Refactor cache counting into a separate helper class

chrome/browser/browsing_data/cache_test_util.cc

+// Copyright 2016 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/browsing_data/cache_test_util.h"
+#include "net/disk_cache/disk_cache.h"
+#include "net/http/http_cache.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_context_getter.h"
+
+using content::BrowserThread;
+
+CacheTestUtil::CacheTestUtil(content::StoragePartition* partition)
+    : partition_(partition), remaining_tasks_(0) {}
+
+CacheTestUtil::~CacheTestUtil() {}
+
+void CacheTestUtil::SetUpOnMainThread() {

[msramek, 2016/12/20 01:02:59]

Couldn't this method's body be merged into the constructor and the following
one's into the destructor?

The SetUp() and TearDown() methods are used by tests so that they can be
inherited and specialized; however, this is not a test. If it's held by the test
in a std::unique_ptr, you have perfect control over when the constructor and
destructor are run (by calling MakeUnique and reset), so it seems there's no
reason to separate this.

[dullweber, 2016/12/21 10:29:19]

yes, sounds good.

+  done_callback_ =
+      base::Bind(&CacheTestUtil::DoneCallback, base::Unretained(this));
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CacheTestUtil::SetUpOnIOThread, base::Unretained(this)));
+  WaitForTasksOnIOThread();
+}
+
+void CacheTestUtil::TearDownOnMainThread() {
+  // The cache iterator must be deleted on the thread where it was created,
+  // which is the IO thread.
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CacheTestUtil::TearDownOnIOThread, base::Unretained(this)));
+  WaitForTasksOnIOThread();
+}
+
+void CacheTestUtil::CreateCacheEntries(const std::set<std::string>& keys) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CacheTestUtil::CreateCacheEntriesOnIOThread,
+                 base::Unretained(this), base::ConstRef(keys)));
+  WaitForTasksOnIOThread();
+}
+
+void CacheTestUtil::SetUpOnIOThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  net::URLRequestContextGetter* context = partition_->GetURLRequestContext();
+
+  net::HttpCache* cache =
+      context->GetURLRequestContext()->http_transaction_factory()->GetCache();
+
+  SetNumberOfWaitedTasks(1);
+  WaitForCompletion(cache->GetBackend(&backend_, done_callback_));
+}
+
+void CacheTestUtil::TearDownOnIOThread() {
+  iterator_.reset();
+  DoneCallback(net::OK);
+}
+
+void CacheTestUtil::CreateCacheEntriesOnIOThread(
+    const std::set<std::string>& keys) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  entries_.resize(keys.size());
+  SetNumberOfWaitedTasks(keys.size());
+
+  int pos = 0;
+  for (const std::string& key : keys) {
+    WaitForCompletion(
+        backend_->CreateEntry(key, &entries_[pos++], done_callback_));
+  }
+}
+
+// Waiting for tasks to be done on IO thread. --------------------------------
+
+void CacheTestUtil::WaitForTasksOnIOThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  run_loop_.reset(new base::RunLoop());
+  run_loop_->Run();
+}
+
+void CacheTestUtil::SetNumberOfWaitedTasks(int count) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  remaining_tasks_ = count;
+}
+
+void CacheTestUtil::WaitForCompletion(int value) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (value >= 0) {
+    // We got the result immediately.
+    DoneCallback(value);
+  } else if (value == net::ERR_IO_PENDING) {
+    // We need to wait for the callback.
+  } else {
+    // An error has occurred.
+    NOTREACHED();
+  }
+}
+
+void CacheTestUtil::DoneCallback(int value) {
+  DCHECK_GE(value, 0);  // Negative values represent an error.
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (--remaining_tasks_ > 0)
+    return;
+
+  if (run_loop_) {
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        base::Bind(&base::RunLoop::Quit, base::Unretained(run_loop_.get())));
+  }
+}
+
+// Check cache content

[msramek, 2016/12/20 01:02:59]

nit: Period at the end of the sentence.

+
+std::vector<std::string> CacheTestUtil::GetEntryKeys() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::Bind(&CacheTestUtil::GetEntryKeysOnIOThread,
+                                     base::Unretained(this)));
+  WaitForTasksOnIOThread();
+  return remaining_keys_;
+}
+
+void CacheTestUtil::GetEntryKeysOnIOThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  remaining_keys_.clear();
+  current_entry_ = nullptr;
+  iterator_ = backend_->CreateIterator();
+  GetNextKey(net::OK);
+}
+
+void CacheTestUtil::GetNextKey(int error) {
+  while (error != net::ERR_IO_PENDING) {
+    if (error == net::ERR_FAILED) {
+      DoneCallback(net::OK);
+      return;
+    }
+
+    if (current_entry_) {
+      remaining_keys_.push_back(current_entry_->GetKey());
+    }
+
+    error = iterator_->OpenNextEntry(
+        &current_entry_,
+        base::Bind(&CacheTestUtil::GetNextKey, base::Unretained(this)));
+  }
+}