libgo/go/internal/testlog/log.go

   1 // Copyright 2017 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Package testlog provides a back-channel communication path
   6 // between tests and package os, so that cmd/go can see which
   7 // environment variables and files a test consults.
   8 package testlog
   9
  10 import "sync/atomic"
  11
  12 // Interface is the interface required of test loggers.
  13 // The os package will invoke the interface's methods to indicate that
  14 // it is inspecting the given environment variables or files.
  15 // Multiple goroutines may call these methods simultaneously.
  16 type Interface interface {
  17         Getenv(key string)
  18         Stat(file string)
  19         Open(file string)
  20         Chdir(dir string)
  21 }
  22
  23 // logger is the current logger Interface.
  24 // We use an atomic.Value in case test startup
  25 // is racing with goroutines started during init.
  26 // That must not cause a race detector failure,
  27 // although it will still result in limited visibility
  28 // into exactly what those goroutines do.
  29 var logger atomic.Value
  30
  31 // SetLogger sets the test logger implementation for the current process.
  32 // It must be called only once, at process startup.
  33 func SetLogger(impl Interface) {
  34         if logger.Load() != nil {
  35                 panic("testlog: SetLogger must be called only once")
  36         }
  37         logger.Store(&impl)
  38 }
  39
  40 // Logger returns the current test logger implementation.
  41 // It returns nil if there is no logger.
  42 func Logger() Interface {
  43         impl := logger.Load()
  44         if impl == nil {
  45                 return nil
  46         }
  47         return *impl.(*Interface)
  48 }
  49
  50 // Getenv calls Logger().Getenv, if a logger has been set.
  51 func Getenv(name string) {
  52         if log := Logger(); log != nil {
  53                 log.Getenv(name)
  54         }
  55 }
  56
  57 // Open calls Logger().Open, if a logger has been set.
  58 func Open(name string) {
  59         if log := Logger(); log != nil {
  60                 log.Open(name)
  61         }
  62 }
  63
  64 // Stat calls Logger().Stat, if a logger has been set.
  65 func Stat(name string) {
  66         if log := Logger(); log != nil {
  67                 log.Stat(name)
  68         }
  69 }