Handle FFmpeg initialization in a lazy instance.

media/filters/ffmpeg_glue.cc

 // Copyright (c) 2012 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 "media/filters/ffmpeg_glue.h"
 
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/synchronization/lock.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 
 namespace media {
 
 // Internal buffer size used by AVIO for reading.
 // TODO(dalecurtis): Experiment with this buffer size and measure impact on
 // performance.  Currently we want to use 32kb to preserve existing behavior
 // with the previous URLProtocol based approach.
@@ skipping 59 matching lines @@
       return 0;
 
     case AV_LOCK_DESTROY:
       delete static_cast<base::Lock*>(*lock);
       *lock = NULL;
       return 0;
   }
   return 1;
 }
 
-static bool InitializeFFmpegInternal() {
-  // Before doing anything disable logging as it interferes with layout tests.
-  av_log_set_level(AV_LOG_QUIET);
+// FFmpeg must only be initialized once, so use a LazyInstance to ensure this.
+class FFmpegInitializer {
+ public:
+  bool initialized() { return initialized_; }
 
-  // Register our protocol glue code with FFmpeg.
-  if (av_lockmgr_register(&LockManagerOperation) != 0)
-    return false;
+ private:
+  friend struct base::DefaultLazyInstanceTraits<FFmpegInitializer>;
 
-  // Now register the rest of FFmpeg.
-  av_register_all();
-  return true;
-}
+  FFmpegInitializer()
+      : initialized_(false) {
+    // Before doing anything disable logging as it interferes with layout tests.
+    av_log_set_level(AV_LOG_QUIET);
+
+    // Register our protocol glue code with FFmpeg.
+    if (av_lockmgr_register(&LockManagerOperation) != 0)
+      return;
+
+    // Now register the rest of FFmpeg.
+    av_register_all();
+
+    initialized_ = true;
+  }
+
+  ~FFmpegInitializer() {

[scherkus (not reviewing), 2012/11/02 23:39:28]

I wonder if this ever gets called :)

[DaleCurtis, 2012/11/02 23:45:55]

Yes, unless you declare it as:

static base::LazyInstance<DeleteLogger>::Leaky li = ...

Which I think we should do since we don't actually need to remove the lock
manager and sail mentioned AtExit stuff slows down mac shutdown.  WDYT?

[scherkus (not reviewing), 2012/11/02 23:48:05]

I'm ok w/ a leaky FFmpeg initializer. This is essentially called when loading
the library into address space and it's not like we need to cleanly unload the
library at certain points in time.

[DaleCurtis, 2012/11/02 23:49:39]

Done.

+    if (initialized_)
+      av_lockmgr_register(NULL);
+  }
+
+  bool initialized_;
+
+  DISALLOW_COPY_AND_ASSIGN(FFmpegInitializer);
+};
 
 void FFmpegGlue::InitializeFFmpeg() {
-  // FFmpeg only needs to be initialized once.
-  static const bool kStatus = InitializeFFmpegInternal();
-  CHECK(kStatus);
+  static base::LazyInstance<FFmpegInitializer> li = LAZY_INSTANCE_INITIALIZER;
+  CHECK(li.Get().initialized());
 }
 
 FFmpegGlue::FFmpegGlue(FFmpegURLProtocol* protocol)
     : open_called_(false) {
   InitializeFFmpeg();
 
   // Initialize an AVIOContext using our custom read and seek operations.  Don't
   // keep pointers to the buffer since FFmpeg may reallocate it on the fly.  It
   // will be cleaned up
   format_context_ = avformat_alloc_context();
@@ skipping 62 matching lines @@
         avcodec_close(stream->codec);
       }
     }
   }
 
   avformat_close_input(&format_context_);
   av_free(avio_context_->buffer);
 }
 
 }  // namespace media