First public version.

.gitignore

@@ -1,12 +1,3 @@
-# Binaries for programs and plugins
-*.exe
-*.exe~
-*.dll
-*.so
-*.dylib
-
-# Test binary, build with `go test -c`
-*.test
-
-# Output of the go coverage tool, specifically when used with LiteIDE
-*.out
+data.bin
+.idea
+build

.golangci.yml

@@ -0,0 +1,205 @@
+# This file contains all available configuration options
+# with their default values.
+
+# options for analysis running
+run:
+  # default concurrency is a available CPU number
+  concurrency: 4
+
+  # timeout for analysis, e.g. 30s, 5m, default is 1m
+  deadline: 5m
+
+  # exit code when at least one issue was found, default is 1
+  issues-exit-code: 1
+
+  # include test files or not, default is true
+  tests: true
+
+  # list of build tags, all linters use it. Default is empty list.
+  build-tags: []
+
+  # which dirs to skip: they won't be analyzed;
+  # can use regexp here: generated.*, regexp is applied on full path;
+  # default value is empty list, but next dirs are always skipped independently
+  # from this option's value:
+  #   	vendor$, third_party$, testdata$, examples$, Godeps$, builtin$
+  skip-dirs:
+    - vendor
+
+  # which files to skip: they will be analyzed, but issues from them
+  # won't be reported. Default value is empty list, but there is
+  # no need to include all autogenerated files, we confidently recognize
+  # autogenerated files. If it's not please let us know.
+  skip-files:
+    - ".*easyjson.*"
+
+  # by default isn't set. If set we pass it to "go list -mod={option}". From "go help modules":
+  # If invoked with -mod=readonly, the go command is disallowed from the implicit
+  # automatic updating of go.mod described above. Instead, it fails when any changes
+  # to go.mod are needed. This setting is most useful to check that go.mod does
+  # not need updates, such as in a continuous integration and testing system.
+  # If invoked with -mod=vendor, the go command assumes that the vendor
+  # directory holds the correct copies of dependencies and ignores
+  # the dependency descriptions in go.mod.
+  # FIXME:
+  # modules-download-mode: vendor
+
+
+# output configuration options
+output:
+  # colored-line-number|line-number|json|tab|checkstyle|code-climate, default is "colored-line-number"
+  format: colored-line-number
+
+  # print lines of code with issue, default is true
+  print-issued-lines: true
+
+  # print linter name in the end of issue text, default is true
+  print-linter-name: true
+
+
+# all available settings of specific linters
+linters-settings:
+  errcheck:
+    # report about not checking of errors in type assetions: `a := b.(MyStruct)`;
+    # default is false: such cases aren't reported by default.
+    check-type-assertions: true
+
+    # report about assignment of errors to blank identifier: `num, _ := strconv.Atoi(numStr)`;
+    # default is false: such cases aren't reported by default.
+    check-blank: false
+
+    # [deprecated] comma-separated list of pairs of the form pkg:regex
+    # the regex is used to ignore names within pkg. (default "fmt:.*").
+    # see https://github.com/kisielk/errcheck#the-deprecated-method for details
+    ignore: fmt:.*,io/ioutil:^Read.*
+
+  govet:
+    # report about shadowed variables
+    check-shadowing: true
+
+    # settings per analyzer
+    settings:
+      printf: # analyzer name, run `go tool vet help` to see all analyzers
+        funcs: # run `go tool vet help printf` to see available settings for `printf` analyzer
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Infof
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Warnf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Errorf
+          - (github.com/golangci/golangci-lint/pkg/logutils.Log).Fatalf
+  golint:
+    # minimal confidence for issues, default is 0.8
+    min-confidence: 0.8
+  gofmt:
+    # simplify code: gofmt with `-s` option, true by default
+    simplify: true
+  goimports:
+    # put imports beginning with prefix after 3rd-party packages;
+    # it's a comma-separated list of prefixes
+    # local-prefixes:
+  gocyclo:
+    # minimal code complexity to report, 30 by default (but we recommend 10-20)
+    min-complexity: 30
+  goconst:
+    # minimal length of string constant, 3 by default
