diff options
Diffstat (limited to 'extensions/browser/quota_service.cc')
| -rw-r--r-- | extensions/browser/quota_service.cc | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/extensions/browser/quota_service.cc b/extensions/browser/quota_service.cc new file mode 100644 index 0000000..ce21b25 --- /dev/null +++ b/extensions/browser/quota_service.cc @@ -0,0 +1,192 @@ +// Copyright 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 "extensions/browser/quota_service.h" + +#include "base/message_loop/message_loop.h" +#include "base/stl_util.h" +#include "chrome/browser/extensions/extension_function.h" +#include "extensions/common/error_utils.h" + +namespace { + +// If the browser stays open long enough, we reset state once a day. +// Whatever this value is, it should be an order of magnitude longer than +// the longest interval in any of the QuotaLimitHeuristics in use. +const int kPurgeIntervalInDays = 1; + +const char kOverQuotaError[] = "This request exceeds the * quota."; + +} // namespace + +namespace extensions { + +QuotaService::QuotaService() { + if (base::MessageLoop::current() != NULL) { // Null in unit tests. + purge_timer_.Start(FROM_HERE, + base::TimeDelta::FromDays(kPurgeIntervalInDays), + this, + &QuotaService::Purge); + } +} + +QuotaService::~QuotaService() { + DCHECK(CalledOnValidThread()); + purge_timer_.Stop(); + Purge(); +} + +std::string QuotaService::Assess(const std::string& extension_id, + ExtensionFunction* function, + const base::ListValue* args, + const base::TimeTicks& event_time) { + DCHECK(CalledOnValidThread()); + + if (function->ShouldSkipQuotaLimiting()) + return std::string(); + + // Lookup function list for extension. + FunctionHeuristicsMap& functions = function_heuristics_[extension_id]; + + // Lookup heuristics for function, create if necessary. + QuotaLimitHeuristics& heuristics = functions[function->name()]; + if (heuristics.empty()) + function->GetQuotaLimitHeuristics(&heuristics); + + if (heuristics.empty()) + return std::string(); // No heuristic implies no limit. + + ViolationErrorMap::iterator violation_error = + violation_errors_.find(extension_id); + if (violation_error != violation_errors_.end()) + return violation_error->second; // Repeat offender. + + QuotaLimitHeuristic* failed_heuristic = NULL; + for (QuotaLimitHeuristics::iterator heuristic = heuristics.begin(); + heuristic != heuristics.end(); + ++heuristic) { + // Apply heuristic to each item (bucket). + if (!(*heuristic)->ApplyToArgs(args, event_time)) { + failed_heuristic = *heuristic; + break; + } + } + + if (!failed_heuristic) + return std::string(); + + std::string error = failed_heuristic->GetError(); + DCHECK_GT(error.length(), 0u); + + PurgeFunctionHeuristicsMap(&functions); + function_heuristics_.erase(extension_id); + violation_errors_[extension_id] = error; + return error; +} + +void QuotaService::PurgeFunctionHeuristicsMap(FunctionHeuristicsMap* map) { + FunctionHeuristicsMap::iterator heuristics = map->begin(); + while (heuristics != map->end()) { + STLDeleteElements(&heuristics->second); + map->erase(heuristics++); + } +} + +void QuotaService::Purge() { + DCHECK(CalledOnValidThread()); + std::map<std::string, FunctionHeuristicsMap>::iterator it = + function_heuristics_.begin(); + for (; it != function_heuristics_.end(); function_heuristics_.erase(it++)) + PurgeFunctionHeuristicsMap(&it->second); +} + +void QuotaLimitHeuristic::Bucket::Reset(const Config& config, + const base::TimeTicks& start) { + num_tokens_ = config.refill_token_count; + expiration_ = start + config.refill_interval; +} + +void QuotaLimitHeuristic::SingletonBucketMapper::GetBucketsForArgs( + const base::ListValue* args, + BucketList* buckets) { + buckets->push_back(&bucket_); +} + +QuotaLimitHeuristic::QuotaLimitHeuristic(const Config& config, + BucketMapper* map, + const std::string& name) + : config_(config), bucket_mapper_(map), name_(name) {} + +QuotaLimitHeuristic::~QuotaLimitHeuristic() {} + +bool QuotaLimitHeuristic::ApplyToArgs(const base::ListValue* args, + const base::TimeTicks& event_time) { + BucketList buckets; + bucket_mapper_->GetBucketsForArgs(args, &buckets); + for (BucketList::iterator i = buckets.begin(); i != buckets.end(); ++i) { + if ((*i)->expiration().is_null()) // A brand new bucket. + (*i)->Reset(config_, event_time); + if (!Apply(*i, event_time)) + return false; // It only takes one to spoil it for everyone. + } + return true; +} + +std::string QuotaLimitHeuristic::GetError() const { + return extensions::ErrorUtils::FormatErrorMessage(kOverQuotaError, name_); +} + +QuotaService::SustainedLimit::SustainedLimit(const base::TimeDelta& sustain, + const Config& config, + BucketMapper* map, + const std::string& name) + : QuotaLimitHeuristic(config, map, name), + repeat_exhaustion_allowance_(sustain.InSeconds() / + config.refill_interval.InSeconds()), + num_available_repeat_exhaustions_(repeat_exhaustion_allowance_) {} + +bool QuotaService::TimedLimit::Apply(Bucket* bucket, + const base::TimeTicks& event_time) { + if (event_time > bucket->expiration()) + bucket->Reset(config(), event_time); + + return bucket->DeductToken(); +} + +bool QuotaService::SustainedLimit::Apply(Bucket* bucket, + const base::TimeTicks& event_time) { + if (event_time > bucket->expiration()) { + // We reset state for this item and start over again if this request breaks + // the bad cycle that was previously being tracked. This occurs if the + // state in the bucket expired recently (it has been long enough since the + // event that we don't care about the last event), but the bucket still has + // tokens (so pressure was not sustained over that time), OR we are more + // than 1 full refill interval away from the last event (so even if we used + // up all the tokens in the last bucket, nothing happened in the entire + // next refill interval, so it doesn't matter). + if (bucket->has_tokens() || + event_time > bucket->expiration() + config().refill_interval) { + bucket->Reset(config(), event_time); + num_available_repeat_exhaustions_ = repeat_exhaustion_allowance_; + } else if (--num_available_repeat_exhaustions_ > 0) { + // The last interval was saturated with requests, and this is the first + // event in the next interval. If this happens + // repeat_exhaustion_allowance_ times, it's a violation. Reset the bucket + // state to start timing from the end of the last interval (and we'll + // deduct the token below) so we can detect this each time it happens. + bucket->Reset(config(), bucket->expiration()); + } else { + // No allowances left; this request is a violation. + return false; + } + } + + // We can go negative since we check has_tokens when we get to *next* bucket, + // and for the small interval all that matters is whether we used up all the + // tokens (which is true if num_tokens_ <= 0). + bucket->DeductToken(); + return true; +} + +} // namespace extensions |