Bug 44971 – Fix ThreadableBlobRegistry methods not to rely on WorkerContext

• Status: RESOLVED
• Resolution: FIXED
• Component: WebCore JavaScript

[Jian Li]

Fix ThreadableBlobRegistry methods not to rely on WorkerContext. This is because WorkerContext could be destructed when we're performing cleanup in ScriptExecutionContext destructor.

[Jian Li]

Created attachment 66082 [details]
Proposed Patch

[David Levin]

Mid-air collision -- :)

Here's my comments. Please feel free to address and submit. (In other words, r=me also.)

> diff --git a/WebCore/ChangeLog b/WebCore/ChangeLog
> [phone]  Jian Li  <[e-mail]>
> +
> +        Reviewed by NOBODY (OOPS!).
> +
> +        Fix ThreadableBlobRegistry methods not to rely on WorkerContext.
> +        https://bugs.webkit.org/show_bug.cgi?id=44971
> +
> +        This could happen when we're performing some blob related cleanup

"This"
What could happen?

> +        in ScriptExecutionContext destructor when WorkerContext dies. The fix
> +        is to use isMainThread and callOnMainThread.
> +

> diff --git a/WebCore/fileapi/ThreadableBlobRegistry.cpp b/WebCore/fileapi/ThreadableBlobRegistry.cpp

> +static void registerBlobURLTask(void* context)
>  {
> -    blobRegistry().registerBlobURL(url, blobData);
> +    OwnPtr<BlobRegistryContext> blobRegistryContext = adoptPtr(static_cast<BlobRegistryContext*>(context));
> +    blobRegistry().registerBlobURL(blobRegistryContext->url, blobRegistryContext->blobData.release());
>  }
>  
> -void ThreadableBlobRegistry::registerBlobURL(ScriptExecutionContext* scriptExecutionContext, const KURL& url, PassOwnPtr<BlobData> blobData)
> +void ThreadableBlobRegistry::registerBlobURL(ScriptExecutionContext*, const KURL& url, PassOwnPtr<BlobData> blobData)
>  {
> -    if (scriptExecutionContext->isWorkerContext())
> -        postTaskToMainThread(scriptExecutionContext, createCallbackTask(&registerBlobURLTask, url, blobData));
> +    if (isMainThread())
> +        blobRegistry().registerBlobURL(url, blobData);
>      else
> -        registerBlobURLTask(scriptExecutionContext, url, blobData);
> +        callOnMainThread(&registerBlobURLTask, new BlobRegistryContext(url, blobData));

Please use a create method and a leakPtr (see "[webkit-dev] Naked new considered harmful").

[Jian Li]

Committed as http://trac.webkit.org/changeset/66528.