Add new simple disk cache backend.

net/disk_cache/simple/simple_backend_impl.cc

+// Copyright (c) 2013 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 "net/disk_cache/simple/simple_backend_impl.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/file_util.h"
+#include "base/location.h"
+#include "base/message_loop_proxy.h"
+#include "base/threading/worker_pool.h"
+#include "net/base/net_errors.h"
+#include "net/disk_cache/simple/simple_entry_impl.h"
+
+using base::FilePath;
+using base::MessageLoopProxy;
+using base::Time;
+using base::WorkerPool;
+using file_util::DirectoryExists;
+using file_util::CreateDirectory;
+
+namespace {
+
+const char* kSimpleBackendSubdirectory = "Simple";
+
+}  // namespace
+
+namespace disk_cache {
+
+// static
+int SimpleBackendImpl::CreateBackend(
+    const FilePath& full_path,
+    bool force,
+    int max_bytes,
+    net::CacheType type,
+    uint32 flags,
+    scoped_refptr<base::TaskRunner> task_runner,
+    net::NetLog* net_log,
+    Backend** backend,
+    const CompletionCallback& callback) {
+  // TODO(gavinp): Use the |net_log|.
+  DCHECK_EQ(net::DISK_CACHE, type);
+  FilePath simple_cache_path =
+      full_path.AppendASCII(kSimpleBackendSubdirectory);
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&SimpleBackendImpl::
+                                      EnsureCachePathExistsOnWorkerThread,

[pasko-google - do not use, 2013/02/11 13:59:25]

nit: here and below adjust amount of leading space

[gavinp, 2013/02/11 17:55:50]

Previously I had lines like this with FROM_HERE on the next line, so the
indentation of the bind was cleaner. Ricardo nitted all those FROM_HERE lines up
to the line with the (.

I'm happy to respond to your nit, but I don't know exactly what you're looking
for, and Ricardo's earlier suggestion puts me in a "bind" here. Maybe it'd be
clearest if I put the base::Bind() in a temp variable? Otherwise if you can give
me some instruction so clear even I understand it, I'll be happy. :)

[pasko-google - do not use, 2013/02/11 18:13:44]

ouch sorry, this specific leading space is fine, I was referring to something
rather like SimpleBackendImpl::CreateEntry(...), where you auto-renamed, but did
not auto-format after that.

[gavinp, 2013/02/11 18:32:26]

Aha! Good catch. Fixed.

+                                  simple_cache_path,
+                                  MessageLoopProxy::current(), callback,
+                                  backend),
+                       true);
+  return net::ERR_IO_PENDING;
+}
+
+SimpleBackendImpl::~SimpleBackendImpl() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+net::CacheType SimpleBackendImpl::GetCacheType() const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return net::DISK_CACHE;
+}
+
+int32 SimpleBackendImpl::GetEntryCount() const {
+  // TODO(gavinp): Provide implementation for this function.
+  return 0;
+}
+
+int SimpleBackendImpl::OpenEntry(const std::string& key,
+                                     Entry** entry,
+                                     const CompletionCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return SimpleEntryImpl::OpenEntry(path_, key, entry, callback);
+}
+
+int SimpleBackendImpl::CreateEntry(const std::string& key,
+                                       Entry** entry,
+                                       const CompletionCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return SimpleEntryImpl::CreateEntry(path_, key, entry, callback);
+}
+
+int SimpleBackendImpl::DoomEntry(const std::string& key,
+                                     const net::CompletionCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return SimpleEntryImpl::DoomEntry(path_, key, callback);
+}
+
+int SimpleBackendImpl::DoomAllEntries(const CompletionCallback& callback) {
+  // TODO(gavinp): Provide implementation for this function.
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return net::ERR_FAILED;
+}
+
+int SimpleBackendImpl::DoomEntriesBetween(
+    const Time initial_time,
+    const Time end_time,
+    const CompletionCallback& callback) {
+  // TODO(gavinp): Provide implementation for this function.
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return net::ERR_FAILED;
+}
+
+int SimpleBackendImpl::DoomEntriesSince(
+    const Time initial_time,
+    const CompletionCallback& callback) {
+  // TODO(gavinp): Provide implementation for this function.
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return net::ERR_FAILED;
+}
+
+int SimpleBackendImpl::OpenNextEntry(void** iter,
+                                         Entry** next_entry,
+                                         const CompletionCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  NOTREACHED() << "Not implemented.";
+  return net::ERR_FAILED;
+}
+
+void SimpleBackendImpl::EndEnumeration(void** iter) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  NOTREACHED() << "Not implemented.";
+}
+
+void SimpleBackendImpl::GetStats(
+    std::vector<std::pair<std::string, std::string> >* stats) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  NOTREACHED() << "Not implemented.";
+}
+
+void SimpleBackendImpl::OnExternalCacheHit(const std::string& key) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  NOTREACHED() << "Not implemented.";
+}
+
+SimpleBackendImpl::SimpleBackendImpl(
+    const FilePath& path) : path_(path) {
+}
+
+// static
+void SimpleBackendImpl::EnsureCachePathExistsOnWorkerThread(
+    const FilePath& path,
+    const scoped_refptr<base::TaskRunner>& callback_runner,
+    const CompletionCallback& callback,
+    Backend** backend) {
+  int result = net::OK;
+  if (!DirectoryExists(path) && !CreateDirectory(path))
+    result = net::ERR_FAILED;
+  callback_runner->PostTask(FROM_HERE,
+                            base::Bind(&SimpleBackendImpl::OnCachePathCreated,
+                                       result, path, callback, backend));
+}
+
+// static
+void SimpleBackendImpl::OnCachePathCreated(
+    int result,
+    const FilePath& path,
+    const CompletionCallback& callback,
+    Backend** backend) {
+  if (result == net::OK)
+    *backend = new SimpleBackendImpl(path);
+  else
+    *backend = NULL;
+  callback.Run(result);
+}
+
+}  // namespace disk_cache