Revert 56832 - Support change detection and reloading in ConfigDirPolicyProvi...

chrome/browser/policy/config_dir_policy_provider.cc

 // Copyright (c) 2010 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/policy/config_dir_policy_provider.h"
 
 #include <set>
 
 #include "base/file_util.h"
 #include "base/logging.h"
+#include "base/scoped_ptr.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/common/json_value_serializer.h"
 
-namespace {
-
-// Amount of time we wait for the files in the policy directory to settle before
-// trying to load it. This alleviates the problem of reading partially written
-// files and allows to batch quasi-simultaneous changes.
-const int kSettleIntervalSeconds = 5;
-
-// The time interval for rechecking policy. This is our fallback in case the
-// directory watch fails or doesn't report a change.
-const int kReloadIntervalMinutes = 15;
-
-}  // namespace
-
-// PolicyDirLoader implementation:
-
-PolicyDirLoader::PolicyDirLoader(
-    base::WeakPtr<ConfigDirPolicyProvider> provider,
-    const FilePath& config_dir,
-    int settle_interval_seconds,
-    int reload_interval_minutes)
-    : provider_(provider),
-      origin_loop_(MessageLoop::current()),
-      config_dir_(config_dir),
-      reload_task_(NULL),
-      settle_interval_seconds_(settle_interval_seconds),
-      reload_interval_minutes_(reload_interval_minutes) {
-  // Force an initial load, so GetPolicy() works.
-  policy_.reset(Load());
-  DCHECK(policy_.get());
+ConfigDirPolicyProvider::ConfigDirPolicyProvider(const FilePath& config_dir)
+    : config_dir_(config_dir) {
 }
 
-void PolicyDirLoader::Stop() {
-  if (!ChromeThread::CurrentlyOn(ChromeThread::FILE)) {
-    ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE,
-                           NewRunnableMethod(this, &PolicyDirLoader::Stop));
-    return;
-  }
-
-  if (reload_task_) {
-    reload_task_->Cancel();
-    reload_task_ = NULL;
-  }
+bool ConfigDirPolicyProvider::Provide(ConfigurationPolicyStore* store) {
+  scoped_ptr<DictionaryValue> policy(ReadPolicies());
+  DecodePolicyValueTree(policy.get(), store);
+  return true;
 }
 
-void PolicyDirLoader::Reload() {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
-
-  // Check the directory time in order to see whether a reload is required.
-  base::Time now = base::Time::Now();
-  base::TimeDelta delay;
-  if (!IsSafeToReloadPolicy(now, &delay)) {
-    ScheduleReloadTask(delay);
-    return;
-  }
-
-  // Load the policy definitions.
-  scoped_ptr<DictionaryValue> new_policy(Load());
-
-  // Check again in case the directory has changed while reading it.
-  if (!IsSafeToReloadPolicy(now, &delay)) {
-    ScheduleReloadTask(delay);
-    return;
-  }
-
-  // Replace policy definition.
-  bool changed = false;
-  {
-    AutoLock lock(lock_);
-    changed = !policy_->Equals(new_policy.get());
-    policy_.reset(new_policy.release());
-  }
-
-  // There's a change, report it!
-  if (changed) {
-    LOG(INFO) << "Policy reload from " << config_dir_.value() << " succeeded.";
-    origin_loop_->PostTask(FROM_HERE,
-        NewRunnableMethod(this, &PolicyDirLoader::NotifyPolicyChanged));
-  }
-
-  // As a safeguard in case the file watcher fails, schedule a reload task
-  // that'll make us recheck after a reasonable interval.
-  ScheduleReloadTask(base::TimeDelta::FromMinutes(reload_interval_minutes_));
-}
-
-DictionaryValue* PolicyDirLoader::GetPolicy() {
-  AutoLock lock(lock_);
-  return static_cast<DictionaryValue*>(policy_->DeepCopy());
-}
-
-void PolicyDirLoader::OnFilePathChanged(const FilePath& path) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
-  Reload();
-}
-
-void PolicyDirLoader::OnError() {
-  LOG(ERROR) << "FileWatcher on " << config_dir_.value() << " failed.";
-}
-
-DictionaryValue* PolicyDirLoader::Load() {
+DictionaryValue* ConfigDirPolicyProvider::ReadPolicies() {
   // Enumerate the files and sort them lexicographically.
   std::set<FilePath> files;
   file_util::FileEnumerator file_enumerator(config_dir_, false,
                                             file_util::FileEnumerator::FILES);
   for (FilePath config_file_path = file_enumerator.Next();
        !config_file_path.empty(); config_file_path = file_enumerator.Next())
     files.insert(config_file_path);
 
