From 75b6417b4d8fa68d565ad942d55f5da74280ef93 Mon Sep 17 00:00:00 2001
From: hissssst <csqcsqcsq@yandex.ru>
Date: Sat, 14 Dec 2024 10:05:41 +0100
Subject: [PATCH 1/2] Hot path optimizations

---
 lib/peep/buckets/custom.ex  | 94 ++++++++++++++++++++++++++++++++-----
 lib/peep/event_handler.ex   | 32 +++++++++----
 lib/peep/storage/striped.ex |  4 +-
 3 files changed, 109 insertions(+), 21 deletions(-)

diff --git a/lib/peep/buckets/custom.ex b/lib/peep/buckets/custom.ex
index aa7a23d..ae4f9cd 100644
--- a/lib/peep/buckets/custom.ex
+++ b/lib/peep/buckets/custom.ex
@@ -34,22 +34,95 @@ defmodule Peep.Buckets.Custom do
     end
   end
 
+  ## Bucket binary search
+
   defp bucket_for_ast(buckets) do
-    bucket_defns =
-      for {boundary, bucket_idx} <- Enum.with_index(buckets) do
-        quote do
-          def bucket_for(n, _) when n < unquote(boundary), do: unquote(bucket_idx)
-        end
+    int_buckets = int_buckets(buckets, nil, 0)
+
+    float_buckets =
+      buckets
+      |> Enum.map(&(&1 * 1.0))
+      |> Enum.with_index()
+
+    variable = Macro.var(:x, nil)
+
+    int_length = length(int_buckets)
+    int_tree = build_bucket_tree(int_buckets, int_length, length(buckets), variable)
+
+    float_length = length(float_buckets)
+    float_tree = build_bucket_tree(float_buckets, float_length, length(buckets), variable)
+
+    quote do
+      def bucket_for(unquote(variable), _) when is_integer(unquote(variable)) do
+        unquote(int_tree)
       end
 
-    final_defn =
-      quote do
-        def bucket_for(_, _), do: unquote(length(buckets))
+      def bucket_for(unquote(variable), _) when is_float(unquote(variable)) do
+        unquote(float_tree)
       end
+    end
 
-    bucket_defns ++ [final_defn]
+    # |> tap(&IO.puts(Code.format_string!(Macro.to_string(&1))))
+  end
+
+  defp build_bucket_tree([{bound, lval}], 1, rval, variable) do
+    quote do
+      case unquote(variable) do
+        x when x < unquote(bound) ->
+          unquote(lval)
+
+        _ ->
+          unquote(rval)
+      end
+    end
   end
 
+  defp build_bucket_tree([{lbound, lval}, {rbound, mval}], 2, rval, variable) do
+    quote do
+      case unquote(variable) do
+        x when x < unquote(lbound) ->
+          unquote(lval)
+
+        x when x < unquote(rbound) ->
+          unquote(mval)
+
+        _ ->
+          unquote(rval)
+      end
+    end
+  end
+
+  defp build_bucket_tree(bounds, length, rval, variable) do
+    llength = div(length, 2)
+    rlength = length - llength - 1
+
+    {lbounds, rbounds} = Enum.split(bounds, llength)
+    [{bound, lval} | rbounds] = rbounds
+
+    quote do
+      case unquote(variable) do
+        x when x < unquote(bound) ->
+          unquote(build_bucket_tree(lbounds, llength, lval, variable))
+
+        _ ->
+          unquote(build_bucket_tree(rbounds, rlength, rval, variable))
+      end
+    end
+  end
+
+  defp int_buckets([], _prev, _counter) do
+    []
+  end
+
+  defp int_buckets([curr | tail], prev, counter) do
+    case ceil(curr) do
+      ^prev -> int_buckets(tail, prev, counter + 1)
+      curr -> [{curr, counter} | int_buckets(tail, curr, counter + 1)]
+    end
+  end
+
+  ## Upper bound
+
   defp upper_bound_ast(buckets) do
     bucket_defns =
       for {boundary, bucket_idx} <- Enum.with_index(buckets) do
@@ -67,7 +140,6 @@ defmodule Peep.Buckets.Custom do
   end
 
   defp int_to_float_string(int) do
-    # kind of a hack, but nothing else came to mind
-    to_string(:math.pow(int, 1))
+    to_string(int * 1.0)
   end
 end
diff --git a/lib/peep/event_handler.ex b/lib/peep/event_handler.ex
index 21e614f..bc8b884 100644
--- a/lib/peep/event_handler.ex
+++ b/lib/peep/event_handler.ex
@@ -2,6 +2,8 @@ defmodule Peep.EventHandler do
   @moduledoc false
   require Logger
 
