Allow BlobDataHandles to be copied, and have their UUIDs read, on any thread.

BUG=108012

Review URL: https://codereview.chromium.org/259773006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266817 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 72 insertions, 36 deletions

diff --git a/content/browser/fileapi/blob_storage_context_unittest.cc b/content/browser/fileapi/blob_storage_context_unittest.cc
index fd58880..05498b5 100644
--- a/content/browser/fileapi/blob_storage_context_unittest.cc
+++ b/content/browser/fileapi/blob_storage_context_unittest.cc
@@ -41,6 +41,7 @@ TEST(BlobStorageContextTest, IncrementDecrementRef) {
   blob_data_handle = context.GetBlobDataFromUUID(kId);
   EXPECT_TRUE(blob_data_handle);
   blob_data_handle.reset();
+  fake_io_message_loop.RunUntilIdle();
 
   // Make sure its still there after inc/dec.
   EXPECT_TRUE(host.IncrementBlobRefCount(kId));
@@ -48,6 +49,7 @@ TEST(BlobStorageContextTest, IncrementDecrementRef) {
   blob_data_handle = context.GetBlobDataFromUUID(kId);
   EXPECT_TRUE(blob_data_handle);
   blob_data_handle.reset();
+  fake_io_message_loop.RunUntilIdle();
 
   // Make sure it goes away in the end.
   EXPECT_TRUE(host.DecrementBlobRefCount(kId));
@@ -82,6 +84,7 @@ TEST(BlobStorageContextTest, BlobDataHandle) {
   // Should disappear after dropping both handles.
   blob_data_handle.reset();
   another_handle.reset();
+  fake_io_message_loop.RunUntilIdle();
   blob_data_handle = context.GetBlobDataFromUUID(kId);
   EXPECT_FALSE(blob_data_handle);
 }
@@ -150,6 +153,7 @@ TEST(BlobStorageContextTest, PublicBlobUrls) {
   ASSERT_TRUE(blob_data_handle.get());
   EXPECT_EQ(kId, blob_data_handle->data()->uuid());
   blob_data_handle.reset();
+  fake_io_message_loop.RunUntilIdle();
 
   // The url registration should keep the blob alive even after
   // explicit references are dropped.
@@ -157,6 +161,7 @@ TEST(BlobStorageContextTest, PublicBlobUrls) {
   blob_data_handle = context.GetBlobDataFromPublicURL(kUrl);
   EXPECT_TRUE(blob_data_handle);
   blob_data_handle.reset();
+  fake_io_message_loop.RunUntilIdle();
 
   // Finally get rid of the url registration and the blob.
   EXPECT_TRUE(host.RevokePublicBlobURL(kUrl));
diff --git a/webkit/browser/blob/blob_data_handle.cc b/webkit/browser/blob/blob_data_handle.cc
index fd0ae54..8ccba74 100644
--- a/webkit/browser/blob/blob_data_handle.cc
+++ b/webkit/browser/blob/blob_data_handle.cc
@@ -13,44 +13,56 @@
 
 namespace webkit_blob {
 
-BlobDataHandle::BlobDataHandle(BlobData* blob_data, BlobStorageContext* context,
-                               base::SequencedTaskRunner* task_runner)
+BlobDataHandle::BlobDataHandleShared::BlobDataHandleShared(
+    BlobData* blob_data,
+    BlobStorageContext* context,
+    base::SequencedTaskRunner* task_runner)
     : blob_data_(blob_data),
-      context_(context->AsWeakPtr()),
-      io_task_runner_(task_runner) {
-  // Ensures the uuid remains registered and the underlying data is not deleted.
-  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+      context_(context->AsWeakPtr()) {
   context_->IncrementBlobRefCount(blob_data->uuid());
-  blob_data_->AddRef();
 }
 
-BlobDataHandle::~BlobDataHandle() {
-  if (io_task_runner_->RunsTasksOnCurrentThread()) {
-    // Note: Do not test context_ or alter the blob_data_ refcount
-    // on the wrong thread.
-    if (context_.get())
-      context_->DecrementBlobRefCount(blob_data_->uuid());
-    blob_data_->Release();
-    return;
-  }
+BlobData* BlobDataHandle::BlobDataHandleShared::data() const {
+  return blob_data_;
+}
 
