cipd: instance cache

client/cmd/cipd/main.go

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Client side of for Chrome Infra Package Deployer.
 //
 // Subcommand starting with 'pkg-' are low level commands operating on package
 // files on disk.
 package main
 
 import (
         "encoding/json"
         "flag"
         "fmt"
         "io/ioutil"
+        "math/rand"
         "net/http"
         "os"
         "path/filepath"
         "strings"
         "sync"
         "time"
 
         "github.com/maruel/subcommands"
         gol "github.com/op/go-logging"
 
@@ skipping 1638 matching lines @@
         newArgs := []string{}
         if cmd != "" {
                 newArgs = append(newArgs, cmd)
         }
         newArgs = append(newArgs, flags...)
         newArgs = append(newArgs, positional...)
         return newArgs
 }
 
 func main() {
+        rand.Seed(time.Now().Unix())

[Vadim Sh., 2016/04/11 16:52:03]

I was bit in the ass by this construct. Multiple processes may start in exact
same second.

Seed from crypto/rand instead, e.g.

	var seed int64
	if err := binary.Read(cryptorand.Reader, binary.LittleEndian, &seed); err !=
nil {
		panic(err)
	}
	rand.Seed(seed)

[nodir, 2016/04/11 22:16:16]

Done.

         os.Exit(subcommands.Run(application, fixFlagsPosition(os.Args[1:])))
 }