+  @compile :inline
+
   alias Telemetry.Metrics.{Counter, Summary, Distribution}
 
   def attach(metrics, name, global_tags) do
@@ -28,7 +30,7 @@ defmodule Peep.EventHandler do
   end
 
   def detach(handler_ids) do
-    Enum.each(handler_ids, fn id -> :telemetry.detach(id) end)
+    for id <- handler_ids, do: :telemetry.detach(id)
   end
 
   def handle_event(_event, measurements, metadata, %{
@@ -37,12 +39,19 @@ defmodule Peep.EventHandler do
         global_tags: global_tags
       }) do
     for metric <- metrics do
-      if value = keep?(metric, metadata) && fetch_measurement(metric, measurements, metadata) do
+      %{
+        measurement: measurement,
+        tag_values: tag_values,
+        tags: tags,
+        keep: keep
+      } = metric
+
+      if value = keep?(keep, metadata) && fetch_measurement(measurement, measurements, metadata) do
         tag_values =
           global_tags
-          |> Map.merge(metric.tag_values.(metadata))
+          |> Map.merge(tag_values.(metadata))
 
-        tags = Map.new(metric.tags, &{&1, Map.get(tag_values, &1, "")})
+        tags = Map.new(tags, &{&1, Map.get(tag_values, &1, "")})
 
         Peep.insert_metric(name, metric, value, tags)
       end
@@ -53,15 +62,15 @@ defmodule Peep.EventHandler do
     {__MODULE__, peep_name, event_name}
   end
 
-  defp keep?(%{keep: nil}, _metadata), do: true
-  defp keep?(%{keep: keep}, metadata), do: keep.(metadata)
+  defp keep?(nil, _metadata), do: true
+  defp keep?(keep, metadata), do: keep.(metadata)
 
   defp fetch_measurement(%Counter{}, _measurements, _metadata) do
     1
   end
 
-  defp fetch_measurement(metric, measurements, metadata) do
-    case metric.measurement do
+  defp fetch_measurement(measurement, measurements, metadata) do
+    case measurement do
       nil ->
         nil
 
@@ -72,7 +81,12 @@ defmodule Peep.EventHandler do
         fun.(measurements, metadata)
 
       key ->
-        measurements[key] || 1
+        case measurements do
+          %{^key => nil} -> 1
+          %{^key => false} -> 1
+          %{^key => value} -> value
+          _ -> 1
+        end
     end
   end
 
diff --git a/lib/peep/storage/striped.ex b/lib/peep/storage/striped.ex
index e22123b..8c7ebfb 100644
--- a/lib/peep/storage/striped.ex
+++ b/lib/peep/storage/striped.ex
@@ -7,6 +7,8 @@ defmodule Peep.Storage.Striped do
 
   @type tids() :: %{pos_integer() => :ets.tid()}
 
+  @compile :inline
+
   @spec new() :: tids()
   @impl true
   def new() do
@@ -47,7 +49,7 @@ defmodule Peep.Storage.Striped do
 
   def insert_metric(tids, %Metrics.LastValue{} = metric, value, %{} = tags) do
     tid = get_tid(tids)
-    now = System.monotonic_time()
+    now = :erlang.monotonic_time()
     key = {metric, tags}
     :ets.insert(tid, {key, {now, value}})
   end

From cba7aca7e4877c96549b8a37d51a595824126b8c Mon Sep 17 00:00:00 2001
From: Hissssst <37012324+hissssst@users.noreply.github.com>
Date: Sat, 14 Dec 2024 12:41:58 +0000
Subject: [PATCH 2/2] Apply suggestions from code review
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: José Valim <jose.valim@gmail.com>
---
 lib/peep/event_handler.ex   | 1 +
 lib/peep/storage/striped.ex | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/peep/event_handler.ex b/lib/peep/event_handler.ex
index bc8b884..6de54ba 100644
--- a/lib/peep/event_handler.ex
+++ b/lib/peep/event_handler.ex
@@ -31,6 +31,7 @@ defmodule Peep.EventHandler do
 
   def detach(handler_ids) do
     for id <- handler_ids, do: :telemetry.detach(id)
+    :ok
   end
 
   def handle_event(_event, measurements, metadata, %{
diff --git a/lib/peep/storage/striped.ex b/lib/peep/storage/striped.ex
index 8c7ebfb..df6621d 100644
--- a/lib/peep/storage/striped.ex
+++ b/lib/peep/storage/striped.ex
@@ -49,7 +49,7 @@ defmodule Peep.Storage.Striped do
 
   def insert_metric(tids, %Metrics.LastValue{} = metric, value, %{} = tags) do
     tid = get_tid(tids)
-    now = :erlang.monotonic_time()
+    now = System.monotonic_time()
     key = {metric, tags}
     :ets.insert(tid, {key, {now, value}})
   end