   // Start with an empty dictionary and merge the files' contents.
   DictionaryValue* policy = new DictionaryValue;
@@ skipping 12 matching lines @@
       LOG(WARNING) << "Expected JSON dictionary in configuration file "
                    << config_file_iter->value();
       continue;
     }
     policy->MergeDictionary(static_cast<DictionaryValue*>(value.get()));
   }
 
   return policy;
 }
 
-bool PolicyDirLoader::IsSafeToReloadPolicy(const base::Time& now,
-                                           base::TimeDelta* delay) {
-  DCHECK(delay);
-  file_util::FileInfo dir_info;
-
-  // Reading an empty directory or a file is always safe.
-  if (!file_util::GetFileInfo(config_dir_, &dir_info) ||
-      !dir_info.is_directory) {
-    return true;
-  }
-
-  // Check for too recent changes.
-  base::TimeDelta settleInterval(
-      base::TimeDelta::FromSeconds(settle_interval_seconds_));
-  base::TimeDelta age = now - dir_info.last_modified;
-  if (age < settleInterval) {
-    *delay = settleInterval - age;
-    return false;
-  }
-
-  return true;
-}
-
-void PolicyDirLoader::ScheduleReloadTask(const base::TimeDelta& delay) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
-
-  if (reload_task_)
-    reload_task_->Cancel();
-
-  reload_task_ = NewRunnableMethod(this, &PolicyDirLoader::ReloadFromTask);
-  ChromeThread::PostDelayedTask(ChromeThread::FILE, FROM_HERE, reload_task_,
-                                delay.InMilliseconds());
-}
-
-void PolicyDirLoader::NotifyPolicyChanged() {
-  DCHECK_EQ(origin_loop_, MessageLoop::current());
-  if (provider_)
-    provider_->NotifyStoreOfPolicyChange();
-}
-
-void PolicyDirLoader::ReloadFromTask() {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
-
-  // Drop the reference to the reload task, since the task might be the only
-  // referer that keeps us alive, so we should not Cancel() it.
-  reload_task_ = NULL;
-
-  Reload();
-}
-
-// PolicyDirWatcher implementation:
-
-void PolicyDirWatcher::Init(PolicyDirLoader* loader) {
-  // Initialization can happen early when the file thread is not yet available.
-  // So post a task to ourselves on th UI thread which will run after threading
-  // is up and schedule watch initialization on the file thread.
-  ChromeThread::PostTask(ChromeThread::UI, FROM_HERE,
-      NewRunnableMethod(this,
-                        &PolicyDirWatcher::InitWatcher,
-                        scoped_refptr<PolicyDirLoader>(loader)));
-}
-
-void PolicyDirWatcher::InitWatcher(
-    const scoped_refptr<PolicyDirLoader>& loader) {
-  if (!ChromeThread::CurrentlyOn(ChromeThread::FILE)) {
-    ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE,
-        NewRunnableMethod(this, &PolicyDirWatcher::InitWatcher, loader));
-    return;
-  }
-
-  if (!Watch(loader->config_dir(), loader.get()))
-    loader->OnError();
-
-  // There might have been changes to the directory in the time between
-  // construction of the loader and initialization of the watcher. Call reload
-  // to detect if that is the case.
-  loader->Reload();
-}
-
-// ConfigDirPolicyProvider implementation:
-
-ConfigDirPolicyProvider::ConfigDirPolicyProvider(const FilePath& config_dir) {
-  loader_ = new PolicyDirLoader(AsWeakPtr(), config_dir, kSettleIntervalSeconds,
-                                kReloadIntervalMinutes);
-  watcher_ = new PolicyDirWatcher;
-  watcher_->Init(loader_.get());
-}
-
-ConfigDirPolicyProvider::~ConfigDirPolicyProvider() {
-  loader_->Stop();
-}
-
-bool ConfigDirPolicyProvider::Provide(ConfigurationPolicyStore* store) {
-  scoped_ptr<DictionaryValue> policy(loader_->GetPolicy());
-  DCHECK(policy.get());
-  DecodePolicyValueTree(policy.get(), store);
-  return true;
-}
-
 void ConfigDirPolicyProvider::DecodePolicyValueTree(
     DictionaryValue* policies,
     ConfigurationPolicyStore* store) {
   const PolicyValueMap* mapping = PolicyValueMapping();
   for (PolicyValueMap::const_iterator i = mapping->begin();
        i != mapping->end(); ++i) {
     const PolicyValueMapEntry& entry(*i);
     Value* value;
     if (policies->Get(entry.name, &value) && value->IsType(entry.value_type))
       store->Apply(entry.policy_type, value->DeepCopy());
   }
 
   // TODO(mnissler): Handle preference overrides once |ConfigurationPolicyStore|
   // supports it.
 }
+