` (BPF event handling), `/internal/flamegraph/` (FlameGraph generation), `/internal/c/` (BPF programs)  
-- **Output**: Compressed zstd files, collapsed stack format compatible with Inferno FlameGraphs
+- **Output**: Compressed `.ior.zst` trace data and native SVG flamegraphs (served via embedded web server in `-ior` mode)
 - **TUI package**: `/internal/tui/` contains top-level Bubble Tea orchestration (`tui.go`), shared key map (`keys.go`), and styles (`styles.go`).
 - **Dashboard tabs**: `/internal/tui/dashboard/` contains tab renderers (overview/syscalls/files/processes/latency/gaps) and tab framework model.
 - **Export modal**: `/internal/tui/export/model.go` implements the centered modal used for CSV export flow in TUI mode.
diff --git a/Magefile.go b/Magefile.go
index 57ce61c..09b219c 100644
--- a/Magefile.go
+++ b/Magefile.go
@@ -238,7 +238,7 @@ func Clean() error {
 // Mrproper removes build artifacts and generated output files.
 func Mrproper() error {
 	mg.SerialDeps(Clean)
-	patterns := []string{"*.zst", "*.collapsed", "*.svg", "*profile", "*.pdf", "*.tmp", "palette.map"}
+	patterns := []string{"*.zst", "*.svg", "*profile", "*.pdf", "*.tmp", "palette.map"}
 	for _, pattern := range patterns {
 		if err := removeFilesByGlob(pattern); err != nil {
 			return err
diff --git a/README.md b/README.md
index dce3849..e5c41bb 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ Important details:
 - `durationToPrevNs` is tracked per `tid` (thread), not globally across all threads.
 - The first observed syscall pair for a thread has `durationToPrevNs = 0` because there is no prior exit timestamp.
 - `durationToPrevNs` is attributed to the current syscall pair (the one whose `enter` closes the gap).
-- There is no separate "idle" pseudo-event bucket; use the `durationToPrev` count field when collapsed/aggregated output should emphasize inter-syscall time.
+- There is no separate "idle" pseudo-event bucket; use the `durationToPrev` count field when aggregated flamegraph output should emphasize inter-syscall time.
 
 ## Fedora
 
@@ -57,10 +57,16 @@ make
 sudo cp -v ./libelf/libelf.a /usr/lib64/
 ```
 
-## Inferno Flamegraphs
+## Native Flamegraph Generation
 
-We are using Inferno Flamegraphs:  https://github.com/jonhoo/inferno
+Flamegraphs are generated natively by `ior` from `.ior.zst` data files; no external flamegraph tool is required.
 
 ```sh
-cargo install inferno
+./ior -ior=trace.ior.zst -fields=pid,path,tracepoint -count=count
+```
+
+This generates an SVG and starts an embedded web server. The terminal prints a URL like:
+
+```text
+Flamegraph available at http://HOSTNAME:PORT/abs/path/to.svg
 ```
diff --git a/integrationtests/cleanup_test.go b/integrationtests/cleanup_test.go
index 6fecd10..18a0531 100644
--- a/integrationtests/cleanup_test.go
+++ b/integrationtests/cleanup_test.go
@@ -55,7 +55,7 @@ func TestCleanupOutputDirContainsOnlyExpectedFiles(t *testing.T) {
 
 	workloadBin := writeScript(t, tmpDir, "workload", `echo $$`)
 	iorBin := writeScript(t, tmpDir, "ior",
-		`touch test.ior.zst test.collapsed.zst test.svg`)
+		`touch test.ior.zst test.svg`)
 
 	h := TestHarness{
 		IorBinary:      iorBin,
@@ -80,7 +80,6 @@ func TestCleanupOutputDirContainsOnlyExpectedFiles(t *testing.T) {
 	for _, e := range entries {
 		name := e.Name()
 		validSuffix := strings.HasSuffix(name, ".ior.zst") ||
-			strings.HasSuffix(name, ".collapsed.zst") ||
 			strings.HasSuffix(name, ".svg") ||
 			name == "ior.bpf.o" // symlink created by startIor
 		if !validSuffix {
@@ -204,7 +203,6 @@ func TestCleanupNoArtifactsOutsideOutputDir(t *testing.T) {
 	}
 	for _, e := range entries {
 		if strings.HasSuffix(e.Name(), ".ior.zst") ||
-			strings.HasSuffix(e.Name(), ".collapsed.zst") ||
 			strings.HasSuffix(e.Name(), ".svg") {
 			t.Errorf("artifact leaked to script dir: %s", e.Name())
 		}
diff --git a/internal/flags/flags.go b/internal/flags/flags.go
index 5bde9c6..9354bc3 100644
--- a/internal/flags/flags.go
+++ b/internal/flags/flags.go
@@ -21,8 +21,6 @@ var (
 	pidFilter atomic.Int64
 )
 
-const flamegraphToolDefault = ""
-
 var (
 	validCollapsedFields = []string{
 		"path",
@@ -60,13 +58,10 @@ type Flags struct {
 	FlamegraphName   string
 	TUIExportEnable  bool
 
