blob: 24edc98869177a54fe057ab4d673478c4dda078c [file] [log] [blame]
// Copyright (c) 2018 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 "quic/core/qpack/qpack_header_table.h"
#include "absl/strings/string_view.h"
#include "quic/core/qpack/qpack_static_table.h"
#include "quic/platform/api/quic_logging.h"
namespace quic {
QpackHeaderTable::QpackHeaderTable()
: static_entries_(ObtainQpackStaticTable().GetStaticEntries()),
static_index_(ObtainQpackStaticTable().GetStaticIndex()),
static_name_index_(ObtainQpackStaticTable().GetStaticNameIndex()),
dynamic_table_size_(0),
dynamic_table_capacity_(0),
maximum_dynamic_table_capacity_(0),
max_entries_(0),
dropped_entry_count_(0),
dynamic_table_entry_referenced_(false) {}
QpackHeaderTable::~QpackHeaderTable() {
for (auto& entry : observers_) {
entry.second->Cancel();
}
}
const QpackEntry* QpackHeaderTable::LookupEntry(bool is_static,
uint64_t index) const {
if (is_static) {
if (index >= static_entries_.size()) {
return nullptr;
}
return &static_entries_[index];
}
if (index < dropped_entry_count_) {
return nullptr;
}
index -= dropped_entry_count_;
if (index >= dynamic_entries_.size()) {
return nullptr;
}
return &dynamic_entries_[index];
}
QpackHeaderTable::MatchType QpackHeaderTable::FindHeaderField(
absl::string_view name,
absl::string_view value,
bool* is_static,
uint64_t* index) const {
QpackEntry query(name, value);
// Look for exact match in static table.
auto index_it = static_index_.find(&query);
if (index_it != static_index_.end()) {
DCHECK((*index_it)->IsStatic());
*index = (*index_it)->InsertionIndex();
*is_static = true;
return MatchType::kNameAndValue;
}
// Look for exact match in dynamic table.
index_it = dynamic_index_.find(&query);
if (index_it != dynamic_index_.end()) {
DCHECK(!(*index_it)->IsStatic());
*index = (*index_it)->InsertionIndex();
*is_static = false;
return MatchType::kNameAndValue;
}
// Look for name match in static table.
auto name_index_it = static_name_index_.find(name);
if (name_index_it != static_name_index_.end()) {
DCHECK(name_index_it->second->IsStatic());
*index = name_index_it->second->InsertionIndex();
*is_static = true;
return MatchType::kName;
}
// Look for name match in dynamic table.
name_index_it = dynamic_name_index_.find(name);
if (name_index_it != dynamic_name_index_.end()) {
DCHECK(!name_index_it->second->IsStatic());
*index = name_index_it->second->InsertionIndex();
*is_static = false;
return MatchType::kName;
}
return MatchType::kNoMatch;
}
const QpackEntry* QpackHeaderTable::InsertEntry(absl::string_view name,
absl::string_view value) {
const uint64_t entry_size = QpackEntry::Size(name, value);
if (entry_size > dynamic_table_capacity_) {
return nullptr;
}
const uint64_t index = dropped_entry_count_ + dynamic_entries_.size();
dynamic_entries_.push_back({name, value, /* is_static = */ false, index});
QpackEntry* const new_entry = &dynamic_entries_.back();
// Evict entries after inserting the new entry instead of before
// in order to avoid invalidating |name| and |value|.
dynamic_table_size_ += entry_size;
EvictDownToCurrentCapacity();
auto index_result = dynamic_index_.insert(new_entry);
if (!index_result.second) {
// An entry with the same name and value already exists. It needs to be
// replaced, because |dynamic_index_| tracks the most recent entry for a
// given name and value.
DCHECK_GT(new_entry->InsertionIndex(),
(*index_result.first)->InsertionIndex());
dynamic_index_.erase(index_result.first);
auto result = dynamic_index_.insert(new_entry);
CHECK(result.second);
}
auto name_result = dynamic_name_index_.insert({new_entry->name(), new_entry});
if (!name_result.second) {
// An entry with the same name already exists. It needs to be replaced,
// because |dynamic_name_index_| tracks the most recent entry for a given
// name.
