initial commit Change-Id: Iecee6de665d30e5db1587444d8112c44bb592b4e
diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..d645695 --- /dev/null +++ b/LICENSE
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diff --git a/README.md b/README.md new file mode 100644 index 0000000..befcde4 --- /dev/null +++ b/README.md
@@ -0,0 +1,44 @@ +# Go example projects + +This repository contains a collection of Go programs and libraries that +demonstrate the language, standard libraries, and tools. + +## The examples + +### [hello](hello/) and [stringutil](stringutil/) + + go get github.com/golang/example/hello + +A trivial "Hello, world" program that uses a stringutil package. + +Command [hello](hello/) covers: + +* The basic form of an executable command +* Importing packages (from the standard library and the local repository) +* Printing strings ([fmt](//golang.org/pkg/fmt/)) + +Library [stringutil](stringutil/) covers: + +* The basic form of a library +* Conversion between string and []rune +* Table-driven unit tests ([testing](//golang.org/pkg/testing/)) + +### [outyet](outyet/) + + go get github.com/golang/example/outyet + +A web server that answers the question: "Is Go 1.x out yet?" + +Topics covered: + +* Command-line flags ([flag](//golang.org/pkg/flag/)) +* Web servers ([net/http](//golang.org/pkg/net/http/)) +* HTML Templates ([html/template](//golang.org/pkg/html/template/)) +* Logging ([log](//golang.org/pkg/log/)) +* Long-running background processes +* Synchronizing data access between goroutines ([sync](//golang.org/pkg/sync/)) +* Exporting server state for monitoring ([expvar](//golang.org/pkg/expvar/)) +* Unit and integration tests ([testing](//golang.org/pkg/testing/)) +* Dependency injection +* Time ([time](//golang.org/pkg/time/)) +
diff --git a/hello/hello.go b/hello/hello.go new file mode 100644 index 0000000..9353cc8 --- /dev/null +++ b/hello/hello.go
@@ -0,0 +1,27 @@ +/* +Copyright 2014 Google Inc. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +package main + +import ( + "fmt" + + "github.com/golang/example/stringutil" +) + +func main() { + fmt.Println(stringutil.Reverse("!selpmaxe oG ,olleH")) +}
diff --git a/outyet/main.go b/outyet/main.go new file mode 100644 index 0000000..7d64edd --- /dev/null +++ b/outyet/main.go
@@ -0,0 +1,140 @@ +/* +Copyright 2014 Google Inc. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +// outyet is a web server that announces whether or not a particular Go version +// has been tagged. +package main + +import ( + "expvar" + "flag" + "fmt" + "html/template" + "log" + "net/http" + "sync" + "time" +) + +// Command-line flags. +var ( + httpAddr = flag.String("http", ":8080", "Listen address") + pollPeriod = flag.Duration("poll", 5*time.Second, "Poll period") + version = flag.String("version", "1.4", "Go version") +) + +const baseChangeURL = "https://code.google.com/p/go/source/detail?r=" + +func main() { + flag.Parse() + changeURL := fmt.Sprintf("%sgo%s", baseChangeURL, *version) + http.Handle("/", NewServer(*version, changeURL, *pollPeriod)) + log.Fatal(http.ListenAndServe(*httpAddr, nil)) +} + +// Exported variables for monitoring the server. +// These are exported via HTTP as a JSON object at /debug/vars. +var ( + hitCount = expvar.NewInt("hitCount") + pollCount = expvar.NewInt("pollCount") + pollError = expvar.NewString("pollError") + pollErrorCount = expvar.NewInt("pollErrorCount") +) + +// Server implements the outyet server. +// It serves the user interface (it's an http.Handler) +// and polls the remote repository for changes. +type Server struct { + version string + url string + period time.Duration + + mu sync.RWMutex // protects the yes variable + yes bool +} + +// NewServer returns an initialized outyet server. +func NewServer(version, url string, period time.Duration) *Server { + s := &Server{version: version, url: url, period: period} + go s.poll() + return s +} + +// poll polls the change URL for the specified period until the tag exists. +// Then it sets the Server's yes field true and exits. +func (s *Server) poll() { + for !isTagged(s.url) { + pollSleep(s.period) + } + s.mu.Lock() + s.yes = true + s.mu.Unlock() + pollDone() +} + +// Hooks that may be overridden for integration tests. +var ( + pollSleep = time.Sleep + pollDone = func() {} +) + +// isTagged makes an HTTP HEAD request to the given URL and reports