[BlobAsync] Disk support for blob storage

content/browser/blob_storage/chrome_blob_storage_context.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 "content/browser/blob_storage/chrome_blob_storage_context.h"
 
 #include <utility>
 
 #include "base/bind.h"
+#include "base/files/file.h"
+#include "base/files/file_enumerator.h"
+#include "base/files/file_util.h"
 #include "base/guid.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "content/public/browser/blob_handle.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "storage/browser/blob/blob_data_builder.h"
 #include "storage/browser/blob/blob_data_handle.h"
 #include "storage/browser/blob/blob_storage_context.h"
 
+using base::FilePath;
 using base::UserDataAdapter;
 using storage::BlobStorageContext;
 
 namespace content {
 
 namespace {
+const char kBlobStorageParentDirectory[] = "blob_storage";
+
+void CreateBlobDirectory(const FilePath& blob_storage_dir,
+                         scoped_refptr<base::TaskRunner> io_runner,
+                         const base::Closure& done) {
+  base::File::Error error;
+  bool success = base::CreateDirectoryAndGetError(blob_storage_dir, &error);
+  LOCAL_HISTOGRAM_BOOLEAN("Storage.Blob.DirectorySuccess", success);
+  if (!success) {
+    LOCAL_HISTOGRAM_ENUMERATION("Storage.Blob.DirectorySuccess.Error", -error,
+                                -base::File::FILE_ERROR_MAX);
+  } else {
+    io_runner->PostTask(FROM_HERE, done);
+  }
+}
+
+// Removes all folders in the parent directory except for the
+// |current_run_dir| folder. If this path is empty, then we delete all folders.
+void RemoveOldBlobStorageDirectories(const FilePath& blob_storage_parent,
+                                     const FilePath& current_run_dir) {
+  if (!base::DirectoryExists(blob_storage_parent)) {
+    return;
+  }
+  base::FileEnumerator enumerator(blob_storage_parent, false,
+                                  base::FileEnumerator::DIRECTORIES);
+  std::vector<std::string> components;
+  bool success = true;
+  for (base::FilePath name = enumerator.Next(); !name.empty();
+       name = enumerator.Next()) {
+    if (current_run_dir.empty() || name != current_run_dir)
+      success &= base::DeleteFile(name, true);
+  }
+  LOCAL_HISTOGRAM_BOOLEAN("Storage.Blob.CleanupSuccess", success);
+}
 
 const char kBlobStorageContextKeyName[] = "content_blob_storage_context";
 
 class BlobHandleImpl : public BlobHandle {
  public:
   explicit BlobHandleImpl(std::unique_ptr<storage::BlobDataHandle> handle)
       : handle_(std::move(handle)) {}
 
   ~BlobHandleImpl() override {}
 
   std::string GetUUID() override { return handle_->uuid(); }
 
  private:
   std::unique_ptr<storage::BlobDataHandle> handle_;
 };
 
 }  // namespace
 
 ChromeBlobStorageContext::ChromeBlobStorageContext() {}
 
 ChromeBlobStorageContext* ChromeBlobStorageContext::GetFor(
     BrowserContext* context) {
   if (!context->GetUserData(kBlobStorageContextKeyName)) {
     scoped_refptr<ChromeBlobStorageContext> blob =
         new ChromeBlobStorageContext();
     context->SetUserData(
         kBlobStorageContextKeyName,
         new UserDataAdapter<ChromeBlobStorageContext>(blob.get()));
+
     // Check first to avoid memory leak in unittests.
-    if (BrowserThread::IsMessageLoopValid(BrowserThread::IO)) {
+    bool io_thread_valid = BrowserThread::IsMessageLoopValid(BrowserThread::IO);
+    if (io_thread_valid) {
       BrowserThread::PostTask(
           BrowserThread::IO, FROM_HERE,
           base::Bind(&ChromeBlobStorageContext::InitializeOnIOThread, blob));
     }
+
+    // If we're not incognito mode, schedule all of our file tasks to enable
+    // disk on the storage context.
+    if (!context->IsOffTheRecord() && io_thread_valid) {
+      // Resolve our storage directories.
+      base::FilePath blob_storage_parent =
+          context->GetPath().Append(kBlobStorageParentDirectory);
+      base::FilePath blob_storage_dir =
+          blob_storage_parent.Append(base::GenerateGUID());
+
+      scoped_refptr<base::SingleThreadTaskRunner> io_runner =
+          BrowserThread::GetTaskRunnerForThread(BrowserThread::IO);
+      scoped_refptr<base::TaskRunner> file_runner =
+          BrowserThread::GetBlockingPool()->GetTaskRunnerWithShutdownBehavior(
+              base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+
+      // This creates our directory and calls |OnBlobDirectoryCreated| if
+      // we're successful.
+      BrowserThread::PostAfterStartupTask(

