Speed up id generator

Makefile

@@ -1,4 +1,4 @@
-.PHONY: doc format api-test
+.PHONY: doc format api-test benchmark
 CONTAINER_ORCHESTRATOR ?= docker-compose
 CONTAINER_ORCHESTRATOR_EXEC_OPTIONS := $(CONTAINER_ORCHESTRATOR_EXEC_OPTIONS)
 
@@ -35,3 +35,6 @@ api-test:
 
 generate-semantic-conventions:
 	$(CONTAINER_ORCHESTRATOR) run --no-deps $(CONTAINER_ORCHESTRATOR_EXEC_OPTIONS) -- openresty bash -c 'pushd tmp && rm -rf opentelemetry-specification && git clone --depth=1 https://github.com/open-telemetry/opentelemetry-specification.git && popd && resty ./utils/generate_semantic_conventions.lua && lua-format -i lib/opentelemetry/semantic_conventions/trace/*.lua'
+
+benchmark:
+	$(CONTAINER_ORCHESTRATOR) run --no-deps $(CONTAINER_ORCHESTRATOR_EXEC_OPTIONS) -- openresty bash -c 'cd /opt/opentelemetry-lua && benchmark/run.sh'

README.md

@@ -335,3 +335,7 @@ local my_metrics_reporter = {
 }
 otel_global.set_metrics_reporter(metrics_reporter)
 ```
+
+### Benchmarks
+
+You can run benchmarks using `make benchmark`.

benchmark/id_generator.lua

@@ -0,0 +1,8 @@
+local id_generator = require("lib.opentelemetry.trace.id_generator")
+local start = os.clock()
+
+for _ = 1, 5000000 do
+    id_generator.new_ids()
+end
+
+print('5m new ids: ' .. (os.clock() - start) ..' seconds.')

benchmark/run.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+FILES="benchmark/*.lua"
+for f in $FILES
+do
+  if [ -f "$f" ]
+  then
+    resty -I /opt/opentelemetry-lua/lib "$f"
+  fi
+done

lib/opentelemetry/trace/id_generator.lua

@@ -4,39 +4,22 @@ local bit = require 'bit'
 local tohex = bit.tohex
 local fmt = string.format
 local random = util.random
+local FFFFFFFF = 4294967295 -- FFFFFFFF in hexadecimal is 4294967295 in decimal
 
 local _M = {}
 
 function _M.new_span_id()
-    return fmt("%s%s%s%s%s%s%s%s",
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2),
-                tohex(random(0, 255), 2))
+    return fmt("%s%s",
+        tohex(random(0, FFFFFFFF), 8),
+        tohex(random(0, FFFFFFFF), 8))
 end
 
 function _M.new_ids()
-    return fmt("%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2),
-            tohex(random(0, 255), 2)), _M.new_span_id()
+    return fmt("%s%s%s%s",
+        tohex(random(0, FFFFFFFF), 8),
+        tohex(random(0, FFFFFFFF), 8),
+        tohex(random(0, FFFFFFFF), 8),
+        tohex(random(0, FFFFFFFF), 8)), _M.new_span_id()
 end
 
 return _M

spec/trace/id_generator_spec.lua

@@ -0,0 +1,19 @@
+local id_generator = require("opentelemetry.trace.id_generator")
+
+describe("new_span_id", function()
+    it("generates a 16 character hex string", function()
+        for _ = 0, 100 do
+            assert.is_equal(16, #id_generator.new_span_id())
+        end
+    end)
+end)
+
+describe("new_ids", function()
+    it("generates a 16 character hex string and a 32 character string", function()
+        for _ = 0, 100 do
+            local trace_id, span_id = id_generator.new_ids()
+            assert.is_equal(32, #trace_id)
+            assert.is_equal(16, #span_id)
+        end
+    end)
+end)