+    min-len: 3
+    # minimal occurrences count to trigger, 3 by default
+    min-occurrences: 3
+  depguard:
+    list-type: blacklist
+    include-go-root: false
+  misspell:
+    # Correct spellings using locale preferences for US or UK.
+    # Default is to use a neutral variety of English.
+    # Setting locale to US will correct the British spelling of 'colour' to 'color'.
+    locale: US
+    ignore-words: []
+  lll:
+    # max line length, lines longer will be reported. Default is 120.
+    # '\t' is counted as 1 character by default, and can be changed with the tab-width option
+    line-length: 150
+    # tab width in spaces. Default to 1.
+    tab-width: 2
+  unused:
+    # treat code as a program (not a library) and report unused exported identifiers; default is false.
+    # XXX: if you enable this setting, unused will report a lot of false-positives in text editors:
+    # if it's called for subdir of a project it can't find funcs usages. All text editor integrations
+    # with golangci-lint call it on a directory with the changed file.
+    check-exported: false
+  unparam:
+    # Inspect exported functions, default is false. Set to true if no external program/library imports your code.
+    # XXX: if you enable this setting, unparam will report a lot of false-positives in text editors:
+    # if it's called for subdir of a project it can't find external interfaces. All text editor integrations
+    # with golangci-lint call it on a directory with the changed file.
+    check-exported: false
+  nakedret:
+    # make an issue if func has more lines of code than this setting and it has naked returns; default is 30
+    max-func-lines: 5
+  prealloc:
+    # XXX: we don't recommend using this linter before doing performance profiling.
+    # For most programs usage of prealloc will be a premature optimization.
+
+    # Report preallocation suggestions only on simple loops that have no returns/breaks/continues/gotos in them.
+    # True by default.
+    simple: true
+    range-loops: true # Report preallocation suggestions on range loops, true by default
+    for-loops: false # Report preallocation suggestions on for loops, false by default
+  gocritic:
+    # Which checks should be disabled; can't be combined with 'enabled-checks'; default is empty
+    disabled-checks:
+      - regexpMust
+
+    # Enable multiple checks by tags, run `GL_DEBUG=gocritic golangci-lint` run to see all tags and checks.
+    # Empty list by default. See https://github.com/go-critic/go-critic#usage -> section "Tags".
+    enabled-tags:
+      - performance
+
+    settings: # settings passed to gocritic
+      captLocal: # must be valid enabled check name
+        paramsOnly: true
+      rangeValCopy:
+        sizeThreshold: 32
+
+linters:
+  enable-all: true
+  disable:
+    - maligned
+#    - dupl
+#    - goimports # FIXME
+#    - gocritic  # FIXME
+  disable-all: false
+  fast: false
+
+issues:
+  # Excluding configuration per-path, per-linter, per-text and per-source
+  exclude-rules:
+    # Exclude some linters from running on tests files.
+    - path: _test\.go
+      linters:
+        - gocyclo
+        - errcheck
+        - dupl
+        - gosec
+
+    # Exclude lll issues for long lines with go:generate
+    - linters:
+        - lll
+      text: "^//( )?go:generate "
+
+  # Independently from option `exclude` we use default exclude patterns,
+  # it can be disabled by this option. To list all
+  # excluded by default patterns execute `golangci-lint run --help`.
+  # Default value for this option is true.
+  exclude-use-default: false
+
+  # Maximum issues count per one linter. Set to 0 to disable. Default is 50.
+  max-per-linter: 0
+
+  # Maximum count of issues with the same text. Set to 0 to disable. Default is 3.
+  max-same-issues: 0
+
+  # Show only new issues: if there are unstaged changes or untracked files,
+  # only those changes are analyzed, else only changes in HEAD~ are analyzed.
+  # It's a super-useful option for integration of golangci-lint into existing
+  # large codebase. It's not practical to fix all existing issues at the moment
+  # of integration: much better don't allow issues in new code.
+  # Default is false.
+  new: false

