chromeos: Retry ALSA mixer initialization on failure.

chrome/browser/chromeos/audio_mixer_alsa.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
 #include "chrome/browser/chromeos/audio_mixer_alsa.h"
 
 #include <cmath>
+#include <unistd.h>
 
 #include <alsa/asoundlib.h>
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/task.h"
 #include "base/threading/thread_restrictions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/common/pref_names.h"
@@ skipping 15 matching lines @@
 
 const char kMasterVolume[] = "Master";
 const char kPCMVolume[] = "PCM";
 const double kDefaultMinVolume = -90.0;
 const double kDefaultMaxVolume = 0.0;
 const double kPrefVolumeInvalid = -999.0;
 const int kPrefMuteOff = 0;
 const int kPrefMuteOn = 1;
 const int kPrefMuteInvalid = 2;
 
+// Maximum number of times that we'll attempt to initialize the mixer.
+// We'll fail until the ALSA modules have been loaded; see
+// http://crosbug.com/13162.
+const int kMaxInitAttempts = 20;
+
+// Number of seconds that we'll sleep between each initialization attempt.
+const int kInitRetrySleepSec = 1;
+
 }  // namespace
 
 AudioMixerAlsa::AudioMixerAlsa()
     : min_volume_(kDefaultMinVolume),
       max_volume_(kDefaultMaxVolume),
       save_volume_(0),
       mixer_state_(UNINITIALIZED),
       alsa_mixer_(NULL),
       elem_master_(NULL),
       elem_pcm_(NULL),
@@ skipping 138 matching lines @@
   if (!local_state->FindPreference(prefs::kAudioVolume))
     local_state->RegisterDoublePref(prefs::kAudioVolume, kPrefVolumeInvalid);
   if (!local_state->FindPreference(prefs::kAudioMute))
     local_state->RegisterIntegerPref(prefs::kAudioMute, kPrefMuteInvalid);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Private functions follow
 
 void AudioMixerAlsa::DoInit(InitDoneCallback* callback) {
-  bool success = InitializeAlsaMixer();
+  bool success = false;
+  for (int num_attempts = 0; num_attempts < kMaxInitAttempts; ++num_attempts) {
+    success = InitializeAlsaMixer();
+    if (success) {
+      break;
+    } else {
+      // If the destructor has reset the state, give up.
+      {
+        base::AutoLock lock(mixer_state_lock_);
+        if (mixer_state_ != INITIALIZING)
+          break;
+      }
+      sleep(kInitRetrySleepSec);
+    }
+  }
 
   if (success) {
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,
         NewRunnableMethod(this, &AudioMixerAlsa::RestoreVolumeMuteOnUIThread));
   }
 
   if (callback) {
     callback->Run(success);
     delete callback;
@@ skipping 17 matching lines @@
 
   mixer_state_ = INITIALIZING;
   return true;
 }
 
 void AudioMixerAlsa::InitPrefs() {
   prefs_ = g_browser_process->local_state();
 }
 
 bool AudioMixerAlsa::InitializeAlsaMixer() {
+  // We can block; make sure that we're not on the UI thread.
+  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   base::AutoLock lock(mixer_state_lock_);
   if (mixer_state_ != INITIALIZING)
     return false;
 
   int err;
   snd_mixer_t* handle = NULL;
   const char* card = "default";
 
   if ((err = snd_mixer_open(&handle, 0)) < 0) {
     LOG(ERROR) << "ALSA mixer " << card << " open error: " << snd_strerror(err);
@@ skipping 273 matching lines @@
   if (alsa_result != 0) {
     LOG(WARNING) << "snd_mixer_selem_set_playback_switch_all() failed: "
                  << snd_strerror(alsa_result);
   } else {
     VLOG(1) << "Set playback switch " << snd_mixer_selem_get_name(elem)
             << " to " << enabled;
   }
 }
 
 }  // namespace chromeos