From 9f1b891312e2c28f466d984b47ff8ce6d52e940d Mon Sep 17 00:00:00 2001
From: Anirudh Sudhir <anirudh.sudhir1@gmail.com>
Date: Fri, 5 Apr 2024 22:01:11 +0530
Subject: [PATCH] perf: implement worker pool

---
 pkg/engine/user_engine.go                     | 63 +++++++++++--------
 .../engine/render_user_defined/rendered/.html |  1 +
 2 files changed, 39 insertions(+), 25 deletions(-)

diff --git a/pkg/engine/user_engine.go b/pkg/engine/user_engine.go
index 4415ce1..2c29625 100644
--- a/pkg/engine/user_engine.go
+++ b/pkg/engine/user_engine.go
@@ -4,18 +4,24 @@ import (
 	"bytes"
 	"html/template"
 	"os"
-	"runtime"
 	"strings"
-	"sync"
 
 	"github.com/acmpesuecc/anna/pkg/parser"
 )
 
+// TODO: Eliminate this struct
 type postsTemplateData struct {
 	Posts []parser.TemplateData
 	parser.TemplateData
 }
 
+type Job struct {
+	FileInPath   string
+	FileOutPath  string
+	TemplateData parser.TemplateData
+	Templ        *template.Template
+}
+
 func (e *Engine) RenderEngineGeneratedFiles(fileOutPath string, templ *template.Template) {
 	// Rendering "posts.html"
 	var postsBuffer bytes.Buffer
@@ -41,37 +47,44 @@ func (e *Engine) RenderEngineGeneratedFiles(fileOutPath string, templ *template.
 }
 
 func (e *Engine) RenderUserDefinedPages(fileOutPath string, templ *template.Template) {
-	numCPU := runtime.NumCPU()
 	numTemplates := len(e.Templates)
-	concurrency := numCPU * 2 // Adjust the concurrency factor based on system hardware resources
 
-	if numTemplates < concurrency {
-		concurrency = numTemplates
-	}
+	numJobs := numTemplates / 5
 
-	templateURLs := make([]string, 0, numTemplates)
-	for templateURL := range e.Templates {
-		templateURLs = append(templateURLs, string(templateURL))
+	jobs := make(chan Job, numTemplates)
+	results := make(chan struct{}, numTemplates)
+
+	//Starting workers
+	for i := 0; i <= numJobs; i++ {
+		go e.RenderPageWorker(jobs, results)
 	}
 
-	var wg sync.WaitGroup
-	semaphore := make(chan struct{}, concurrency)
+	// Sending jobs over a channel
+	for templateURL := range e.Templates {
+		templData := e.Templates[template.URL(templateURL)]
+		fileInPath := strings.TrimSuffix(string(templData.CompleteURL), ".html")
 
-	for _, templateURL := range templateURLs {
-		wg.Add(1)
-		semaphore <- struct{}{}
+		job := Job{
+			FileInPath:   fileInPath,
+			FileOutPath:  fileOutPath,
+			TemplateData: templData,
+			Templ:        templ,
+		}
 
-		go func(templateURL string) {
-			defer func() {
-				<-semaphore
-				wg.Done()
-			}()
+		jobs <- job
+	}
+	close(jobs)
 
-			templData := e.Templates[template.URL(templateURL)]
-			fileInPath := strings.TrimSuffix(string(templData.CompleteURL), ".html")
-			e.RenderPage(fileOutPath, template.URL(fileInPath), templData, templ, "page")
-		}(templateURL)
+	for i := 1; i <= numTemplates; i++ {
+		<-results
 	}
 
-	wg.Wait()
+}
+
+func (e *Engine) RenderPageWorker(jobs <-chan Job, results chan<- struct{}) {
+	for job := range jobs {
+		fileInPath := job.FileInPath
+		e.RenderPage(job.FileOutPath, template.URL(fileInPath), job.TemplateData, job.Templ, "page")
+		results <- struct{}{}
+	}
 }
diff --git a/test/engine/render_user_defined/rendered/.html b/test/engine/render_user_defined/rendered/.html
index c3dcf98..3dd0104 100644
--- a/test/engine/render_user_defined/rendered/.html
+++ b/test/engine/render_user_defined/rendered/.html
@@ -8,3 +8,4 @@
 <h1>Index Page</h1>
 </body>
 </html>
+