-	// To convert ior data into collapsed format
+	// To convert ior data into native SVG format
 	IorDataFile     string
 	CollapsedFields []string
 	CountField      string
-
-	// To generate the Flamegraph SVGs
-	FlamegraphTool string
 }
 
 func Get() Flags {
@@ -110,22 +105,14 @@ func parse() {
 	flag.StringVar(&singleton.FlamegraphName, "name", "default", "Name of the flamegraph, used to generate the SVG file")
 	flag.BoolVar(&singleton.TUIExportEnable, "tuiExport", true, "Enable writing TUI snapshot export files")
 
-	flag.StringVar(&singleton.IorDataFile, "ior", "", "IOR data file to convert into collapsed format")
+	flag.StringVar(&singleton.IorDataFile, "ior", "", "IOR data file to convert into native SVG flamegraph")
 	fields := flag.String("fields", "",
 		fmt.Sprintf("Comma separated list of fields to collapse, valid are: %v", validCollapsedFields))
 	flag.StringVar(&singleton.CountField, "count", "count",
-		fmt.Sprintf("Count field to collaps, valid are: %v", validCollapsedCounts))
-
-	// https://github.com/brendangregg/FlameGraph
-	flag.StringVar(&singleton.FlamegraphTool, "flamegraphTool",
-		"", "Path to the flamegraph tool (e.g. flamegraph.pl or inferno-flamegraph)")
+		fmt.Sprintf("Count field to collapse, valid are: %v", validCollapsedCounts))
 	flag.Parse()
 	pidFilter.Store(int64(singleton.PidFilter))
 
-	if singleton.FlamegraphTool == "" {
-		singleton.FlamegraphTool = flamegraphToolDefault
-	}
-
 	singleton.TracepointsToAttach = extractTracepointFlags(*tracepointsToAttach)
 	singleton.TracepointsToExclude = extractTracepointFlags(*tracepointsToExclude)
 
diff --git a/internal/flamegraph/collapsed.go b/internal/flamegraph/collapsed.go
deleted file mode 100644
index f04a38d..0000000
--- a/internal/flamegraph/collapsed.go
+++ /dev/null
@@ -1,76 +0,0 @@
-package flamegraph
-
-import (
-	"fmt"
-	"os"
-	"strings"
-
-	"github.com/DataDog/zstd"
-)
-
-// Collapsed represents a structure used to process and store information
-// related to a collapsed flamegraph. It includes the following fields:
-//   - iorFile: The path to the input/output report file.
-//   - fields: A list of field names used in the flamegraph processing.
-//   - countField: The name of the field that represents the count or weight
-//     in the flamegraph data.
-type Collapsed struct {
-	iorFile    string   // Path to the input/output report file.
-	fields     []string // List of field names used in processing.
-	countField string   // Field name representing the count or weight.
-}
-
-func NewCollapsed(iorFile string, fields []string, countField string) Collapsed {
-	return Collapsed{iorFile: iorFile, fields: fields, countField: countField}
-}
-
-func (c Collapsed) Write(iorDataFile string) (string, error) {
-	outFile := fmt.Sprintf("%s.%s-by-%s.collapsed.zst",
-		strings.TrimSuffix(iorDataFile, ".ior.zst"),
-		strings.Join(c.fields, ":"),
-		c.countField,
-	)
-
-	if _, err := os.Stat(outFile); err == nil {
-		fmt.Println(outFile, "already exists!")
-		return outFile, nil
-	}
-
-	// outFD should be zstd compressed
-	outFd, err := os.Create(outFile)
-	if err != nil {
-		return outFile, err
-	}
-	defer outFd.Close()
-
-	fmt.Println("Reading", iorDataFile)
-	iod, err := newIorDataFromFile(iorDataFile)
-	if err != nil {
-		return outFile, err
-	}
-
-	fmt.Println("Writing", outFile)
-	writer := zstd.NewWriter(outFd)
-	if err != nil {
-		return outFile, err
-	}
-	defer writer.Close()
-
-	for record := range iod.iter() {
-		var fieldValues []string
-		for _, fieldName := range c.fields {
-			v, err := record.StringByName(fieldName)
-			if err != nil {
-				return outFile, fmt.Errorf("field %s: %w", fieldName, err)
-			}
-			fieldValues = append(fieldValues, v)
-		}
-		writer.Write([]byte(fmt.Sprintf("%s %d\n",
-			strings.Join(fieldValues, ";"),
-			record.Cnt.ValueByName(c.countField),
-		)))
-	}
-	writer.Flush()
-
-	return outFile, nil
-}
diff --git a/internal/flamegraph/tool.go b/internal/flamegraph/tool.go
deleted file mode 100644
index a83c44f..0000000
--- a/internal/flamegraph/tool.go
+++ /dev/null
@@ -1,114 +0,0 @@
-package flamegraph
-
-import (
-	"fmt"
-	"io"
-	"ior/internal/flags"
-	"os"
-	"os/exec"
-	"strings"
-
-	"github.com/DataDog/zstd"
-)
-
-// Tool represents a utility for generating flamegraphs.