Makefile

@@ -0,0 +1,15 @@
+.PHONY: build lint test vendor
+
+default: build
+
+build:
+	go build -mod=vendor -o build/probe -ldflags "-s -w" cmd/main.go
+
+lint:
+	golangci-lint run
+
+test:
+	go test ./...
+
+vendor:
+	go mod tidy && go mod vendor

README.md

@@ -0,0 +1,48 @@
+## Probe
+Is in-memory cache server with simple text-based protocol.
+
+### Features
+* TTL per key
+* Dump and Restore from disk
+* Thread-safety
+* Commands:
+    * `set <key> <value> <ttl>`
+    * `get <key>`
+    * `del <key>`
+    * `quit`
+
+### Why?
+For fun and profit :-)
+
+### How to use
+You need just start a server and connect to it from `nc`, like this:
+
+```bash
+nc 127.0.0.1 4000
+```
+
+Set value:
+```bash
+set mykey myvalue 300s
+OK
+```
+
+Get value:
+```bash
+get mykey
+myvalue
+```
+
+Delete value:
+```bash
+del mykey
+OK
+```
+
+### ToDo
+* Tests and benchmarks
+* Metrics
+* Dump and restore without reflection
+* Build in GitHub Actions
+
+

cmd/main.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"golang.org/x/sync/errgroup"
+
+	"probe/internal/cache"
+	"probe/internal/server"
+)
+
+var errCanceled = errors.New("canceled")
+
+func main() {
+	address := flag.String("addr", "127.0.0.1:4000", "TCP server address")
+	dataFile := flag.String("path", "data.bin", "Path to data file")
+	interval := flag.Duration("interval", time.Minute, "Eviction interval")
+	flag.Parse()
+
+	logger := log.New(os.Stdout, "", log.LstdFlags|log.Lshortfile)
+
+	file, err := os.OpenFile(*dataFile, os.O_RDWR|os.O_CREATE, 0600)
+	if err != nil {
+		logger.Fatalf("Failed to open file: %v", err)
+	}
+	defer func() {
+		if err = file.Close(); err != nil {
+			logger.Printf("Failed to close file: %v", err)
+		}
+	}()
+
+	inMemCache := cache.New()
+
+	if err = inMemCache.Restore(file); err != nil {
+		logger.Printf("Warning. Failed to restore cache: %v", err)
+	}
+
+	gr, ctx := errgroup.WithContext(context.Background())
+
+	gr.Go(func() error {
+		return server.New(*address, inMemCache, logger).Listen(ctx)
+	})
+
+	gr.Go(func() error {
+		inMemCache.Eviction(ctx, *interval)
+		return nil
+	})
+
+	gr.Go(func() error {
+		signals := make(chan os.Signal, 1)
+		signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)
+		for {
+			select {
+			case <-ctx.Done():
+				return nil
+			case <-signals:
+				logger.Println("Caught stop signal. Exiting...")
+				return errCanceled
+			}
+		}
+	})
+
+	if err = gr.Wait(); err != nil && err != errCanceled {
+		logger.Fatalf("Failed to start: %v", err)
+	}
+
+	if err := file.Truncate(0); err != nil {
+		logger.Fatalf("Failed to truncate file: %v", err)
+	}
+
+	if err := inMemCache.Dump(file); err != nil {
+		logger.Fatalf("Failed to dump cache: %v", err)
+	}
+}

go.mod

@@ -0,0 +1,5 @@
+module probe
+
+go 1.13
+
+require golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e h1:vcxGaoTs7kV8m5Np9uUNQin4BrLOthgV7252N8V+FwY=
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=