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// Copyright 2015 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/base/backoff_entry_serializer.h"
#include <utility>
#include "base/strings/string_number_conversions.h"
#include "base/time/tick_clock.h"
#include "base/values.h"
#include "net/base/backoff_entry.h"
namespace {
// Increment this number when changing the serialization format, to avoid old
// serialized values loaded from disk etc being misinterpreted.
const int kSerializationFormatVersion = 1;
} // namespace
namespace net {
scoped_ptr<base::Value> BackoffEntrySerializer::SerializeToValue(
const BackoffEntry& entry, base::Time time_now) {
scoped_ptr<base::ListValue> serialized(new base::ListValue());
serialized->AppendInteger(kSerializationFormatVersion);
serialized->AppendInteger(entry.failure_count());
// Can't use entry.GetTimeUntilRelease as it doesn't allow negative deltas.
base::TimeDelta backoff_duration =
entry.GetReleaseTime() - entry.tick_clock()->NowTicks();
// Redundantly stores both the remaining time delta and the absolute time.
// The delta is used to work around some cases where wall clock time changes.
serialized->AppendDouble(backoff_duration.InSecondsF());
base::Time absolute_release_time = backoff_duration + time_now;
serialized->AppendString(
base::Int64ToString(absolute_release_time.ToInternalValue()));
return std::move(serialized);
}
scoped_ptr<BackoffEntry> BackoffEntrySerializer::DeserializeFromValue(
const base::Value& serialized, const BackoffEntry::Policy* policy,
base::TickClock* tick_clock, base::Time time_now) {
const base::ListValue* serialized_list = nullptr;
if (!serialized.GetAsList(&serialized_list))
return nullptr;
if (serialized_list->GetSize() != 4)
return nullptr;
int version_number;
if (!serialized_list->GetInteger(0, &version_number) ||
version_number != kSerializationFormatVersion) {
return nullptr;
}
int failure_count;
if (!serialized_list->GetInteger(1, &failure_count) || failure_count < 0)
return nullptr;
double original_backoff_duration_double;
if (!serialized_list->GetDouble(2, &original_backoff_duration_double))
return nullptr;
std::string absolute_release_time_string;
if (!serialized_list->GetString(3, &absolute_release_time_string))
return nullptr;
int64_t absolute_release_time_us;
if (!base::StringToInt64(absolute_release_time_string,
&absolute_release_time_us) ||
absolute_release_time_us < 0) {
return nullptr;
}
scoped_ptr<BackoffEntry> entry(new BackoffEntry(policy, tick_clock));
for (int n = 0; n < failure_count; n++)
entry->InformOfRequest(false);
base::TimeDelta original_backoff_duration =
base::TimeDelta::FromSecondsD(original_backoff_duration_double);
base::Time absolute_release_time =
base::Time::FromInternalValue(absolute_release_time_us);
base::TimeDelta backoff_duration = absolute_release_time - time_now;
// In cases where the system wall clock is rewound, use the redundant
// original_backoff_duration to ensure the backoff duration isn't longer
// than it was before serializing (note that it's not possible to protect
// against the clock being wound forward).
if (backoff_duration > original_backoff_duration)
backoff_duration = original_backoff_duration;
entry->SetCustomReleaseTime(
entry->BackoffDurationToReleaseTime(backoff_duration));
return entry;
}
} // namespace net
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