whether it +// returned a 200 OK response. +func isTagged(url string) bool { + pollCount.Add(1) + r, err := http.Head(url) + if err != nil { + log.Print(err) + pollError.Set(err.Error()) + pollErrorCount.Add(1) + return false + } + return r.StatusCode == http.StatusOK +} + +// ServeHTTP implements the HTTP user interface. +func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) { + hitCount.Add(1) + s.mu.RLock() + data := struct { + URL string + Version string + Yes bool + }{ + s.url, + s.version, + s.yes, + } + s.mu.RUnlock() + err := tmpl.Execute(w, data) + if err != nil { + log.Print(err) + } +} + +// tmpl is the HTML template that drives the user interface. +var tmpl = template.Must(template.New("tmpl").Parse(` +<!DOCTYPE html><html><body><center> + <h2>Is Go {{.Version}} out yet?</h2> + <h1> + {{if .Yes}} + <a href="{{.URL}}">YES!</a> + {{else}} + No. :-( + {{end}} + </h1> +</center></body></html> +`))
diff --git a/outyet/main_test.go b/outyet/main_test.go new file mode 100644 index 0000000..d21a22c --- /dev/null +++ b/outyet/main_test.go
@@ -0,0 +1,99 @@ +/* +Copyright 2014 Google Inc. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +package main + +import ( + "net/http" + "net/http/httptest" + "strings" + "testing" + "time" +) + +// statusHandler is an http.Handler that writes an empty response using itself +// as the response status code. +type statusHandler int + +func (h *statusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) { + w.WriteHeader(int(*h)) +} + +func TestIsTagged(t *testing.T) { + // Set up a fake "Google Code" web server reporting 404 not found. + status := statusHandler(http.StatusNotFound) + s := httptest.NewServer(&status) + defer s.Close() + + if isTagged(s.URL) { + t.Fatal("isTagged == true, want false") + } + + // Change fake server status to 200 OK and try again. + status = http.StatusOK + + if !isTagged(s.URL) { + t.Fatal("isTagged == false, want true") + } +} + +func TestIntegration(t *testing.T) { + status := statusHandler(http.StatusNotFound) + ts := httptest.NewServer(&status) + defer ts.Close() + + // Replace the pollSleep with a closure that we can block and unblock. + sleep := make(chan bool) + pollSleep = func(time.Duration) { + sleep <- true + sleep <- true + } + + // Replace pollDone with a closure that will tell us when the poller is + // exiting. + done := make(chan bool) + pollDone = func() { done <- true } + + // Put things as they were when the test finishes. + defer func() { + pollSleep = time.Sleep + pollDone = func() {} + }() + + s := NewServer("1.x", ts.URL, 1*time.Millisecond) + + <-sleep // Wait for poll loop to start sleeping. + + // Make first request to the server. + r, _ := http.NewRequest("GET", "/", nil) + w := httptest.NewRecorder() + s.ServeHTTP(w, r) + if b := w.Body.String(); !strings.Contains(b, "No.") { + t.Fatalf("body = %s, want no", b) + } + + status = http.StatusOK + + <-sleep // Permit poll loop to stop sleeping. + <-done // Wait for poller to see the "OK" status and exit. + + // Make second request to the server. + w = httptest.NewRecorder() + s.ServeHTTP(w, r) + if b := w.Body.String(); !strings.Contains(b, "YES!") { + t.Fatalf("body = %q, want yes", b) + } +}
diff --git a/stringutil/reverse.go b/stringutil/reverse.go new file mode 100644 index 0000000..dea9f6b --- /dev/null +++ b/stringutil/reverse.go
@@ -0,0 +1,27 @@ +/* +Copyright 2014 Google Inc. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +// Package stringutil contains utility functions for working with strings. +package stringutil + +// Reverse returns the provided string with its runes in reverse order. +func Reverse(s string) string { + r := []rune(s) + for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 { + r[i], r[j] = r[j], r[i] + } + return string(r) +}
diff --git a/stringutil/reverse_test.go b/stringutil/reverse_test.go new file mode 100644 index 0000000..263a420 --- /dev/null +++ b/stringutil/reverse_test.go
@@ -0,0 +1,34 @@ +/* +Copyright 2014 Google Inc. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +package stringutil + +import "testing" + +func TestReverse(t *testing.T) { + for _, c := range struct { + in, want string + }{ + {"Hello, world", "dlrow ,olleH"}, + {"Hello, 世界", "界世 ,olleH"}, + {"", ""}, + } { + got := Reverse(c.in) + if got != want { + t.Errorf("Reverse(%q) == %q, want %q", c.in, got, want) + } + } +}