net/disk_cache/cache_creator.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/file_util.h"
   6 #include "base/metrics/field_trial.h"
   7 #include "base/stringprintf.h"
   8 #include "net/base/net_errors.h"
   9 #include "net/disk_cache/backend_impl.h"
  10 #include "net/disk_cache/cache_util.h"
  11 #include "net/disk_cache/mem_backend_impl.h"
  12 #include "net/disk_cache/simple/simple_backend_impl.h"
  13
  14 namespace {
  15
  16 // Builds an instance of the backend depending on platform, type, experiments
  17 // etc. Takes care of the retry state. This object will self-destroy when
  18 // finished.
  19 class CacheCreator {
  20  public:
  21   CacheCreator(const base::FilePath& path, bool force, int max_bytes,
  22                net::CacheType type, uint32 flags,
  23                base::MessageLoopProxy* thread, net::NetLog* net_log,
  24                disk_cache::Backend** backend,
  25                const net::CompletionCallback& callback);
  26
  27   // Creates the backend.
  28   int Run();
  29
  30  private:
  31   ~CacheCreator();
  32
  33   void DoCallback(int result);
  34
  35   void OnIOComplete(int result);
  36
  37   const base::FilePath& path_;
  38   bool force_;
  39   bool retry_;
  40   int max_bytes_;
  41   net::CacheType type_;
  42   uint32 flags_;
  43   scoped_refptr<base::MessageLoopProxy> thread_;
  44   disk_cache::Backend** backend_;
  45   net::CompletionCallback callback_;
  46   disk_cache::Backend* created_cache_;
  47   net::NetLog* net_log_;
  48
  49   DISALLOW_COPY_AND_ASSIGN(CacheCreator);
  50 };
  51
  52 CacheCreator::CacheCreator(
  53     const base::FilePath& path, bool force, int max_bytes,
  54     net::CacheType type, uint32 flags,
  55     base::MessageLoopProxy* thread, net::NetLog* net_log,
  56     disk_cache::Backend** backend,
  57     const net::CompletionCallback& callback)
  58     : path_(path),
  59       force_(force),
  60       retry_(false),
  61       max_bytes_(max_bytes),
  62       type_(type),
  63       flags_(flags),
  64       thread_(thread),
  65       backend_(backend),
  66       callback_(callback),
  67       created_cache_(NULL),
  68       net_log_(net_log) {
  69   }
  70
  71 CacheCreator::~CacheCreator() {
  72 }
  73
  74 int CacheCreator::Run() {
  75   // TODO(pasko): The two caches should never coexist on disk. Each individual
  76   // cache backend should fail to initialize if it observes the index that does
  77   // not belong to it.
  78   if (base::FieldTrialList::FindFullName("SimpleCacheTrial") == "Yes") {
  79     // TODO(gavinp,pasko): While simple backend development proceeds, we're only
  80     // testing it against net::DISK_CACHE. Turn it on for more cache types as
  81     // appropriate.
  82     if (type_ == net::DISK_CACHE) {
  83       disk_cache::SimpleBackendImpl* simple_cache =
  84           new disk_cache::SimpleBackendImpl(path_, max_bytes_, type_, thread_,
  85                                             net_log_);
  86       created_cache_ = simple_cache;
  87       return simple_cache->Init(
  88           base::Bind(&CacheCreator::OnIOComplete, base::Unretained(this)));
  89     }
  90   }
  91   disk_cache::BackendImpl* new_cache =
  92       new disk_cache::BackendImpl(path_, thread_, net_log_);
  93   created_cache_ = new_cache;
  94   new_cache->SetMaxSize(max_bytes_);
  95   new_cache->SetType(type_);
  96   new_cache->SetFlags(flags_);
  97   int rv = new_cache->Init(
  98       base::Bind(&CacheCreator::OnIOComplete, base::Unretained(this)));
  99   DCHECK_EQ(net::ERR_IO_PENDING, rv);
 100   return rv;
 101 }
 102
 103 void CacheCreator::DoCallback(int result) {
 104   DCHECK_NE(net::ERR_IO_PENDING, result);
 105   if (result == net::OK)
 106     *backend_ = created_cache_;
 107   else {
 108     LOG(ERROR) << "Unable to create cache";
 109     *backend_ = NULL;
 110     delete created_cache_;
 111   }
 112   callback_.Run(result);
 113   delete this;
 114 }
 115
 116 // If the initialization of the cache fails, and |force| is true, we will
 117 // discard the whole cache and create a new one.
 118 void CacheCreator::OnIOComplete(int result) {
 119   if (result == net::OK || !force_ || retry_)
 120     return DoCallback(result);
 121
 122   // This is a failure and we are supposed to try again, so delete the object,
 123   // delete all the files, and try again.
 124   retry_ = true;
 125   delete created_cache_;
 126   created_cache_ = NULL;
 127   if (!disk_cache::DelayedCacheCleanup(path_))
 128     return DoCallback(result);
 129
 130   // The worker thread will start deleting files soon, but the original folder
 131   // is not there anymore... let's create a new set of files.
 132   int rv = Run();
 133   DCHECK_EQ(net::ERR_IO_PENDING, rv);
 134 }
 135
 136 }  // namespace
 137
 138 namespace disk_cache {
 139
 140 int CreateCacheBackend(net::CacheType type, const base::FilePath& path,
 141                        int max_bytes,
 142                        bool force, base::MessageLoopProxy* thread,
 143                        net::NetLog* net_log, Backend** backend,
 144                        const net::CompletionCallback& callback) {
 145   DCHECK(!callback.is_null());
 146   if (type == net::MEMORY_CACHE) {
 147     *backend = disk_cache::MemBackendImpl::CreateBackend(max_bytes, net_log);
 148     return *backend ? net::OK : net::ERR_FAILED;
 149   }
 150   DCHECK(thread);
 151   CacheCreator* creator = new CacheCreator(path, force, max_bytes, type, kNone,
 152                                            thread, net_log, backend, callback);
 153   return creator->Run();
 154 }
 155
 156 }  // namespace disk_cache