| // Copyright (c) 2011 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 "content/common/inter_process_time_ticks_converter.h" |
| |
| #include "base/logging.h" |
| #include "base/strings/string_number_conversions.h" |
| |
| namespace content { |
| |
| InterProcessTimeTicksConverter::InterProcessTimeTicksConverter( |
| const LocalTimeTicks& local_lower_bound, |
| const LocalTimeTicks& local_upper_bound, |
| const RemoteTimeTicks& remote_lower_bound, |
| const RemoteTimeTicks& remote_upper_bound) |
| : remote_lower_bound_(remote_lower_bound.value_), |
| remote_upper_bound_(remote_upper_bound.value_) { |
| int64_t target_range = local_upper_bound.value_ - local_lower_bound.value_; |
| int64_t source_range = remote_upper_bound.value_ - remote_lower_bound.value_; |
| DCHECK_GE(target_range, 0); |
| DCHECK_GE(source_range, 0); |
| if (source_range <= target_range) { |
| // We fit! Center the source range on the target range. |
| numerator_ = 1; |
| denominator_ = 1; |
| local_base_time_ = |
| local_lower_bound.value_ + (target_range - source_range) / 2; |
| // When converting times, remote bounds should fall within local bounds. |
| DCHECK_LE(local_lower_bound.value_, |
| ToLocalTimeTicks(remote_lower_bound).value_); |
| DCHECK_GE(local_upper_bound.value_, |
| ToLocalTimeTicks(remote_upper_bound).value_); |
| return; |
| } |
| |
| // Interpolate values so that remote range will be will exactly fit into the |
| // local range, if possible. |
| numerator_ = target_range; |
| denominator_ = source_range; |
| local_base_time_ = local_lower_bound.value_; |
| // When converting times, remote bounds should equal local bounds. |
| DCHECK_EQ(local_lower_bound.value_, |
| ToLocalTimeTicks(remote_lower_bound).value_); |
| DCHECK_EQ(local_upper_bound.value_, |
| ToLocalTimeTicks(remote_upper_bound).value_); |
| DCHECK_EQ(target_range, Convert(source_range)); |
| } |
| |
| LocalTimeTicks InterProcessTimeTicksConverter::ToLocalTimeTicks( |
| const RemoteTimeTicks& remote_ms) const { |
| // If input time is "null", return another "null" time. |
| if (remote_ms.value_ == 0) |
| return LocalTimeTicks(0); |
| |
| RemoteTimeDelta remote_delta = remote_ms - remote_lower_bound_; |
| |
| DCHECK_LE(remote_ms.value_, remote_upper_bound_); |
| // For remote times that come before remote time range, apply just time |
| // offset and ignore scaling, so as to avoid extrapolation error for values |
| // long in the past. |
| if (remote_ms.value_ < remote_lower_bound_) |
| return LocalTimeTicks(local_base_time_ + remote_delta.value_); |
| |
| return LocalTimeTicks(local_base_time_ + |
| ToLocalTimeDelta(remote_delta).value_); |
| } |
| |
| LocalTimeDelta InterProcessTimeTicksConverter::ToLocalTimeDelta( |
| const RemoteTimeDelta& remote_delta) const { |
| DCHECK_GE(remote_upper_bound_, remote_lower_bound_ + remote_delta.value_); |
| return LocalTimeDelta(Convert(remote_delta.value_)); |
| } |
| |
| int64_t InterProcessTimeTicksConverter::Convert(int64_t value) const { |
| if (value <= 0) { |
| return value; |
| } |
| return numerator_ * value / denominator_; |
| } |
| |
| base::TimeDelta InterProcessTimeTicksConverter::GetSkewForMetrics() const { |
| return base::TimeTicks::FromInternalValue(remote_lower_bound_) - |
| base::TimeTicks::FromInternalValue(local_base_time_); |
| } |
| |
| } // namespace content |