From 6cfe875939e7f386cdd13d26794455b215ecd8d1 Mon Sep 17 00:00:00 2001
From: Ryan Gonzalez <git@refi64.dev>
Date: Sun, 20 Aug 2023 19:16:18 -0500
Subject: [PATCH] converter: Add support for outputting folded stacks and
 flamegraphs

---
 .gitignore              |  3 ++-
 README.md               | 31 +++++++++++++++++++++--
 tools/alys_converter.cr | 55 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 0d03a79..6b42623 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@
 *.alys.*
 .gdb_history
 /demo
-profile*.svg
+*.folded
+*.svg
 tools/llvm-project-*
 tools/pprof/profile.proto
diff --git a/README.md b/README.md
index 78f24ce..6c84d2d 100644
--- a/README.md
+++ b/README.md
@@ -44,8 +44,9 @@ ALYS_TRACING=file:myfile.alys ./myapp
 
 ### Examing Traces with `alys_converter`
 
-The `.alys` file is in a custom binary format, but it can be converted into a
-JSON file or a Go pprof file via:
+The `.alys` file is in a custom binary format, but it can be converted into
+JSON, Go pprof, folded stacks (for use with flamegraph), or a direct flamegraph
+via:
 
 ```bash
 # Outputs myfile.alys.json:
@@ -60,6 +61,16 @@ bin/alys_converter --indent myfile.alys myfile.json
 bin/alys_converter -f pprof myfile.alys
 # You can rename the output file:
 bin/alys_converter -f pprof myfile.alys myfile.pb.gz
+
+# Outputs myfile.folded (folded stacks):
+bin/alys_converter -f folded-stacks myfile.alys
+# You can rename the output file:
+bin/alys_converter -f folded-stacks myfile.alys myfile.folded
+
+# Outputs myfile.svg (flamegraph, via inferno-flamegraph):
+bin/alys_converter -f inferno-flamegraph myfile.alys
+# You can rename the output file:
+bin/alys_converter -f inferno-flamegraph myfile.alys myfile.svg
 ```
 
 (Note that .alys files are only compatible with an identical alys_converter
@@ -130,6 +141,22 @@ on `PORT`, use:
 pprof -http localhost:PORT myfile.pb.gz
 ```
 
+#### Folded stacks and Inferno
+
+Folded stacks files are usually converted to flamegraphs
+[flamegraphs](https://www.brendangregg.com/flamegraphs.html); you can also go
+straight from .alys -> flamegraph via the `inferno-flamegraph` format (requires
+[Inferno](https://github.com/jonhoo/inferno) to be installed). In the latter
+case, additional options can be passed to the `inferno-flamegraph` CLI via
+`--inferno-opt`:
+
+```bash
+# Pass --flamechart and --title=test to inferno-flamegraph:
+bin/alys_converter -f inferno-flamegraph myfile.alys \
+  --inferno-opt flamechart --inferno-opt title=test
+
+```
+
 ### Backtraces
 
 By default, Alys will also capture a backtrace on each allocation or
diff --git a/tools/alys_converter.cr b/tools/alys_converter.cr
index d8b6477..b7a16c4 100644
--- a/tools/alys_converter.cr
+++ b/tools/alys_converter.cr
@@ -517,9 +517,38 @@ class PProfEventWriter < EventVisitor
   end
 end
 
+class FoldedStacksEventWriter < EventVisitor
+  def self.write(from reader : EventReader, to dest : IO)
+    visitor = FoldedStacksEventWriter.new dest
+    reader.read visitor
+  end
+
+  protected def initialize(@io : IO)
+  end
+
+  private def format_stack(stack : StackTrace) : String
+    stack.map { |(frame, symbol)| symbol.name || "#<#{frame.ip}>" }.join ';'
+  end
+
+  def visit_alloc(event, time_offset, info, stack)
+    @io << "#{format_stack stack} #{info.size}\n"
+  end
+
+  def visit_realloc(event, time_offset, prev_info, info, stack)
+    unless info.size <= prev_info.size
+      @io << "#{format_stack stack} #{info.size - prev_info.size}\n"
+    end
+  end
+
+  def visit_free(event, time_offset, info)
+  end
+end
+
 enum Format
   JSON
   PProf
+  FoldedStacks
+  InfernoFlamegraph
 
   def ext
     case self
@@ -527,12 +556,17 @@ enum Format
       "json"
     when PProf
       "pb.gz"
+    when FoldedStacks
+      "folded"
+    when InfernoFlamegraph
+      "svg"
     end
   end
 end
 
 struct Options
   property indent_json = false
+  property inferno_opts = [] of String
   property symbolize_with : String? = nil
   property format = Format::JSON
 end
@@ -544,6 +578,23 @@ def convert(*, from reader : EventReader, to dest : IO, options : Options)
       indent_json: options.indent_json
   when Format::PProf
     PProfEventWriter.write from: reader, to: dest
+  when Format::FoldedStacks
+    FoldedStacksEventWriter.write from: reader, to: dest
+  when Format::InfernoFlamegraph
+    IO.pipe do |stacks_reader, stacks_writer|
+      p = Process.new "inferno-flamegraph",
+        options.inferno_opts.map { |o| "--#{o}" },
+        input: stacks_reader,
+        output: dest,
+        error: :inherit
+      spawn do
+        FoldedStacksEventWriter.write from: reader, to: stacks_writer
+        stacks_writer.close
+      end
+
+      status = p.wait
+      raise "inferno-flamegraph failed" if !status.success?
+    end
   end
 end
 
@@ -573,6 +624,10 @@ def run
       options.indent_json = true
     end
 
+    parser.on "--inferno-opt=opt", "Pass the given option to inferno-flamegraph" do |opt|
+      options.inferno_opts << opt
+    end
+
     parser.on "--symbolize=exe", "Resolve addresses with the given executable" do |exe|
       options.symbolize_with = exe
     end
-- 
2.45.2