[michaeln, 2016/08/15 22:44:42]

I mentioned this earlier but it got lost in other back/forth comments.

Can creation/deletion of the active directory be managed internally by the
BlobStorageContext. We know at the time of construction what path to
provide, seems like the context could create it on demand when it determines
it's needed. Give a FilePath and taskrunner to the BlobStorageContext ctor and
let it do its thing as needed. I think that's a cleaner division of labor.

Removing the old directories feels like a good job for the wrapper.

+          FROM_HERE, file_runner,
+          base::Bind(
+              &CreateBlobDirectory, blob_storage_dir, io_runner,
+              base::Bind(&ChromeBlobStorageContext::OnBlobDirectoryCreated,
+                         blob, blob_storage_dir)));
+
+      // Removes our old blob directories if they exist.
+      BrowserThread::PostAfterStartupTask(
+          FROM_HERE, file_runner,
+          base::Bind(&RemoveOldBlobStorageDirectories, blob_storage_parent,
+                     blob_storage_dir));
+    }
   }
 
   return UserDataAdapter<ChromeBlobStorageContext>::Get(
       context, kBlobStorageContextKeyName);
 }
 
 void ChromeBlobStorageContext::InitializeOnIOThread() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   context_.reset(new BlobStorageContext());
+  if (!blob_storage_dir_.empty()) {
+    // This happens if we create our blob storage folder before this method is
+    // called, so we enable disk here.
+    context_->EnableDisk(blob_storage_dir_, BrowserThread::GetBlockingPool());

[michaeln, 2016/08/15 22:44:42]

that would also remove the need for the EnableDisk public api and the need for
it to be called from two places

+  }
 }
 
 std::unique_ptr<BlobHandle> ChromeBlobStorageContext::CreateMemoryBackedBlob(
     const char* data,
     size_t length) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   std::string uuid(base::GenerateGUID());
   storage::BlobDataBuilder blob_data_builder(uuid);
   blob_data_builder.AppendData(data, length);
@@ skipping 33 matching lines @@
 
 void ChromeBlobStorageContext::DeleteOnCorrectThread() const {
   if (BrowserThread::IsMessageLoopValid(BrowserThread::IO) &&
       !BrowserThread::CurrentlyOn(BrowserThread::IO)) {
     BrowserThread::DeleteSoon(BrowserThread::IO, FROM_HERE, this);
     return;
   }
   delete this;
 }
 
+void ChromeBlobStorageContext::OnBlobDirectoryCreated(
+    const base::FilePath& blob_storage_directory) {
+  LOG(ERROR) << "Blob directory successfully created "
+             << blob_storage_directory.value();
+  DCHECK(blob_storage_dir_.empty());
+  blob_storage_dir_ = blob_storage_directory;
+  if (context_) {
+    scoped_refptr<base::TaskRunner> file_runner =
+        BrowserThread::GetBlockingPool()->GetTaskRunnerWithShutdownBehavior(
+            base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+    context_->EnableDisk(blob_storage_dir_, file_runner);
+  }
+}
+
 }  // namespace content