-// It contains the path to the flamegraph tool, the arguments to be passed to it,
-// and the output file where the generated flamegraph will be stored.
-type Tool struct {
-	flamegraphTool string   // Path to the flamegraph tool executable.
-	args           []string // Arguments to be passed to the flamegraph tool.
-	outFile        string   // Path to the output file where the flamegraph will be saved.
-}
-
-func NewTool(collapsedFile string) (Tool, error) {
-	if strings.HasSuffix(collapsedFile, ".zst") {
-		var err error
-		collapsedFile, err = decompress(collapsedFile)
-		if err != nil {
-			return Tool{}, err
-		}
-	}
-
-	t := Tool{
-		flamegraphTool: flags.Get().FlamegraphTool,
-		args:           []string{collapsedFile, "--hash"},
-		outFile:        strings.TrimSuffix(collapsedFile, ".collapsed") + ".svg",
-	}
-
-	t.args = append(t.args, "--title")
-	t.args = append(t.args, fmt.Sprintf("I/O Traces (%s by %s)",
-		strings.Join(flags.Get().CollapsedFields, ","), flags.Get().CountField,
-	))
-
-	return t, nil
-}
-
-func (t Tool) WriteSVG() error {
-	defer deleteFileIfEmpty(t.outFile)
-
-	if _, err := os.Stat(t.outFile); err == nil {
-		fmt.Println(t.outFile, "already exists!")
-		return nil
-	}
-	cmd := exec.Command(t.flamegraphTool, t.args...)
-	fmt.Println("Running", cmd)
-
-	outFd, err := os.Create(t.outFile)
-	if err != nil {
-		return err
-	}
-	defer outFd.Close()
-
-	cmd.Stdout = outFd
-	cmd.Stderr = os.Stderr
-
-	if err := cmd.Run(); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (t Tool) OutFile() string {
-	return t.outFile
-}
-
-func decompress(compressedFile string) (string, error) {
-	decompressedFile := strings.TrimSuffix(compressedFile, ".zst")
-
-	file, err := os.Open(compressedFile)
-	if err != nil {
-		return decompressedFile, err
-	}
-	defer file.Close()
-
-	decoder := zstd.NewReader(file)
-	defer decoder.Close()
-
-	decompressedFd, err := os.Create(decompressedFile)
-	if err != nil {
-		return decompressedFile, err
-	}
-	defer decompressedFd.Close()
-
-	_, err = io.Copy(decompressedFd, decoder)
-	if err != nil {
-		return decompressedFile, err
-	}
-
-	return decompressedFile, nil
-}
-
-func deleteFileIfEmpty(file string) error {
-	if _, err := os.Stat(file); err == nil {
-		fileInfo, err := os.Stat(file)
-		if err != nil {
-			return err
-		}
-		if fileInfo.Size() == 0 {
-			fmt.Println("Deleting", file, "as it is empty")
-			return os.Remove(file)
-		}
-	}
-	return nil
-}
diff --git a/internal/ior.go b/internal/ior.go
index 599736d..b136931 100644
--- a/internal/ior.go
+++ b/internal/ior.go
@@ -99,29 +99,10 @@ func Run() error {
 
 	if iorFile != "" {
 		noTraceRun = true
-		var svgFile string
-		if cfg.FlamegraphTool != "" {
-			collapsed := flamegraph.NewCollapsed(iorFile, cfg.CollapsedFields, cfg.CountField)
-			collapsedFile, err := collapsed.Write(iorFile)
-			if err != nil {
-				return err
-			}
-
-			tool, err := flamegraph.NewTool(collapsedFile)
-			if err != nil {
-				return err
-			}
-			if err := tool.WriteSVG(); err != nil {
-				return err
-			}
-			svgFile = tool.OutFile()
-		} else {
-			native := flamegraph.NewNativeSVG(cfg.CollapsedFields, cfg.CountField)
-			var err error
-			svgFile, err = native.WriteSVGFromFile(iorFile)
-			if err != nil {
-				return err
-			}
+		native := flamegraph.NewNativeSVG(cfg.CollapsedFields, cfg.CountField)
+		svgFile, err := native.WriteSVGFromFile(iorFile)
+		if err != nil {
+			return err
 		}
 
 		if err := flamegraph.ServeSVG(svgFile); err != nil {