DCHECK_GT(new_entry->InsertionIndex(),
name_result.first->second->InsertionIndex());
dynamic_name_index_.erase(name_result.first);
auto result = dynamic_name_index_.insert({new_entry->name(), new_entry});
CHECK(result.second);
}
// Notify and deregister observers whose threshold is met, if any.
while (!observers_.empty()) {
auto it = observers_.begin();
if (it->first > inserted_entry_count()) {
break;
}
Observer* observer = it->second;
observers_.erase(it);
observer->OnInsertCountReachedThreshold();
}
return new_entry;
}
uint64_t QpackHeaderTable::MaxInsertSizeWithoutEvictingGivenEntry(
uint64_t index) const {
DCHECK_LE(dropped_entry_count_, index);
if (index > inserted_entry_count()) {
// All entries are allowed to be evicted.
return dynamic_table_capacity_;
}
// Initialize to current available capacity.
uint64_t max_insert_size = dynamic_table_capacity_ - dynamic_table_size_;
for (const auto& entry : dynamic_entries_) {
if (entry.InsertionIndex() >= index) {
break;
}
max_insert_size += entry.Size();
}
return max_insert_size;
}
bool QpackHeaderTable::SetDynamicTableCapacity(uint64_t capacity) {
if (capacity > maximum_dynamic_table_capacity_) {
return false;
}
dynamic_table_capacity_ = capacity;
EvictDownToCurrentCapacity();
DCHECK_LE(dynamic_table_size_, dynamic_table_capacity_);
return true;
}
bool QpackHeaderTable::SetMaximumDynamicTableCapacity(
uint64_t maximum_dynamic_table_capacity) {
if (maximum_dynamic_table_capacity_ == 0) {
maximum_dynamic_table_capacity_ = maximum_dynamic_table_capacity;
max_entries_ = maximum_dynamic_table_capacity / 32;
return true;
}
// If the value is already set, it should not be changed.
return maximum_dynamic_table_capacity == maximum_dynamic_table_capacity_;
}
void QpackHeaderTable::RegisterObserver(uint64_t required_insert_count,
Observer* observer) {
DCHECK_GT(required_insert_count, 0u);
observers_.insert({required_insert_count, observer});
}
void QpackHeaderTable::UnregisterObserver(uint64_t required_insert_count,
Observer* observer) {
auto it = observers_.lower_bound(required_insert_count);
while (it != observers_.end() && it->first == required_insert_count) {
if (it->second == observer) {
observers_.erase(it);
return;
}
++it;
}
// |observer| must have been registered.
QUIC_NOTREACHED();
}
uint64_t QpackHeaderTable::draining_index(float draining_fraction) const {
DCHECK_LE(0.0, draining_fraction);
DCHECK_LE(draining_fraction, 1.0);
const uint64_t required_space = draining_fraction * dynamic_table_capacity_;
uint64_t space_above_draining_index =
dynamic_table_capacity_ - dynamic_table_size_;
if (dynamic_entries_.empty() ||
space_above_draining_index >= required_space) {
return dropped_entry_count_;
}
auto it = dynamic_entries_.begin();
while (space_above_draining_index < required_space) {
space_above_draining_index += it->Size();
++it;
if (it == dynamic_entries_.end()) {
return inserted_entry_count();
}
}
return it->InsertionIndex();
}
void QpackHeaderTable::EvictDownToCurrentCapacity() {
while (dynamic_table_size_ > dynamic_table_capacity_) {
DCHECK(!dynamic_entries_.empty());
QpackEntry* const entry = &dynamic_entries_.front();
const uint64_t entry_size = entry->Size();
DCHECK_GE(dynamic_table_size_, entry_size);
dynamic_table_size_ -= entry_size;
auto index_it = dynamic_index_.find(entry);
// Remove |dynamic_index_| entry only if it points to the same
// QpackEntry in |dynamic_entries_|. Note that |dynamic_index_| has a
// comparison function that only considers name and value, not actual
// QpackEntry* address, so find() can return a different entry if name and
// value match.
if (index_it != dynamic_index_.end() && *index_it == entry) {
dynamic_index_.erase(index_it);
}
auto name_it = dynamic_name_index_.find(entry->name());
// Remove |dynamic_name_index_| entry only if it points to the same
// QpackEntry in |dynamic_entries_|.
if (name_it != dynamic_name_index_.end() && name_it->second == entry) {
dynamic_name_index_.erase(name_it);
}
dynamic_entries_.pop_front();
++dropped_entry_count_;
}
}
} // namespace quic