From 9ed5a2f85af06798bdcd61373059523ef300111a Mon Sep 17 00:00:00 2001
From: Konstantin Grachev <me@grachevko.ru>
Date: Thu, 15 Feb 2024 18:39:41 +0300
Subject: [PATCH] worker-pool: init

---
 worker-pool/Makefile     | 53 ++++++++++++++++++++++++++++++++++++++++
 worker-pool/go.mod       | 11 +++++++++
 worker-pool/main.go      | 21 ++++++++++++++++
 worker-pool/main_test.go | 41 +++++++++++++++++++++++++++++++
 4 files changed, 126 insertions(+)
 create mode 100644 worker-pool/Makefile
 create mode 100644 worker-pool/go.mod
 create mode 100644 worker-pool/main.go
 create mode 100644 worker-pool/main_test.go

diff --git a/worker-pool/Makefile b/worker-pool/Makefile
new file mode 100644
index 0000000..977c1c9
--- /dev/null
+++ b/worker-pool/Makefile
@@ -0,0 +1,53 @@
+.DEFAULT_GOAL := help
+
+# ==================================================================================== #
+# HELPERS
+# ==================================================================================== #
+
+## help: print this help message
+.PHONY: help
+help:
+	@echo 'Usage:'
+	@sed -n 's/^##//p' ${MAKEFILE_LIST} | column -t -s ':' |  sed -e 's/^/ /'
+
+## all: tidy + audit + test/cover
+all: generate tidy test lint test/cover
+
+
+# ==================================================================================== #
+# QUALITY CONTROL
+# ==================================================================================== #
+
+## tidy: format code and tidy modfile
+.PHONY: tidy
+tidy:
+	go fmt ./...
+	goimports -local=$(shell cat go.mod | grep module | awk '{print $$2}')/ -w .
+	go mod tidy -v
+
+## audit: run quality control checks
+.PHONY: lint
+lint:
+	go mod verify
+	go run github.com/golangci/golangci-lint/cmd/golangci-lint@latest run -v ./...
+
+
+# ==================================================================================== #
+# DEVELOPMENT
+# ==================================================================================== #
+
+## generate: run all generators
+.PHONY: generate
+generate:
+	go generate ./...
+
+## test: run all tests
+.PHONY: test
+test:
+	go test -race -buildvcs ./...
+
+## test/cover: run all tests and display coverage
+.PHONY: test/cover
+test/cover:
+	go test -race -buildvcs -coverprofile=/tmp/coverage.out ./...
+	go tool cover -html=/tmp/coverage.out
diff --git a/worker-pool/go.mod b/worker-pool/go.mod
new file mode 100644
index 0000000..a01eea9
--- /dev/null
+++ b/worker-pool/go.mod
@@ -0,0 +1,11 @@
+module worker-pool
+
+go 1.21.6
+
+require github.com/stretchr/testify v1.8.4
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/worker-pool/main.go b/worker-pool/main.go
new file mode 100644
index 0000000..1abe752
--- /dev/null
+++ b/worker-pool/main.go
@@ -0,0 +1,21 @@
+package main
+
+import (
+	"fmt"
+)
+
+func WorkerPool[T any](limit int, worker func(int, T)) chan<- T {
+	tasks := make(chan T, limit)
+
+	for i := 1; i <= limit; i++ {
+		go func(i int) {
+			defer fmt.Printf("worker:%d done\n", i)
+
+			for t := range tasks {
+				worker(i, t)
+			}
+		}(i)
+	}
+
+	return tasks
+}
diff --git a/worker-pool/main_test.go b/worker-pool/main_test.go
new file mode 100644
index 0000000..1511387
--- /dev/null
+++ b/worker-pool/main_test.go
@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWorkerPool(t *testing.T) {
+	const tasks = 5
+
+	var wg sync.WaitGroup
+	wg.Add(tasks)
+
+	var mt sync.Mutex
+	done := make(map[int]bool, tasks)
+
+	worker := func(pid int, task int) {
+		defer wg.Done()
+
+		mt.Lock()
+		done[pid] = true
+		mt.Unlock()
+
+		fmt.Printf("task:%+v\n", task)
+	}
+
+	pool := WorkerPool(tasks, worker)
+
+	for j := 0; j < tasks; j++ {
+		pool <- j
+	}
+	close(pool)
+	wg.Wait()
+
+	for _, v := range done {
+		assert.True(t, v)
+	}
+}