-  io_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&DeleteHelper, context_, base::Unretained(blob_data_)));
+const std::string& BlobDataHandle::BlobDataHandleShared::uuid() const {
+  return blob_data_->uuid();
+}
+
+BlobDataHandle::BlobDataHandleShared::~BlobDataHandleShared() {
+  if (context_.get())
+    context_->DecrementBlobRefCount(blob_data_->uuid());
+}
+
+BlobDataHandle::BlobDataHandle(BlobData* blob_data,
+                               BlobStorageContext* context,
+                               base::SequencedTaskRunner* task_runner)
+    : io_task_runner_(task_runner),
+      shared_(new BlobDataHandleShared(blob_data, context, task_runner)) {
+  DCHECK(io_task_runner_);
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+}
+
+BlobDataHandle::BlobDataHandle(const BlobDataHandle& other) {
+  io_task_runner_ = other.io_task_runner_;
+  shared_ = other.shared_;
+}
+
+BlobDataHandle::~BlobDataHandle() {
+  BlobDataHandleShared* raw = shared_.get();
+  raw->AddRef();
+  shared_ = 0;
+  io_task_runner_->ReleaseSoon(FROM_HERE, raw);
 }
 
 BlobData* BlobDataHandle::data() const {
   DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
-  return blob_data_;
+  return shared_->data();
 }
 
-// static
-void BlobDataHandle::DeleteHelper(
-    base::WeakPtr<BlobStorageContext> context,
-    BlobData* blob_data) {
-  if (context.get())
-    context->DecrementBlobRefCount(blob_data->uuid());
-  blob_data->Release();
+std::string BlobDataHandle::uuid() const {
+  return shared_->uuid();
 }
 
 }  // namespace webkit_blob
diff --git a/webkit/browser/blob/blob_data_handle.h b/webkit/browser/blob/blob_data_handle.h
index 5f870f2..917a0b3 100644
--- a/webkit/browser/blob/blob_data_handle.h
+++ b/webkit/browser/blob/blob_data_handle.h
@@ -28,23 +28,42 @@ class BlobStorageContext;
 class WEBKIT_STORAGE_BROWSER_EXPORT BlobDataHandle
     : public base::SupportsUserData::Data {
  public:
+  BlobDataHandle(const BlobDataHandle& other);  // May be copied on any thread.
   virtual ~BlobDataHandle();  // Maybe be deleted on any thread.
   BlobData* data() const;  // May only be accessed on the IO thread.
 
+  std::string uuid() const;  // May be accessed on any thread.
+
  private:
+  class BlobDataHandleShared
+      : public base::RefCountedThreadSafe<BlobDataHandleShared> {
+   public:
+    BlobDataHandleShared(BlobData* blob_data,
+                         BlobStorageContext* context,
+                         base::SequencedTaskRunner* task_runner);
+
+    BlobData* data() const;
+    const std::string& uuid() const;
+
+   private:
+    friend class base::DeleteHelper<BlobDataHandleShared>;
+    friend class base::RefCountedThreadSafe<BlobDataHandleShared>;
+    friend class BlobDataHandle;
+
+    virtual ~BlobDataHandleShared();
+
+    scoped_refptr<BlobData> blob_data_;
+    base::WeakPtr<BlobStorageContext> context_;
+
+    DISALLOW_COPY_AND_ASSIGN(BlobDataHandleShared);
+  };
+
   friend class BlobStorageContext;
   BlobDataHandle(BlobData* blob_data, BlobStorageContext* context,
                  base::SequencedTaskRunner* task_runner);
 
-  static void DeleteHelper(
-      base::WeakPtr<BlobStorageContext> context,
-      BlobData* blob_data);
-
-  BlobData* blob_data_;  // Intentionally a raw ptr to a non-thread-safe ref.
-  base::WeakPtr<BlobStorageContext> context_;
   scoped_refptr<base::SequencedTaskRunner> io_task_runner_;
-
-  DISALLOW_COPY_AND_ASSIGN(BlobDataHandle);
+  scoped_refptr<BlobDataHandleShared> shared_;
 };
 
 }  // namespace webkit_blob
diff --git a/webkit/browser/blob/blob_storage_context.h b/webkit/browser/blob/blob_storage_context.h
index dda669a..a753c59 100644
--- a/webkit/browser/blob/blob_storage_context.h
+++ b/webkit/browser/blob/blob_storage_context.h
@@ -53,7 +53,7 @@ class WEBKIT_STORAGE_BROWSER_EXPORT BlobStorageContext
 
  private:
   friend class content::BlobStorageHost;
-  friend class BlobDataHandle;
+  friend class BlobDataHandle::BlobDataHandleShared;
   friend class ViewBlobInternalsJob;
 
   enum EntryFlags {